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Handforth A, Singh RP, Kosoyan HP, Kadam PA. A Role for GABA A Receptor β3 Subunits in Mediating Harmaline Tremor Suppression by Alcohol: Implications for Essential Tremor Therapy. Tremor Other Hyperkinet Mov (N Y) 2024; 14:20. [PMID: 38681506 PMCID: PMC11049614 DOI: 10.5334/tohm.834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 03/31/2024] [Indexed: 05/01/2024] Open
Abstract
Background Essential tremor patients may find that low alcohol amounts suppress tremor. A candidate mechanism is modulation of α6β3δ extra-synaptic GABAA receptors, that in vitro respond to non-intoxicating alcohol levels. We previously found that low-dose alcohol reduces harmaline tremor in wild-type mice, but not in littermates lacking δ or α6 subunits. Here we addressed whether low-dose alcohol requires the β3 subunit for tremor suppression. Methods We tested whether low-dose alcohol suppresses tremor in cre-negative mice with intact β3 exon 3 flanked by loxP, and in littermates in which this region was excised by cre expressed under the α6 subunit promotor. Tremor in the harmaline model was measured as a percentage of motion power in the tremor bandwidth divided by overall motion power. Results Alcohol, 0.500 and 0.575 g/kg, reduced harmaline tremor compared to vehicle-treated controls in floxed β3 cre- mice, but had no effect on tremor in floxed β3 cre+ littermates that have β3 knocked out. This was not due to potential interference of α6 expression by the insertion of the cre gene into the α6 gene since non-floxed β3 cre+ and cre- littermates exhibited similar tremor suppression by alcohol. Discussion As α6β3δ GABAA receptors are sensitive to low-dose alcohol, and cerebellar granule cells express β3 and are the predominant brain site for α6 and δ expression together, our overall findings suggest alcohol acts to suppress tremor by modulating α6β3δ GABAA receptors on these cells. Novel drugs that target this receptor may potentially be effective and well-tolerated for essential tremor. Highlights We previously found with the harmaline essential tremor model that GABAA receptors containing α6 and δ subunits mediate tremor suppression by alcohol. We now show that β3 subunits in α6-expressing cells, likely cerebellar granule cells, are also required, indicating that alcohol suppresses tremor by modulating α6β3δ extra-synaptic GABAA receptors.
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Affiliation(s)
- Adrian Handforth
- Neurology Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Ram P. Singh
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Hovsep P. Kosoyan
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Pournima A. Kadam
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, USA
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Zhan X, Do LV, Zou L, Zhan RS, Jones M, Nawaz S, Manaye K. Harmaline toxicity on dorsal striatal neurons and its role in tremor. Neurotoxicology 2023; 99:152-161. [PMID: 37838252 DOI: 10.1016/j.neuro.2023.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 08/28/2023] [Accepted: 10/08/2023] [Indexed: 10/16/2023]
Abstract
Harmaline is one of the β-carboline derivative compounds that is widely distributed in the food chain and human tissues. Harmine, a dehydrogenated form of harmaline, appeared to have a higher concentration in the brain, and appeared to be elevated in essential tremor (ET) and Parkinson's disease. Exogenous harmaline exposure in high concentration has myriad consequences, including inducing tremor, and causing neurodegeneration of Purkinje cells in the cerebellum. Harmaline-induced tremor is an established animal model for human ET, but its underlying mechanism is still controversial. One hypothesis posits that the inferior olive-cerebellum pathway is involved, and CaV3.1 T-type Ca2+ channel is a critical target of action. However, accumulating evidence indicates that tremor can be generated without disturbing T-type channels. This implies that additional neural circuits or molecular targets are involved. Using in vitro slice Ca2+-imaging and patch clamping, we demonstrated that harmaline reduced intracellular Ca2+ and suppressed depolarization-induced spiking activity of medium spiny striatal neurons (MSN), and this effect of harmaline can be partially attenuated by sulpiride (5 µM). In addition, the frequencies of spontaneous excitatory post-synaptic currents (sEPSCs) on MSNs were also significantly attenuated. Furthermore, the induced tremor in C57BL/6 J mice by harmaline injections (i.p. 12.5-18 mg/kg) was also shown to be attenuated by sulpiride (20 mg/kg). This series of experiments suggests that the dorsal striatum is a site of harmaline toxic action and might contribute to tremor generation. The findings also provide evidence that D2 signaling might be a part of the mechanism underlying essential tremor.
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Affiliation(s)
- Xiping Zhan
- Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, DC 20059, USA; Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Ly V Do
- Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, DC 20059, USA
| | - Li Zou
- Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, DC 20059, USA
| | - Ryan Shu Zhan
- Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, DC 20059, USA
| | - Michael Jones
- Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, DC 20059, USA
| | - Saba Nawaz
- Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, DC 20059, USA
| | - Kebreten Manaye
- Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, DC 20059, USA
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Handforth A, Singh RP, Treven M, Ernst M. Search for Novel Therapies for Essential Tremor Based on Positive Modulation of α6-Containing GABA A Receptors. Tremor Other Hyperkinet Mov (N Y) 2023; 13:39. [PMID: 37900009 PMCID: PMC10607569 DOI: 10.5334/tohm.796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 10/10/2023] [Indexed: 10/31/2023] Open
Abstract
Background Prior work using GABAA receptor subunit knockouts and the harmaline model has indicated that low-dose alcohol, gaboxadol, and ganaxolone suppress tremor via α6βδ GABAA receptors. This suggests that drugs specifically enhancing the action of α6βδ or α6βγ2 GABAA receptors, both predominantly expressed on cerebellar granule cells, would be effective against tremor. We thus examined three drugs described by in vitro studies as selective α6βδ (ketamine) or α6βγ2 (Compound 6, flumazenil) receptor modulators. Methods In the first step of evaluation, the maximal dose was sought at which 6/6 mice pass straight wire testing, a sensitive test for psychomotor impairment. Only non-impairing doses were used to evaluate for anti-tremor efficacy in the harmaline model, which was assessed in wildtype and α6 subunit knockout littermates. Results Ketamine, in maximally tolerated doses of 2.0 and 3.5 mg/kg had minimal effect on harmaline tremor in both genotypes. Compound 6, at well-tolerated doses of 1-10 mg/kg, effectively suppressed tremor in both genotypes. Flumazenil suppressed tremor in wildtype mice at doses (0.015-0.05 mg/kg) far lower than those causing straight wire impairment, and did not suppress tremor in α6 knockout mice. Discussion Modulators of α6βδ and α6βγ2 GABAA receptors warrant attention for novel therapies as they are anticipated to be effective and well-tolerated. Ketamine likely failed to attain α6βδ-active levels. Compound 6 is an attractive candidate, but further study is needed to clarify its mechanism of action. The flumazenil results provide proof of principle that targeting α6βγ2 receptors represents a worthy strategy for developing essential tremor therapies. Highlights We tested for harmaline tremor suppression drugs previously described as in vitro α6βδ or α6βγ2 GABAA receptor-selective modulators. Well-tolerated flumazenil doses suppressed tremor in α6-wildtype but not α6-knockout mice. Compound 6 and ketamine failed to display this profile, likely from off-target effects. Selective α6 modulators hold promise as tremor therapy.
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Affiliation(s)
- Adrian Handforth
- Neurology Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
| | - Ram P. Singh
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
| | - Marco Treven
- Department of Neurology, Medical Neuroscience Cluster, Medical University of Vienna, Vienna, Austria
| | - Margot Ernst
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Vienna, Austria
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Nayak R, Lee J, Sotoudehnia S, Chang SY, Fatemi M, Alizad A. Mapping Pharmacologically Evoked Neurovascular Activation and Its Suppression in a Rat Model of Tremor Using Functional Ultrasound: A Feasibility Study. SENSORS (BASEL, SWITZERLAND) 2023; 23:6902. [PMID: 37571686 PMCID: PMC10422538 DOI: 10.3390/s23156902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 06/26/2023] [Accepted: 08/01/2023] [Indexed: 08/13/2023]
Abstract
Functional ultrasound (fUS), an emerging hemodynamic-based functional neuroimaging technique, is especially suited to probe brain activity and primarily used in animal models. Increasing use of pharmacological models for essential tremor extends new research to the utilization of fUS imaging in such models. Harmaline-induced tremor is an easily provoked model for the development of new therapies for essential tremor (ET). Furthermore, harmaline-induced tremor can be suppressed by the same classic medications used for essential tremor, which leads to the utilization of this model for preclinical testing. However, changes in local cerebral activities under the effect of tremorgenic doses of harmaline have not been completely investigated. In this study, we explored the feasibility of fUS imaging for visualization of cerebral activation and deactivation associated with harmaline-induced tremor and tremor-suppressing effects of propranolol. The spatial resolution of fUS using a high frame rate imaging enabled us to visualize time-locked and site-specific changes in cerebral blood flow associated with harmaline-evoked tremor. Intraperitoneal administration of harmaline generated significant neural activity changes in the primary motor cortex and ventrolateral thalamus (VL Thal) regions during tremor and then gradually returned to baseline level as tremor subsided with time. To the best of our knowledge, this is the first functional ultrasound study to show the neurovascular activation of harmaline-induced tremor and the therapeutic suppression in a rat model. Thus, fUS can be considered a noninvasive imaging method for studying neuronal activities involved in the ET model and its treatment.
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Affiliation(s)
- Rohit Nayak
- Department of Radiology, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA
| | - Jeyeon Lee
- Department of Radiology, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA
| | - Setayesh Sotoudehnia
- Department of Radiology, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA
| | - Su-Youne Chang
- Department of Neurologic Surgery, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA;
| | - Mostafa Fatemi
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA;
| | - Azra Alizad
- Department of Radiology, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA;
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d’Apolito M, Ceccarini C, Savino R, Adipietro I, di Bari I, Santacroce R, Curcetti M, D’Andrea G, Croce AI, Cesarano C, Polito AN, Margaglione M. A Novel KCNN2 Variant in a Family with Essential Tremor Plus: Clinical Characteristics and In Silico Analysis. Genes (Basel) 2023; 14:1380. [PMID: 37510285 PMCID: PMC10379157 DOI: 10.3390/genes14071380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 06/26/2023] [Accepted: 06/27/2023] [Indexed: 07/30/2023] Open
Abstract
BACKGROUND Essential tremor (ET) is one of the more common movement disorders. Current diagnosis is solely based on clinical findings. ET appears to be inherited in an autosomal dominant pattern. Several loci on specific chromosomes have been studied by linkage analysis, but the causes of essential tremor are still unknown in many patients. Genetic studies described the association of several genes with familial ET. However, they were found only in distinct families, suggesting that some can be private pathogenic variants. AIM OF THE STUDY to characterize the phenotype of an Italian family with ET and identify the genetic variant associated. METHODS Clinical and genetic examinations were performed. Genetic testing was done with whole-exome sequencing (WES) using the Illumina platform. Bidirectional capillary Sanger sequencing was used to investigate the presence of variant in all affected members of the family. In silico prediction of pathogenicity was used to study the effect of gene variants on protein structure. RESULTS The proband was a 15-year-old boy. The patient was the first of two children of a non-consanguineous couple. Family history was remarkable for tremor in the mother line. His mother suffered from bilateral upper extremity kinetic tremors (since she was 20 years old), anxiety, and depression. Other relatives referred bilateral upper extremity tremors. In the index case, WES analysis performed supposing a dominant mode of inheritance, identified a novel heterozygous missense variant in potassium calcium-activated channel subfamily N member 2 (KCNN2) (NM_021614.3: c.1145G>A, p.Gly382Asp). In the pedigree investigation, all carriers of the gene variant had ET and showed variable expressivity, the elder symptomatic relative showing cognitive impairment and hallucinations in the last decade, in addition to tremor since a young age. The amino acid residue #382 is located in a transmembrane region and in silico analysis suggested a causative role for the variant. Modelling of the mutant protein structure showed that the variant causes a clash in the protein structure. Therefore, the variant could cause a conformational change that alters the ability of the protein in the modulation of ion channels Conclusions: The KCNN2 gene variant identified could be associated with ET. The variant could modify a voltage-independent potassium channel activated by intracellular calcium.
