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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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2
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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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3
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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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4
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Baumel Y, Yamin HG, Cohen D. Chemical suppression of harmaline-induced body tremor yields recovery of pairwise neuronal coherence in cerebellar nuclei neurons. Front Syst Neurosci 2023; 17:1135799. [PMID: 37251003 PMCID: PMC10211344 DOI: 10.3389/fnsys.2023.1135799] [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: 01/01/2023] [Accepted: 04/21/2023] [Indexed: 05/31/2023] Open
Abstract
Neuronal oscillations occur in health and disease; however, their characteristics can differ across conditions. During voluntary movement in freely moving rats, cerebellar nuclei (CN) neurons display intermittent but coherent oscillations in the theta frequency band (4-12 Hz). However, in the rat harmaline model of essential tremor, a disorder attributed to cerebellar malfunction, CN neurons display aberrant oscillations concomitantly with the emergence of body tremor. To identify the oscillation features that may underlie the emergence of body tremor, we analyzed neuronal activity recorded chronically from the rat CN under three conditions: in freely behaving animals, in harmaline-treated animals, and during chemical suppression of the harmaline-induced body tremor. Suppression of body tremor did not restore single neuron firing characteristics such as firing rate, the global and local coefficients of variation, the likelihood of a neuron to fire in bursts or their tendency to oscillate at a variety of dominant frequencies. Similarly, the fraction of simultaneously recorded neuronal pairs oscillating at a similar dominant frequency (<1 Hz deviation) and the mean frequency deviation within pairs remained similar to the harmaline condition. Moreover, the likelihood that pairs of CN neurons would co-oscillate was not only significantly lower than that measured in freely moving animals, but was significantly worse than chance. By contrast, the chemical suppression of body tremor fully restored pairwise neuronal coherence; that is, unlike in the harmaline condition, pairs of neurons that oscillated at the same time and frequency displayed high coherence, as in the controls. We suggest that oscillation coherence in CN neurons is essential for the execution of smooth movement and its loss likely underlies the emergence of body tremor.
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Affiliation(s)
| | | | - Dana Cohen
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel
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5
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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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6
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Srinivasan SR. Targeting Circuit Abnormalities in Neurodegenerative Disease. Mol Pharmacol 2023; 103:38-44. [PMID: 36310030 DOI: 10.1124/molpharm.122.000563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 10/18/2022] [Accepted: 10/24/2022] [Indexed: 02/03/2023] Open
Abstract
Despite significant improvement in our ability to diagnose both common and rare neurodegenerative diseases and understand their underlying biologic mechanisms, there remains a disproportionate lack of effective treatments, reflecting the complexity of these disorders. Successfully advancing novel treatments for neurodegenerative disorders will require reconsideration of traditional approaches, which to date have focused largely on specific disease proteins or cells of origin. This article proposes reframing these diseases as conditions of dysfunctional circuitry as a complement to ongoing efforts. Specifically reviewed is how aberrant spiking is a common downstream mechanism in numerous neurodegenerative diseases, often driven by dysfunction in specific ion channels. Surgical modification of this electrical activity via deep brain stimulation is already an approved modality for many of these disorders. Therefore, restoring proper electrical activity by targeting these channels pharmacologically represents a viable strategy for intervention, not only for symptomatic management but also as a potential disease-modifying therapy. Such an approach is likely to be a promising route to treating these devastating disorders, either as monotherapy or in conjunction with current drugs. SIGNIFICANCE STATEMENT: Despite extensive research and improved understanding of the biology driving neurodegenerative disease, there has not been a concomitant increase in approved therapies. Accordingly, it is time to shift our perspective and recognize these diseases also as disorders of circuitry to further yield novel drug targets and new interventions. An approach focused on treating dysfunctional circuitry has the potential to reduce or reverse patient symptoms and potentially modify disease course.
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Wagle Shukla A. Reduction of neuronal hyperexcitability with modulation of T-type calcium channel or SK channel in essential tremor. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2022; 163:335-355. [PMID: 35750369 DOI: 10.1016/bs.irn.2022.02.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Essential tremor is one of the most prevalent movement disorders. Propranolol and primidone are the first-line pharmacological therapies. They provide symptomatic control in less than 50% of patients. Topiramate, alprazolam, clonazepam, gabapentin, and botulinum toxin injections are the next line of treatments. These medications lead to modest improvements and are therefore commonly used as add-on agents. Surgical therapies, including deep brain stimulation (DBS) surgery and focused ultrasound beam targeted to the thalamus, are considered for treating tremor refractory to medications and lead to greater than 75% improvements in tremor symptoms. However, DBS is a costly and an invasive procedure; some patients report tolerance to benefits. Focused ultrasound therapy leading to brain lesions is associated with a possibility for permanent clinical deficits. Therefore, research efforts to develop the next generation of oral medications with greater benefits and lesser adverse effects are warranted. There is considerable evidence that the increased functions of calcium channels (P/Q-type and T-type channels) and reduced functions of calcium-activated potassium channels (SK channels) located in the neuronal membranes lead to tremor oscillations. Consequently, many new pharmacological studies have targeted these channels to leverage better clinical outcomes. The current review will discuss the pathophysiology, the specific importance of these channels, and the early clinical experience of using compounds targeting these channels to treat essential tremor.
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Affiliation(s)
- Aparna Wagle Shukla
- Department of Neurology, Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, United States.
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8
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Bellows S, Jimenez-Shahed J. Is essential tremor a disorder of GABA dysfunction? No. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2022; 163:285-310. [PMID: 35750366 DOI: 10.1016/bs.irn.2022.02.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Although essential tremor is common, its underlying pathophysiology remains uncertain, and several hypotheses seek to explain the tremor mechanism. The GABA hypothesis states that disinhibition of deep cerebellar neurons due to reduced GABAergic input from Purkinje cells results in increased pacemaker activity, leading to rhythmic output to the thalamo-cortical circuit and resulting in tremor. However, some neuroimaging, spectroscopy, and pathology studies have not shown a clear or consistent GABA deficiency in essential tremor, and animal models have indicated that large reductions of Purkinje cell inhibition may improve tremor. Instead, tremor is increasingly attributable to dysfunction in oscillating networks, where altered (but not necessarily reduced) inhibitory signaling can result in tremor. Hypersynchrony of Purkinje cell activity may account for excessive oscillatory cerebellar output, with potential contributions along multiple sites of the olivocerebellar loop. Although older animal tremor models, such as harmaline tremor, have explored contributions from the inferior olivary body, increasing evidence has pointed to the role of aberrant climbing fiber synaptic organization in oscillatory cerebellar activity and tremor generation. New animal models such as hotfoot17j mice, which exhibit abnormal climbing fiber organization due to mutations in Grid2, have recapitulated many features of ET. Similar abnormal climbing fiber architecture and excessive cerebellar oscillations as measured by EEG have been found in humans with essential tremor. Further understanding of hypersynchrony and excessive oscillatory activity in ET phenotypes may lead to more targeted and effective treatment options.
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9
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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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Shetty N. Essential Tremor-Do We Have Better Therapeutics? A Review of Recent Advances and Future Directions. Curr Neurol Neurosci Rep 2022; 22:197-208. [PMID: 35235170 DOI: 10.1007/s11910-022-01185-8] [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] [Accepted: 01/18/2022] [Indexed: 11/30/2022]
Abstract
PURPOSE OF REVIEW Essential tremor (ET) is a very common condition that significantly impacts quality of life. Current medical treatments are quite limited, and while surgical treatments like deep brain stimulation (DBS) can be very effective, they come with their own limitations as well as procedural risks. This article reviews updates on recent advances and future directions in the treatment of ET. RECENT FINDINGS A new generation of pharmacologic agents specifically designed for ET is in clinical trials. Advances in DBS technology continue to improve this therapy. MRI-guided focused ultrasound (MRgFUS) is now an approved noninvasive ablative treatment for ET that is effective and shows potential for continuing improvement. The first peripheral stimulation device for ET has also now been approved. This article reviews updates on the treatment of ET, encompassing pharmacologic agents in clinical trials, DBS, MRgFUS, and noninvasive stimulation therapies. Recent treatment advances and future directions of development show a great deal of promise for ET therapeutics.
