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Lee JE, Kim HN, Kim DY, Shin YJ, Shin JY, Lee PH. Memantine exerts neuroprotective effects by modulating α-synuclein transmission in a parkinsonian model. Exp Neurol 2021; 344:113810. [PMID: 34270920 DOI: 10.1016/j.expneurol.2021.113810] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 06/26/2021] [Accepted: 07/11/2021] [Indexed: 01/10/2023]
Abstract
Ample evidence has demonstrated that α-Synuclein can propagate from one area of the brain to others via cell-to-cell transmission, which might be the underlying mechanism for pathological propagation and the disease progression of Parkinson's disease (PD). Recent reports have demonstrated cell surface receptor-mediated cell-to-cell transmission of α-synuclein. Memantine decreased the levels of internalized cytosolic α-synuclein and led to attenuation in α-synuclein-induced cell death. Specifically, memantine attenuated α-synuclein-induced expression of clathrin and EEA1, and increased expression of NR2A subunits. Moreover, memantine inhibited propagation of extracellular α-synuclein and thus, decreased the expression of the phosphorylated form of α-synuclein in dopaminergic neurons of the substantia nigra, which was accompanied by increased survival of dopaminergic neurons with functional improvement of motor deficits. The present study demonstrated that memantine modulates extracellular α-synuclein propagation by inhibiting interactions between α-synuclein and NR2A subunits, which leads to neuroprotective effects on nigral dopaminergic neurons against α-synuclein-enriched conditions. The repositioning use of memantine in α-synuclein propagation needs to be further evaluated in patients with α-synucleinopathies as an effective therapeutic approach.
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Affiliation(s)
- Ji Eun Lee
- Department of Neurology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Ha Na Kim
- Department of Neurology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Dong-Yeol Kim
- Department of Neurology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Yu Jin Shin
- Department of Neurology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jin Young Shin
- Department of Neurology, Yonsei University College of Medicine, Seoul, Republic of Korea; Severance Biomedical Science Institute, Yonsei University, Seoul, Republic of Korea.
| | - Phil Hyu Lee
- Department of Neurology, Yonsei University College of Medicine, Seoul, Republic of Korea; Severance Biomedical Science Institute, Yonsei University, Seoul, Republic of Korea.
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2
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Naik S, Pandey A, Lewis SA, Rao BSS, Mutalik S. Neuroprotection: A versatile approach to combat glaucoma. Eur J Pharmacol 2020; 881:173208. [PMID: 32464192 DOI: 10.1016/j.ejphar.2020.173208] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 05/10/2020] [Accepted: 05/18/2020] [Indexed: 12/19/2022]
Abstract
In most retinal diseases, neuronal loss is the main cause of vision loss. Neuroprotection is the alteration of neurons and/or their environment to encourage the survival and function of the neurons, especially in environments that are deleterious to the neuronal health. The area of neuroprotection progresses with a therapeutically-based hope of improving vision and clinical outcomes for patients through the developments in neurotrophic therapy, antioxidative therapy, anti-excitotoxic, anti-ischemic, anti-inflammatory, and anti-apoptotic care. In this review, we summarize the various neuroprotection strategies for the treatment of glaucoma, genetics of glaucoma and the role of various nanoplatforms in the treatment of glaucoma.
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Affiliation(s)
- Santoshi Naik
- Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka State, India
| | - Abhijeet Pandey
- Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka State, India
| | - Shaila A Lewis
- Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka State, India
| | - Bola Sadashiva Satish Rao
- Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka State, India
| | - Srinivas Mutalik
- Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka State, India.
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3
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Ladagu AD, Olopade FE, Folarin OR, Elufioye TO, Wallach JV, Dybek MB, Olopade JO, Adejare A. Novel NMDA-receptor antagonists ameliorate vanadium neurotoxicity. Naunyn Schmiedebergs Arch Pharmacol 2020; 393:1729-1738. [PMID: 32388602 DOI: 10.1007/s00210-020-01882-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 04/22/2020] [Indexed: 12/17/2022]
Abstract
Various NMDA-receptor antagonists have been investigated for their therapeutic potential in Alzheimer's disease with memantine shown to be safe and with relative efficacy. There is, however, need to develop novel drugs to counter tolerance and with better efficacy in ameliorating neurodegeneration. We have shown neurodegeneration in different models of vanadium-exposed mice. This study was designed to evaluate and ascertain the potency of three novel NMDA-receptor antagonists (Compounds A, B and C) to ameliorate neurodegeneration in vanadium-exposed mice. One-month-old mice (n = 6) received sterile water (control) and another group (n = 6) was treated with vanadium (3 mg/kg sodium metavanadate) intraperitoneally for 1 month. Three other groups (n = 6) received vanadium and compounds A, B and C (4.35 mg/kg, 30 mg/kg and 100 mg/kg, respectively) simultaneously for the same period. Assessment of pathologies and neurodegeneration in different brain regions was done to test the ameliorative effects of the 3 antagonists using different immunohistochemical markers. Vanadium exposure resulted in reduced calbindin expression and pyknosis of Purkinje cells, cell loss and destruction of apical dendrites with greater percentage of cytoplasmic vacuolations, morphological alterations characterized by cell clustering and multiple layering patterns in the Purkinje cell layer. In addition, the observed degeneration included demyelination, increased GFAP-immunoreactive cells and microgliosis. Simultaneous administration of the compounds to vanadium-exposed mice resulted in the preservation of cellular integrity in the same anatomical regions and restoration of the cells' vitality with reduced astroglial and microglial activation.
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Affiliation(s)
- A D Ladagu
- Department of Veterinary Anatomy, University of Ibadan, Oyo, Nigeria
| | - F E Olopade
- Department of Anatomy, University of Ibadan, Oyo, Nigeria
| | - O R Folarin
- Department of Veterinary Anatomy, University of Ibadan, Oyo, Nigeria
| | - T O Elufioye
- Department of Pharmacognosy, University of Ibadan, Oyo, Nigeria
| | - J V Wallach
- Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of the Sciences, Philadelphia, PA, USA
| | - M B Dybek
- Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of the Sciences, Philadelphia, PA, USA
| | - J O Olopade
- Department of Veterinary Anatomy, University of Ibadan, Oyo, Nigeria.
| | - A Adejare
- Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of the Sciences, Philadelphia, PA, USA
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4
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Neuroprotective Strategies for Retinal Ganglion Cell Degeneration: Current Status and Challenges Ahead. Int J Mol Sci 2020; 21:ijms21072262. [PMID: 32218163 PMCID: PMC7177277 DOI: 10.3390/ijms21072262] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/19/2020] [Accepted: 03/20/2020] [Indexed: 12/12/2022] Open
Abstract
The retinal ganglion cells (RGCs) are the output cells of the retina into the brain. In mammals, these cells are not able to regenerate their axons after optic nerve injury, leaving the patients with optic neuropathies with permanent visual loss. An effective RGCs-directed therapy could provide a beneficial effect to prevent the progression of the disease. Axonal injury leads to the functional loss of RGCs and subsequently induces neuronal death, and axonal regeneration would be essential to restore the neuronal connectivity, and to reestablish the function of the visual system. The manipulation of several intrinsic and extrinsic factors has been proposed in order to stimulate axonal regeneration and functional repairing of axonal connections in the visual pathway. However, there is a missing point in the process since, until now, there is no therapeutic strategy directed to promote axonal regeneration of RGCs as a therapeutic approach for optic neuropathies.
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Jantas D, Grygier B, Gołda S, Chwastek J, Zatorska J, Tertil M. An endogenous and ectopic expression of metabotropic glutamate receptor 8 (mGluR8) inhibits proliferation and increases chemosensitivity of human neuroblastoma and glioma cells. Cancer Lett 2018; 432:1-16. [DOI: 10.1016/j.canlet.2018.06.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/06/2018] [Accepted: 06/03/2018] [Indexed: 12/11/2022]
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Shi T, Hao JX, Wiesenfeld-Hallin Z, Xu XJ. Gabapentin and NMDA receptor antagonists interacts synergistically to alleviate allodynia in two rat models of neuropathic pain. Scand J Pain 2018; 18:687-693. [DOI: 10.1515/sjpain-2018-0083] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 06/12/2018] [Indexed: 11/15/2022]
Abstract
Abstract
Background and aims
The clinical management of neuropathic pain remains a challenge. We examined the interaction between gabapentin and NMDA receptor antagonists dextromethrophan and MK-801 in alleviating neuropathic pain-like behaviors in rats after spinal cord or sciatic nerve injury.