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Affiliation(s)
- Maria d’Apolito
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Caterina Ceccarini
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Rosa Savino
- Neuropsychiatry for Child and Adolescent Unit, Department of Woman and Child, Policlinico Riuniti, 70122 Foggia, Italy; (R.S.); (A.N.P.)
| | - Iolanda Adipietro
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Ighli di Bari
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Rosa Santacroce
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Maria Curcetti
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Giovanna D’Andrea
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Anna-Irma Croce
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Carla Cesarano
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Anna Nunzia Polito
- Neuropsychiatry for Child and Adolescent Unit, Department of Woman and Child, Policlinico Riuniti, 70122 Foggia, Italy; (R.S.); (A.N.P.)
| | - Maurizio Margaglione
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
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Handforth A, Kosoyan HP, Kadam PA, Singh RP. Alcohol and Ganaxolone Suppress Tremor via Extra-Synaptic GABA A Receptors in the Harmaline Model of Essential Tremor. Tremor Other Hyperkinet Mov (N Y) 2023; 13:18. [PMID: 37214542 PMCID: PMC10198231 DOI: 10.5334/tohm.760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 05/06/2023] [Indexed: 05/24/2023] Open
Abstract
Background A long-standing question is why essential tremor often responds to non-intoxicating amounts of alcohol. Blood flow imaging and high-density electroencephalography have indicated that alcohol acts on tremor within the cerebellum. As extra-synaptic δ-subunit-containing GABAA receptors are sensitive to low alcohol levels, we wondered whether these receptors mediate alcohol's anti-tremor effect and, moreover, whether the δ-associated GABAA receptor α6 subunit, found abundantly in the cerebellum, is required. Methods We tested the hypotheses that low-dose alcohol will suppress harmaline-induced tremor in wild-type mice, but not in littermates lacking GABAA receptor δ subunits, nor in littermates lacking α6 subunits. As the neurosteroid ganaxolone also activates extra-synaptic GABAA receptors, we similarly assessed this compound. The harmaline mouse model of essential tremor was utilized to generate tremor, measured as a percentage of motion power in the tremor bandwidth (9-16 Hz) divided by background motion power at 0.25-32 Hz. Results Ethanol, 0.500 and 0.575 g/kg, and ganaxolone, 7 and 10 mg/kg, doses that do not impair performance in a sensitive psychomotor task, reduced harmaline tremor compared to vehicle-treated controls in wild-type mice but failed to suppress tremor in littermates lacking the δ or the α6 GABAA receptor subunit. Discussion As cerebellar granule cells are the predominant brain site intensely expressing GABAA receptors containing both α6 and δ subunits, these findings suggest that this is where alcohol acts to suppress tremor. It is anticipated that medications designed specifically to target α6βδ-containing GABAA receptors may be effective and well-tolerated for treating essential tremor. Highlights How does alcohol temporarily ameliorate essential tremor? This study with a mouse model found that two specific kinds of GABA receptor subunits were needed for alcohol to work. As receptors with both these subunits are found mainly in cerebellum, this work suggests this is where alcohol acts to suppress tremor.
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Affiliation(s)
- Adrian Handforth
- Neurology Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
| | - Hovsep P. Kosoyan
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
| | - Pournima A. Kadam
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
| | - Ram P. Singh
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
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Huang YH, Lee MT, Hsueh HY, Knutson DE, Cook J, Mihovilovic MD, Sieghart W, Chiou LC. Cerebellar α6GABA A Receptors as a Therapeutic Target for Essential Tremor: Proof-of-Concept Study with Ethanol and Pyrazoloquinolinones. Neurotherapeutics 2023; 20:399-418. [PMID: 36696034 PMCID: PMC10121996 DOI: 10.1007/s13311-023-01342-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/29/2022] [Indexed: 01/26/2023] Open
Abstract
Ethanol has been shown to suppress essential tremor (ET) in patients at low-to-moderate doses, but its mechanism(s) of action remain unknown. One of the ET hypotheses attributes the ET tremorgenesis to the over-activated firing of inferior olivary neurons, causing synchronic rhythmic firings of cerebellar Purkinje cells. Purkinje cells, however, also receive excitatory inputs from granule cells where the α6 subunit-containing GABAA receptors (α6GABAARs) are abundantly expressed. Since ethanol is a positive allosteric modulator (PAM) of α6GABAARs, such action may mediate its anti-tremor effect. Employing the harmaline-induced ET model in male ICR mice, we evaluated the possible anti-tremor effects of ethanol and α6GABAAR-selective pyrazoloquinolinone PAMs. The burrowing activity, an indicator of well-being in rodents, was measured concurrently. Ethanol significantly and dose-dependently attenuated action tremor at non-sedative doses (0.4-2.4 g/kg, i.p.). Propranolol and α6GABAAR-selective pyrazoloquinolinones also significantly suppressed tremor activity. Neither ethanol nor propranolol, but only pyrazoloquinolinones, restored burrowing activity in harmaline-treated mice. Importantly, intra-cerebellar micro-injection of furosemide (an α6GABAAR antagonist) had a trend of blocking the effect of pyrazoloquinolinone Compound 6 or ethanol on harmaline-induced tremor. In addition, the anti-tremor effects of Compound 6 and ethanol were synergistic. These results suggest that low doses of ethanol and α6GABAAR-selective PAMs can attenuate action tremor, at least partially by modulating cerebellar α6GABAARs. Thus, α6GABAARs are potential therapeutic targets for ET, and α6GABAAR-selective PAMs may be a potential mono- or add-on therapy.
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Affiliation(s)
- Ya-Hsien Huang
- Department and Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, No. 1, Jen-Ai Rd., Section 1, Taipei, 10051, Taiwan
| | - Ming Tatt Lee
- Department and Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, No. 1, Jen-Ai Rd., Section 1, Taipei, 10051, Taiwan
- Faculty of Pharmaceutical Sciences, UCSI University, Kuala Lumpur, 56000, Malaysia
| | - Han-Yun Hsueh
- Department and Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, No. 1, Jen-Ai Rd., Section 1, Taipei, 10051, Taiwan
| | - Daniel E Knutson
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, 53211, USA
| | - James Cook
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, 53211, USA
| | | | - Werner Sieghart
- Center for Brain Research, Department of Molecular Neurosciences, Medical University Vienna, Vienna, 1090, Austria
| | - Lih-Chu Chiou
- Department and Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, No. 1, Jen-Ai Rd., Section 1, Taipei, 10051, Taiwan.
- Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan.
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, 40402, Taiwan.
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Matthews LG, Puryear CB, Correia SS, Srinivasan S, Belfort GM, Pan MK, Kuo SH. T-type calcium channels as therapeutic targets in essential tremor and Parkinson's disease. Ann Clin Transl Neurol 2023; 10:462-483. [PMID: 36738196 PMCID: PMC10109288 DOI: 10.1002/acn3.51735] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 12/20/2022] [Accepted: 12/21/2022] [Indexed: 02/05/2023] Open
Abstract
Neuronal action potential firing patterns are key components of healthy brain function. Importantly, restoring dysregulated neuronal firing patterns has the potential to be a promising strategy in the development of novel therapeutics for disorders of the central nervous system. Here, we review the pathophysiology of essential tremor and Parkinson's disease, the two most common movement disorders, with a focus on mechanisms underlying the genesis of abnormal firing patterns in the implicated neural circuits. Aberrant burst firing of neurons in the cerebello-thalamo-cortical and basal ganglia-thalamo-cortical circuits contribute to the clinical symptoms of essential tremor and Parkinson's disease, respectively, and T-type calcium channels play a key role in regulating this activity in both the disorders. Accordingly, modulating T-type calcium channel activity has received attention as a potentially promising therapeutic approach to normalize abnormal burst firing in these diseases. In this review, we explore the evidence supporting the theory that T-type calcium channel blockers can ameliorate the pathophysiologic mechanisms underlying essential tremor and Parkinson's disease, furthering the case for clinical investigation of these compounds. We conclude with key considerations for future investigational efforts, providing a critical framework for the development of much needed agents capable of targeting the dysfunctional circuitry underlying movement disorders such as essential tremor, Parkinson's disease, and beyond.
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Affiliation(s)
| | - Corey B Puryear
- Praxis Precision Medicines, Boston, Massachusetts, 02110, USA
| | | | - Sharan Srinivasan
- Praxis Precision Medicines, Boston, Massachusetts, 02110, USA.,Department of Neurology, University of Michigan, Ann Arbor, Michigan, 48109, USA
| | | | - Ming-Kai Pan
- Department and Graduate Institute of Pharmacology, National Taiwan University College of Medicine, Taipei, 10051, Taiwan.,Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, 10617, Taiwan.,Department of Medical Research, National Taiwan University Hospital, Taipei, 10002, Taiwan.,Cerebellar Research Center, National Taiwan University Hospital, Yun-Lin Branch, Yun-Lin, 64041, Taiwan
| | - Sheng-Han Kuo
- Department of Neurology, Columbia University, New York, New York, 10032, USA.,Initiative for Columbia Ataxia and Tremor, Columbia University, New York, New York, 10032, USA
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Kosmowska B, Paleczna M, Biała D, Kadłuczka J, Wardas J, Witkin JM, Cook JM, Sharmin D, Marcinkowska M, Kuter KZ. GABA-A Alpha 2/3 but Not Alpha 1 Receptor Subunit Ligand Inhibits Harmaline and Pimozide-Induced Tremor in Rats. Biomolecules 2023; 13:biom13020197. [PMID: 36830567 PMCID: PMC9953228 DOI: 10.3390/biom13020197] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/11/2023] [Accepted: 01/15/2023] [Indexed: 01/20/2023] Open
Abstract
Treatment of tremors, such as in essential tremor (ET) and Parkinson's disease (PD) is mostly ineffective. Exact tremor pathomechanisms are unknown and relevant animal models are missing. GABA-A receptor is a target for tremorolytic medications, but current non-selective drugs produce side effects and have safety liabilities. The aim of this study was a search for GABA-A subunit-specific tremorolytics using different tremor-generating mechanisms. Two selective positive allosteric modulators (PAMs) were tested. Zolpidem, targeting GABA-A α1, was not effective in models of harmaline-induced ET, pimozide- or tetrabenazine-induced tremulous jaw movements (TJMs), while the novel GABA-A α2/3 selective MP-III-024 significantly reduced both the harmaline-induced ET tremor and pimozide-induced TJMs. While zolpidem decreased the locomotor activity of the rats, MP-III-024 produced small increases. These results provide important new clues into tremor suppression mechanisms initiated by the enhancement of GABA-driven inhibition in pathways controlled by α2/3 but not α1 containing GABA-A receptors. Tremor suppression by MP-III-024 provides a compelling reason to consider selective PAMs targeting α2/3-containing GABA-A receptors as novel therapeutic drug targets for ET and PD-associated tremor. The possibility of the improved tolerability and safety of this mechanism over non-selective GABA potentiation provides an additional rationale to further pursue the selective α2/3 hypothesis.
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Affiliation(s)
- Barbara Kosmowska
- Department of Neuropsychopharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna St., 31-343 Krakow, Poland
| | - Martyna Paleczna
- Department of Neuropsychopharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna St., 31-343 Krakow, Poland
| | - Dominika Biała
- Department of Neuropsychopharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna St., 31-343 Krakow, Poland
| | - Justyna Kadłuczka
- Department of Neuropsychopharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna St., 31-343 Krakow, Poland
| | - Jadwiga Wardas
- Department of Neuropsychopharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna St., 31-343 Krakow, Poland
| | - Jeffrey M. Witkin
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
- RespireRx Pharmaceuticals Inc., Glen Rock, NJ 07452, USA
| | - James M. Cook
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
- RespireRx Pharmaceuticals Inc., Glen Rock, NJ 07452, USA
| | - Dishary Sharmin
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
| | - Monika Marcinkowska
- Department of Pharmaceutical Chemistry, Jagiellonian University, Medical College, 9 Medyczna St., 30-688 Krakow, Poland
| | - Katarzyna Z. Kuter
- Department of Neuropsychopharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna St., 31-343 Krakow, Poland
- Correspondence: ; Tel.: +48-12-662-32-26
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10
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Zhou J, Van der Heijden ME, Salazar Leon LE, Lin T, Miterko LN, Kizek DJ, Perez RM, Pavešković M, Brown AM, Sillitoe RV. Propranolol Modulates Cerebellar Circuit Activity and Reduces Tremor. Cells 2022; 11:cells11233889. [PMID: 36497147 PMCID: PMC9740691 DOI: 10.3390/cells11233889] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/10/2022] [Accepted: 11/29/2022] [Indexed: 12/03/2022] Open
Abstract
Tremor is the most common movement disorder. Several drugs reduce tremor severity, but no cures are available. Propranolol, a β-adrenergic receptor blocker, is the leading treatment for tremor. However, the in vivo circuit mechanisms by which propranolol decreases tremor remain unclear. Here, we test whether propranolol modulates activity in the cerebellum, a key node in the tremor network. We investigated the effects of propranolol in healthy control mice and Car8wdl/wdl mice, which exhibit pathophysiological tremor and ataxia due to cerebellar dysfunction. Propranolol reduced physiological tremor in control mice and reduced pathophysiological tremor in Car8wdl/wdl mice to control levels. Open field and footprinting assays showed that propranolol did not correct ataxia in Car8wdl/wdl mice. In vivo recordings in awake mice revealed that propranolol modulates the spiking activity of control and Car8wdl/wdl Purkinje cells. Recordings in cerebellar nuclei neurons, the targets of Purkinje cells, also revealed altered activity in propranolol-treated control and Car8wdl/wdl mice. Next, we tested whether propranolol reduces tremor through β1 and β2 adrenergic receptors. Propranolol did not change tremor amplitude or cerebellar nuclei activity in β1 and β2 null mice or Car8wdl/wdl mice lacking β1 and β2 receptor function. These data show that propranolol can modulate cerebellar circuit activity through β-adrenergic receptors and may contribute to tremor therapeutics.