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Affiliation(s)
- Neil Shetty
- Parkinson's Disease and Movement Disorders Center, Department of Neurology, Northwestern University Feinberg School of Medicine, Abbott Hall, 11th Floor, 710 N. Lake Shore Drive, Chicago, IL, 60611, USA.
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11
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Pan MK, Kuo SH. Essential tremor: Clinical perspectives and pathophysiology. J Neurol Sci 2022; 435:120198. [PMID: 35299120 PMCID: PMC10363990 DOI: 10.1016/j.jns.2022.120198] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/01/2021] [Accepted: 02/17/2022] [Indexed: 12/12/2022]
Abstract
Essential tremor (ET) is one of the most common neurological disorders and can be highly disabling. In recent years, studies on the clinical perspectives and pathophysiology have advanced our understanding of ET. Specifically, clinical heterogeneity of ET, with co-existence of tremor and other neurological features such as dystonia, ataxia, and cognitive dysfunction, has been identified. The cerebellum has been found to be the key brain region for tremor generation, and structural alterations of the cerebellum have been extensively studied in ET. Finally, four main ET pathophysiologies have been proposed: 1) environmental exposures to β-carboline alkaloids and the consequent olivocerebellar hyper-excitation, 2) cerebellar GABA deficiency, 3) climbing fiber synaptic pathology with related cerebellar oscillatory activity, 4) extra-cerebellar oscillatory activity. While these four theories are not mutually exclusive, they can represent distinctive ET subtypes, indicating multiple types of abnormal brain circuitry can lead to action tremor. This article is part of the Special Issue "Tremor" edited by Daniel D. Truong, Mark Hallett, and Aasef Shaikh.
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12
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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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13
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Gironell A. Is essential tremor a disorder of primary GABA dysfunction? Yes. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2022; 163:259-284. [PMID: 35750365 PMCID: PMC9446196 DOI: 10.1016/bs.irn.2022.02.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Dysfunction in gamma-aminobutyric acid (GABA) neurotransmission has emerged as a prime suspect for the underlying neurochemical dysfunction in essential tremor (ET). This dysfunction has been termed the GABA hypothesis. We review findings to date supporting the 4 steps in this hypothesis in studies of cerebrospinal fluid, pathology, genetics, animal models, imaging, computational models, and human drugs, while not overlooking the evidence of negative studies and controversies. It remains to be elucidated whether reduced GABAergic tone is a primary contributing factor to ET pathophysiology, a consequence of altered Purkinje cell function, or even a result of Purkinje cell death. More studies are clearly needed to confirm both the neurodegenerative nature of ET and the reduction in GABA activity in the cerebellum. Also necessary is to test further therapies to enhance GABA transmission specifically focused on the cerebellar area.
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Affiliation(s)
- Alexandre Gironell
- Movement Disorders Unit, Department of Neurology, Sant Pau Hospital, Autonomous University of Barcelona, Catalonia, Spain.
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14
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Shao J, Liu Y, Gao D, Tu J, Yang F. Neural Burst Firing and Its Roles in Mental and Neurological Disorders. Front Cell Neurosci 2021; 15:741292. [PMID: 34646123 PMCID: PMC8502892 DOI: 10.3389/fncel.2021.741292] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 08/26/2021] [Indexed: 11/29/2022] Open
Abstract
Neural firing patterns are critical for specific information coding and transmission, and abnormal firing is implicated in a series of neural pathologies. Recent studies have indicated that enhanced burst firing mediated by T-type voltage-gated calcium channels (T-VGCCs) in specific neuronal subtypes is involved in several mental or neurological disorders such as depression and epilepsy, while suppression of T-VGCCs relieve related symptoms. Burst firing consists of groups of relatively high-frequency spikes separated by quiescence. Neurons in a variety of brain areas, including the thalamus, hypothalamus, cortex, and hippocampus, display burst firing, but the ionic mechanisms that generating burst firing and the related physiological functions vary among regions. In this review, we summarize recent findings on the mechanisms underlying burst firing in various brain areas, as well as the roles of burst firing in several mental and neurological disorders. We also discuss the ion channels and receptors that may regulate burst firing directly or indirectly, with these molecules highlighted as potential intervention targets for the treatment of mental and neurological disorders.
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Affiliation(s)
- Jie Shao
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Yunhui Liu
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China
| | - Dashuang Gao
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Jie Tu
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Fan Yang
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Beijing, China
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15
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Akman Ö, Utkan T, Arıcıoğlu F, Güllü K, Ateş N, Karson A. Agmatine has beneficial effect on harmaline-induced essential tremor in rat. Neurosci Lett 2021; 753:135881. [PMID: 33838255 DOI: 10.1016/j.neulet.2021.135881] [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: 03/01/2021] [Revised: 03/28/2021] [Accepted: 04/01/2021] [Indexed: 10/21/2022]
Abstract
Essential tremor (ET) is one of the most prevalent movement disorders and the most common cause of abnormal tremors. However, it cannot be treated efficiently with the currently available pharmacotherapy options. The pathophysiology of harmaline-induced tremor, most commonly used model of ET, involves various neurotransmitter systems including glutamate as well as ion channels. Agmatine, an endogenous neuromodulator, interacts with various glutamate receptor subtypes and ion channels, which have been associated with its' beneficial effects on several neurological disorders. The current study aims to assess the effect of agmatine on the harmaline model of ET. Two separate groups of male rats were injected either with saline or agmatine (40 mg/kg) 30 min prior to single intraperitoneal injection of harmaline (20 mg/kg). The percent duration, intensity and frequency of tremor and locomotor activity were evaluated by a custom-built tremor and locomotion analysis system. Pretreatment with agmatine reduced the percent tremor duration and intensity of tremor induced by harmaline, without affecting the tremor frequency. However, it did not affect the decreased spontaneous locomotor activity due to harmaline. This pattern of ameliorating effects of agmatine on harmaline-induced tremor provide the first evidence for being considered as a treatment option for ET.
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Affiliation(s)
- Özlem Akman
- Department of Physiology, Faculty of Medicine, Demiroglu Bilim University, Istanbul, Turkey.
| | - Tijen Utkan
- Kocaeli University, Faculty of Medicine, Department of Pharmacology, Kocaeli, Turkey.
| | - Feyza Arıcıoğlu
- Marmara University, Faculty of Pharmacy, Department of Pharmacology and Psychopharmacology Research Unit, Istanbul, Turkey.
| | - Kemal Güllü
- Department of Electrical and Electronics Engineering, İzmir Bakircay University, İzmir, Turkey.
| | - Nurbay Ateş
- Kocaeli University, Faculty of Medicine, Department of Physiology, Kocaeli, Turkey.
| | - Ayşe Karson
- Kocaeli University, Faculty of Medicine, Department of Physiology, Kocaeli, Turkey.