Methods
Female and male rats were produced with Ischemic spinal cord injury and sciatic nerve injury. Gabapentin, dextromethorphan, MK-801 or drug combinations were injected with increasing doses. Mechanical response thresholds were tested with von Frey hairs to graded mechanical touch/pressure, and ethyl chloride spray was applied to assess the cold sensitivity before and after injuries.
Results
In spinally injured rats, gabapentin and dextromethorphan did not affect allodynia-like behaviors at doses of 30 and 20 mg/kg, respectively. In contrast, combination of 15 or 30 mg/kg gabapentin with dextromethorphan at 10 mg/kg produced total alleviation of allodynia to mechanical or cold stimulation. Further reducing the dose of gapapentin to 7.5 mg/kg and dextromethorphan to 5 mg/kg still produced significant effect. MK-801, another NMDA receptor antagonist, also enhanced the effect of gabapentin in spinally injured rats. Similar synergistic anti-allodynic effect between dextromethorphan and gabapentin was also observed in a rat model of partial sciatic nerve injury. No increased side effect was seen following the combination between gabapentin and dextromethorphan.
Conclusions
In conclusion, the present study suggested that combining NMDA receptor antagonists with gabapentin could provide synergistic effect to alleviate neuropathic pain and reduced side effects.
Implications
Combining NMDA receptor antagonists with gabapentin may provide a new approach in alleviating neuropathic pain with increased efficacy and reduced side effects.
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Affiliation(s)
- Tiansheng Shi
- Department of Physiology and Pharmacology, Section of Integrative Pain Research, Karolinska Institutet , S-171 77 Stockholm , Sweden
| | - Jing-Xia Hao
- Department of Physiology and Pharmacology, Section of Integrative Pain Research, Karolinska Institutet , Stockholm , Sweden
| | - Zsuzsanna Wiesenfeld-Hallin
- Department of Physiology and Pharmacology, Section of Integrative Pain Research, Karolinska Institutet , Stockholm , Sweden
| | - Xiao-Jun Xu
- Department of Physiology and Pharmacology, Section of Integrative Pain Research, Karolinska Institutet , Stockholm , Sweden
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Neuroprotective Effect of Magnesium Acetyltaurate Against NMDA-Induced Excitotoxicity in Rat Retina. Neurotox Res 2016; 31:31-45. [PMID: 27568334 DOI: 10.1007/s12640-016-9658-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Revised: 07/31/2016] [Accepted: 08/09/2016] [Indexed: 12/13/2022]
Abstract
Glutamate excitotoxicity plays a major role in the loss of retinal ganglion cells (RGCs) in glaucoma. The toxic effects of glutamate on RGCs are mediated by the overstimulation of N-methyl-D-aspartate (NMDA) receptors. Accordingly, NMDA receptor antagonists have been suggested to inhibit excitotoxicity in RGCs and delay the progression and visual loss in glaucoma patients. The purpose of the present study was to examine the potential neuroprotective effect of Mg acetyltaurate (MgAT) on RGC death induced by NMDA. MgAT was proposed mainly due to the combination of magnesium (Mg) and taurine which may provide neuroprotection by dual mechanisms of action, i.e., inhibition of NMDA receptors and antioxidant effects. Rats were divided into 5 groups and were given intravitreal injections. Group 1 (PBS group) was injected with vehicle; group 2 (NMDA group) was injected with NMDA while groups 3 (pre-), 4 (co-), and 5 (post-) treatments were injected with MgAT, 24 h before, in combination or 24 h after NMDA injection respectively. NMDA and MgAT were injected in PBS at doses 160 and 320 nmol, respectively. Seven days after intravitreal injection, the histological changes in the retina were evaluated using hematoxylin & eosin (H&E) staining. Optic nerves were dissected and stained in Toluidine blue for grading on morphological neurodegenerative changes. The extent of apoptosis in retinal tissue was assessed by TUNEL assay and caspase-3 immunohistochemistry staining. The estimation of neurotrophic factor, oxidative stress, pro/anti-apoptotic factors and caspase-3 activity in retina was done using enzyme-linked immunosorbent assay (ELISA) technique. The retinal morphometry showed reduced thickness of ganglion cell layer (GCL) and reduction in the number of retinal cells in GCL in NMDA group compared to the MgAT-treated groups. TUNEL and caspase-3 staining showed increased number of apoptotic cells in inner retina. The results were further corroborated by the estimation of neurotrophic factor, oxidative stress, pro/anti-apoptotic factors, and caspase-3 activity in retina. In conclusion, current study revealed that intravitreal MgAT prevents retinal and optic nerve damage induced by NMDA. Overall, our data demonstrated that the pretreatment with MgAT was more effective than co- and posttreatment. This protective effect of MgAT against NMDA-induced retinal cell apoptosis could be attributed to the reduction of retinal oxidative stress and activation of BDNF-related neuroprotective mechanisms.
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Preferential Inhibition of Tonically over Phasically Activated NMDA Receptors by Pregnane Derivatives. J Neurosci 2016; 36:2161-75. [PMID: 26888927 DOI: 10.1523/jneurosci.3181-15.2016] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Postsynaptic N-methyl-d-aspartate receptors (NMDARs) phasically activated by presynaptically released glutamate are critical for synaptic transmission and plasticity. However, under pathological conditions, excessive activation of NMDARs by tonically increased ambient glutamate contributes to excitotoxicity associated with various acute and chronic neurological disorders. Here, using heterologously expressed GluN1/GluN2A and GluN1/GluN2B receptors and rat autaptic hippocampal microisland cultures, we show that pregnanolone sulfate inhibits NMDAR currents induced by a prolonged glutamate application with a higher potency than the NMDAR component of EPSCs. For synthetic pregnanolone derivatives substituted with a carboxylic acid moiety at the end of an aliphatic chain of varying length and attached to the steroid skeleton at C3, the difference in potency between tonic and phasic inhibition increased with the length of the residue. The steroid with the longest substituent, pregnanolone hemipimelate, had no effect on phasically activated receptors while inhibiting tonically activated receptors. In behavioral tests, pregnanolone hemipimelate showed neuroprotective activity without psychomimetic symptoms. These results provide insight into the influence of steroids on neuronal function and stress their potential use in the development of novel therapeutics with neuroprotective action. SIGNIFICANCE STATEMENT Synaptic activation of N-methyl-d-aspartate receptors (NMDARs) plays a key role in synaptic plasticity, but excessive tonic NMDAR activation mediates excitotoxicity associated with many neurological disorders. Therefore, there is much interest in pharmacological agents capable of selectively blocking tonically activated NMDARs while leaving synaptically activated NMDARs intact. Here, we show that an endogenous neurosteroid pregnanolone sulfate is more potent at inhibiting tonically than synaptically activated NMDARs. Further, we report that a novel synthetic analog of pregnanolone sulfate, pregnanolone hemipimelate, inhibits tonic NMDAR currents without inhibiting the NMDAR component of the EPSC and shows neuroprotective activity in vivo without inducing psychomimetic side effects. These results suggest steroids may have a clinical advantage over other known classes of NMDAR inhibitors.
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Doozandeh A, Yazdani S. Neuroprotection in Glaucoma. J Ophthalmic Vis Res 2016; 11:209-20. [PMID: 27413504 PMCID: PMC4926571 DOI: 10.4103/2008-322x.183923] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Accepted: 08/03/2015] [Indexed: 11/04/2022] Open
Abstract
Glaucoma is a degenerative optic neuropathy characterized by retinal ganglion cell (RGC) loss and visual field defects. It is known that in some glaucoma patients, death of RGCs continues despite intraocular pressure (IOP) reduction. Neuroprotection in the field of glaucoma is defined as any treatment, independent of IOP reduction, which prevents RGC death. Glutamate antagonists, ginkgo biloba extract, neurotrophic factors, antioxidants, calcium channel blockers, brimonidine, glaucoma medications with blood regulatory effect and nitric oxide synthase inhibitors are among compounds with possible neuroprotective activity in preclinical studies. A few agents (such as brimonidine or memantine) with neuroprotective effects in experimental studies have advanced to clinical trials; however the results of clinical trials for these agents have not been conclusive. Nevertheless, lack of compelling clinical evidence has not prevented the off-label use of some of these compounds in glaucoma practice. Stem cell transplantation has been reported to halt experimental neurodegenerative disease processes in the absence of cell replacement. It has been hypothesized that transplantation of some types of stem cells activates multiple neuroprotective pathways via secretion of various factors. The advantage of this approach is a prolonged and targeted effect. Important concerns in this field include the secretion of unwanted harmful mediators, graft survival issues and tumorigenesis. Neuroprotection in glaucoma, pharmacologically or by stem cell transplantation, is an interesting subject waiting for broad and multidisciplinary collaborative studies to better clarify its role in clinical practice.