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Affiliation(s)
- Joy Zhou
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Meike E. Van der Heijden
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
| | - Luis E. Salazar Leon
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Tao Lin
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
| | - Lauren N. Miterko
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
- Program in Development, Disease Models & Therapeutics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Dominic J. Kizek
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
| | - Ross M. Perez
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
- Program in Development, Disease Models & Therapeutics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Matea Pavešković
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Amanda M. Brown
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
| | - Roy V. Sillitoe
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
- Program in Development, Disease Models & Therapeutics, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
- Correspondence: ; Tel.: +1-832-824-8913
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11
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Khatoun A, Asamoah B, Boogers A, Mc Laughlin M. Epicranial Direct Current Stimulation Suppresses Harmaline Tremor in Rats. Neuromodulation 2022:S1094-7159(22)01223-5. [DOI: 10.1016/j.neurom.2022.08.448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 07/19/2022] [Accepted: 08/01/2022] [Indexed: 10/14/2022]
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12
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Lee J, Kim J, Cortez J, Chang SY. Thalamo-cortical network is associated with harmaline-induced tremor in rodent model. Exp Neurol 2022; 358:114210. [PMID: 36007599 DOI: 10.1016/j.expneurol.2022.114210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 08/19/2022] [Indexed: 11/04/2022]
Abstract
Essential tremor (ET) is the most frequent form of pathologic tremor and one of the most common adult-onset neurologic impairments. However, underlying mechanisms by which structural alterations within the tremor circuit generate the pathological state and how rhythmic neuronal activities propagate and drive tremor remains unclear. Harmaline (HA)-induced tremor model has been most frequently utilized animal model for ET studies, however, there is still a dearth of knowledge over the degree to whether HA-induced tremor mimics the actual underlying pathophysiology of ET, particularly the involvement of thalamo-cortical region. In this study, we investigated the electrophysiological response of the motor circuit including the ventrolateral thalamus (vlTh) and the primary motor cortex (M1), and the modulatory effect of thalamic deep brain stimulation (DBS) using a rat HA-induced tremor model. We found that the theta and high-frequency oscillation (HFO) band power significantly increased after HA administration in both vlTh and M1, and the activity was modulated by the tremor suppression drug (propranolol) and the thalamic DBS. The theta band phase synchronization between the vlTh and M1 was significantly enhanced during the HA-induced tremor, and the transition of cross-frequency coupling in vlTh was found to be associated with the state of HA-induced tremor. Our findings support that the HA tremor could be useful as a valid preclinical model of ET in the context of thalamo-cortical neural network interaction.
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Affiliation(s)
- Jeyeon Lee
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | - Jiwon Kim
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Joshua Cortez
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Su-Youne Chang
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA.
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13
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Kuo SH, Louis ED. The future of pharmacotherapies for essential tremor: Enhancing GABA neurotransmission or reducing neuronal hyperexcitability? INTERNATIONAL REVIEW OF NEUROBIOLOGY 2022; 163:311-315. [PMID: 36172063 PMCID: PMC9512121 DOI: 10.1016/s0074-7742(22)00061-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Affiliation(s)
- Sheng-Han Kuo
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, United States
- Initiative for Columbia Ataxia and Tremor, Columbia University, New York, NY, United States
| | - Elan D Louis
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, United States
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14
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Quantitative behavioral models for high-resolution measurement and characterization of tremor in rodents. Brain Res Bull 2022; 186:8-15. [PMID: 35487386 DOI: 10.1016/j.brainresbull.2022.04.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 04/16/2022] [Accepted: 04/20/2022] [Indexed: 01/25/2023]
Abstract
Tremor is an involuntary, rhythmic movement disorder. Despite its prevalence, the underlying pathophysiology remains poorly understood and effective treatment options are limited. Animal models are essential in enhancing our understanding of the mechanisms of tremorogenesis and developing new therapeutic interventions. Although tremor is amenable to measurement by automated systems, visual observation is still the most prevalent method for recording tremor in animal studies. This review gives a brief summary of two behavioral methods that enable quantitative measurement of forelimb tremor (the press-while-licking task) and whole-body tremor (the force-plate actometer) in rodents. These methods utilize force transducer and computing technologies to generate high-resolution force-time waveforms for automated detection and characterization of tremor. The focus will be on the sensitive, precise, and quantitative measurement of tremors induced in rodents by low-dose pharmacological agents, brain lesion, physical training, and genetic mutations. The methods reviewed here provide new tools that can facilitate preclinical assessment of treatment strategies for tremor.
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15
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Ondo W. Enhancing GABA inhibition is the next generation of medications for essential tremor. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2022; 163:317-334. [PMID: 35750368 DOI: 10.1016/bs.irn.2022.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
γ-Aminobutyric acid (GABA) is the most prevalent inhibitory CNS neurotransmitter. Activating GABA-A receptors hyperpolarizes cells via Cl- influx, which inhibits action potentials. Although the exact pathophysiologies of tremor are incompletely understood, proposed neuroanatomy extensively implicates GABA pathways. Pathological studies and imaging studies also show GABA abnormalities in patients with ET. Most importantly, medications that activate GABA-A receptors, such as primidone, often improve tremor. Ongoing clinical trials and physiology research should further refine potential future GABAergic targets and treatments, which are currently the most promising targets for pharmacological intervention.
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Affiliation(s)
- William Ondo
- Houston Methodist Hospital, Weill Cornel Medical School, Houston, TX, United States.
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16
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Scott L, Puryear CB, Belfort GM, Raines S, Hughes ZA, Matthews LG, Ravina B, Wittmann M. Translational Pharmacology of PRAX-944, a Novel T-Type Calcium Channel Blocker in Development for the Treatment of Essential Tremor. Mov Disord 2022; 37:1193-1201. [PMID: 35257414 PMCID: PMC9310641 DOI: 10.1002/mds.28969] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 12/16/2021] [Accepted: 01/13/2022] [Indexed: 12/15/2022] Open
Abstract
Background Essential tremor is the most common movement disorder with clear unmet need. Mounting evidence indicates tremor is caused by increased neuronal burst firing and oscillations in cerebello‐thalamo‐cortical circuitry and may be dependent on T‐type calcium channel activity. T‐type calcium channels regulate sigma band electroencephalogram (EEG) power during non‐rapid eye movement sleep, representing a potential biomarker of channel activity. PRAX‐944 is a novel T‐type calcium channel blocker in development for essential tremor. Objectives Using a rat tremor model and sigma‐band EEG power, we assessed pharmacodynamically‐active doses of PRAX‐944 and their translation into clinically tolerated doses in healthy participants, informing dose selection for future efficacy trials. Methods Harmaline‐induced tremor and spontaneous locomotor activity were used to assess PRAX‐944 efficacy and tolerability, respectively, in rats. Sigma‐power was used as a translational biomarker of T‐type calcium channel blockade in rats and, subsequently, in a phase 1 trial assessing pharmacologic activity and tolerability in healthy participants. Results In rats, PRAX‐944 dose‐dependently reduced tremor by 50% and 72% at 1 and 3 mg/kg doses, respectively, without locomotor side effects. These doses also reduced sigma‐power by ~30% to 50% in rats. In healthy participants, sigma‐power was similarly reduced by 34% to 50% at 10 to 100 mg, with no further reduction at 120 mg. All doses were well tolerated. Conclusions In rats, PRAX‐944 reduced sigma‐power at concentrations that reduced tremor without locomotor side effects. In healthy participants, comparable reductions in sigma‐power indicate that robust T‐type calcium channel blockade was achieved at well‐tolerated doses that may hold promise for reducing tremor in patients with essential tremor. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society
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Affiliation(s)
- Liam Scott
- Praxis Precision Medicines, Boston, Massachusetts, USA
| | | | | | - Shane Raines
- Praxis Precision Medicines, Boston, Massachusetts, USA
| | - Zoë A Hughes
- Praxis Precision Medicines, Boston, Massachusetts, USA
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17
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Kim E, Kum J, Kim H. Trans-Spinal Focused Ultrasound Stimulation Selectively Modulates Descending Motor Pathway. IEEE Trans Neural Syst Rehabil Eng 2022; 30:314-320. [PMID: 35108206 DOI: 10.1109/tnsre.2022.3148877] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Compared to current non-invasive methods utilizing magnetic and electrical means, focused ultrasound provides greater spatial resolution and penetration depth. Despite the broad application of ultrasound stimulation, there is a lack of studies dedicated to the investigation of acoustic neuromodulation on the spinal cord. This study aims to apply focused ultrasound on the spinal cord to modulate the descending pathways in a non-invasive fashion. The application of trans-spinal focused ultrasound (tsFUS) was examined on the motor deficit mouse model. tsFUS was achieved using a single-element focused ultrasound transducer operating at 3 MHz. The sonication was performed on anesthetized 6 week-old mice targeting T12 and L3 vertebrae. The effect was analyzed by comparing electromyography responses from the hindlimb induced by electrical stimulation of the motor cortex. Further, the mouse model with the Harmaline-induced essential tremor was selected to investigate the potential clinical application of tsFUS. The safety was verified by histological assessment. Sonication at the T12 area inhibited motor response, while sonication over the L3 region provided signal enhancement. Sonication of T12 of the ET mouse also showed the ability of ultrasound to suppress tremors. Meanwhile, the histological examination did not show any abnormalities with the highest applied acoustic pressure. In this work, a non-invasive motor signal modulation was achieved using tsFUS. Moreover, the results showed the ability of focused ultrasound to manage tremors in a safe manner. This study provides a stepping stone for the trans-spinal application of focused ultrasound to motor-related disorders.
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18
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Woodward K, Apps R, Goodfellow M, Cerminara NL. Cerebello-Thalamo-Cortical Network Dynamics in the Harmaline Rodent Model of Essential Tremor. Front Syst Neurosci 2022; 16:899446. [PMID: 35965995 PMCID: PMC9365993 DOI: 10.3389/fnsys.2022.899446] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 06/22/2022] [Indexed: 11/18/2022] Open
Abstract
Essential Tremor (ET) is a common movement disorder, characterised by a posture or movement-related tremor of the upper limbs. Abnormalities within cerebellar circuits are thought to underlie the pathogenesis of ET, resulting in aberrant synchronous oscillatory activity within the thalamo-cortical network leading to tremors. Harmaline produces pathological oscillations within the cerebellum, and a tremor that phenotypically resembles ET. However, the neural network dynamics in cerebellar-thalamo-cortical circuits in harmaline-induced tremor remains unclear, including the way circuit interactions may be influenced by behavioural state. Here, we examined the effect of harmaline on cerebello-thalamo-cortical oscillations during rest and movement. EEG recordings from the sensorimotor cortex and local field potentials (LFP) from thalamic and medial cerebellar nuclei were simultaneously recorded in awake behaving rats, alongside measures of tremor using EMG and accelerometery. Analyses compared neural oscillations before and after systemic administration of harmaline (10 mg/kg, I.P), and coherence across periods when rats were resting vs. moving. During movement, harmaline increased the 9-15 Hz behavioural tremor amplitude and increased thalamic LFP coherence with tremor. Medial cerebellar nuclei and cerebellar vermis LFP coherence with tremor however remained unchanged from rest. These findings suggest harmaline-induced cerebellar oscillations are independent of behavioural state and associated changes in tremor amplitude. By contrast, thalamic oscillations are dependent on behavioural state and related changes in tremor amplitude. This study provides new insights into the role of cerebello-thalamo-cortical network interactions in tremor, whereby neural oscillations in thalamocortical, but not cerebellar circuits can be influenced by movement and/or behavioural tremor amplitude in the harmaline model.
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Affiliation(s)
- Kathryn Woodward
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Richard Apps
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Marc Goodfellow
- Department of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, United Kingdom
- Living Systems Institute, University of Exeter, Exeter, United Kingdom
| | - Nadia L. Cerminara
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
- *Correspondence: Nadia L. Cerminara
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Lang EJ, Handforth A. Is the inferior olive central to essential tremor? Yes. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2022; 163:133-165. [PMID: 35750361 DOI: 10.1016/bs.irn.2022.02.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We consider the question whether the inferior olive (IO) is required for essential tremor (ET). Much evidence shows that the olivocerebellar system is the main system capable of generating the widespread synchronous oscillatory Purkinje cell (PC) complex spike (CS) activity across the cerebellar cortex that would be capable of generating the type of bursting cerebellar output from the deep cerebellar nuclei (DCN) that could underlie tremor. Normally, synchronous CS activity primarily reflects the effective electrical coupling of IO neurons by gap junctions, and traditionally, ET research has focused on the hypothesis of increased coupling of IO neurons as the cause of hypersynchronous CS activity underlying tremor. However, recent pathology studies of brains from humans with ET and evidence from mutant mice, particularly the hotfoot17 mouse, that largely replicate the pathology of ET, suggest that the abnormal innervation of multiple Purkinje cells (PCs) by climbing fibers (Cfs) is related to tremor. In addition, ET brains show partial PC loss and axon terminal sprouting by surviving PCs. This may provide another mechanism for tremor. It is proposed that in ET, these three mechanisms may promote tremor. They all involve hypersynchronous DCN activity and an intact IO, but the level at which excessive synchronization occurs may be at the IO level (from abnormal afferent activity to this nucleus), the PC level (via aberrant Cfs), or the DCN level (via terminal PC collateral innervation).