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16
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Papapetropoulos S, Lee MS, Versavel S, Newbold E, Jinnah HA, Pahwa R, Lyons KE, Elble R, Ondo W, Zesiewicz T, Hedera P, Handforth A, Elder J, Versavel M. A Phase 2 Proof-of-Concept, Randomized, Placebo-Controlled Trial of CX-8998 in Essential Tremor. Mov Disord 2021; 36:1944-1949. [PMID: 33764619 PMCID: PMC8451783 DOI: 10.1002/mds.28584] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 01/29/2021] [Accepted: 03/02/2021] [Indexed: 11/26/2022] Open
Abstract
Background Available essential tremor (ET) therapies have limitations. Objectives The objective of this study was to evaluate CX‐8998, a selective T‐type calcium channel modulator, in essential tremor. Methods Patients 18–75 years old with moderate to severe essential tremor were randomized 1:1 to receive CX‐8998 (titrated to 10 mg twice daily) or placebo. The primary end point was change from baseline to day 28 in The Essential Tremor Rating Assessment Scale performance subscale scored by independent blinded video raters. Secondary outcomes included in‐person blinded investigator rating of The Essential Tremor Rating Assessment Scale performance subscale, The Essential Tremor Rating Assessment Scale activities of daily living subscale, and Kinesia ONE accelerometry. Results The video‐rated The Essential Tremor Rating Assessment Scale performance subscale was not different for CX‐8998 (n = 39) versus placebo (n = 44; P = 0.696). CX‐8998 improved investigator‐rated The Essential Tremor Rating Assessment Scale performance subscale (P = 0.017) and The Essential Tremor Rating Assessment Scale activities of daily living (P = 0.049) but not Kinesia ONE (P = 0.421). Adverse events with CX‐8998 included dizziness (21%), headache (8%), euphoric mood (6%), and insomnia (6%). Conclusions The primary efficacy end point was not met; however, CX‐8998 improved some assessments of essential tremor, supporting further clinical investigation. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
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Affiliation(s)
| | | | | | - Evan Newbold
- Jazz Pharmaceuticals, Philadelphia, Pennsylvania, USA
| | - Hyder A Jinnah
- Emory University School of Medicine, Atlanta, Georgia, USA
| | - Rajesh Pahwa
- University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Kelly E Lyons
- University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Rodger Elble
- Southern Illinois University School of Medicine, Springfield, Illinois, USA
| | - William Ondo
- Houston Methodist Neurological Institute, Houston, Texas, USA
| | - Theresa Zesiewicz
- University of South Florida Ataxia Research Center, Tampa, Florida, USA
| | - Peter Hedera
- Department of Neurology, University of Louisville, Louisville, Kentucky, USA
| | - Adrian Handforth
- VA Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Jenna Elder
- PharPoint Research, Inc., Wilmington, North Carolina, USA
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17
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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: 21] [Impact Index Per Article: 5.3] [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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18
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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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19
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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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20
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Jiménez-Jiménez FJ, Alonso-Navarro H, García-Martín E, Agúndez JA. An Update on the Neurochemistry of Essential Tremor. Curr Med Chem 2020; 27:1690-1710. [DOI: 10.2174/0929867325666181112094330] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Revised: 09/03/2018] [Accepted: 11/05/2018] [Indexed: 12/21/2022]
Abstract
Background:
The pathophysiology and neurochemical mechanisms of essential
tremor (ET) are not fully understood, because only a few post-mortem studies have been reported,
and there is a lack of good experimental model for this disease.
Objective:
The main aim of this review is to update data regarding the neurochemical features
of ET. Alterations of certain catecholamine systems, the dopaminergic, serotonergic,
GABAergic, noradrenergic, and adrenergic systems have been described, and are the object of
this revision.
Methods:
For this purpose, we performed a literature review on alterations of the neurotransmitter
or neuromodulator systems (catecholamines, gammaaminobutyric acid or GABA,
excitatory amino acids, adenosine, T-type calcium channels) in ET patients (both post-mortem
or in vivo) or in experimental models resembling ET.
Results and Conclusion:
The most consistent data regarding neurochemistry of ET are related
with the GABAergic and glutamatergic systems, with a lesser contribution of adenosine
and dopaminergic and adrenergic systems, while there is not enough evidence of a definite
role of other neurotransmitter systems in ET. The improvement of harmaline-induced tremor
in rodent models achieved with T-type calcium channel antagonists, cannabinoid 1 receptor,
sphingosine-1-phosphate receptor agonists, and gap-junction blockers, suggests a potential
role of these structures in the pathogenesis of ET.
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Affiliation(s)
| | | | - Elena García-Martín
- University Institute of Molecular Pathology Biomarkers, UNEx. ARADyAL Instituto de Salud Carlos III, Caceres, Spain
| | - José A.G. Agúndez
- University Institute of Molecular Pathology Biomarkers, UNEx. ARADyAL Instituto de Salud Carlos III, Caceres, Spain
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21
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Abstract
Established medications that improve tremor include beta-adrenergic antagonists, primidone, topiramate, and ethanol. Less consistent efficacy is reported with many other medications, usually antiepileptic drugs. A number of investigational medications, including T-type calcium channel blockers and allosteric gamma-aminobutyric acid-A modulators, are being developed for tremor. Deep brain stimulation techniques continues to be refined and focused ultrasound thalamotomy now offers an incisionless surgical option. Finally a number of peripheral electrical and mechanical devices are under development for tremor.
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Affiliation(s)
- William George Ondo
- Movement Disorders-Methodist Neurological Institute, Weill Cornel Medical School, 6560 Fannin Suite 1002, Houston, TX 77025, USA.
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22
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Alonso-Navarro H, García-Martín E, Agúndez JA, Jiménez-Jiménez FJ. Current and Future Neuropharmacological Options for the Treatment of Essential Tremor. Curr Neuropharmacol 2020; 18:518-537. [PMID: 31976837 PMCID: PMC7457404 DOI: 10.2174/1570159x18666200124145743] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 10/31/2019] [Accepted: 01/23/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Essential Tremor (ET) is likely the most frequent movement disorder. In this review, we have summarized the current pharmacological options for the treatment of this disorder and discussed several future options derived from drugs tested in experimental models of ET or from neuropathological data. METHODS A literature search was performed on the pharmacology of essential tremors using PubMed Database from 1966 to July 31, 2019. RESULTS To date, the beta-blocker propranolol and the antiepileptic drug primidone are the drugs that have shown higher efficacy in the treatment of ET. Other drugs tested in ET patients have shown different degrees of efficacy or have not been useful. CONCLUSION Injections of botulinum toxin A could be useful in the treatment of some patients with ET refractory to pharmacotherapy. According to recent neurochemical data, drugs acting on the extrasynaptic GABAA receptors, the glutamatergic system or LINGO-1 could be interesting therapeutic options in the future.
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Affiliation(s)
| | | | | | - Félix J. Jiménez-Jiménez
- Address correspondence to this author at the Section of Neurology, Hospital Universitario del Sureste, Arganda del Rey, Madrid, Spain; Tel: +34636968395; Fax: +34913280704; E-mails: ;
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23
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Kuo SH, Louis ED, Faust PL, Handforth A, Chang SY, Avlar B, Lang EJ, Pan MK, Miterko LN, Brown AM, Sillitoe RV, Anderson CJ, Pulst SM, Gallagher MJ, Lyman KA, Chetkovich DM, Clark LN, Tio M, Tan EK, Elble RJ. Current Opinions and Consensus for Studying Tremor in Animal Models. CEREBELLUM (LONDON, ENGLAND) 2019; 18:1036-1063. [PMID: 31124049 PMCID: PMC6872927 DOI: 10.1007/s12311-019-01037-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Tremor is the most common movement disorder; however, we are just beginning to understand the brain circuitry that generates tremor. Various neuroimaging, neuropathological, and physiological studies in human tremor disorders have been performed to further our knowledge of tremor. But, the causal relationship between these observations and tremor is usually difficult to establish and detailed mechanisms are not sufficiently studied. To overcome these obstacles, animal models can provide an important means to look into human tremor disorders. In this manuscript, we will discuss the use of different species of animals (mice, rats, fruit flies, pigs, and monkeys) to model human tremor disorders. Several ways to manipulate the brain circuitry and physiology in these animal models (pharmacology, genetics, and lesioning) will also be discussed. Finally, we will discuss how these animal models can help us to gain knowledge of the pathophysiology of human tremor disorders, which could serve as a platform towards developing novel therapies for tremor.
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Affiliation(s)
- Sheng-Han Kuo
- Department of Neurology, Columbia University, 650 West 168th Street, Room 305, New York, NY, 10032, USA.
| | - Elan D Louis
- Department of Neurology, Yale School of Medicine, Yale University, 800 Howard Avenue, Ste Lower Level, New Haven, CT, 06519, USA.
- Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale University, New Haven, CT, USA.
- Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine, Yale University, New Haven, CT, USA.
| | - Phyllis L Faust
- Department of Pathology and Cell Biology, Columbia University Medical Center and the New York Presbyterian Hospital, New York, NY, USA
| | - Adrian Handforth
- Neurology Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Su-Youne Chang
- Department of Neurologic Surgery and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | - Billur Avlar
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Eric J Lang
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Ming-Kai Pan
- Department of Medical Research and Neurology, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Lauren N Miterko
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
| | - Amanda M Brown
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Roy V Sillitoe
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Collin J Anderson
- 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
| | | | - Kyle A Lyman
- Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | | | - Lorraine N Clark
- Department of Pathology and Cell Biology, Columbia University Medical Center and the New York Presbyterian Hospital, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Murni Tio
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
- Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Eng-King Tan
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
- Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Rodger J Elble
- Department of Neurology, Southern Illinois University School of Medicine, Springfield, IL, USA
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24
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Papapetropoulos S, Lee MS, Boyer S, Newbold EJ. A Phase 2, Randomized, Double-Blind, Placebo-Controlled Trial of CX-8998, a Selective Modulator of the T-Type Calcium Channel in Inadequately Treated Moderate to Severe Essential Tremor: T-CALM Study Design and Methodology for Efficacy Endpoint and Digital Biomarker Selection. Front Neurol 2019; 10:597. [PMID: 31244760 PMCID: PMC6579833 DOI: 10.3389/fneur.2019.00597] [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: 03/18/2019] [Accepted: 05/21/2019] [Indexed: 11/13/2022] Open
Abstract
Background: Essential tremor (ET) is a common, progressive neurological syndrome with bilateral upper-limb dysfunction of at least 3-year duration, with or without tremor in other body locations. This disorder has a negative impact on daily function and quality of life. A single oral therapy has been approved by FDA for ET. Off-label pharmacotherapies have inadequate efficacy and poor tolerability with high rates of patient dissatisfaction and discontinuation. Safe and efficacious pharmacotherapies are urgently needed to decrease tremor and improve daily living. T-CALM (Tremor-CAv3 modulation) protocol is designed to assess safety and efficacy of CX-8998, a selective modulator of the T-type calcium channel, for ET therapy. Methods/Design: T-CALM is a phase 2, proof of concept, randomized, double-blind, placebo-controlled trial. Titrated doses of CX-8998 to 10 mg BID or placebo will be administered for 28 days to moderate to severe ET patients who are inadequately treated with existing therapies. The primary endpoint will be change from baseline to day 28 of The Essential Tremor Rating Assessment Performance Subscale (TETRAS-PS). Secondary efficacy endpoints for clinician and patient perception of daily function will include TETRAS Activity of Daily Living (ADL), Quality of Life in Essential Tremor Questionnaire (QUEST), Clinical Global Impression-Improvement (CGI-I), Patient Global Impression of Change (PGIC), and Goal Attainment Scale (GAS). Kinesia One, Kinesia 360, and iMotor will biometrically evaluate motor function and tremor amplitude. Safety will be assessed by adverse events, physical and neurological exams and laboratory tests. Sample size of 43 patients per group is estimated to have 90% power to detect a 5.5-point difference between CX-8998 and placebo for TETRAS-PS. Efficacy analyses will be performed with covariance (ANCOVA) and 2-sided test at 0.05 significance level. Discussion: T-CALM has a unique design with physician rating scales, patient-focused questionnaires and scales and objective motor measurements to assess clinically meaningful and congruent efficacy. Patient perception of ET debilitation and therapy with CX-8998 will be key findings. Overall goal of T-CALM is generation of safety and efficacy data to support a go, no-go decision to further develop CX-8998 for ET. Design of T-CALM may guide future clinical studies of ET pharmacotherapies. Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT03101241
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25
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T-type calcium channel enhancer SAK3 promotes dopamine and serotonin releases in the hippocampus in naive and amyloid precursor protein knock-in mice. PLoS One 2018; 13:e0206986. [PMID: 30571684 PMCID: PMC6301769 DOI: 10.1371/journal.pone.0206986] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Accepted: 10/23/2018] [Indexed: 01/12/2023] Open
Abstract
T-type calcium channels in the brain mediate the pathophysiology of epilepsy, pain, and sleep. Recently, we developed a novel therapeutic candidate, SAK3 (ethyl 8'-methyl-2',4-dioxo-2-(piperidin-1-yl)-2'H-spiro[cyclopentane-1,3'-imidazo[1,2-a] pyridine]-2-ene-3-carboxylate), for Alzheimer's disease (AD). The cognitive improvement by SAK3 is closely associated with enhanced acetylcholine (ACh) release in the hippocampus. Since monoamines such as dopamine (DA), noradrenaline (NA), and serotonin (5-HT) are also involved in hippocampus-dependent learning and psychomotor behaviors in mice, we investigated the effects of SAK3 on these monoamine releases in the mouse brain. Oral administration of SAK3 (0.5 mg/kg, p.o.) significantly promoted DA and 5-HT releases in the naive mouse hippocampal CA1 region but not in the medial prefrontal cortex (mPFC), while SAK3 did not affect NA release in either brain region. The T-type calcium channel-specific inhibitor, NNC 55-0396 (1 μM) significantly antagonized SAK3-enhanced DA and 5-HT releases in the hippocampus. Interestingly, the α7 nicotinic ACh receptor (nAChR) antagonist, methyllycaconitine (1 nM) significantly inhibited DA release, and the α4 nAChR antagonist, dihydro-β-erythroidine (100 μM) significantly blocked both DA and 5-HT releases following SAK3 (0.5 mg/kg, p.o.) administration in the hippocampus. SAK3 did not alter basal monoamine contents both in the mPFC and hippocampus. SAK3 (0.5 mg/kg, p.o.) administration also significantly elevated DA and 5-HT releases in the hippocampal CA1 region of amyloid-precursor protein (APP)NL-GF knock-in (KI) mice. Moreover, hippocampal DA and 5-HT contents were significantly decreased in APPNL-GF KI mice. Taken together, our data suggest that SAK3 promotes monoamine DA and 5-HT releases by enhancing the T-type calcium channel and nAChR in the mouse hippocampus.
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26
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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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Kunisawa N, Shimizu S, Kato M, Iha HA, Iwai C, Hashimura M, Ogawa M, Kawaji S, Kawakita K, Abe K, Ohno Y. Pharmacological characterization of nicotine-induced tremor: Responses to anti-tremor and anti-epileptic agents. J Pharmacol Sci 2018; 137:162-169. [PMID: 29945769 DOI: 10.1016/j.jphs.2018.05.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/18/2018] [Accepted: 05/23/2018] [Indexed: 12/19/2022] Open
Abstract
We previously showed that nicotine evoked kinetic tremor by activating the inferior olive, which is implicated in the pathogenesis of essential tremor, via α7 nicotinic acetylcholine receptors. Here, we evaluated the effects of various anti-tremor and anti-epileptic agents on nicotine-induced tremor in mice to clarify the pharmacological characteristics of nicotine tremor. Drugs effective for essential tremor, propranolol, diazepam and phenobarbital, all significantly inhibited kinetic tremor induced by an intraperitoneal (i.p.) injection of nicotine (1 mg/kg). In contrast, none of the medications for Parkinson's disease, l-DOPA, bromocriptine or trihexyphenidyl, affected the nicotine tremor. Among the anti-epileptic agents examined, valproate, carbamazepine and ethosuximide, significantly inhibited nicotine-induced tremor. In addition, a selective T-type Ca2+ channel blocker, TTA-A2, also suppressed the nicotine tremor. However, neither gabapentin, topiramate, zonisamide nor levetiracetam significantly affected nicotine-induced tremor. The present results show that nicotine-induced tremor resembles essential tremor not only on the neural basis, but also in terms of the pharmacological responses to anti-tremor agents, implying that nicotine-induced tremor can serve as a model for essential tremor. In addition, it is suggested that anti-epileptic agents, which have stimulant actions on the GABAergic system or blocking actions on voltage-gated Na+ channels and T-type Ca2+ channels, can alleviate essential tremor.