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Affiliation(s)
- Azadeh Doozandeh
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Shahin Yazdani
- Ocular Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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10
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Ingle SV, Joshi KA. Electron density topography based model to explore N-methyl-d-aspartate receptor channel blockers. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.01.070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Abstract
This review compares the biological and physiological function of Sigma receptors [σRs] and their potential therapeutic roles. Sigma receptors are widespread in the central nervous system and across multiple peripheral tissues. σRs consist of sigma receptor one (σ1R) and sigma receptor two (σ2R) and are expressed in numerous regions of the brain. The sigma receptor was originally proposed as a subtype of opioid receptors and was suggested to contribute to the delusions and psychoses induced by benzomorphans such as SKF-10047 and pentazocine. Later studies confirmed that σRs are non-opioid receptors (not an µ opioid receptor) and play a more diverse role in intracellular signaling, apoptosis and metabolic regulation. σ1Rs are intracellular receptors acting as chaperone proteins that modulate Ca2+ signaling through the IP3 receptor. They dynamically translocate inside cells, hence are transmembrane proteins. The σ1R receptor, at the mitochondrial-associated endoplasmic reticulum membrane, is responsible for mitochondrial metabolic regulation and promotes mitochondrial energy depletion and apoptosis. Studies have demonstrated that they play a role as a modulator of ion channels (K+ channels; N-methyl-d-aspartate receptors [NMDAR]; inositol 1,3,5 triphosphate receptors) and regulate lipid transport and metabolism, neuritogenesis, cellular differentiation and myelination in the brain. σ1R modulation of Ca2+ release, modulation of cardiac myocyte contractility and may have links to G-proteins. It has been proposed that σ1Rs are intracellular signal transduction amplifiers. This review of the literature examines the mechanism of action of the σRs, their interaction with neurotransmitters, pharmacology, location and adverse effects mediated through them.
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Affiliation(s)
- Colin G Rousseaux
- a Department of Pathology and Laboratory Medicine , University of Ottawa , Ottawa , ON , Canada and
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12
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Gooshe M, Abdolghaffari AH, Aleyasin AR, Chabouk L, Tofigh S, Hassanzadeh GR, Payandemehr B, Partoazar A, Azizi Y, Dehpour AR. Hypoxia/ischemia a key player in early post stroke seizures: modulation by opioidergic and nitrergic systems. Eur J Pharmacol 2014; 746:6-13. [PMID: 25449041 DOI: 10.1016/j.ejphar.2014.11.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Revised: 11/05/2014] [Accepted: 11/06/2014] [Indexed: 01/14/2023]
Abstract
Stroke is a leading cause of death, disability, and socioeconomic loss worldwide. All attempts at pharmacological reduction of the complications of stroke (e.g. post-stroke seizure, and brain׳s vulnerability to hypoxic/ischemic injury) have failed. Endogenous opioids and nitric oxide (NO) overproduction has been documented in brain hypoxia/ischemia (H/I), which can exert pro-convulsive effects. In this study, we aimed to examine the possible involvement of opioidergic and nitrergic pathways in the pathogenesis of post-stroke seizure. H/I was induced by right common carotid ligation and sham-operated mice served as controls. We demonstrated that right common carotid ligation decreases the threshold for clonic seizures induced by pentylenetetrazole (PTZ), a GABA antagonist. Furthermore, pro-convulsive effect of H/I following right common carotid ligation was blocked by naltrexone (NTX) (3mg/kg), NG-Nitro-l-arginine methyl ester (l-NAME) (10mg/kg), and aminoguanidine (AG) (100mg/kg) administration (P<0.001). Interestingly, co-administration of non-effective doses of NTX and l-NAME (1 and 0.5mg/kg, respectively) reverses epileptogenesis of H/I (P<0.001). In the same way, co-administration of non-effective doses of NTX and AG (1 and 5mg/kg, respectively), reverses epileptogenesis of H/I (P<0.001). Indeed, the histological studies performed on mice exposed to H/I confirmed our previous data. These findings suggest hyper-susceptibility to PTZ induced seizure following H/I is mediated by interaction of opioidergic, and iNOS/NO pathways. Therefore, our results identify new pharmacological targets and provide the rationale for a novel strategy to promote recovery after stroke and possibly other brain injuries.
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Affiliation(s)
- Maziar Gooshe
- Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran; Students׳ Scientific Research Center (SSRC), Tehran University of Medical Sciences, Tehran, Iran; Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Amir Hossein Abdolghaffari
- Pharmacology and Applied Medicine, Department of Medicinal Plants Research Center, Institute of Medicinal Plants, ACECR, Karaj, Iran; International Campus, ICTUMS, Tehran University of Medical Sciences, Tehran, Iran
| | - Ali Reza Aleyasin
- Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran; Students׳ Scientific Research Center (SSRC), Tehran University of Medical Sciences, Tehran, Iran; Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Leila Chabouk
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Sina Tofigh
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Gholam Reza Hassanzadeh
- Department of Anatomy, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Borna Payandemehr
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Alireza Partoazar
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Yaser Azizi
- Department of Physiology, School of Medicine, Tehran University of Medical Science, Tehran, Iran
| | - Ahmad Reza Dehpour
- Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran; Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
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Wang F, Liang W, Lei C, Kinden R, Sang H, Xie Y, Huang Y, Qu Y, Xiong L. Combination of HBO and Memantine in Focal Cerebral Ischemia: Is There a Synergistic Effect? Mol Neurobiol 2014; 52:1458-1466. [DOI: 10.1007/s12035-014-8949-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 10/20/2014] [Indexed: 11/30/2022]
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14
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Anesthetic sevoflurane reduces levels of hippocalcin and postsynaptic density protein 95. Mol Neurobiol 2014; 51:853-63. [PMID: 24870966 DOI: 10.1007/s12035-014-8746-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 05/06/2014] [Indexed: 12/14/2022]
Abstract
Sevoflurane, the commonly used inhalation anesthetic in children, has been shown to enhance cytosolic calcium levels and induce cognitive impairment in young mice. However, the downstream consequences of the sevoflurane-induced elevation in cytosolic calcium levels and the upstream mechanisms of the sevoflurane-induced cognitive impairment remain largely to be determined. Hippocalcin is one of the neuronal calcium sensor proteins, and also binds to postsynaptic density protein 95 (PSD-95). We therefore set out to determine the effects of sevoflurane on the levels of hippocalcin and PSD-95 in vitro and in vivo. Hippocampus neurons from mice and 6-day-old mice were treated with 4.1% sevoflurane for 6 h or 3% sevoflurane 2 h daily for 3 days, respectively. We then measured the levels of hippocalcin and PSD-95, and assessed whether BAPTA, an intracellular calcium chelator, and memantine, a partial antagonist of the NMDA receptor, could inhibit the sevoflurane's effects. We found that sevoflurane decreased the levels of hippocalcin and PSD-95 in the neurons; and decreased the levels of hippocalcin and PSD-95 in the hippocampus of mice immediately after the anesthesia, but only the PSD-95 levels three weeks after the anesthesia. BAPTA inhibited the sevoflurane's effects in the neurons. Memantine attenuated the sevoflurane-induced reductions in the levels of hippocalcin and PSD-95, as well as the sevoflurane-induced cognitive impairment in mice. These data suggested that sevoflurane decreased the levels of hippocalcin and PSD-95, which could serve as one of bridge mechanisms between the sevoflurane-induced elevation of cytosolic calcium levels and the sevoflurane-induced cognitive impairment.
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Lima MG, Maximino C, Matos Oliveira KR, Brasil A, Crespo-Lopez ME, Batista EDJO, Rocha FADF, Picanço-Diniz DLW, Herculano AM. Nitric oxide as a regulatory molecule in the processing of the visual stimulus. Nitric Oxide 2013; 36:44-50. [PMID: 24275015 DOI: 10.1016/j.niox.2013.10.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 10/18/2013] [Accepted: 10/30/2013] [Indexed: 01/02/2023]
Abstract
Nitric oxide (NO) is a highly reactive gas with considerable diffusion power that is produced pre- and post synaptically in the central nervous system (CNS). In the visual system, it is involved in the processing of the visual information from the retina to superior visual centers. In this review we discuss the main mechanisms through which nitric oxide acts, in physiological levels, on the retina, lateral geniculate nucleus (LGN) and primary visual cortex. In the retina, the cGMP-dependent nitric oxide activity initially amplifies the signal, subsequently increasing the inhibitory activity, suggesting that the signal is "filtered". In the thalamus, on dLGN, neuronal activity is amplified by NO derived from brainstem cholinergic cells, in a cGMP-independent mechanism; the result is the amplification of the signal arriving from retina. Finally, on the visual cortex (V1), NO acts through changes on the cGMP levels, increasing signal detection. These observations suggest that NO works like a filter, modulating the signal along the visual pathways.