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20
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Sieghart W, Chiou LC, Ernst M, Fabjan J, M Savić M, Lee MT. α6-Containing GABA A Receptors: Functional Roles and Therapeutic Potentials. Pharmacol Rev 2022; 74:238-270. [PMID: 35017178 DOI: 10.1124/pharmrev.121.000293] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 09/08/2021] [Indexed: 12/11/2022] Open
Abstract
GABAA receptors containing the α6 subunit are highly expressed in cerebellar granule cells and less abundantly in many other neuronal and peripheral tissues. Here, we for the first time summarize their importance for the functions of the cerebellum and the nervous system. The cerebellum is not only involved in motor control but also in cognitive, emotional, and social behaviors. α6βγ2 GABAA receptors located at cerebellar Golgi cell/granule cell synapses enhance the precision of inputs required for cerebellar timing of motor activity and are thus involved in cognitive processing and adequate responses to our environment. Extrasynaptic α6βδ GABAA receptors regulate the amount of information entering the cerebellum by their tonic inhibition of granule cells, and their optimal functioning enhances input filtering or contrast. The complex roles of the cerebellum in multiple brain functions can be compromised by genetic or neurodevelopmental causes that lead to a hypofunction of cerebellar α6-containing GABAA receptors. Animal models mimicking neuropsychiatric phenotypes suggest that compounds selectively activating or positively modulating cerebellar α6-containing GABAA receptors can alleviate essential tremor and motor disturbances in Angelman and Down syndrome as well as impaired prepulse inhibition in neuropsychiatric disorders and reduce migraine and trigeminal-related pain via α6-containing GABAA receptors in trigeminal ganglia. Genetic studies in humans suggest an association of the human GABAA receptor α6 subunit gene with stress-associated disorders. Animal studies support this conclusion. Neuroimaging and post-mortem studies in humans further support an involvement of α6-containing GABAA receptors in various neuropsychiatric disorders, pointing to a broad therapeutic potential of drugs modulating α6-containing GABAA receptors. SIGNIFICANCE STATEMENT: α6-Containing GABAA receptors are abundantly expressed in cerebellar granule cells, but their pathophysiological roles are widely unknown, and they are thus out of the mainstream of GABAA receptor research. Anatomical and electrophysiological evidence indicates that these receptors have a crucial function in neuronal circuits of the cerebellum and the nervous system, and experimental, genetic, post-mortem, and pharmacological studies indicate that selective modulation of these receptors offers therapeutic prospects for a variety of neuropsychiatric disorders and for stress and its consequences.
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Affiliation(s)
- Werner Sieghart
- Center for Brain Research, Department of Molecular Neurosciences (W.S.), and Center for Brain Research, Department of Pathobiology of the Nervous System (M.E., J.F.), Medical University Vienna, Vienna, Austria; Graduate Institute of Pharmacology (L.-C.C., M.T.L.), and Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan (L.-C.C., M.T.L.); Faculty of Pharmacy, Department of Pharmacology, University of Belgrade, Belgrade, Serbia (M.M.S.); Faculty of Pharmaceutical Sciences, UCSI University, Kuala Lumpur, Malaysia (M.T.L.); and Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan (L.-C.C.)
| | - Lih-Chu Chiou
- Center for Brain Research, Department of Molecular Neurosciences (W.S.), and Center for Brain Research, Department of Pathobiology of the Nervous System (M.E., J.F.), Medical University Vienna, Vienna, Austria; Graduate Institute of Pharmacology (L.-C.C., M.T.L.), and Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan (L.-C.C., M.T.L.); Faculty of Pharmacy, Department of Pharmacology, University of Belgrade, Belgrade, Serbia (M.M.S.); Faculty of Pharmaceutical Sciences, UCSI University, Kuala Lumpur, Malaysia (M.T.L.); and Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan (L.-C.C.)
| | - Margot Ernst
- Center for Brain Research, Department of Molecular Neurosciences (W.S.), and Center for Brain Research, Department of Pathobiology of the Nervous System (M.E., J.F.), Medical University Vienna, Vienna, Austria; Graduate Institute of Pharmacology (L.-C.C., M.T.L.), and Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan (L.-C.C., M.T.L.); Faculty of Pharmacy, Department of Pharmacology, University of Belgrade, Belgrade, Serbia (M.M.S.); Faculty of Pharmaceutical Sciences, UCSI University, Kuala Lumpur, Malaysia (M.T.L.); and Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan (L.-C.C.)
| | - Jure Fabjan
- Center for Brain Research, Department of Molecular Neurosciences (W.S.), and Center for Brain Research, Department of Pathobiology of the Nervous System (M.E., J.F.), Medical University Vienna, Vienna, Austria; Graduate Institute of Pharmacology (L.-C.C., M.T.L.), and Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan (L.-C.C., M.T.L.); Faculty of Pharmacy, Department of Pharmacology, University of Belgrade, Belgrade, Serbia (M.M.S.); Faculty of Pharmaceutical Sciences, UCSI University, Kuala Lumpur, Malaysia (M.T.L.); and Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan (L.-C.C.)
| | - Miroslav M Savić
- Center for Brain Research, Department of Molecular Neurosciences (W.S.), and Center for Brain Research, Department of Pathobiology of the Nervous System (M.E., J.F.), Medical University Vienna, Vienna, Austria; Graduate Institute of Pharmacology (L.-C.C., M.T.L.), and Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan (L.-C.C., M.T.L.); Faculty of Pharmacy, Department of Pharmacology, University of Belgrade, Belgrade, Serbia (M.M.S.); Faculty of Pharmaceutical Sciences, UCSI University, Kuala Lumpur, Malaysia (M.T.L.); and Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan (L.-C.C.)
| | - Ming Tatt Lee
- Center for Brain Research, Department of Molecular Neurosciences (W.S.), and Center for Brain Research, Department of Pathobiology of the Nervous System (M.E., J.F.), Medical University Vienna, Vienna, Austria; Graduate Institute of Pharmacology (L.-C.C., M.T.L.), and Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan (L.-C.C., M.T.L.); Faculty of Pharmacy, Department of Pharmacology, University of Belgrade, Belgrade, Serbia (M.M.S.); Faculty of Pharmaceutical Sciences, UCSI University, Kuala Lumpur, Malaysia (M.T.L.); and Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan (L.-C.C.)
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21
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Kosmowska B, Wardas J. The Pathophysiology and Treatment of Essential Tremor: The Role of Adenosine and Dopamine Receptors in Animal Models. Biomolecules 2021; 11:1813. [PMID: 34944457 PMCID: PMC8698799 DOI: 10.3390/biom11121813] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/25/2021] [Accepted: 11/30/2021] [Indexed: 12/13/2022] Open
Abstract
Essential tremor (ET) is one of the most common neurological disorders that often affects people in the prime of their lives, leading to a significant reduction in their quality of life, gradually making them unable to independently perform the simplest activities. Here we show that current ET pharmacotherapy often does not sufficiently alleviate disease symptoms and is completely ineffective in more than 30% of patients. At present, deep brain stimulation of the motor thalamus is the most effective ET treatment. However, like any brain surgery, it can cause many undesirable side effects; thus, it is only performed in patients with an advanced disease who are not responsive to drugs. Therefore, it seems extremely important to look for new strategies for treating ET. The purpose of this review is to summarize the current knowledge on the pathomechanism of ET based on studies in animal models of the disease, as well as to present and discuss the results of research available to date on various substances affecting dopamine (mainly D3) or adenosine A1 receptors, which, due to their ability to modulate harmaline-induced tremor, may provide the basis for the development of new potential therapies for ET in the future.
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Affiliation(s)
| | - Jadwiga Wardas
- Department of Neuropsychopharmacology, Maj Institute of Pharmacology Polish Academy of Sciences, 31-343 Kraków, Poland;
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22
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Bello EM, Blumenfeld M, Dao J, Krieg JDS, Wilmerding LK, Johnson MD. Considerations Using Harmaline for a Primate Model of Tremor. Tremor Other Hyperkinet Mov (N Y) 2021; 11:35. [PMID: 34611499 PMCID: PMC8447964 DOI: 10.5334/tohm.634] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 08/25/2021] [Indexed: 11/20/2022] Open
Abstract
Background While harmaline has been used as a pharmacological model of essential tremor (ET) in rodents and pigs, less is known about the effects of this pharmacological treatment in awake-behaving non-human primates. In this study, we investigated the time-course, amplitude, frequency, and consistency of harmaline tremor in primates. Methods Three rhesus macaques were administered doses of harmaline ranging from 2-12 mg/kg (i.m.), and tremorous movements were quantified with accelerometers. One subject was also trained to perform a self-paced cued reaching task, with task engagement assessed under harmaline doses ranging from 2-8 mg/kg (i.m.). Results Whole-body tremors manifested within 30 minutes of threshold-dose administration, and peak oscillatory frequency ranged between 10-14 Hz. However, large differences in tremor intensity and intermittency were observed across individual subjects under similar dosing levels. Additionally, engagement with the reaching task was dependent on harmaline dose, with performance mostly unaffected at 2 mg/kg and with little task-engagement at 8 mg/kg. Discussion We provide a detailed assessment of factors that may underlie the heterogeneous responses to harmaline, and lay out important caveats towards the applicability of the behaving harmaline-tremoring non-human primate as a preclinical model for ET. Highlights The harmaline-primate is revisited for its potential as a preclinical model of tremor. Spontaneous tremor was heterogenous in amplitude across subjects despite similar harmaline doses, action tremors were not consistently observed, and performance on a behavioral task degraded with higher dosages.
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Affiliation(s)
- Edward M. Bello
- Biomedical Engineering Department, University of Minnesota, US
| | | | - Joan Dao
- Biomedical Engineering Department, University of Minnesota, US
| | | | | | - Matthew D. Johnson
- Biomedical Engineering Department, University of Minnesota, US
- Institute for Translational Neuroscience, University of Minnesota, US
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23
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Objective detection of microtremors in netrin-G2 knockout mice. J Neurosci Methods 2021; 351:109074. [PMID: 33450333 DOI: 10.1016/j.jneumeth.2021.109074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/04/2021] [Accepted: 01/07/2021] [Indexed: 11/21/2022]
Abstract
BACKGROUND Essential tremor is the most prevalent movement disorder and is thought to be caused by abnormalities in the cerebellar system; however, its underlying neural mechanism is poorly understood. In this study, we found that mice lacking netrin-G2, a cell adhesion molecule which is expressed in neural circuits related to the cerebellar system, exhibited a microtremor resembling an essential tremor. However, it was difficult to quantify microtremors in netrin-G2 KO mice. NEW METHOD We developed a new tremor detector which can quantify the intensity and frequency of a tremor. RESULTS Using this system, we were able to characterize both the microtremors in netrin-G2 KO mice and low-dose harmaline-induced tremors which, to date, had been difficult to detect. Alcohol and anti-tremor drugs, which are effective in decreasing the symptoms of essential tremor in patients, were examined in netrin-G2 KO mice. We found that some drugs lowered the tremor frequency, but had little effect on tremor intensity. Forced swim as a stress stimulus in netrin-G2 KO mice dramatically enhanced tremor symptoms. COMPARISON WITH EXISTING METHODS The detection performance even for tremors induced by low-dose harmaline was similar to that in previous studies or more sensitive than the others. CONCLUSIONS Microtremors in netrin-G2 KO mice are reliably and quantitatively detected by our new tremor detection system. We found different effects of medicines and factors between human essential tremors and microtremors in netrin-G2 KO mice, suggesting that the causations, mechanisms, and symptoms of tremors vary and are heterogeneous, and the objective analyses are required.
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Wang Y, Wang H, Zhang L, Zhang Y, Deng G, Li S, Cao N, Guan H, Cheng X, Wang C. Potential mechanisms of tremor tolerance induced in rats by the repeated administration of total alkaloid extracts from the seeds of Peganum harmala Linn. JOURNAL OF ETHNOPHARMACOLOGY 2020; 262:113183. [PMID: 32730891 DOI: 10.1016/j.jep.2020.113183] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 06/14/2020] [Accepted: 07/12/2020] [Indexed: 06/11/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE The seeds of Peganum harmala Linn have been widely used for the treatment of nervous, cardiovascular, gastrointestinal, respiratory, and endocrine diseases and many other human ailments. However, tremor toxicity occurs after overdose and is tolerated following multiple dosing. Thus far, little is known about the underlying mechanisms of tremors and tremor tolerance. AIM OF THE STUDY To investigate the potential mechanisms of tremors and tremor tolerance induced in rats by the repeated administration of total alkaloid extracts from the seeds of P. harmala (TAEP). MATERIALS AND METHODS A tremor model was induced in male Wistar rats by administering TAEP at a dose of 150 mg/kg/day. To evaluate tremor action, behavioral assessment was conducted by using a custom-built tremor acquisition and analysis system. To investigate the relationships between tremors and neurotransmitter levels in the brain, various neurotransmitters were simultaneously quantified by an ultra-performance liquid chromatography combined with electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) system, and the association between these two parameters was analyzed using Pearson correlation coefficients. To further elucidate the potential mechanisms of the alterations of neurotransmitter levels in cortical tissues, the protein expression levels of several important enzymes and transporters that are closely related to neurotransmitter levels were investigated. In addition, neuropathological analysis was conducted to assess the effect of TAEP on neurons in the brain. To further clarify the potential mechanisms of TAEP-induced neurodegeneration in the brain, c-fos was subjected to immunohistochemical analysis, and oxidative stress markers were examined. RESULTS Tremors initially occurred in rats after the oral administration of TAEP at a dose of 150 mg/kg/day. However, they were tolerated following repeated dosing. The levels of 5-hydroxytryptamine (5-HT) and glycine (Gly) in cortical tissues were most likely associated with the tremor response. Tremor tolerance also likely resulted from the degeneration of cerebellar Purkinje cells. Furthermore, the alteration of 5-HT levels was mainly attributed to the downregulated expression of monoamine oxidase A (MAO-A). The degeneration of Purkinje neurons might have resulted from the overexpression of c-fos and increased oxidative stress in the cerebellum after the multiple dosing of TAEP. CONCLUSION The tremor response induced by TAEP at high doses is closely related to the concentrations of 5-HT and Gly in cortical tissues. Tremor tolerance may also be attributed to the degeneration of cerebellar Purkinje cells after the repeated dosing of TAEP. Further studies should be conducted to elucidate the interaction of the alkaloids on the neurotransmitter receptors, the expression of related neurotransmitter receptors, the specific signaling pathway involved in regulating MAO-A, and the mechanism of the loss and functional recovery of cerebellar Purkinje neurons.