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Affiliation(s)
- Naofumi Kunisawa
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Saki Shimizu
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Masaki Kato
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Higor A Iha
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Chihiro Iwai
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Mai Hashimura
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Mizuki Ogawa
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Shohei Kawaji
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Kazuma Kawakita
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Keisuke Abe
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Yukihiro Ohno
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan.
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Schaefer SM, Vives Rodriguez A, Louis ED. Brain circuits and neurochemical systems in essential tremor: insights into current and future pharmacotherapeutic approaches. Expert Rev Neurother 2017; 18:101-110. [PMID: 29206482 DOI: 10.1080/14737175.2018.1413353] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
INTRODUCTION There are few medications that are available for the treatment of essential tremor (ET) and they are only moderately effective. Areas covered: Data were obtained from a PubMed search. Original articles, review articles, and clinical guidelines were included. Two disease models for ET have been proposed: 1) the olivary model, which attributes ET to a pathological pacemaker in the inferior olivary nucleus, and 2) the cerebellar degeneration model, which postulates that ET originates in the cerebellum and could be related to deficient or abnormal Purkinje cell (PC) output. Underlying biochemical dysfunction in T-type calcium channels (T-tCaC) may loosely be linked to the first model and deficiency/abnormality in γ-aminobutyric acid (GABA) neurotransmission, to the second. Expert commentary: Human data points robustly to the role of GABA in ET. Numerous medications that target the GABA system have been tried, with variable success. Given the many different types of GABA-ergic neurons, and the multitude of GABAA receptor subtypes, a given medication could have competing/cancelling effects. It would seem that influencing GABA receptors broadly is not as effective as targeting certain GABAA receptor subtypes. Future research should seek to identify molecular candidates that have a more targeted effect within the GABA system.
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Affiliation(s)
- Sara M Schaefer
- a Department of Neurology , Yale School of Medicine, Yale University , New Haven , CT , USA
| | - Ana Vives Rodriguez
- a Department of Neurology , Yale School of Medicine, Yale University , New Haven , CT , USA
| | - Elan D Louis
- a Department of Neurology , Yale School of Medicine, Yale University , New Haven , CT , USA.,b Department of Chronic Disease Epidemiology , Yale School of Public Health, Yale University , New Haven , CT , USA.,c Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine , Yale University , New Haven , CT , USA
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Bezençon O, Heidmann B, Siegrist R, Stamm S, Richard S, Pozzi D, Corminboeuf O, Roch C, Kessler M, Ertel EA, Reymond I, Pfeifer T, de Kanter R, Toeroek-Schafroth M, Moccia LG, Mawet J, Moon R, Rey M, Capeleto B, Fournier E. Discovery of a Potent, Selective T-type Calcium Channel Blocker as a Drug Candidate for the Treatment of Generalized Epilepsies. J Med Chem 2017; 60:9769-9789. [PMID: 29116786 DOI: 10.1021/acs.jmedchem.7b01236] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We report here the discovery and pharmacological characterization of N-(1-benzyl-1H-pyrazol-3-yl)-2-phenylacetamide derivatives as potent, selective, brain-penetrating T-type calcium channel blockers. Optimization focused mainly on solubility, brain penetration, and the search for an aminopyrazole metabolite that would be negative in an Ames test. This resulted in the preparation and complete characterization of compound 66b (ACT-709478), which has been selected as a clinical candidate.
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Affiliation(s)
- Olivier Bezençon
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Bibia Heidmann
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Romain Siegrist
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Simon Stamm
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Sylvia Richard
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Davide Pozzi
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Olivier Corminboeuf
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Catherine Roch
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Melanie Kessler
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Eric A Ertel
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Isabelle Reymond
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Thomas Pfeifer
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Ruben de Kanter
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Michael Toeroek-Schafroth
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Luca G Moccia
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Jacques Mawet
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Richard Moon
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Markus Rey
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Bruno Capeleto
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| | - Elvire Fournier
- Chemistry, Biology and Pharmacology & Pre-clinical Development, Drug Discovery, Idorsia Pharmaceuticals Ltd. , Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
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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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Walton KD, Maillet EL, Garcia J, Cardozo T, Galatzer-Levy I, Llinás RR. Differential Modulation of Rhythmic Brain Activity in Healthy Adults by a T-Type Calcium Channel Blocker: An MEG Study. Front Hum Neurosci 2017; 11:24. [PMID: 28217089 PMCID: PMC5289965 DOI: 10.3389/fnhum.2017.00024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 01/11/2017] [Indexed: 01/08/2023] Open
Abstract
1-octanol is a therapeutic candidate for disorders involving the abnormal activation of the T-type calcium current since it blocks this current specifically. Such disorders include essential tremor and a group of neurological and psychiatric disorders resulting from thalamocortical dysrhythmia (TCD). For example, clinically, the observable phenotype in essential tremor is the tremor itself. The differential diagnostic of TCD is not based only on clinical signs and symptoms. Rather, TCD incorporates an electromagnetic biomarker, the presence of abnormal thalamocortical low frequency brain oscillations. The effect of 1-octanol on brain activity has not been tested. As a preliminary step to such a TCD study, we examined the short-term effects of a single dose of 1-octanol on resting brain activity in 32 healthy adults using magnetoencephalograpy. Visual inspection of baseline power spectra revealed that the subjects fell into those with strong low frequency activity (set 2, n = 11) and those without such activity, but dominated by an alpha peak (set 1, n = 22). Cross-validated linear discriminant analysis, using mean spectral density (MSD) in nine frequency bands as predictors, found overall that 82.5% of the subjects were classified as determined by visual inspection. The effect of 1-octanol on the MSD in narrow frequency bands differed between the two subject groups. In set 1 subjects the MSD increased in the 4.5-6.5Hz and 6.5-8.5 Hz bands. This was consistent with a widening of the alpha peak toward lower frequencies. In the set two subjects the MSD decrease in the 2.5-4.5 Hz and 4.5-6.5 Hz bands. This decreased power is consistent with the blocking effect of 1-octanol on T-type calcium channels. The subjects reported no adverse effects of the 1-octanol. Since stronger low frequency activity is characteristic of patients with TCD, 1-octanol and other T-type calcium channel blockers are good candidates for treatment of this group of disorders following a placebo-controlled study.
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Affiliation(s)
- Kerry D Walton
- Center for Neuromagnetism, Department of Neuroscience and Physiology, New York University School of Medicine, New York NY, USA
| | - Emeline L Maillet
- Center for Neuromagnetism, Department of Neuroscience and Physiology, New York University School of Medicine, New York NY, USA
| | - John Garcia
- Center for Neuromagnetism, Department of Neuroscience and Physiology, New York University School of Medicine, New York NY, USA
| | - Timothy Cardozo
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York NY, USA
| | - Isaac Galatzer-Levy
- Steven and Alexandra Cohen Veterans Center for PostTraumatic Stress and Traumatic Brain Injury, Department of Psychiatry, New York University School of Medicine, New York NY, USA
| | - Rodolfo R Llinás
- Center for Neuromagnetism, Department of Neuroscience and Physiology, New York University School of Medicine, New York NY, USA
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Yabuki Y, Matsuo K, Izumi H, Haga H, Yoshida T, Wakamori M, Kakei A, Sakimura K, Fukuda T, Fukunaga K. Pharmacological properties of SAK3, a novel T-type voltage-gated Ca 2+ channel enhancer. Neuropharmacology 2017; 117:1-13. [PMID: 28093211 DOI: 10.1016/j.neuropharm.2017.01.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Revised: 12/27/2016] [Accepted: 01/12/2017] [Indexed: 11/30/2022]
Abstract
T-type voltage-gated Ca2+ channels (T-VGCCs) function in the pathophysiology of epilepsy, pain and sleep. However, their role in cognitive function remains unclear. We previously reported that the cognitive enhancer ST101, which stimulates T-VGCCs in rat cortical slices, was a potential Alzheimer's disease therapeutic. Here, we introduce a more potent T-VGCC enhancer, SAK3 (ethyl 8'-methyl-2',4-dioxo-2-(piperidin-1-yl)-2'H-spiro[cyclopentane-1,3'-imidazo [1,2-a]pyridin]-2-ene-3-carboxylate), and characterize its pharmacological properties in brain. Based on whole cell patch-clamp analysis, SAK3 (0.01-10 nM) significantly enhanced Cav3.1 currents in neuro2A cells ectopically expressing Cav3.1. SAK3 (0.1-10 nM nM) also enhanced Cav3.3 but not Cav3.2 currents in the transfected cells. Notably, Cav3.1 and Cav3.3 T-VGCCs were localized in cholinergic neurve systems in hippocampus and in the medial septum. Indeed, acute oral administration of SAK3 (0.5 mg/kg, p.o.), but not ST101 (0.5 mg/kg, p.o.) significantly enhanced acetylcholine (ACh) release in the hippocampal CA1 region of naïve mice. Moreover, acute SAK3 (0.5 mg/kg, p.o.) administration significantly enhanced hippocampal ACh levels in olfactory-bulbectomized (OBX) mice, rescuing impaired memory-related behaviors. Treatment of OBX mice with the T-VGCC-specific blocker NNC 55-0396 (12.5 mg/kg, i.p.) antagonized both enhanced ACh release and memory improvements elicited by SAK3 administration. We also observed that SAK3-induced ACh releases were significantly blocked in the hippocampus from Cav3.1 knockout (KO) mice. These findings suggest overall that T-VGCCs play a key role in cognition by enhancing hippocampal ACh release and that the cognitive enhancer SAK3 could be a candidate therapeutic in Alzheimer's disease.