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Affiliation(s)
- Monica Gomes Lima
- Laboratory of Neuroendocrinology, Biological Sciences Institute, Federal University of Pará, Av. Augusto Correa, 01 Guamá, Belém, Pará 66075-110, Brazil.
| | - Caio Maximino
- Laboratory of Neuroendocrinology, Biological Sciences Institute, Federal University of Pará, Av. Augusto Correa, 01 Guamá, Belém, Pará 66075-110, Brazil; Zebrafish Neuroscience Research Consortium (ZNRC) Slidell, Louisiana 70458, USA.
| | - Karen Renata Matos Oliveira
- Laboratory of Neuroendocrinology, Biological Sciences Institute, Federal University of Pará, Av. Augusto Correa, 01 Guamá, Belém, Pará 66075-110, Brazil.
| | - Alódia Brasil
- Laboratory of Neuroendocrinology, Biological Sciences Institute, Federal University of Pará, Av. Augusto Correa, 01 Guamá, Belém, Pará 66075-110, Brazil.
| | - Maria Elena Crespo-Lopez
- Laboratory of Molecular Pharmacology, Biological Sciences Institute, Federal University of Pará, Av. Augusto Correa, 01 Guamá, Belém, Pará CEP 66075-110, Brazil.
| | - Evander de Jesus Oliveira Batista
- Laboratory of Neuroendocrinology, Biological Sciences Institute, Federal University of Pará, Av. Augusto Correa, 01 Guamá, Belém, Pará 66075-110, Brazil.
| | - Fernando Allan de Farias Rocha
- Laboratory of Neuroscience Dr. Eduardo Oswaldo Cruz, Biological Sciences Institute, Federal University of Pará, Av. Augusto Correa, 01 Guamá, Belém, Pará CEP 66075-110, Brazil
| | - Domingos Luiz Wanderley Picanço-Diniz
- Nucleus Oriximiná, Federal University of Western Pará, University Campus Oriximiná, Rodovia PA-254, n° 257 Bairro Santíssimo, Oriximiná, Pará CEP 68270-000, Brazil.
| | - Anderson Manoel Herculano
- Laboratory of Neuroendocrinology, Biological Sciences Institute, Federal University of Pará, Av. Augusto Correa, 01 Guamá, Belém, Pará 66075-110, Brazil; Zebrafish Neuroscience Research Consortium (ZNRC) Slidell, Louisiana 70458, USA.
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Stamler JS. Redox pioneer: Professor Stuart A. Lipton. Antioxid Redox Signal 2013; 19:757-64. [PMID: 23815466 PMCID: PMC3749706 DOI: 10.1089/ars.2013.5388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 06/14/2013] [Accepted: 07/01/2013] [Indexed: 11/12/2022]
Abstract
[Figure: see text] Stuart A. Lipton, M.D., Ph.D. is recognized here as a Redox Pioneer because of his publication of four articles that have been cited more than 1000 times, and 96 reports which have been cited more than 100 times. In the redox field, Dr. Lipton is best known for his work on the regulation by S-nitrosylation of the NMDA-subtype of neuronal glutamate receptor, which provided early evidence for in situ regulation of protein activity by S-nitrosylation and a prototypic model of allosteric control by this post-translational modification. Over the past several years, Lipton's group has pioneered the discovery of aberrant protein nitrosylation that may contribute to a number of neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis (Lou Gehrig's disease). In particular, the phenotypic effects of rare genetic mutations may be understood to be enhanced or mimicked by nitrosative (and oxidative) modifications of cysteines and thereby help explain common sporadic forms of disease. Thus, Lipton has contributed in a major way to the understanding that nitrosative stress may result from modifications of specific proteins and may operate in conjunction with genetic mutation to create disease phenotype. Lipton (collaborating with Jonathan S. Stamler) has also employed the concept of targeted S-nitrosylation to produce novel neuroprotective drugs that act at allosteric sites in the NMDA receptor. Lipton has won a number of awards, including the Ernst Jung Prize in Medicine, and is an elected fellow of the AAAS. Antioxid. Redox Signal. 19, 757-764.
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Affiliation(s)
- Jonathan S Stamler
- Institute for Transformative Molecular Medicine and Harrington Discovery Institute, Case Western Reserve University and University Hospital Case Medical Center, Cleveland, Ohio 44106, USA.
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Functional protective effects of long-term memantine treatment in the DBA/2J mouse. Doc Ophthalmol 2013; 126:221-32. [DOI: 10.1007/s10633-013-9380-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 03/04/2013] [Indexed: 01/02/2023]
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Sabino V, Narayan AR, Zeric T, Steardo L, Cottone P. mTOR activation is required for the anti-alcohol effect of ketamine, but not memantine, in alcohol-preferring rats. Behav Brain Res 2013; 247:9-16. [PMID: 23466691 DOI: 10.1016/j.bbr.2013.02.030] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 02/23/2013] [Accepted: 02/25/2013] [Indexed: 02/06/2023]
Abstract
Glutamate NMDA receptors mediate many molecular and behavioral effects of alcohol, and they play a key role in the development of excessive drinking. Uncompetitive NMDA receptor antagonists may, therefore, have therapeutic potential for alcoholism. The first aim was to compare the effects of the NMDA antagonists memantine and ketamine on ethanol and saccharin drinking in alcohol-preferring rats. The second aim was to determine whether the effects of the two NMDA receptor antagonists were mediated by the mammalian target of rapamycin (mTOR). TSRI Sardinian alcohol-preferring rats were allowed to self-administer either 10% w/v ethanol or 0.08% w/v saccharin, and water. Operant responding and motor activity were assessed following administration of either memantine (0-10mg/kg) or ketamine (0-20mg/kg). Finally, ethanol self-administration was assessed in rats administered with either memantine or ketamine but pretreated with the mTOR inhibitor rapamycin (2.5mg/kg). The uncompetitive NMDA receptor antagonists memantine and ketamine dose-dependently reduced ethanol drinking in alcohol-preferring rats; while memantine had a preferential effect on alcohol over saccharin, ketamine reduced responding for both solutions. Neither antagonist induced malaise, as shown by the lack of effect on water intake and motor activity. The mTOR inhibitor rapamycin blocked the effects of ketamine, but not those of memantine. Memantine and ketamine both reduce alcohol drinking in alcohol-preferring rats, but only memantine is selective for alcohol. The effects of ketamine, but not memantine, are mediated by mTOR. The results support the therapeutic potential of uncompetitive NMDA receptor antagonists, especially memantine, in alcohol addiction.
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Affiliation(s)
- Valentina Sabino
- Laboratory of Addictive Disorders (LAD), Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA.
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Newman EL, Chu A, Bahamón B, Takahashi A, DeBold JF, Miczek KA. NMDA receptor antagonism: escalation of aggressive behavior in alcohol-drinking mice. Psychopharmacology (Berl) 2012; 224:167-77. [PMID: 22588250 PMCID: PMC3694321 DOI: 10.1007/s00213-012-2734-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 04/24/2012] [Indexed: 01/09/2023]
Abstract
RATIONALE Memantine is a potential treatment for alcoholic patients, yet few studies investigate the effect of concurrent treatment with memantine and ethanol on aggression. We evaluated aggressive behavior following ethanol consumption and treatment with glutamatergic drugs to characterize interactions between these compounds. OBJECTIVE This study aimed to use rodent models of aggression to examine interactions between glutamatergic compounds and ethanol. MATERIALS AND METHODS Once male CFW mice reliably self-administered 1 g/kg ethanol or water, they were assessed for aggression in resident-intruder confrontations. Alternatively, aggression was evaluated following a social-instigation procedure. Animals were then injected with memantine, ketamine, neramexane, MTEP, or LY379268 before aggressive confrontations. Effects of the pharmacological manipulations on salient aggressive and non-aggressive behaviors were analyzed. RESULTS Moderate doses of memantine, neramexane, and MTEP interacted with ethanol to increase the frequency of attack bites while ketamine did not. The highest dose of LY379268, an mGluR(2/3) agonist, reduced both aggressive and non-aggressive behaviors after water and ethanol self-administration. Attack bites increased with social instigation and decreased with administration of high doses of MTEP and LY379268. Memantine and MTEP both reduced attack bite frequency in the instigation condition without reducing locomotor behavior. CONCLUSIONS Memantine and neramexane interacted with ethanol to heighten aggression. The binding characteristics of these compounds allow for 'partial trapping' by which some NMDARs are unblocked between depolarizations. We propose that this feature may contribute to the differential aggression-heightening interactions between these compounds and ethanol. MTEP also interacted with ethanol to escalate aggression, possibly through inhibition of mGluR(5) modulation of NMDARs.