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Affiliation(s)
- Youxu Wang
- Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines, Shanghai R&D Centre for Standardization of Chinese Medicines, 1200 Cailun Road, Shanghai, 201203, China
| | - Hanxue Wang
- Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines, Shanghai R&D Centre for Standardization of Chinese Medicines, 1200 Cailun Road, Shanghai, 201203, China; Shanghai TCM-integrated Hospital, Shanghai University of Traditional Chinese Medicine, 230 Baoding Road, Shanghai, 200082, China
| | - Liuhong Zhang
- Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines, Shanghai R&D Centre for Standardization of Chinese Medicines, 1200 Cailun Road, Shanghai, 201203, China
| | - Yunpeng Zhang
- Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines, Shanghai R&D Centre for Standardization of Chinese Medicines, 1200 Cailun Road, Shanghai, 201203, China
| | - Gang Deng
- Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines, Shanghai R&D Centre for Standardization of Chinese Medicines, 1200 Cailun Road, Shanghai, 201203, China
| | - Shuping Li
- Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines, Shanghai R&D Centre for Standardization of Chinese Medicines, 1200 Cailun Road, Shanghai, 201203, China
| | - Ning Cao
- Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines, Shanghai R&D Centre for Standardization of Chinese Medicines, 1200 Cailun Road, Shanghai, 201203, China
| | - Huida Guan
- Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines, Shanghai R&D Centre for Standardization of Chinese Medicines, 1200 Cailun Road, Shanghai, 201203, China
| | - Xuemei Cheng
- Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines, Shanghai R&D Centre for Standardization of Chinese Medicines, 1200 Cailun Road, Shanghai, 201203, China
| | - Changhong Wang
- Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines, Shanghai R&D Centre for Standardization of Chinese Medicines, 1200 Cailun Road, Shanghai, 201203, China.
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Handforth A, Lang EJ. Increased Purkinje Cell Complex Spike and Deep Cerebellar Nucleus Synchrony as a Potential Basis for Syndromic Essential Tremor. A Review and Synthesis of the Literature. THE CEREBELLUM 2020; 20:266-281. [PMID: 33048308 DOI: 10.1007/s12311-020-01197-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/29/2020] [Indexed: 12/19/2022]
Abstract
We review advances in understanding Purkinje cell (PC) complex spike (CS) physiology that suggest increased CS synchrony underlies syndromic essential tremor (ET). We searched PubMed for papers describing factors that affect CS synchrony or cerebellar circuits potentially related to tremor. Inferior olivary (IO) neurons are electrically coupled, with the degree of coupling controlled by excitatory and GABAergic inputs. Clusters of coupled IO neurons synchronize CSs within parasagittal bands via climbing fibers (Cfs). When motor cortex is stimulated in rats at varying frequencies, whisker movement occurs at ~10 Hz, correlated with synchronous CSs, indicating that the IO/CS oscillatory rhythm gates movement frequency. Intra-IO injection of the GABAA receptor antagonist picrotoxin increases CS synchrony, increases whisker movement amplitude, and induces tremor. Harmaline and 5-HT2a receptor activation also increase IO coupling and CS synchrony and induce tremor. The hotfoot17 mouse displays features found in ET brains, including cerebellar GluRδ2 deficiency and abnormal PC Cf innervation, with IO- and PC-dependent cerebellar oscillations and tremor likely due to enhanced CS synchrony. Heightened coupling within the IO oscillator leads, through its dynamic control of CS synchrony, to increased movement amplitude and, when sufficiently intense, action tremor. Increased CS synchrony secondary to aberrant Cf innervation of multiple PCs likely also underlies hotfoot17 tremor. Deep cerebellar nucleus (DCN) hypersynchrony may occur secondary to increased CS synchrony but might also occur from PC axonal terminal sprouting during partial PC loss. Through these combined mechanisms, increased CS/DCN synchrony may plausibly underlie syndromic ET.
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Affiliation(s)
- Adrian Handforth
- Neurology Service, Veterans Affairs Greater Los Angeles Healthcare System, 11301 Wilshire Blvd., Los Angeles, CA, 90073, USA.
| | - Eric J Lang
- Department of Neuroscience and Physiology, New York University, School of Medicine, New York, NY, USA
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26
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Nietz A, Krook-Magnuson C, Gutierrez H, Klein J, Sauve C, Hoff I, Christenson Wick Z, Krook-Magnuson E. Selective loss of the GABA Aα1 subunit from Purkinje cells is sufficient to induce a tremor phenotype. J Neurophysiol 2020; 124:1183-1197. [PMID: 32902350 DOI: 10.1152/jn.00100.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Previously, an essential tremor-like phenotype has been noted in animals with a global knockout of the GABAAα1 subunit. Given the hypothesized role of the cerebellum in tremor, including essential tremor, we used transgenic mice to selectively knock out the GABAAα1 subunit from cerebellar Purkinje cells. We examined the resulting phenotype regarding impacts on inhibitory postsynaptic currents, survival rates, gross motor abilities, and expression of tremor. Purkinje cell specific knockout of the GABAAα1 subunit abolished all GABAA-mediated inhibition in Purkinje cells, while leaving GABAA-mediated inhibition to cerebellar molecular layer interneurons intact. Selective loss of GABAAα1 from Purkinje cells did not produce deficits on the accelerating rotarod, nor did it result in decreased survival rates. However, a tremor phenotype was apparent, regardless of sex or background strain. This tremor mimicked the tremor seen in animals with a global knockout of the GABAAα1 subunit, and, like essential tremor in patients, was responsive to ethanol. These findings indicate that reduced inhibition to Purkinje cells is sufficient to induce a tremor phenotype, highlighting the importance of the cerebellum, inhibition, and Purkinje cells in tremor.NEW & NOTEWORTHY Animals with a global knockout of the GABAAα1 subunit show a tremor phenotype reminiscent of essential tremor. Here we show that selective knockout of GABAAα1 from Purkinje cells is sufficient to produce a tremor phenotype, although this tremor is less severe than seen in animals with a global knockout. These findings illustrate that the cerebellum can play a key role in the genesis of the observed tremor phenotype.
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Affiliation(s)
- Angela Nietz
- University of Minnesota, Department of Neuroscience, Minneapolis, Minnesota
| | | | - Haruna Gutierrez
- University of Minnesota, Department of Neuroscience, Minneapolis, Minnesota
| | - Julia Klein
- University of Minnesota, Department of Neuroscience, Minneapolis, Minnesota
| | - Clarke Sauve
- University of Minnesota, Department of Neuroscience, Minneapolis, Minnesota
| | - Isaac Hoff
- University of Minnesota, Department of Neuroscience, Minneapolis, Minnesota
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27
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Wu J, Tang H, Chen S, Cao L. Mechanisms and Pharmacotherapy for Ethanol-Responsive Movement Disorders. Front Neurol 2020; 11:892. [PMID: 32982923 PMCID: PMC7477383 DOI: 10.3389/fneur.2020.00892] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 07/13/2020] [Indexed: 12/12/2022] Open
Abstract
Ethanol-responsive movement disorders are a group of movement disorders of which clinical manifestation could receive significant improvement after ethanol intake, including essential tremor, myoclonus-dystonia, and some other hyperkinesia. Emerging evidence supports that the sensitivity of these conditions to ethanol might be attributed to similar anatomical targets and pathophysiologic mechanisms. Cerebellum and cerebellum-related networks play a critical role in these diseases. Suppression of inhibitory neurotransmission and hyper-excitability of these regions are the key points for pathogenesis. GABA pathways, the main inhibitory system involved in these regions, were firstly linked to the pathogenesis of these diseases, and GABAA receptors and GABAB receptors play critical roles in ethanol responsiveness. Moreover, impairment of low-voltage-activated calcium channels, which were considered as a contributor to oscillation activity of the nervous system, also participates in the sensitivity of ethanol in relevant disease. Glutamate transporters and receptors that are closely associated with GABA pathways are the action sites for ethanol as well. Accordingly, alternative medicines aiming at these shared mechanisms appeared subsequently to mimic ethanol-like effects with less liability, and some of them have achieved positive effects on different diseases with well-tolerance. However, more clinical trials with a large sample and long-term follow-ups are needed for pragmatic use of these medicines, and further investigations on mechanisms will continue to deepen the understanding of these diseases and also accelerate the discovery of ideal treatment.
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Affiliation(s)
| | | | | | - Li Cao
- Department of Neurology and Institute of Neurology, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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28
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Kosmowska B, Ossowska K, Konieczny J, Lenda T, Berghauzen-Maciejewska K, Wardas J. Inhibition of Excessive Glutamatergic Transmission in the Ventral Thalamic Nuclei by a Selective Adenosine A1 Receptor Agonist, 5′-Chloro-5′-Deoxy-(±)-ENBA Underlies its Tremorolytic Effect in the Harmaline-Induced Model of Essential Tremor. Neuroscience 2020; 429:106-118. [DOI: 10.1016/j.neuroscience.2019.12.045] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 12/16/2019] [Accepted: 12/28/2019] [Indexed: 12/20/2022]
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29
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Amrutkar DV, Dyhring T, Jacobsen TA, Larsen JS, Sandager-Nielsen K. Anti-Tremor Action of Subtype Selective Positive Allosteric Modulators of GABAA Receptors in a Rat Model of Essential Tremors. THE CEREBELLUM 2020; 19:265-274. [DOI: 10.1007/s12311-020-01106-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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30
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Lee J, Chang SY. Altered Primary Motor Cortex Neuronal Activity in a Rat Model of Harmaline-Induced Tremor During Thalamic Deep Brain Stimulation. Front Cell Neurosci 2019; 13:448. [PMID: 31680866 PMCID: PMC6803555 DOI: 10.3389/fncel.2019.00448] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 09/19/2019] [Indexed: 01/30/2023] Open
Abstract
Although deep brain stimulation (DBS) is a clinically effective surgical treatment for essential tremor (ET), and its neurophysiological mechanisms are not fully understood. As the motor thalamus is the most popular DBS target for ET, and it is known that the thalamic nucleus plays a key role in relaying information about the external environment to the cerebral cortex, it is important to investigate mechanisms of thalamic DBS in the context of the cerebello-thalamo-cortical neuronal network. To examine this, we measured single-unit neuronal activities in the resting state in M1 during VL thalamic DBS in harmaline-induced tremor rats and analyzed neuronal activity patterns in the thalamo-cortical circuit. Four activity patterns - including oscillatory burst, oscillatory non-burst, irregular burst, and irregular non-burst - were identified by harmaline administration; and those firing patterns were differentially affected by VL thalamic DBS, which seems to drive pathologic cortical signals to signals in normal status. As specific neuronal firing patterns like oscillation or burst are considered important for information processing, our results suggest that VL thalamic DBS may modify pathophysiologic relay information rather than simply inhibit the information transmission.
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Affiliation(s)
- Jihyun Lee
- Laboratory of Brain & Cognitive Sciences for Convergence Medicine, College of Medicine, Hallym University, Anyang, South Korea
| | - Su-Youne Chang
- Department of Neurologic Surgery, Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States
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31
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Lee J, Jo HJ, Kim I, Lee J, Min HK, In MH, Knight EJ, Chang SY. Mapping BOLD Activation by Pharmacologically Evoked Tremor in Swine. Front Neurosci 2019; 13:985. [PMID: 31619955 PMCID: PMC6759958 DOI: 10.3389/fnins.2019.00985] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 09/02/2019] [Indexed: 11/26/2022] Open
Abstract
Harmaline-induced tremor is one of the most commonly utilized disease models for essential tremor (ET). However, the underlying neural networks involved in harmaline-induced tremor and the degree to which these are a representative model of the pathophysiologic mechanism of ET are incompletely understood. In this study, we evaluated the functional brain network effects induced by systemic injection of harmaline using pharmacological functional magnetic resonance imaging (ph-fMRI) in the swine model. With harmaline administration, we observed significant activation changes in cerebellum, thalamus, and inferior olivary nucleus (ION). In addition, inter-regional correlations in activity between cerebellum and deep cerebellar nuclei and between cerebellum and thalamus were significantly enhanced. These harmaline-induced effects gradually decreased with repeated administration of drug, replicating the previously demonstrated ‘tolerance’ effect. This study demonstrates that harmaline-induced tremor is associated with activity changes in brain regions previously implicated in humans with ET. Thus, harmaline-induction of tremor in the swine may be a useful model to explore the neurological effects of novel therapeutic agents and/or neuromodulation techniques for ET.