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Affiliation(s)
- Yasushi Yabuki
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Kazuya Matsuo
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Hisanao Izumi
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Hidaka Haga
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Takashi Yoshida
- Department of Oral Biology, Graduate School of Dentistry, Tohoku University, Sendai, Japan
| | - Minoru Wakamori
- Department of Oral Biology, Graduate School of Dentistry, Tohoku University, Sendai, Japan
| | - Akikazu Kakei
- Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, Nagano, Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Takaichi Fukuda
- Department of Anatomy and Neurobiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Kohji Fukunaga
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
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Abbassian H, Esmaeili P, Tahamtan M, Aghaei I, Vaziri Z, Sheibani V, Whalley BJ, Shabani M. Cannabinoid receptor agonism suppresses tremor, cognition disturbances and anxiety-like behaviors in a rat model of essential tremor. Physiol Behav 2016; 164:314-20. [DOI: 10.1016/j.physbeh.2016.06.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Revised: 06/13/2016] [Accepted: 06/14/2016] [Indexed: 11/25/2022]
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Remen L, Bezençon O, Simons L, Gaston R, Downing D, Gatfield J, Roch C, Kessler M, Mosbacher J, Pfeifer T, Grisostomi C, Rey M, Ertel EA, Moon R. Preparation, Antiepileptic Activity, and Cardiovascular Safety of Dihydropyrazoles as Brain-Penetrant T-Type Calcium Channel Blockers. J Med Chem 2016; 59:8398-411. [DOI: 10.1021/acs.jmedchem.6b00756] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Lubos Remen
- Drug
Discovery Chemistry, Biology and Pharmacology, Actelion Pharmaceuticals Ltd., Gewerbestrasse 16, CH-4123 Allschwil, Switzerland
| | - Olivier Bezençon
- Drug
Discovery Chemistry, Biology and Pharmacology, Actelion Pharmaceuticals Ltd., Gewerbestrasse 16, CH-4123 Allschwil, Switzerland
| | - Lloyd Simons
- Kalexsyn, Inc., 4502 Campus Drive, Kalamazoo, Michigan 49008, United States
| | - Rick Gaston
- Kalexsyn, Inc., 4502 Campus Drive, Kalamazoo, Michigan 49008, United States
| | - Dennis Downing
- Kalexsyn, Inc., 4502 Campus Drive, Kalamazoo, Michigan 49008, United States
| | - John Gatfield
- Drug
Discovery Chemistry, Biology and Pharmacology, Actelion Pharmaceuticals Ltd., Gewerbestrasse 16, CH-4123 Allschwil, Switzerland
| | - Catherine Roch
- Drug
Discovery Chemistry, Biology and Pharmacology, Actelion Pharmaceuticals Ltd., Gewerbestrasse 16, CH-4123 Allschwil, Switzerland
| | - Melanie Kessler
- Drug
Discovery Chemistry, Biology and Pharmacology, Actelion Pharmaceuticals Ltd., Gewerbestrasse 16, CH-4123 Allschwil, Switzerland
| | - Johannes Mosbacher
- Drug
Discovery Chemistry, Biology and Pharmacology, Actelion Pharmaceuticals Ltd., Gewerbestrasse 16, CH-4123 Allschwil, Switzerland
| | - Thomas Pfeifer
- Drug
Discovery Chemistry, Biology and Pharmacology, Actelion Pharmaceuticals Ltd., Gewerbestrasse 16, CH-4123 Allschwil, Switzerland
| | - Corinna Grisostomi
- Drug
Discovery Chemistry, Biology and Pharmacology, Actelion Pharmaceuticals Ltd., Gewerbestrasse 16, CH-4123 Allschwil, Switzerland
| | - Markus Rey
- Drug
Discovery Chemistry, Biology and Pharmacology, Actelion Pharmaceuticals Ltd., Gewerbestrasse 16, CH-4123 Allschwil, Switzerland
| | - Eric A. Ertel
- Drug
Discovery Chemistry, Biology and Pharmacology, Actelion Pharmaceuticals Ltd., Gewerbestrasse 16, CH-4123 Allschwil, Switzerland
| | - Richard Moon
- Drug
Discovery Chemistry, Biology and Pharmacology, Actelion Pharmaceuticals Ltd., Gewerbestrasse 16, CH-4123 Allschwil, Switzerland
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Gironell A, Marin-Lahoz J. Ethosuximide for Essential Tremor: An Open-Label Trial. Tremor Other Hyperkinet Mov (N Y) 2016; 6:378. [PMID: 27625899 PMCID: PMC4947198 DOI: 10.7916/d8fq9wn0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 05/05/2016] [Indexed: 06/06/2023] Open
Abstract
BACKGROUND T-type calcium channel activation has been postulated to underlie rhythmicity in the olivo-cerebellar system that is implicated in ET. Ethosuximide reduces T-type calcium currents and can suppress tremor in two animal models of ET. We explored the effects of ethosuximide in subjects with ET in an open-label trial using both clinical scales and accelerometric recordings measures. We initially planned to conduct the trial with 15 patients, but due to lack of efficacy and a high incidence of adverse effects, the trial was stopped after seven patients had participated. METHODS Seven patients diagnosed with ET were included in the study. The ethosuximide dose was 500 mg daily (BID). The main outcome measures were: 1) tremor clinical rating scale (TCRS) score, 2) accelerometric recordings, and 3) self-reported disability scale score. RESULTS Five patients completed the study, and two dropped out due to adverse effects. There were no significant changes in clinical scores in motor task performance (TCRS 1+2), daily living activities (TCRS 3), or in the patients' subjective assessment (TCRS 4) and global appraisal. There were no differences observed for accelerometry data or disability scale scores. Anxiety, nervousness, headache, and dizziness were reported by two patients while on ethosuximide, causing them to stop the trial. No patient preferred to continue ethosuximide treatment. DISCUSSION The results of our exploratory study suggest that ethosuximide is not an effective treatment for ET.