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Affiliation(s)
| | - Adam Chu
- Tufts University Psychology Dept, Medford, MA 02144
| | | | | | | | - Klaus A. Miczek
- Tufts University Psychology Dept, Medford, MA 02144,Tufts University Neuroscience Dept, Boston, MA 02111
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Filippi L, Fiorini P, Daniotti M, Catarzi S, Savelli S, Fonda C, Bartalena L, Boldrini A, Giampietri M, Scaramuzzo R, Papoff P, Del Balzo F, Spalice A, la Marca G, Malvagia S, Della Bona ML, Donzelli G, Tinelli F, Cioni G, Pisano T, Falchi M, Guerrini R. Safety and efficacy of topiramate in neonates with hypoxic ischemic encephalopathy treated with hypothermia (NeoNATI). BMC Pediatr 2012; 12:144. [PMID: 22950861 PMCID: PMC3478965 DOI: 10.1186/1471-2431-12-144] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 08/31/2012] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Despite progresses in neonatal care, the mortality and the incidence of neuro-motor disability after perinatal asphyxia have failed to show substantial improvements. In countries with a high level of perinatal care, the incidence of asphyxia responsible for moderate or severe encephalopathy is still 2-3 per 1000 term newborns. Recent trials have demonstrated that moderate hypothermia, started within 6 hours after birth and protracted for 72 hours, can significantly improve survival and reduce neurologic impairment in neonates with hypoxic-ischemic encephalopathy. It is not currently known whether neuroprotective drugs can further improve the beneficial effects of hypothermia. Topiramate has been proven to reduce brain injury in animal models of neonatal hypoxic ischemic encephalopathy. However, the association of mild hypothermia and topiramate treatment has never been studied in human newborns. The objective of this research project is to evaluate, through a multicenter randomized controlled trial, whether the efficacy of moderate hypothermia can be increased by concomitant topiramate treatment. METHODS/DESIGN Term newborns (gestational age ≥ 36 weeks and birth weight ≥ 1800 g) with precocious metabolic, clinical and electroencephalographic (EEG) signs of hypoxic-ischemic encephalopathy will be randomized, according to their EEG pattern, to receive topiramate added to standard treatment with moderate hypothermia or standard treatment alone. Topiramate will be administered at 10 mg/kg once a day for the first 3 days of life. Topiramate concentrations will be measured on serial dried blood spots. 64 participants will be recruited in the study. To evaluate the safety of topiramate administration, cardiac and respiratory parameters will be continuously monitored. Blood samplings will be performed to check renal, liver and metabolic balance. To evaluate the efficacy of topiramate, the neurologic outcome of enrolled newborns will be evaluated by serial neurologic and neuroradiologic examinations. Visual function will be evaluated by means of behavioural standardized tests. DISCUSSION This pilot study will explore the possible therapeutic role of topiramate in combination with moderate hypothermia. Any favourable results of this research might open new perspectives about the reduction of cerebral damage in asphyxiated newborns.
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Affiliation(s)
- Luca Filippi
- Neonatal Intensive Care Unit, Medical Surgical Feto-Neonatal Department, A. Meyer University Children's Hospital, Viale Pieraccini, 24, I-50139, Florence, Italy.
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Hossain MI, Kamaruddin MA, Cheng HC. Aberrant regulation and function of Src family tyrosine kinases: Their potential contributions to glutamate-induced neurotoxicity. Clin Exp Pharmacol Physiol 2012; 39:684-91. [DOI: 10.1111/j.1440-1681.2011.05621.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Kutzing MK, Luo V, Firestein BL. Protection from glutamate-induced excitotoxicity by memantine. Ann Biomed Eng 2011; 40:1170-81. [PMID: 22203191 DOI: 10.1007/s10439-011-0494-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 12/17/2011] [Indexed: 11/25/2022]
Abstract
This study investigates whether the uncompetitive N-methyl-D-aspartic acid receptor antagonist, memantine, is able to protect dissociated cortical neurons from glutamate-induced excitotoxicity (GIE). Treatment with glutamate resulted in a significant loss of synchronization of neuronal activity as well as a significant increase in the duration of synchronized bursting events (SBEs). By administering memantine at the same time as glutamate, we were able to completely prevent these changes to the neuronal activity. Pretreatment with memantine was somewhat effective in preventing changes to the culture synchronization but was unable to fully protect the synchronization of electrical activity between neurons that showed high levels of synchronization prior to injury. Additionally, memantine pretreatment was unable to prevent the increase in the duration of SBEs caused by GIE. Thus, the timing of memantine treatment is important for conferring neuroprotection against glutamate-induced neurotoxicity. Finally, we found that GIE leads to a significant increase in the burst duration. Our data suggest that this may be due to an alteration in the inhibitory function of the neurons.
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Affiliation(s)
- Melinda K Kutzing
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854-8082, USA
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Bicca MA, Figueiredo CP, Piermartiri TC, Meotti FC, Bouzon ZL, Tasca CI, Medeiros R, Calixto JB. The selective and competitive N-methyl-D-aspartate receptor antagonist, (-)-6-phosphonomethyl-deca-hydroisoquinoline-3-carboxylic acid, prevents synaptic toxicity induced by amyloid-β in mice. Neuroscience 2011; 192:631-41. [PMID: 21756976 DOI: 10.1016/j.neuroscience.2011.06.038] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 06/09/2011] [Accepted: 06/10/2011] [Indexed: 10/18/2022]
Abstract
The toxicity of amyloid β (Aβ) is highly associated with Alzheimer's disease (AD), which has a high incidence in elderly people worldwide. While the current treatment for moderate and severe AD includes blockage of the N-methyl-d-aspartate receptor (NMDAR), the molecular mechanisms of its effect are still poorly understood. Herein, we report that a single i.p. administration of the selective and competitive (NMDAR) antagonist LY235959 reduced Aβ neurotoxicity by preventing the down-regulation of glial glutamate transporters (glutamate-aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1)), the decrease in glutamate uptake, and the production of reactive oxygen species (ROS) induced by Aβ(1-40). Importantly, the blockage of NMDAR restored the Aβ(1-40)-induced synaptic dysfunction and cognitive impairment. However, LY235959 failed to prevent the inflammatory response associated with Aβ(1-40) treatment. Altogether, our data indicate that the acute administration of Aβ promotes oxidative stress, a decrease in glutamate transporter expression, and neurotoxicity. Our results reinforce the idea that NMDAR plays a critical regulatory action in Aβ toxicity and they provide further pre-clinical evidence for the potential role of the selective and competitive NMDAR antagonists in the treatment of AD.
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Affiliation(s)
- M A Bicca
- Departamento de Farmacologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, 88049-900, Florianópolis, Santa Catarina, Brazil
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Abstract
Glaucoma is a neurodegenerative disease characterized by loss of retinal ganglion cells and their axons. Recent evidence suggests that intraocular pressure (IOP) is only one of the many risk factors for this disease. Current treatment options for this disease have been limited to the reduction of IOP; however, it is clear now that the disease progression continues in many patients despite effective lowering of IOP. In the search for newer modalities in treating this disease, much data have emerged from experimental research the world over, suggesting various pathological processes involved in this disease and newer possible strategies to treat it. This review article looks into the current understanding of the pathophysiology of glaucoma, the importance of neuroprotection, the various possible pharmacological approaches for neuroprotection and evidence of current available medications.
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Affiliation(s)
- Sushil K Vasudevan
- Centre for Eye Research Australia, University of Melbourne and Glaucoma Unit, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC 3002, Australia.