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Affiliation(s)
- Jeyeon Lee
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States
| | - Hang Joon Jo
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States.,Department of Radiology, Mayo Clinic, Rochester, MN, United States.,Department of Neurology, Mayo Clinic, Rochester, MN, United States.,Department of Physiology, College of Medicine, Hanyang University, Seoul, South Korea
| | - Inyong Kim
- Department of Neurology, Mayo Clinic, Rochester, MN, United States
| | - Jihyun Lee
- Laboratory of Brain and Cognitive Sciences for Convergence Medicine, Hallym University College of Medicine, Anyang, South Korea
| | - Hoon-Ki Min
- Department of Radiology, Mayo Clinic, Rochester, MN, United States
| | - Myung-Ho In
- Department of Radiology, Mayo Clinic, Rochester, MN, United States
| | - Emily J Knight
- Department of Developmental Behavioral Pediatrics, University of Rochester, Rochester, NY, United States
| | - Su-Youne Chang
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States
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Carlsen EMM, Amrutkar DV, Sandager-Nielsen K, Perrier JF. Accurate and affordable assessment of physiological and pathological tremor in rodents using the accelerometer of a smartphone. J Neurophysiol 2019; 122:970-974. [DOI: 10.1152/jn.00281.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Tremor is a common symptom for the most prevalent neurological disorders, including essential tremor, spinal cord injury, multiple sclerosis, or Parkinson’s disease. Despite the devastating effects of tremor on life quality, available treatments are few and unspecific. Because of the need for specific and costly devices, tremor is rarely quantified by laboratories studying motor control without a genuine interest in trembling. We present a simple, reliable, and affordable method aimed at monitoring tremor in rodents, with an accuracy comparable to that of expensive, commercially available equipment. We took advantage of the accelerometer integrated in modern mobile phones working with operating systems capable of running downloaded apps. By fixing a smartphone to a cage suspended by rubber bands, we were able to detect faint vibrations of the cage. With a mouse in the cage, we showed that the acceleration signals on two horizontal axes were sufficient for the detection of physiological tremor and harmaline-induced tremor. We discuss the advantages and limitations of our method. NEW & NOTEWORTHY The majority of patients suffering from neurological disorders suffer from tremor that severely disrupts their life quality. Because of the high cost of specific scientific equipment, tremor is rarely quantified by laboratories working on motor behavior. For this reason, the potential anti-tremor effect of most compounds tested in animals remains unknown. We describe an affordable technique that will allow any laboratory to measure tremor accurately with a smartphone.
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Affiliation(s)
- Eva Maria Meier Carlsen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | | | | | - Jean-François Perrier
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
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33
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Chang S, Kim DH, Jang EY, Yoon SS, Gwak YS, Yi YJ, Lee JY, Ahn SH, Kim JM, Ryu YH, Kim SN, Roh HS, Lee MY, Kim SC, Lee BH, Kim HY, Yang CH. Acupuncture attenuates alcohol dependence through activation of endorphinergic input to the nucleus accumbens from the arcuate nucleus. SCIENCE ADVANCES 2019; 5:eaax1342. [PMID: 31517050 PMCID: PMC6726441 DOI: 10.1126/sciadv.aax1342] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 08/02/2019] [Indexed: 05/08/2023]
Abstract
A withdrawal-associated impairment in β-endorphin neurotransmission in the arcuate nucleus (ARC) of the hypothalamus is associated with alcohol dependence characterized by a chronic relapsing disorder. Although acupuncture activates β-endorphin neurons in the ARC projecting to the nucleus accumbens (NAc), a role for ARC β-endorphin neurons in alcohol dependence and acupuncture effects has not been examined. Here, we show that acupuncture at Shenmen (HT7) points attenuates behavioral manifestation of alcohol dependence by activating endorphinergic input to the NAc from the ARC. Acupuncture attenuated ethanol withdrawal tremor, anxiety-like behaviors, and ethanol self-administration in ethanol-dependent rats, which are mimicked by local injection of β-endorphin into the NAc. Acupuncture also reversed the decreased β-endorphin levels in the NAc and a reduction of neuronal activity in the ARC during ethanol withdrawal. These results suggest that acupuncture may provide a novel, potential treatment strategy for alcohol use disorder by direct activation of the brain pathway.
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Affiliation(s)
- Suchan Chang
- College of Korean Medicine, Daegu Haany University, Daegu 42158, Republic of Korea
| | - Dan Hyo Kim
- College of Korean Medicine, Daegu Haany University, Daegu 42158, Republic of Korea
| | - Eun Young Jang
- College of Korean Medicine, Daegu Haany University, Daegu 42158, Republic of Korea
| | - Seong Shoon Yoon
- College of Korean Medicine, Daegu Haany University, Daegu 42158, Republic of Korea
| | - Young Seob Gwak
- Department of Anesthesiology, Wake Forest Baptist Medical Center, Winston-Salem, NC 27157, USA
| | - Yoo Jung Yi
- College of Korean Medicine, Daegu Haany University, Daegu 42158, Republic of Korea
| | - Jun Yeon Lee
- College of Korean Medicine, Daegu Haany University, Daegu 42158, Republic of Korea
| | - Song Hee Ahn
- College of Korean Medicine, Daegu Haany University, Daegu 42158, Republic of Korea
| | - Jin Mook Kim
- College of Korean Medicine, Daegu Haany University, Daegu 42158, Republic of Korea
| | - Yeon-Hee Ryu
- Acupuncture, Moxibustion & Meridian Research Center, Korea Institute of Oriental Medicine, Daejeon 34054, Republic of Korea
| | - Seung-Nam Kim
- College of Korean Medicine, Dongguk University, Goyang 10326, Republic of Korea
| | - Hyo Sun Roh
- College of Korean Medicine, Dongguk University, Goyang 10326, Republic of Korea
| | - Mi-Young Lee
- College of Biomedical Science, Daegu Haany University, Gyeongbuk 38610, Republic of Korea
| | - Sang Chan Kim
- College of Korean Medicine, Daegu Haany University, Daegu 42158, Republic of Korea
| | - Bong Hyo Lee
- College of Korean Medicine, Daegu Haany University, Daegu 42158, Republic of Korea
| | - Hee Young Kim
- College of Korean Medicine, Daegu Haany University, Daegu 42158, Republic of Korea
- Corresponding author. (C.H.Y.); (H.Y.K.)
| | - Chae Ha Yang
- College of Korean Medicine, Daegu Haany University, Daegu 42158, Republic of Korea
- Corresponding author. (C.H.Y.); (H.Y.K.)
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Dahmardeh N, Shabani M, Basiri M, Kalantaripour TP, Asadi-Shekaari M. Functional Antagonism of Sphingosine-1-Phosphate Receptor 1 Prevents Harmaline-Induced Ultrastructural Alterations and Caspase-3 Mediated Apoptosis. Malays J Med Sci 2019; 26:28-38. [PMID: 31496891 PMCID: PMC6719891 DOI: 10.21315/mjms2019.26.4.4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 07/22/2019] [Indexed: 12/21/2022] Open
Abstract
Background There is a meaningful necessity for a targeted therapy of essential tremor (ET), as medications have not been developed specifically for ET. For nearly a century, many drugs have been applied in the treatment of tremor but the drug treatment of ET remains still unknown. Some potential therapeutic factors such fingolimod (FTY720) can be effectively used to treat ET in animals. In the present research, the effect of FTY720, the immunomodulatory sphingosine 1-phosphate (S1P) analog, on degeneration of cerebellar and olivary neurons induced by harmaline in male rats was investigated. Methods The animals were allotted into control dimethyl sulfoxide (DMSO), saline + harmaline [30 mg/kg, intraperitoneally, (i.p.)], harmaline + FTY720 (1 mg/kg, i.p, 1 h and 24 h before harmaline injection) groups (n = 10). The cerebellum and inferior olive nucleus (ION) were studied for neuronal degeneration using immunohistochemistry (IHC) and ultrastructural study by transmission electron microscopy (TEM) techniques. Results Harmaline caused neuronal cell loss, caspase-3 mediated apoptosis, astrocytosis and ultrastructural changes in cerebellar Purkinje cells and inferior olive neurons. FTY720 exhibited neuroprotective effects on cerebellar Purkinje cells and inferior olivary neurons. Conclusion These results suggest that FTY720 has potential efficacy for prevention of ET neurodegeneration and astrocytosis induced by harmaline in male rats.
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Affiliation(s)
- Narjes Dahmardeh
- Department of Anatomical Sciences, Afzalipour Medical Faculty, Kerman University of Medical Sciences, Kerman, Iran.,Department of Anatomical Sciences, Faculty of Medicine, Zabol University of Medical Sciences, Zabol, Iran
| | - Mohammad Shabani
- Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran
| | - Mohsen Basiri
- Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran
| | - Taj Pari Kalantaripour
- Department of Physiology, School of Medicine, Kerman Branch, Islamic Azad University, Kerman, Iran
| | - Majid Asadi-Shekaari
- Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran
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Reddy P, Rochfort S, Read E, Deseo M, Jaehne E, Van Den Buuse M, Guthridge K, Combs M, Spangenberg G, Quinn J. Tremorgenic effects and functional metabolomics analysis of lolitrem B and its biosynthetic intermediates. Sci Rep 2019; 9:9364. [PMID: 31249318 PMCID: PMC6597573 DOI: 10.1038/s41598-019-45170-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 05/30/2019] [Indexed: 01/02/2023] Open
Abstract
The neuroactive mycotoxin lolitrem B causes a neurological syndrome in grazing livestock resulting in hyperexcitability, muscle tremors, ataxia and, in severe cases, clonic seizures and death. To define the effects of the major toxin lolitrem B in the brain, a functional metabolomic study was undertaken in which motor coordination and tremor were quantified and metabolomic profiling undertaken to determine relative abundance of both toxin and key neurotransmitters in various brain regions in male mice. Marked differences were observed in the duration of tremor and coordination between lolitrem B pathway members, with some showing protracted effects and others none at all. Lolitrem B was identified in liver, kidney, cerebral cortex and thalamus but not in brainstem or cerebellum which were hypothesised previously to be the primary site of action. Metabolomic profiling showed significant variation in specific neurotransmitter and amino acid profiles over time. This study demonstrates accumulation of lolitrem B in the brain, with non-detectable levels of toxin in the brainstem and cerebellum, inducing alterations in metabolites such as tyrosine, suggesting a dynamic catecholaminergic response over time. Temporal characterisation of key pathways in the pathophysiological response of lolitrem B in the brain were also identified.
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Affiliation(s)
- Priyanka Reddy
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, Victoria, 3083, Australia
- School of Applied Systems Biology, La Trobe University, Bundoora, Victoria, 3083, Australia
| | - Simone Rochfort
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, Victoria, 3083, Australia.
- School of Applied Systems Biology, La Trobe University, Bundoora, Victoria, 3083, Australia.
| | - Elizabeth Read
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, Victoria, 3083, Australia
- School of Applied Systems Biology, La Trobe University, Bundoora, Victoria, 3083, Australia
| | - Myrna Deseo
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, Victoria, 3083, Australia
| | - Emily Jaehne
- School of Psychology and Public Health, La Trobe University, Bundoora, Victoria, 3083, Australia
| | - Maarten Van Den Buuse
- School of Psychology and Public Health, La Trobe University, Bundoora, Victoria, 3083, Australia
| | - Kathryn Guthridge
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, Victoria, 3083, Australia
| | - Martin Combs
- School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, NSW, 2678, Australia
- Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW, 2650, Australia
| | - German Spangenberg
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, Victoria, 3083, Australia
- School of Applied Systems Biology, La Trobe University, Bundoora, Victoria, 3083, Australia
| | - Jane Quinn
- School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, NSW, 2678, Australia
- Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW, 2650, Australia
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Combs MD, Hamlin A, Quinn JC. A single exposure to the tremorgenic mycotoxin lolitrem B inhibits voluntary motor activity and spatial orientation but not spatial learning or memory in mice. Toxicon 2019; 168:58-66. [PMID: 31254599 DOI: 10.1016/j.toxicon.2019.06.228] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 06/19/2019] [Accepted: 06/25/2019] [Indexed: 10/26/2022]
Abstract
The indole diterpenoid toxin lolitrem B is a tremorgenic agent found in the common grass species, perennial ryegrass (Lolium perenne). The toxin is produced by a symbiotic fungus Epichloë festucae (var. lolii) and ingestion of infested grass with sufficient toxin levels causes a movement disorder in grazing herbivores known as 'ryegrass staggers'. Beside ataxia, lolitrem B intoxicated animals frequently show indicators of cognitive dysfunction or exhibition of erratic and unpredictable behaviours during handling. Evidence from field cases in livestock and controlled feeding studies in horses have indicated that intoxication with lolitrem B may affect higher cortical or subcortical functioning. In order to define the role of lolitrem B in voluntary motor control, spatial learning and memory under controlled conditions, mice were exposed to a known dose of purified lolitrem B toxin and tremor, coordination, voluntary motor activity and spatial learning and memory assessed. Motor activity, coordination and spatial memory were compared to tremor intensity using a novel quantitative piezo-electronic tremor analysis. Peak tremor was observed as frequencies between 15 and 25Hz compared to normal movement at approximately 1.4-10Hz. A single exposure to a known tremorgenic dose of lolitrem B (2 mg/kg IP) induced measureable tremor for up to 72 h in some animals. Initially, intoxication with lolitrem B significantly decreased voluntary movement. By 25 h post exposure a return to normal voluntary movement was observed in this group, despite continuing evidence of tremor. This effect was not observed in animals exposed to the short-acting tremorgenic toxin paxilline. Lolitrem B intoxicated mice demonstrated a random search pattern and delayed latency to escape a 3 h post intoxication, however by 27 h post exposure latency to escape matched controls and mice had returned to normal searching behavior indicating normal spatial learning and memory. Together these data indicate that the tremor exhibited by lolitrem B intoxicated mice does not directly impair spatial learning and memory but that exposure does reduce voluntary motor activity in intoxicated animals. Management of acutely affected livestock suffering toxicosis should be considered in the context of their ability to spatially orientate with severe toxicity.