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Affiliation(s)
- Alexandre Gironell
- Movement Disorders Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, Catalonia, Spain
| | - Juan Marin-Lahoz
- Movement Disorders Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, Catalonia, Spain
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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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Handforth A. Linking Essential Tremor to the Cerebellum—Animal Model Evidence. THE CEREBELLUM 2015; 15:285-98. [DOI: 10.1007/s12311-015-0750-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Devergnas A, Chen E, Ma Y, Hamada I, Pittard D, Kammermeier S, Mullin AP, Faundez V, Lindsley CW, Jones C, Smith Y, Wichmann T. Anatomical localization of Cav3.1 calcium channels and electrophysiological effects of T-type calcium channel blockade in the motor thalamus of MPTP-treated monkeys. J Neurophysiol 2015; 115:470-85. [PMID: 26538609 DOI: 10.1152/jn.00858.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 11/03/2015] [Indexed: 12/28/2022] Open
Abstract
Conventional anti-Parkinsonian dopamine replacement therapy is often complicated by side effects that limit the use of these medications. There is a continuing need to develop nondopaminergic approaches to treat Parkinsonism. One such approach is to use medications that normalize dopamine depletion-related firing abnormalities in the basal ganglia-thalamocortical circuitry. In this study, we assessed the potential of a specific T-type calcium channel blocker (ML218) to eliminate pathologic burst patterns of firing in the basal ganglia-receiving territory of the motor thalamus in Parkinsonian monkeys. We also carried out an anatomical study, demonstrating that the immunoreactivity for T-type calcium channels is strongly expressed in the motor thalamus in normal and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys. At the electron microscopic level, dendrites accounted for >90% of all tissue elements that were immunoreactive for voltage-gated calcium channel, type 3.2-containing T-type calcium channels in normal and Parkinsonian monkeys. Subsequent in vivo electrophysiologic studies in awake MPTP-treated Parkinsonian monkeys demonstrated that intrathalamic microinjections of ML218 (0.5 μl of a 2.5-mM solution, injected at 0.1-0.2 μl/min) partially normalized the thalamic activity by reducing the proportion of rebound bursts and increasing the proportion of spikes in non-rebound bursts. The drug also attenuated oscillatory activity in the 3-13-Hz frequency range and increased gamma frequency oscillations. However, ML218 did not normalize Parkinsonism-related changes in firing rates and oscillatory activity in the beta frequency range. Whereas the described changes are promising, a more complete assessment of the cellular and behavioral effects of ML218 (or similar drugs) is needed for a full appraisal of their anti-Parkinsonian potential.
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Affiliation(s)
- Annaelle Devergnas
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia;
| | - Erdong Chen
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia
| | - Yuxian Ma
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia
| | - Ikuma Hamada
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia
| | - Damien Pittard
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia
| | - Stefan Kammermeier
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia; Klinikum der Universität München, Neurologische Klinik und Poliklinik, München, Germany
| | - Ariana P Mullin
- Department of Cell Biology, Emory University, Atlanta, Georgia
| | - Victor Faundez
- Department of Cell Biology, Emory University, Atlanta, Georgia; Center for Social Translational Neuroscience, Emory University, Atlanta, Georgia
| | - Craig W Lindsley
- Department of Pharmacology and Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, Tennessee; and
| | - Carrie Jones
- Department of Pharmacology and Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, Tennessee; and
| | - Yoland Smith
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia; Department of Neurology, School of Medicine, Emory University, Atlanta, Georgia
| | - Thomas Wichmann
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia; Department of Neurology, School of Medicine, Emory University, Atlanta, Georgia
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Murata M, Hasegawa K, Kanazawa I, Shirakura K, Kochi K, Shimazu R, Kimura T, Yoshida K, Abe T, Kurita K, Yoshizawa K, Tamaoka A, Nakano I, Shimizu T, Hattori N, Mizusawa H, Kuno S, Yokochi F, Hirabayashi K, Horiuchi E, Kawashima N, Koike R, Ishikawa A, Kuriyama M, Mizoguchi K, Mitake S, Washimi Y, Tatsuoka Y, Fujimura H, Toda K, Kondo T, Nakashima K, Nomoto M, Uozumi T, Sato A, Matsuo H, Tsuruta K. Randomized placebo‐controlled trial of zonisamide in patients with Parkinson's disease. ACTA ACUST UNITED AC 2015. [DOI: 10.1111/ncn3.12026] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Miho Murata
- Department of Neurology National Center Hospital National Center of Neurology and Psychiatry Tokyo Japan
| | - Kazuko Hasegawa
- Department of Neurology Sagamihara National Hospital SagamiharaTokyo Japan
| | - Ichiro Kanazawa
- International University of Health and Welfare Graduate School Tokyo Japan
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Yabe I, Ohta M, Egashira T, Sato K, Kano T, Hirotani M, Kunieda Y, Sasaki H. Effectiveness of zonisamide in a patient with Parkinson's disease and various levodopa-induced psychotic symptoms. ACTA ACUST UNITED AC 2014. [DOI: 10.1111/ncn3.126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Ichiro Yabe
- Department of Neurology; Hokkaido University Graduate School of Medicine; Sapporo Japan
| | - Midori Ohta
- Rehabilitation Center; Wakkanai City Hospital; Wakkanai City Japan
| | - Toshiaki Egashira
- Department of Psychiatry; Wakkanai City Hospital; Wakkanai City Japan
| | - Kazunori Sato
- Department of Neurology; Hokkaido University Graduate School of Medicine; Sapporo Japan
| | - Takahiro Kano
- Department of Neurology; Hokkaido University Graduate School of Medicine; Sapporo Japan
| | - Makoto Hirotani
- Department of Neurology; Hokkaido University Graduate School of Medicine; Sapporo Japan
| | - Yasuyuki Kunieda
- Department of Internal Medicine; Wakkanai City Hospital; Wakkanai Japan
| | - Hidenao Sasaki
- Department of Neurology; Hokkaido University Graduate School of Medicine; Sapporo Japan
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Schmouth JF, Dion PA, Rouleau GA. Genetics of essential tremor: From phenotype to genes, insights from both human and mouse studies. Prog Neurobiol 2014; 119-120:1-19. [DOI: 10.1016/j.pneurobio.2014.05.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 04/16/2014] [Accepted: 05/02/2014] [Indexed: 11/30/2022]
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Cataldi M. The changing landscape of voltage-gated calcium channels in neurovascular disorders and in neurodegenerative diseases. Curr Neuropharmacol 2013; 11:276-97. [PMID: 24179464 PMCID: PMC3648780 DOI: 10.2174/1570159x11311030004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 02/02/2013] [Accepted: 02/14/2013] [Indexed: 12/12/2022] Open
Abstract
It is a common belief that voltage-gated calcium channels (VGCC) cannot carry toxic amounts of Ca2+ in neurons. Also, some of them as L-type channels are essential for Ca2+-dependent regulation of prosurvival gene-programs. However, a wealth of data show a beneficial effect of drugs acting on VGCCs in several neurodegenerative and neurovascular diseases. In the present review, we explore several mechanisms by which the “harmless” VGCCs may become “toxic” for neurons. These mechanisms could explain how, though usually required for neuronal survival, VGCCs may take part in neurodegeneration. We will present evidence showing that VGCCs can carry toxic Ca2+ when: a) their density or activity increases because of aging, chronic hypoxia or exposure to β-amyloid peptides or b) Ca2+-dependent action potentials carry high Ca2+ loads in pacemaker neurons. Besides, we will examine conditions in which VGCCs promote neuronal cell death without carrying excess Ca2+. This can happen, for instance, when they carry metal ions into the neuronal cytoplasm or when a pathological decrease in their activity weakens Ca2+-dependent prosurvival gene programs. Finally, we will explore the role of VGCCs in the control of nonneuronal cells that take part to neurodegeneration like those of the neurovascular unit or of microglia.
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Affiliation(s)
- Mauro Cataldi
- Division of Pharmacology, Department of Neuroscience, Reproductive and Odontostomatological Sciences, Federico II University of Naples, Italy
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Park YG, Kim J, Kim D. The potential roles of T-type Ca2+ channels in motor coordination. Front Neural Circuits 2013; 7:172. [PMID: 24191148 PMCID: PMC3808788 DOI: 10.3389/fncir.2013.00172] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 10/06/2013] [Indexed: 11/27/2022] Open
Abstract
Specific behavioral patterns are expressed by complex combinations of muscle coordination. Tremors are simple behavioral patterns and are the focus of studies investigating motor coordination mechanisms in the brain. T-type Ca(2+) channels mediate intrinsic neuronal oscillations and rhythmic burst spiking, and facilitate the generation of tremor rhythms in motor circuits. Despite substantial evidence that T-type Ca(2+) channels mediate pathological tremors, their roles in physiological motor coordination and behavior remain unknown. Here, we review recent progress in understanding the roles that T-type Ca(2+) channels play under pathological conditions, and discuss the potential relevance of these channels in mediating physiological motor coordination.