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Memantine preferentially blocks extrasynaptic over synaptic NMDA receptor currents in hippocampal autapses. J Neurosci 2010; 30:11246-50. [PMID: 20720132 DOI: 10.1523/jneurosci.2488-10.2010] [Citation(s) in RCA: 278] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Glutamate is the major excitatory neurotransmitter in the brain. The NMDA subtype of glutamate receptors (NMDAR) is known to mediate many physiological neural functions. However, excessive activation of NMDARs contributes to neuronal damage in various acute and chronic neurological disorders. To avoid unwanted adverse side effects, blockade of excessive NMDAR activity must therefore be achieved without affecting its physiological function. Memantine, an adamantane derivative, has been used for the treatment of Alzheimer's disease with an excellent clinical safety profile. We previously showed that memantine preferentially blocked neurotoxicity mediated by excessive NMDAR activity while relatively sparing normal neurotransmission, in part because of its uncompetitive antagonism with a fast off-rate. Here, using rat autaptic hippocampal microcultures, we show that memantine at therapeutic concentrations (1-10 microM) preferentially blocks extrasynaptic rather than synaptic currents mediated by NMDARs in the same neuron. We found that memantine blocks extrasynaptic NMDAR-mediated currents induced by bath application of 100 microM NMDA/10 microM glycine with a twofold higher potency than its blockade of the NMDAR component of evoked EPSCs (EPSCs(NMDAR)); this effect persists under conditions of pathological depolarization in the presence of 1 mm extracellular Mg(2+). Thus, our findings provide the first unequivocal evidence to explain the tolerability of memantine based on differential extrasynaptic/synaptic receptor blockade. At therapeutic concentrations, memantine effectively blocks excessive extrasynaptic NMDAR-mediated currents, while relatively sparing normal synaptic activity.
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Baltmr A, Duggan J, Nizari S, Salt TE, Cordeiro MF. Neuroprotection in glaucoma - Is there a future role? Exp Eye Res 2010; 91:554-66. [PMID: 20800593 DOI: 10.1016/j.exer.2010.08.009] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 07/26/2010] [Accepted: 08/06/2010] [Indexed: 02/06/2023]
Abstract
In glaucoma, the major cause of global irreversible blindness, there is an urgent need for treatment modalities that directly target the RGCs. The discovery of an alternative therapeutic approach, independent of IOP reduction, is highly sought after, due to the indirect nature and limited effectiveness of IOP lowering therapy in preventing RGC loss. Several mechanisms have been implicated in initiating the apoptotic cascade in glaucomatous retinopathy and numerous drugs have been shown to be neuroprotective in animal models of glaucoma. These mechanisms and their potential treatment include excitotoxicity, protein misfolding, mitochondrial dysfunction, oxidative stress, inflammation and neurotrophin deprivation. All of these mechanisms ultimately lead to programmed cell death with loss of RGCs. In this article we summarize the mechanisms involved in glaucomatous disease, highlight the rationale for neuroprotection in glaucoma management and review current potential neuroprotective strategies targeting RGCs from the laboratory to the clinic.
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Affiliation(s)
- Abeir Baltmr
- Glaucoma and Retinal Neurodegeneration Research Group, Visual Neurosciences Department, University College London Institute of Ophthalmology, Bath Street, London EC1V 9EL, United Kingdom
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Protective effect of desipramine, venlafaxine and trazodone against experimental animal model of transient global ischemia: possible involvement of NO-cGMP pathway. Brain Res 2010; 1353:204-12. [PMID: 20624374 DOI: 10.1016/j.brainres.2010.07.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 06/29/2010] [Accepted: 07/05/2010] [Indexed: 11/20/2022]
Abstract
The present study has been designed to explore the nitric oxide mechanism in the protective effect of desipramine, venlafaxine and trazodone against I/R induced oxidative stress and mitochondrial dysfunction in mice. Vitamin E was taken as standard antioxidant. Laca mice (25-30 g) were subjected to twice BCCAO occlusion (5 min) at the interval of 10 min, followed by 96 h reperfusion. The drug treatments were started from the day of surgery and continued for the next four days. After 96 h the animals were sacrificed for biochemical (malondialdehyde, nitrite concentration, superoxidedismutase, catalase, redox ratio and GST) and mitochondrial enzyme complex (NADH dehydrogenase, succinate dehydrogenase, MTT assay and cytochrome c oxidase) estimations. Ischemia caused significant oxidative damage and mitochondrial enzyme dysfunction after 96 h of reperfusion as compared to sham operated animals. Antidepressant (desipramine, venlafaxine and trazodone) treatment significantly attenuated oxidative damage and restored mitochondrial enzyme complex activities as compared to control (I/R) group. Further, protective effects of desipramine (15 mg/kg) and/or venlafaxine (5 mg/kg) were attenuated by l-arginine (100 mg/kg) or sildenafil (5 mg/kg) pretreatment. Further, L-NAME (10 mg/kg) or 7-NI (10 mg/kg) pretreatment with desipramine (15 mg/kg) and/or venlafaxine (5 mg/kg) significantly potentiated their protective effect which was significant as compared to their effect alone. The present study highlights the involvement of nitric oxide mechanism in the protective effects of desipramine and venlafaxine against I/R induced oxidative stress and mitochondrial dysfunction in mice.
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Aggarwal A, Gaur V, Kumar A. Nitric oxide mechanism in the protective effect of naringin against post-stroke depression (PSD) in mice. Life Sci 2010; 86:928-35. [DOI: 10.1016/j.lfs.2010.04.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Revised: 02/18/2010] [Accepted: 04/18/2010] [Indexed: 10/19/2022]
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Yan XS, Ma JH, Zhang PH. Modulation of K(ATP) currents in rat ventricular myocytes by hypoxia and a redox reaction. Acta Pharmacol Sin 2009; 30:1399-414. [PMID: 19801996 DOI: 10.1038/aps.2009.134] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
AIM The present study investigated the possible regulatory mechanisms of redox agents and hypoxia on the K(ATP) current (I(KATP)) in acutely isolated rat ventricular myocytes. METHODS Single-channel and whole-cell patch-clamp techniques were used to record the K(ATP) current (I(KATP)) in acutely isolated rat ventricular myocytes. RESULTS Oxidized glutathione (GSSG, 1 mmol/L) increased the I(KATP), while reduced glutathione (GSH, 1 mmol/L) could reverse the increased I(KATP) during normoxia. To further corroborate the effect of the redox agent on the K(ATP) channel, we employed the redox couple DTT (1 mmol/L)/H2O2 (0.3, 0.6, and 1 mmol/L) and repeated the previous processes, which produced results similar to the previous redox couple GSH/GSSG during normoxia. H2O2 increased the I(KATP) in a concentration dependent manner, which was reversed by DTT (1 mmol/L). In addition, our results have shown that 15 min of hypoxia increased the I(KATP), while GSH (1 mmol/L) could reverse the increased I(KATP). Furthermore, in order to study the signaling pathways of the I(KATP) augmented by hypoxia and the redox agent, we applied a protein kinase C(PKC) inhibitor bisindolylmaleimide VI (BIM), a protein kinase G(PKG) inhibitor KT5823, a protein kinase A (PKA) inhibitor H-89, and Ca2+/calmodulin-dependent protein kinase II (CaMKII) inhibitors KN-62 and KN-93. The results indicated that BIM, KT5823, KN-62, and KN-93, but not H-89, inhibited the I(KATP) augmented by hypoxia and GSSG; in addition, these results suggest that the effects of both GSSG and hypoxia on K(ATP) channels involve the activation of the PKC, PKG, and CaMK II pathways, but not the PKA pathway. CONCLUSION The present study provides electrophysiological evidence that hypoxia and the oxidizing reaction are closely related to the modulation of I(KATP).
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van Wageningen H, Jorgensen HA, Specht K, Hugdahl K. A 1H-MR Spectroscopy Study of Changes in Glutamate and Glutamine (Glx) Concentrations in Frontal Spectra after Administration of Memantine. Cereb Cortex 2009; 20:798-803. [DOI: 10.1093/cercor/bhp145] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Paradoxical facilitation of pentylenetetrazole-induced convulsion susceptibility in mice lacking neuronal nitric oxide synthase. Neuroscience 2009; 159:735-43. [DOI: 10.1016/j.neuroscience.2008.12.040] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Revised: 12/07/2008] [Accepted: 12/23/2008] [Indexed: 11/24/2022]
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Nasr P, Carbery T, Geddes JW. N-methyl-D-aspartate receptor antagonists have variable affect in 3-nitropropionic acid toxicity. Neurochem Res 2008; 34:490-8. [PMID: 18688711 DOI: 10.1007/s11064-008-9809-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Accepted: 07/15/2008] [Indexed: 11/28/2022]
Abstract
There is accumulating evidence that excitotoxicity and oxidative stress resulting from excessive activation of glutamate (N-methyl-D-aspartate) NMDA receptors are major participants in striatal degeneration associated with 3-nitropropionic acid (3NP) administration. Although excitotoxic and oxidative mechanisms are implicated in 3NP toxicity, there are conflicting reports as to whether NMDA receptor antagonists attenuate or exacerbate the 3NP-induced neurodegeneration. In the present study, we investigated the involvement of NMDA receptors in striatal degeneration, protein oxidation and motor impairment following systemic 3NP administration. We examined whether NMDA receptor antagonists, memantine and ifenprodil, influence the neurotoxicity of 3NP. The development of striatal lesion and protein oxidation following 3NP administration is delayed by memantine but not affected by ifenprodil. However, in behavioral experiments, memantine failed to improve and ifenprodil exacerbated the motor deficits associated with 3NP toxicity. Together, these findings suggest caution in the application of NMDA receptor antagonists as a neuroprotective agent in neurodegenerative disorders associated with metabolic impairment.