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Affiliation(s)
- M D Combs
- School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, 2560, Australia; Graham Centre for Agricultural Innovation (NSW Department of Primary Industries and Charles Sturt University), Wagga Wagga, New South Wales, 2560, Australia
| | - A Hamlin
- School of Science and Technology, University of New England, Armidale, NSW, 2351, Australia
| | - J C Quinn
- School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, 2560, Australia; Graham Centre for Agricultural Innovation (NSW Department of Primary Industries and Charles Sturt University), Wagga Wagga, New South Wales, 2560, Australia.
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Pan MK, Ni CL, Wu YC, Li YS, Kuo SH. Animal Models of Tremor: Relevance to Human Tremor Disorders. Tremor Other Hyperkinet Mov (N Y) 2018; 8:587. [PMID: 30402338 PMCID: PMC6214818 DOI: 10.7916/d89s37mv] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 08/10/2018] [Indexed: 12/17/2022] Open
Abstract
Background Tremor is the most common movement disorder; however, the pathophysiology of tremor remains elusive. While several neuropathological alterations in tremor disorders have been observed in post-mortem studies of human brains, a full understanding of the relationship between brain circuitry alterations and tremor requires testing in animal models. Additionally, tremor animal models are critical for our understanding of tremor pathophysiology, and/or to serve as a platform for therapy development. Methods A PubMed search was conducted in May 2018 to identify published papers for review. Results The methodology used in most studies on animal models of tremor lacks standardized measurement of tremor frequency and amplitude; instead, these studies are based on the visual inspection of phenotypes, which may fail to delineate tremor from other movement disorders such as ataxia. Of the animal models with extensive tremor characterization, harmaline-induced rodent tremor models provide an important framework showing that rhythmic and synchronous neuronal activities within the olivocerebellar circuit can drive action tremor. In addition, dopamine-depleted monkey and mouse models may develop rest tremor, highlighting the role of dopamine in rest tremor generation. Finally, other animal models of tremor have involvement of the cerebellar circuitry, leading to altered Purkinje cell physiology. Discussion Both the cerebellum and the basal ganglia are likely to play a role in tremor generation. While the cerebellar circuitry can generate rhythmic movements, the nigrostriatal system is likely to modulate the tremor circuit. Tremor disorders are heterogeneous in nature. Therefore, each animal model may represent a subset of tremor disorders, which collectively can advance our understanding of tremor.
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Affiliation(s)
- Ming-Kai Pan
- Department of Medical Research, National Taiwan University, Taipei, TW
| | - Chun-Lun Ni
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Yeuh-Chi Wu
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Yong-Shi Li
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Sheng-Han Kuo
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
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Handforth A, Kadam PA, Kosoyan HP, Eslami P. Suppression of Harmaline Tremor by Activation of an Extrasynaptic GABA A Receptor: Implications for Essential Tremor. TREMOR AND OTHER HYPERKINETIC MOVEMENTS (NEW YORK, N.Y.) 2018; 8:546. [PMID: 30191083 PMCID: PMC6125735 DOI: 10.7916/d8jw9x9k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 06/05/2018] [Indexed: 12/13/2022]
Abstract
Background Metabolic imaging has revealed excessive cerebellar activity in essential tremor patients. Golgi cells control cerebellar activity by releasing gamma-aminobutyric acid (GABA) onto synaptic and extrasynaptic receptors on cerebellar granule cells. We postulated that the extrasynaptic GABAA receptor-specific agonist THIP (gaboxadol; 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) would suppress tremor in the harmaline model of essential tremor and, since cerebellar extrasynaptic receptors contain α6 and δ subunits, would fail to do so in mice lacking either subunit. Methods Digitally measured motion power, expressed as 10-16 Hz power (the tremor bandwidth) divided by background 8-32 Hz motion power, was accessed during pre-harmaline baseline, pre-THIP harmaline exposure, and after THIP administration (0, 2, or 3 mg/kg). These low doses were chosen as they did not impair performance on the straight wire test, a sensitive test for psychomotor impairment. Littermate δ wild-type and knockout (Gabrd+/+, Gabrd-/-) and littermate α6 wild-type and knockout (Gabra6+/+, Gabra6-/- ) mice were tested. Results Gabrd+/+ mice displayed tremor reduction at 3 mg/kg THIP but not 2 mg/kg, and Gabra6+/+ mice showed tremor reduction at 2 and 3 mg/kg. Their respective subunit knockout littermates displayed no tremor reduction compared with vehicle controls at either dose. Discussion The loss of anti-tremor efficacy with deletion of either δ or α6 GABAA receptor subunits indicates that extrasynaptic receptors containing both subunits, most likely located on cerebellar granule cells where they are highly expressed, mediate tremor suppression by THIP. A medication designed to activate only these receptors may display a favorable profile for treating essential tremor.
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Affiliation(s)
- Adrian Handforth
- Neurology Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Pournima A Kadam
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Hovsep P Kosoyan
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Pirooz Eslami
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
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Lee J, Kim I, Lee J, Knight E, Cheng L, Kang SI, Jang DP, Chang SY. Development of Harmaline-induced Tremor in a Swine Model. Tremor Other Hyperkinet Mov (N Y) 2018; 8:532. [PMID: 29686939 PMCID: PMC5910538 DOI: 10.7916/d8j68tv7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 02/05/2018] [Indexed: 12/01/2022] Open
Abstract
Background In the field of translational neuroscience research, it is critical to utilize a large animal model to test the feasibility, safety, and functionality of novel therapies. Here, we describe a protocol for the development of a large animal model of tremor. Methods In a pig model, tremor was induced with harmaline and measured with wireless accelerometers attached to the limbs. Three different doses of harmaline were tested and three repetitive injections were made at 72-hour intervals. To fully characterize the drug-induced tremor, onset time, tremor amplitude, maintained duration, and peak tremor frequency were analyzed. Results Harmaline-induced tremor appeared immediately following intravenous injection of harmaline. Tremor was maintained over 2 hours. Its frequency was 10-16 Hz, which was independent of doses. Dose-dependent responses were observed in tremor amplitude, triggering time, and tremor-maintained duration. Repetitive injection of harmaline desensitized the harmaline effect. Discussion We provide a detailed protocol for training, drug injection, device selection, and tremor recording optimized to create a swine model of tremor with harmaline. Our protocol provides reliable tremor in pigs and suggests pig as a valid translational large animal model of tremor.
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Affiliation(s)
- Jihyun Lee
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Inyong Kim
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Jeyeon Lee
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Emily Knight
- Department of Pediatrics, New York-Presbyterian Weill Cornell Medical Center, New York, NY, USA
| | - Lei Cheng
- Department of Neurosurgery, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Shin il Kang
- Department of Biomedical Engineering, Hanyang University, Hanyang, Korea
| | - Dong Pyo Jang
- Department of Biomedical Engineering, Hanyang University, Hanyang, Korea
| | - Su-Youne Chang
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
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Abstract
Essential tremor (ET) is a progressive and highly prevalent neurologic disease. Along with the tremors, mild to moderate gait ataxia and other signs of cerebellar dysfunction may occur (i.e., subtle saccadic eye movement abnormalities and abnormalities of motor timing) as well as cognitive features, some of which may be due to cerebellar dysfunction. Numerous neuroimaging studies indicate the presence of functional, metabolic, and structural abnormalities in the cerebellum of a patient with ET. In tandem with these clinical and imaging studies, which were gathering increasing support for the notion that the cerebellum and/or cerebellar systems seemed to be at the root of ET, a growing postmortem literature is for the first time beginning to identify microscopic abnormalities in the ET brain, most of which are centered on the Purkinje cells and connected neuronal populations, and are likely to be degenerative. In terms of treatment, most of these pharmacotherapeutic agents serve to enhance GABAergic neurotransmission, further bolstering the notion that ET may very well be a disorder with a primary Purkinje cell dysfunction resulting in reduced cerebellar cortical inhibition. Similarly, the interruption of presumably abnormal cerebellar outflow pathways to the thalamus is the mechanism of deep-brain stimulation surgery, which is highly effective in treating ET.
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Affiliation(s)
- Elan D Louis
- Department of Neurology and Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine, Yale University, New Haven, CT, United States; Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale University, New Haven, CT, United States.
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41
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Hopfner F, Deuschl G. Is essential tremor a single entity? Eur J Neurol 2017; 25:71-82. [DOI: 10.1111/ene.13454] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Accepted: 09/01/2017] [Indexed: 12/18/2022]
Affiliation(s)
- F. Hopfner
- Department of Neurology; Universitätsklinikum Schleswig-Holstein; Kiel Campus Germany
- Christian-Albrechts Universität; Kiel Germany
| | - G. Deuschl
- Department of Neurology; Universitätsklinikum Schleswig-Holstein; Kiel Campus Germany
- Christian-Albrechts Universität; Kiel Germany
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Gan SR, Wang J, Figueroa KP, Pulst SM, Tomishon D, Lee D, Perlman S, Wilmot G, Gomez CM, Schmahmann J, Paulson H, Shakkottai VG, Ying SH, Zesiewicz T, Bushara K, Geschwind MD, Xia G, Subramony SH, Ashizawa T, Kuo SH. Postural Tremor and Ataxia Progression in Spinocerebellar Ataxias. Tremor Other Hyperkinet Mov (N Y) 2017; 7:492. [PMID: 29057148 PMCID: PMC5647398 DOI: 10.7916/d8gm8krh] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 09/07/2017] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Postural tremor can sometimes occur in spinocerebellar ataxias (SCAs). However, the prevalence and clinical characteristics of postural tremor in SCAs are poorly understood, and whether SCA patients with postural tremor have different ataxia progression is not known. METHODS We studied postural tremor in 315 patients with SCA1, 2, 3, and 6 recruited from the Clinical Research Consortium for Spinocerebellar Ataxias (CRC-SCA), which consists of 12 participating centers in the United States, and we evaluated ataxia progression in these patients from January 2010 to August 2012. RESULTS Among 315 SCA patients, postural tremor was most common in SCA2 patients (SCA1, 5.8%; SCA2, 27.5%; SCA3, 12.4%; SCA6, 16.9%; p = 0.007). SCA3 patients with postural tremor had longer CAG repeat expansions than SCA3 patients without postural tremor (73.67 ± 3.12 vs. 70.42 ± 3.96, p = 0.003). Interestingly, SCA1 and SCA6 patients with postural tremor had a slower rate of ataxia progression (SCA1, β = -0.91, p < 0.001; SCA6, β = -1.28, p = 0.025), while SCA2 patients with postural tremor had a faster rate of ataxia progression (β = 1.54, p = 0.034). We also found that the presence of postural tremor in SCA2 patients could be influenced by repeat expansions of ATXN1 (β = -1.53, p = 0.037) and ATXN3 (β = 0.57, p = 0.018), whereas postural tremor in SCA3 was associated with repeat lengths in TBP (β = 0.63, p = 0.041) and PPP2R2B (β = -0.40, p = 0.032). DISCUSSION Postural tremor could be a clinical feature of SCAs, and the presence of postural tremor could be associated with different rates of ataxia progression. Genetic interactions between ataxia genes might influence the brain circuitry and thus affect the clinical presentation of postural tremor.
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Affiliation(s)
- Shi-Rui Gan
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Jie Wang
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Department of Basic and Community Nursing, School of Nursing, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Karla P. Figueroa
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | - Stefan M. Pulst
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | - Darya Tomishon
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Danielle Lee
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Susan Perlman
- Department of Neurology, University of California, Los Angeles, CA, USA
| | - George Wilmot
- Department of Neurology, Emory University, Atlanta, GA, USA
| | | | - Jeremy Schmahmann
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Henry Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | | | - Sarah H. Ying
- Department of Neurology, Johns Hopkins University, Baltimore, MD, USA
| | - Theresa Zesiewicz
- Department of Neurology, University of South Florida, Tampa, FL, USA
| | - Khalaf Bushara
- Department of Neurology, University of Minnesota, Minneapolis, MN, USA
| | | | - Guangbin Xia
- Department of Neurology, School of Medicine, University of New Mexico, Albuquerque, NM, USA
| | - S. H. Subramony
- Department of Neurology, School of Medicine, University of New Mexico, Albuquerque, NM, USA
| | | | - Sheng-Han Kuo
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
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Dahmardeh N, Asadi-Shekaari M, Arjmand S, Kalantaripour T, Basiri M, Shabani M. Modulation of sphingosine-1-phosphate receptor ameliorates harmaline-induced essential tremor in rat. Neurosci Lett 2017. [PMID: 28627375 DOI: 10.1016/j.neulet.2017.06.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Essential tremor (ET) is one of the most common movement disorders with unknown etiology. Despite lack of effective clinical treatments, some potential therapeutic factors and modulation of some neurotransmitters have been utilized to ameliorate motor symptoms in the animal models of tremor. In the current study, male Wistar rats (n=10 in each group) weighing 40-60g were divided into vehicle control groups (saline or DMSO), saline/DMSO+harmaline (30mg/kg, i.p.)+fingolimod (FTY720) (1mg/kg, i.p, 1h before harmaline injection) groups. Open field, rotarod, wire grip and foot print tests were used to evaluate motor function. The results demonstrated that administration of FTY720 can improve harmaline-induced tremor in rats. Moreover, FTY720 ameliorated gait disturbance. The results showed that FTY720 can recover step width, left and right step length; however, FTY720 failed to recover mobility duration. FTY720 also improved falling time and time spent in wire grip and rotarod, respectively. The current study provides the first evidence for the effectiveness of FTY720 on motor function in the harmaline model of ET. Furthermore, neuroprotective effects of FTY720 demonstrated in this study offer sphingosine-1-phosphate receptor (S1PR) modulators as a potential neuroprotective candidate against substance-induced tremor and a possible strategy for the treatment of patients with tremor.