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Affiliation(s)
- Young-Gyun Park
- Department of Biological Sciences, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea
| | - Jeongjin Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea
| | - Daesoo Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea
- KAIST Institute for the BioCentury, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea
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Choi KH. The design and discovery of T-type calcium channel inhibitors for the treatment of central nervous system disorders. Expert Opin Drug Discov 2013; 8:919-31. [DOI: 10.1517/17460441.2013.796926] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Howitt L, Chaston DJ, Sandow SL, Matthaei KI, Edwards FR, Hill CE. Spreading vasodilatation in the murine microcirculation: attenuation by oxidative stress-induced change in electromechanical coupling. J Physiol 2013; 591:2157-73. [PMID: 23440962 PMCID: PMC3634526 DOI: 10.1113/jphysiol.2013.250928] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 02/19/2013] [Indexed: 12/17/2022] Open
Abstract
Regulation of blood flow in microcirculatory networks depends on spread of local vasodilatation to encompass upstream arteries; a process mediated by endothelial conduction of hyperpolarization. Given that endothelial coupling is reduced in hypertension, we used hypertensive Cx40ko mice, in which endothelial coupling is attenuated, to investigate the contribution of the renin-angiotensin system and reduced endothelial cell coupling to conducted vasodilatation of cremaster arterioles in vivo. When the endothelium was disrupted by light dye treatment, conducted vasodilatation, following ionophoresis of acetylcholine, was abolished beyond the site of endothelial damage. In the absence of Cx40, sparse immunohistochemical staining was found for Cx37 in the endothelium, and endothelial, myoendothelial and smooth muscle gap junctions were identified by electron microscopy. Hyperpolarization decayed more rapidly in arterioles from Cx40ko than wild-type mice. This was accompanied by a shift in the threshold potential defining the linear relationship between voltage and diameter, increased T-type calcium channel expression and increased contribution of T-type (3 μmol l(-1) NNC 55-0396), relative to L-type (1 μmol l(-1) nifedipine), channels to vascular tone. The change in electromechanical coupling was reversed by inhibition of the renin-angiotensin system (candesartan, 1.0 mg kg(-1) day(-1) for 2 weeks) or by acute treatment with the superoxide scavenger tempol (1 mmol l(-1)). Candesartan and tempol treatments also significantly improved conducted vasodilatation. We conclude that conducted vasodilatation in Cx40ko mice requires the endothelium, and attenuation results from both a reduction in endothelial coupling and an angiotensin II-induced increase in oxidative stress. We suggest that during cardiovascular disease, the ability of microvascular networks to maintain tissue integrity may be compromised due to oxidative stress-induced changes in electromechanical coupling.
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Affiliation(s)
- Lauren Howitt
- John Curtin School of Medical Research, Australian National University, Canberra ACT 0200, Australia
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Handforth A. Harmaline tremor: underlying mechanisms in a potential animal model of essential tremor. TREMOR AND OTHER HYPERKINETIC MOVEMENTS (NEW YORK, N.Y.) 2012; 2. [PMID: 23440018 PMCID: PMC3572699 DOI: 10.7916/d8td9w2p] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 03/24/2012] [Indexed: 01/18/2023]
Abstract
BACKGROUND Harmaline and harmine are tremorigenic β-carbolines that, on administration to experimental animals, induce an acute postural and kinetic tremor of axial and truncal musculature. This drug-induced action tremor has been proposed as a model of essential tremor. Here we review what is known about harmaline tremor. METHODS Using the terms harmaline and harmine on PubMed, we searched for papers describing the effects of these β-carbolines on mammalian tissue, animals, or humans. RESULTS Investigations over four decades have shown that harmaline induces rhythmic burst-firing activity in the medial and dorsal accessory inferior olivary nuclei that is transmitted via climbing fibers to Purkinje cells and to the deep cerebellar nuclei, then to brainstem and spinal cord motoneurons. The critical structures required for tremor expression are the inferior olive, climbing fibers, and the deep cerebellar nuclei; Purkinje cells are not required. Enhanced synaptic norepinephrine or blockade of ionic glutamate receptors suppresses tremor, whereas enhanced synaptic serotonin exacerbates tremor. Benzodiazepines and muscimol suppress tremor. Alcohol suppresses harmaline tremor but exacerbates harmaline-associated neural damage. Recent investigations on the mechanism of harmaline tremor have focused on the T-type calcium channel. DISCUSSION Like essential tremor, harmaline tremor involves the cerebellum, and classic medications for essential tremor have been found to suppress harmaline tremor, leading to utilization of the harmaline model for preclinical testing of antitremor drugs. Limitations are that the model is acute, unlike essential tremor, and only approximately half of the drugs reported to suppress harmaline tremor are subsequently found to suppress tremor in clinical trials.
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Affiliation(s)
- Adrian Handforth
- Neurology Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
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Miwa H, Kondo T. T-type calcium channel as a new therapeutic target for tremor. THE CEREBELLUM 2012; 10:563-9. [PMID: 21479969 DOI: 10.1007/s12311-011-0277-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Voltage-gated calcium channels play an important role in many physiological and pathological processes. Accumulating studies suggest that the T-type calcium channel is a potential target for the treatment of various neurological disorders, such as epilepsy, insomnia, and neuropathic pain. Here, we highlight recent advances in our understanding of T-type calcium channel regulation and their implications for tremor disorders. Several T-type calcium channel blockers effectively suppressed experimental tremors that have been suggested to originate from either the cerebellum or basal ganglia. Among T-type calcium channel blockers that have been used clinically, the anti-tremor efficacy of zonisamide garnered our attention. Based on both basic and clinical studies, the possibility is emerging that T-type calcium channel blockers that transit into the central nervous system may have therapeutic potentials for tremor disorders.
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Affiliation(s)
- Hideto Miwa
- Department of Neurology, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8510, Japan.
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Bidirectional plasticity in the primate inferior olive induced by chronic ethanol intoxication and sustained abstinence. Proc Natl Acad Sci U S A 2011; 108:10314-9. [PMID: 21642533 DOI: 10.1073/pnas.1017079108] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The brain adapts to chronic ethanol intoxication by altering synaptic and ion-channel function to increase excitability, a homeostatic counterbalance to inhibition by alcohol. Delirium tremens occurs when those adaptations are unmasked during withdrawal, but little is known about whether the primate brain returns to normal with repeated bouts of ethanol abuse and abstinence. Here, we show a form of bidirectional plasticity of pacemaking currents induced by chronic heavy drinking within the inferior olive of cynomolgus monkeys. Intracellular recordings of inferior olive neurons demonstrated that ethanol inhibited the tail current triggered by release from hyperpolarization (I(tail)). Both the slow deactivation of hyperpolarization-activated cyclic nucleotide-gated channels conducting the hyperpolarization-activated inward current and the activation of Ca(v)3.1 channels conducting the T-type calcium current (I(T)) contributed to I(tail), but ethanol inhibited only the I(T) component of I(tail). Recordings of inferior olive neurons obtained from chronically intoxicated monkeys revealed a significant up-regulation in I(tail) that was induced by 1 y of daily ethanol self-administration. The up-regulation was caused by a specific increase in I(T) which (i) greatly increased neurons' susceptibility for rebound excitation following hyperpolarization and (ii) may have accounted for intention tremors observed during ethanol withdrawal. In another set of monkeys, sustained abstinence produced the opposite effects: (i) a reduction in rebound excitability and (ii) a down-regulation of I(tail) caused by the down-regulation of both the hyperpolarization-activated inward current and I(T). Bidirectional plasticity of two hyperpolarization-sensitive currents following chronic ethanol abuse and abstinence may underlie persistent brain dysfunction in primates and be a target for therapy.
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