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Affiliation(s)
- Payman Nasr
- Department of Biological Sciences, Kent State University, Ashtabula, OH 44004, USA.
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Abstract
In recent years the focus of glaucoma research has shifted toward neuroprotection, as the traditional strategies of lowering intraocular pressure have been shown to be unable to prevent progressive vision loss in some glaucoma patients. As a result various neuroprotective drug-based approaches have been shown capable of reducing the death of retinal ganglion cells, which is the hallmark of glaucomatous optic neuropathy. There has been increasing evidence that glaucomatous neurodegeneration is analogous to other neurodegenerative diseases in the central nervous system, with recent work from our group elucidating a strong link between basic cellular processes in glaucoma and Alzheimer's disease. Additionally, there is a growing trend for using existing neuroprotective strategies in central nervous system diseases for the treatment of glaucoma. In fact, a trial treating patients with primary open-angle glaucoma with memantine, a drug approved for the treatment of Alzheimer's disease, has recently been completed. Results of this trial are not yet available. In this review, we will examine currently advocated neuroprotective drug-based strategies in the potential management of glaucoma.
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Isoflurane-induced caspase-3 activation is dependent on cytosolic calcium and can be attenuated by memantine. J Neurosci 2008; 28:4551-60. [PMID: 18434534 DOI: 10.1523/jneurosci.5694-07.2008] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Increasing evidence indicates that caspase activation and apoptosis are associated with a variety of neurodegenerative disorders, including Alzheimer's disease. We reported that anesthetic isoflurane can induce apoptosis, alter processing of the amyloid precursor protein (APP), and increase amyloid-beta protein (Abeta) generation. However, the mechanism by which isoflurane induces apoptosis is primarily unknown. We therefore set out to assess effects of extracellular calcium concentration on isoflurane-induced caspase-3 activation in H4 human neuroglioma cells stably transfected to express human full-length APP (H4-APP cells). In addition, we tested effects of RNA interference (RNAi) silencing of IP(3) receptor, NMDA receptor, and endoplasmic reticulum (ER) calcium pump, sacro-/ER calcium ATPase (SERCA1). Finally, we examined the effects of the NMDA receptor partial antagonist, memantine, in H4-APP cells and brain tissue of naive mice. EDTA (10 mM), BAPTA (10 microM), and RNAi silencing of IP(3) receptor, NMDA receptor, or SERCA1 attenuated caspase-3 activation. Memantine (4 microM) inhibited isoflurane-induced elevations in cytosolic calcium levels and attenuated isoflurane-induced caspase-3 activation, apoptosis, and cell viability. Memantine (20 mg/kg, i.p.) reduced isoflurane-induced caspase-3 activation in brain tissue of naive mice. These results suggest that disruption of calcium homeostasis underlies isoflurane-induced caspase activation and apoptosis. We also show for the first time that the NMDA receptor partial antagonist, memantine, can prevent isoflurane-induced caspase-3 activation and apoptosis in vivo and in vitro. These findings, indicating that isoflurane-induced caspase activation and apoptosis are dependent on cytosolic calcium levels, should facilitate the provision of safer anesthesia care, especially for Alzheimer's disease and elderly patients.
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Rousseaux CG. A Review of Glutamate Receptors I: Current Understanding of Their Biology. J Toxicol Pathol 2008. [DOI: 10.1293/tox.21.25] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Colin G. Rousseaux
- Department of Pathology and Laboratory Medicine, Faculty of Medicine, University of Ottawa
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Guo L, Cordeiro MF. Assessment of neuroprotection in the retina with DARC. PROGRESS IN BRAIN RESEARCH 2008; 173:437-50. [PMID: 18929126 PMCID: PMC2603274 DOI: 10.1016/s0079-6123(08)01130-8] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Currently, assessment of new drug efficacy in glaucoma relies on conventional perimetry to monitor visual field changes. However, visual field defects cannot be detected until 20-40% of retinal ganglion cells (RGCs), the key cells implicated in the development of irreversible blindness in glaucoma, have been lost. We have recently developed a new, noninvasive real-time imaging technology, which is named DARC (detection of apoptosing retinal cells), to visualize single RGC undergoing apoptosis, the earliest sign of glaucoma. Utilizing fluorescently labeled annexin 5 and confocal laser scanning ophthalmoscopy, DARC enables evaluation of treatment effectiveness by monitoring RGC apoptosis in the same living eye over time. Using DARC, we have assessed different neuroprotective therapies in glaucoma-related animal models and demonstrated DARC to be a useful tool in screening neuroprotective strategies. DARC will potentially provide a meaningful clinical end point that is based on the direct assessment of the RGC death process, not only being useful in assessing treatment efficacy, but also leading to the early identification of patients with glaucoma. Clinical trials of DARC in glaucoma patients are due to start in 2008.
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Affiliation(s)
- Li Guo
- Glaucoma & Retinal Degeneration Research Group, UCL Institute of Ophthalmology, London, UK
| | - M. Francesca Cordeiro
- Glaucoma & Retinal Degeneration Research Group, UCL Institute of Ophthalmology, London, UK,The Glaucoma Research Group, Western Eye Hospital, London, UK,Corresponding author. Tel./Fax: +44 207 608 6938
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Seki M, Lipton SA. Targeting excitotoxic/free radical signaling pathways for therapeutic intervention in glaucoma. PROGRESS IN BRAIN RESEARCH 2008; 173:495-510. [DOI: 10.1016/s0079-6123(08)01134-5] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Rousseaux CG. A Review of Glutamate Receptors II: Pathophysiology and Pathology. J Toxicol Pathol 2008. [DOI: 10.1293/tox.21.133] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Colin G. Rousseaux
- Department of Pathology and Laboratory Medicine, Faculty of Medicine, University of Ottawa
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Lipton SA. Perspective author's response: Uncompetitive/Fast Off-rate (UFO) mechanism of pathologically-activated neuroprotective drugs. Nat Rev Neurosci 2007. [DOI: 10.1038/nrn2229-c2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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41
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Miller A, Panitch H. Therapeutic use of dextromethorphan: Key learnings from treatment of pseudobulbar affect. J Neurol Sci 2007; 259:67-73. [PMID: 17433820 DOI: 10.1016/j.jns.2006.06.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2006] [Revised: 06/02/2006] [Accepted: 06/12/2006] [Indexed: 11/17/2022]
Abstract
A variety of neurological conditions and disease states are accompanied by pseudobulbar affect (PBA), an emotional disorder characterized by uncontrollable outbursts of laughing and crying. The causes of PBA are unclear but may involve lesions in neural circuits regulating the motor output of emotional expression. Several agents used in treating other psychiatric disorders have been applied in the treatment of PBA with some success but data are limited and these agents are associated with unpleasant side effects due to nonspecific activity in diffuse neural networks. Dextromethorphan (DM), a widely used cough suppressant, acts at receptors in the brainstem and cerebellum, brain regions implicated in the regulation of emotional output. The combination of DM and quinidine (Q), an enzyme inhibitor that blocks DM metabolism, has recently been tested in phase III clinical trials in patients with multiple sclerosis and amyotrophic lateral sclerosis and was both safe and effective in palliating PBA symptoms. In addition, clinical studies pertaining to the safety and efficacy of DM/Q in a variety of neurological disease states are ongoing.
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Affiliation(s)
- Ariel Miller
- Center for Multiple Sclerosis, Carmel Medical Center, Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel.
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Uehara T. Accumulation of misfolded protein through nitrosative stress linked to neurodegenerative disorders. Antioxid Redox Signal 2007; 9:597-601. [PMID: 17465882 DOI: 10.1089/ars.2006.1517] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Protein quality control is a critical feature of intracellular homeostasis. In particular, unfolded or misfolded proteins resulting from environmental stresses or free radicals are rapidly degraded via the ubiquitin-proteasome pathway. Nitric oxide (NO), a free radical gas, has been reported to be involved in such processes as vasorelaxation and neurotransmission. Conversely, NO also is implicated in neuronal cell death or neurodegeneration. Recent reports suggest that S-nitrosylation of proteins is a significant cause of neural dysfunction leading to neurodegenerative disorders. Specifically, S-nitrosylation of parkin eventually leads to the accumulation of unfolded proteins and subsequent neuronal death. The focus of this review is the identity of the target of NO. Nitrosative stress prevents normal functioning of the endoplasmic reticulum (ER) via S-nitrosylation of protein-disulfide isomerase (PDI), which is located in the ER lumen. This may contribute to the accumulation of misfolded proteins, as well as sustained activation of the unfolded protein response (UPR) pathway. These phenomena may be linked to the development of sporadic neurodegenerative diseases.