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Affiliation(s)
- Narjes Dahmardeh
- Intracellular Recording Lab, Kerman Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran; Department of Anatomical Sciences, Afzalipour Medical Faculty, Kerman University of Medical Sciences, Kerman, Iran
| | - Majid Asadi-Shekaari
- Intracellular Recording Lab, Kerman Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran
| | - Shokouh Arjmand
- Intracellular Recording Lab, Kerman Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran
| | - Tajpari Kalantaripour
- Department of Physiology, School of Medicine, Islamic Azad University, Branch of Kerman, Kerman, Iran
| | - Mohsen Basiri
- Department of Anatomical Sciences, Afzalipour Medical Faculty, Kerman University of Medical Sciences, Kerman, Iran
| | - Mohammad Shabani
- Intracellular Recording Lab, Kerman Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran.
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Marin-Lahoz J, Gironell A. Linking Essential Tremor to the Cerebellum: Neurochemical Evidence. THE CEREBELLUM 2017; 15:243-52. [PMID: 26498765 DOI: 10.1007/s12311-015-0735-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The pathophysiology and the exact anatomy of essential tremor (ET) is not well known. One of the pillars that support the cerebellum as the main anatomical locus in ET is neurochemistry. This review examines the link between neurochemical abnormalities found in ET and cerebellum. The review is based on published data about neurochemical abnormalities described in ET both in human and in animal studies. We try to link those findings with cerebellum. γ-aminobutyric acid (GABA) is the main neurotransmitter involved in the pathophysiology of ET. There are several studies about GABA that clearly points to a main role of the cerebellum. There are few data about other neurochemical abnormalities in ET. These include studies with noradrenaline, glutamate, adenosine, proteins, and T-type calcium channels. One single study reveals high levels of noradrenaline in the cerebellar cortex. Another study about serotonin neurotransmitter results negative for cerebellum involvement. Finally, studies on T-type calcium channels yield positive results linking the rhythmicity of ET and cerebellum. Neurochemistry supports the cerebellum as the main anatomical locus in ET. The main neurotransmitter involved is GABA, and the GABA hypothesis remains the most robust pathophysiological theory of ET to date. However, this hypothesis does not rule out other mechanisms and may be seen as the main scaffold to support findings in other systems. We clearly need to perform more studies about neurochemistry in ET to better understand the relations among the diverse systems implied in ET. This is mandatory to develop more effective pharmacological therapies.
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Affiliation(s)
- Juan Marin-Lahoz
- Movement Disorders Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, Av.Sant Antoni Maria Claret, 167, 08025, Barcelona, Catalonia, Spain
| | - Alexandre Gironell
- Movement Disorders Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, Av.Sant Antoni Maria Claret, 167, 08025, Barcelona, Catalonia, Spain.
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Knowledge gaps and research recommendations for essential tremor. Parkinsonism Relat Disord 2016; 33:27-35. [PMID: 27769649 DOI: 10.1016/j.parkreldis.2016.10.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 08/29/2016] [Accepted: 10/01/2016] [Indexed: 12/17/2022]
Abstract
Essential tremor (ET) is a common cause of significant disability, but its etiologies and pathogenesis are poorly understood. Research has been hampered by the variable definition of ET and by non-standardized research approaches. The National Institute of Neurological Disorders and Stroke (USA) invited experts in ET and related fields to discuss current knowledge, controversies, and gaps in our understanding of ET and to develop recommendations for future research. Discussion focused on phenomenology and phenotypes, therapies and clinical trials, pathophysiology, pathology, and genetics. Across all areas, the need for collaborative and coordinated research on a multinational level was expressed. Standardized data collection using common data elements for genetic, clinical, neurophysiological, and pathological studies was recommended. Large cohorts of patients should be studied prospectively to collect bio-samples, characterize the natural history of the clinical syndrome including patient-oriented outcomes, investigate potential etiologies of various phenotypes, and identify pathophysiological mechanisms. In particular, cellular and system-level mechanisms of tremor oscillations should be elucidated because they may yield effective therapeutic targets and biomarkers. A neuropathology consortium was recommended to standardize postmortem analysis and further characterize neuropathological observations in the cerebellum and elsewhere. Furthermore, genome-wide association studies on large patient cohorts (>10,000 patients) may allow the identification of common genes contributing to risk, and whole exome or genome sequencing may enable the identification of genetic risk and causal mutations in cohorts and well-characterized families.
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Abbassian H, Whalley BJ, Sheibani V, Shabani M. Cannabinoid type 1 receptor antagonism ameliorates harmaline-induced essential tremor in rat. Br J Pharmacol 2016; 173:3196-3207. [PMID: 27545646 DOI: 10.1111/bph.13581] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 08/16/2016] [Accepted: 08/17/2016] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE Essential tremor (ET) is a neurological disorder with unknown aetiology. Its symptoms include cerebellar motor disturbances, cognitive and personality changes, hearing and olfactory deficits. Hyperactivity of excitotoxic cerebellar climbing fibres may underlie essential tremor and has been induced in rodents by systemic harmaline administration. Cannabinoid (CB) receptor agonists can cause motor disturbances; although, there are also anecdotal reports of therapeutic benefits of cannabis in motor disorders. We set out to establish the effects of CB receptor agonism and antagonism on an established rodent model of ET using a battery of accepted behaviour assays in order to determine the risk and therapeutic potential of modulating the endocannabinoid system in ET. EXPERIMENTAL APPROACH Behavioural effects of systemic treatment with a CB receptor agonist (0.1, 0.5 and 1 mg kg-1 WIN55, 212-2) or two CB1 receptor antagonists (1 mg kg-1 AM251 and 10 mg kg-1 rimonabant) on tremor induced in rats by harmaline (30 mg kg-1 ; i.p.), were assessed using tremor scoring, open field, rotarod, grip and gait tests. KEY RESULTS Overall, harmaline induced robust tremor that was typically worsened across the measured behavioural domains by CB receptor agonism but ameliorated by CB1 receptor antagonism. CONCLUSIONS AND IMPLICATIONS These results provide the first evidence of the effects of modulating the endocannabinoid system on motor function in the harmaline model of ET. Our data suggest that CB1 receptor manipulation warrants clinical investigation as a therapeutic approach to protection against behavioural disturbances associated with ET.
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Affiliation(s)
- Hassan Abbassian
- Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran
| | - Benjamin J Whalley
- Department of Pharmacy, School of Chemistry, Food and Nutritional Sciences and Pharmacy, University of Reading, Whiteknights, Reading, Berkshire, UK.
| | - Vahid Sheibani
- Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran
| | - Mohammad Shabani
- Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran. ,
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Stroh MA, Winter MK, Swerdlow RH, McCarson KE, Zhu H. Loss of NCB5OR in the cerebellum disturbs iron pathways, potentiates behavioral abnormalities, and exacerbates harmaline-induced tremor in mice. Metab Brain Dis 2016; 31:951-64. [PMID: 27188291 PMCID: PMC5929129 DOI: 10.1007/s11011-016-9834-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 05/01/2016] [Indexed: 12/13/2022]
Abstract
Iron dyshomeostasis has been implicated in many diseases, including a number of neurological conditions. Cytosolic NADH cytochrome b5 oxidoreductase (NCB5OR) is ubiquitously expressed in animal tissues and is capable of reducing ferric iron in vitro. We previously reported that global gene ablation of NCB5OR resulted in early-onset diabetes and altered iron homeostasis in mice. To further investigate the specific effects of NCB5OR deficiency on neural tissue without contributions from known phenotypes, we generated a conditional knockout (CKO) mouse that lacks NCB5OR only in the cerebellum and midbrain. Assessment of molecular markers in the cerebellum of CKO mice revealed changes in pathways associated with cellular and mitochondrial iron homeostasis. (59)Fe pulse-feeding experiments revealed cerebellum-specific increased or decreased uptake of iron by 7 and 16 weeks of age, respectively. Additionally, we characterized behavioral changes associated with loss of NCB5OR in the cerebellum and midbrain in the context of dietary iron deprivation-evoked generalized iron deficiency. Locomotor activity was reduced and complex motor task execution was altered in CKO mice treated with an iron deficient diet. A sucrose preference test revealed that the reward response was intact in CKO mice, but that iron deficient diet consumption altered sucrose preference in all mice. Detailed gait analysis revealed locomotor changes in CKO mice associated with dysfunctional proprioception and locomotor activation independent of dietary iron deficiency. Finally, we demonstrate that loss of NCB5OR in the cerebellum and midbrain exacerbated harmaline-induced tremor activity. Our findings suggest an essential role for NCB5OR in maintaining both iron homeostasis and the proper functioning of various locomotor pathways in the mouse cerebellum and midbrain.
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Affiliation(s)
- Matthew A Stroh
- Landon Center on Aging, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 1005, Kansas City, KS, 66160, USA
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3030, Kansas City, KS, 66160, USA
- Neuroscience Graduate Program, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3038, Kansas City, KS, 66160, USA
| | - Michelle K Winter
- Kansas Intellectual and Developmental Disabilities Research Center, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3051, Kansas City, KS, 66160, USA
| | - Russell H Swerdlow
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3030, Kansas City, KS, 66160, USA
- Neuroscience Graduate Program, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3038, Kansas City, KS, 66160, USA
- Department of Neurology, University of Kansas Medical Center, 3599 Rainbow Blvd., MSN 2012, Kansas City, KS, 66160, USA
| | - Kenneth E McCarson
- Kansas Intellectual and Developmental Disabilities Research Center, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3051, Kansas City, KS, 66160, USA
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 1018, Kansas City, KS, 66160, USA
| | - Hao Zhu
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3030, Kansas City, KS, 66160, USA.
- Neuroscience Graduate Program, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3038, Kansas City, KS, 66160, USA.
- Department of Clinical Laboratory Sciences, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 4048G-Eaton, Kansas City, KS, 66160, USA.
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Ondo W. Essential Tremor: What We Can Learn from Current Pharmacotherapy. Tremor Other Hyperkinet Mov (N Y) 2016; 6:356. [PMID: 26989572 PMCID: PMC4790207 DOI: 10.7916/d8k35tc3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 12/17/2015] [Indexed: 04/07/2023] Open
Abstract
BACKGROUND The pathophysiology of essential tremor, especially at the cellular level, is poorly understood. Although no drug has been specifically designed to treat essential tremor, several medications improve tremor, and others worsen it. Studying the mechanism of actions of these medications can help our understanding of tremor pathophysiology and contribute to future rational drug design. METHODS We reviewed literature, concentrating on mechanisms of action, of various medications that mitigate tremor. RESULTS Many medications have multiple mechanisms of actions, making simple correlations difficult. Medications that increase the duration of opening of gamma-aminobutyric acid (GABA)-A receptors are most consistently associated with tremor improvement. Interestingly, drugs that increase GABA availability have not been associated with improved tremor. Other mechanisms possibly associated with tremor improvement include antagonism of alpha-2 delta subunits associated with calcium channels, inhibition of carbonic anhydrase, and inhibition of the synaptic vesicle protein 2A. Drugs that block voltage-gaited sodium channels do not affect tremor. The ideal beta-adrenergic blocker requires B2 affinity (non-cardiac selective), has no sympathomimetic properties, does not require membrane stabilization properties, and may benefit from good central nervous system penetration. DISCUSSION To date, serendipitous observations have provided most of our understanding of tremor cellular physiology. Based on similarities to currently effective drugs or rational approximations and inferences, several currently available agents should be considered for tremor trials.
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Affiliation(s)
- William Ondo
- Methodist Neurological Institute, Houston, TX, USA
- *To whom correspondence should be addressed. E-mail:
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Djamshidian A, Bernschneider-Reif S, Poewe W, Lees AJ. Banisteriopsis caapi, a Forgotten Potential Therapy for Parkinson's Disease? Mov Disord Clin Pract 2015; 3:19-26. [PMID: 30713897 DOI: 10.1002/mdc3.12242] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 06/30/2015] [Accepted: 07/07/2015] [Indexed: 01/02/2023] Open
Abstract
Banisteriopsis caapi, a liana indigenous to the Amazon basin with metagnomigenic properties and possible anti-depressant effects is one of the natural sources of harmala alkaloids. A summary of early trials with extracts of Banisteriopsis caapi and Peganum harmala (from which harmine was first isolated) in the 1920s and 1930s on various forms of parkinsonism is given as well as a brief overview of the known pharmacological properties of harmine. Despite its earlier abandonment because of perceived weaker efficacy than solanaceous alkaloids like scopolamine and hyoscine we propose that harmine should be reconsidered as a potential rapidly acting anti-Parkinsonian agent.
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Affiliation(s)
- Atbin Djamshidian
- Department of Molecular Neuroscience and Reta Lila Weston Institute for Neurological Studies University of London London United Kingdom.,Department of Neurology Medical University Innsbruck Innsbruck Austria
| | | | - Werner Poewe
- Department of Neurology Medical University Innsbruck Innsbruck Austria
| | - Andrew J Lees
- Department of Molecular Neuroscience and Reta Lila Weston Institute for Neurological Studies University of London London United Kingdom
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Ossowska K, Głowacka U, Kosmowska B, Wardas J. Apomorphine enhances harmaline-induced tremor in rats. Pharmacol Rep 2015; 67:435-41. [DOI: 10.1016/j.pharep.2014.11.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 11/08/2014] [Accepted: 11/13/2014] [Indexed: 10/24/2022]
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