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Affiliation(s)
- Takashi Uehara
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan.
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Magazanik LG, Tikhonov DB, Tikhonova TB, Lukomskaya NY. Mechanisms of the blockade of glutamate channel receptors: Significance for structural and physiological investigations. ACTA ACUST UNITED AC 2007; 37:277-84. [PMID: 17294104 DOI: 10.1007/s11055-007-0012-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Indexed: 11/29/2022]
Abstract
The mechanism of the blocking action of phenylcyclohexyl derivative IEM-1925 on ionotropic NMDA and AMPA glutamate receptors was studied. Experiments on isolated rat brain neurons (hippocampal pyramidal cells and striatal cholinergic interneurons) were performed using local voltage clamping in the "whole cell" configuration. In equilibrium conditions at a membrane potential of -80 mV, there was no selectivity in the action of IEM-1925 on the open channels of either type of glutamate receptor. However, data were obtained showing significant differences in the mechanisms of the blocking actions. Although IEM-1925 was unable to penetrate into closed channels of either receptor type, molecules were able to leave closed AMPA receptor channels but not closed NMDA receptor channels. In hyperpolarization, the departure of the blocker from open NMDA receptor channels was slowed, while departure from open and closed AMPA receptor channels was accelerated. The blocker thus appeared able to penetrate AMPA receptor channels to enter cells, the gating mechanism of these channels being located above the blocker binding site. The actions of IEM-1925 on NMDA and AMPA receptors were compared with its ability to suppress tremor in mice induced with s.c. doses of arecoline. The results indicated that both types of receptors have a role in producing tremor. The differences in the mechanisms of action on AMPA and NMDA receptors may explain the ambiguous nature of the effects of the glutamate channel blocker in experimental therapy.
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Affiliation(s)
- L G Magazanik
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, Russia
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Wang W, Ma J, Zhang P, Luo A. Redox reaction modulates transient and persistent sodium current during hypoxia in guinea pig ventricular myocytes. Pflugers Arch 2007; 454:461-75. [PMID: 17492311 DOI: 10.1007/s00424-007-0219-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2006] [Revised: 12/17/2006] [Accepted: 01/18/2007] [Indexed: 11/24/2022]
Abstract
Whole-cell and cell-attached patch clamp techniques were applied on isolated guinea pig ventricular myocytes to study the possible regulatory mechanisms of redox agent on persistent and transient sodium current related to hypoxia. The results showed that hypoxia for 15 min increased persistent sodium current (I (Na.P)) and decreased transient sodium current (I (Na.T)) at the same time, while 1 mmol/l of reduced glutathione (GSH) could reverse the increased I (Na.P) and the decreased I (Na.T) simultaneously. Both persistent and transient sodium channel activities could be reversed concurrently again by application of 1 mmol/l oxidized glutathione (GSSG). Hypoxia for 15 min decreased the action potential amplitude (APA) and shortened action potential duration at 90% repolarization (APD(90)) of ventricular papillary cells simultaneously, while 1 mmol/GSH could reverse the decreased APA and the shortened APD(90) at the same time; 1 mmol/l GSSG strengthened the decrease of APA induced by hypoxia and attenuated the decurtation of APD(90) induced by hypoxia compared with pure hypoxia. The correlation between I (Na.P) and I (Na.T) and the effects of GSH and GSSG on them suggested that during hypoxia, redox regulation played a tremendous part in sodium channel activity and that I (Na.P) and I (Na.T) might be charged by the same channel with different gating modes in guinea pig ventricular myocytes. Judging from their alterations during hypoxia and exposure to GSH and GSSG, we speculated that an interconversion might exist between I (Na.P) and I (Na.T). That was when one of them was increased, the other was decreased, and vice versa.
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Affiliation(s)
- Weiping Wang
- Cardio-Electrophysiological Research Laboratory Medical College, Wuhan University of Science and Technology, Wuhan, 430081, China
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Zhao X, Marszalec W, Toth PT, Huang J, Yeh JZ, Narahashi T. In vitro galantamine-memantine co-application: mechanism of beneficial action. Neuropharmacology 2006; 51:1181-91. [PMID: 17011596 DOI: 10.1016/j.neuropharm.2006.08.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Revised: 08/16/2006] [Accepted: 08/17/2006] [Indexed: 01/01/2023]
Abstract
Several drugs are in clinical use for symptomatic treatment of Alzheimer's disease patients. Since Alzheimer's disease is known to be associated with down-regulation of the cholinergic and N-methyl-D-aspartate (NMDA) systems, most of these drugs inhibit acetylcholinesterase, potentiate the activity of nicotinic acetylcholine receptors (nAChRs), or modulate NMDA receptors. Galantamine is an anticholinesterase and allosterically potentiates the activity of the nicotinic receptors. We have recently found that galantamine potentiates the activity of NMDA receptors as well. Memantine is unique in that it inhibits the NMDA receptors. We have developed a hypothesis that combining galantamine and memantine will be more effective for improving the patient's conditions than monotherapy with either drug. Patch clamp and intracellular Ca(2+) imaging experiments using rat cortical and hippocampal neurons clearly provided the in vitro bases for our hypothesis. Memantine blocked the extrasynaptic NMDA receptor 100 times more potently than the synaptic NMDA receptor at negative membrane potentials and the block of both types of NMDA receptors was attenuated with depolarization. However, galantamine potentiation of the NMDA receptors was not voltage dependent. Thus, co-application of memantine with galantamine prevented the galantamine potentiation and the activation of extrasynaptic NMDA receptors, but membrane depolarization revealed the galantamine potentiation. Therefore, cell death is expected to be prevented by memantine near the resting potential while the NMDA-mediated synaptic transmission, which is down-regulated in the patients, is maintained and potentiated by galantamine. These results provide in vitro bases for the beneficial actions of galantamine and memantine combinations.
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Affiliation(s)
- Xilong Zhao
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, 303 E. Chicago Avenue, Chicago, IL 60611, USA
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Abstract
Most neuroprotective drugs have failed in clinical trials because of side-effects, causing normal brain function to become compromised. A case in point concerns antagonists of the N-methyl-D-aspartate type of glutamate receptor (NMDAR). Glutamate receptors are essential to the normal function of the central nervous system. However, their excessive activation by excitatory amino acids, such as glutamate itself, is thought to contribute to neuronal damage in many neurological disorders ranging from acute hypoxic-ischemic brain injury to chronic neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. The dual role of NMDARs in particular for normal and abnormal functioning of the nervous system imposes important constraints on possible therapeutic strategies aimed at ameliorating neurological diseases. Blockade of excessive NMDAR activity must therefore be achieved without interference with its normal function. In general, NMDAR antagonists can be categorized pharmacologically according to the site of action on the receptor-channel complex. These include drugs acting at the agonist (NMDA) or co-agonist (glycine) sites, channel pore, and modulatory sites, such as the S-nitrosylation site where nitric oxide (NO) reacts with critical cysteine thiol groups. Because glutamate is thought to be the major excitatory transmitter in the brain, generalized inhibition of a glutamate receptor subtype like the NMDAR causes side-effects that clearly limit the potential for clinical applications. Both competitive NMDA and glycine antagonists, even although effective in preventing glutamate-mediated neurotoxicity, will cause generalized inhibition of NMDAR activities and thus have failed in many clinical trials. Open-channel block with the property of uncompetitive antagonism is the most appealing strategy for therapeutic intervention during excessive NMDAR activation as this action of blockade requires prior activation of the receptor. This property, in theory, leads to a higher degree of channel blockade in the presence of excessive levels of glutamate and little blockade at relatively lower levels, for example, during physiological neurotransmission. Utilizing this molecular strategy of action, we review here the logical process that we applied over the past decade to help develop memantine as the first clinically tolerated yet effective agent against NMDAR-mediated neurotoxicity. Phase 3 (final) clinical trials have shown that memantine is effective in treating moderate-to-severe Alzheimer's disease while being well tolerated. Memantine is also currently in trials for additional neurological disorders, including other forms of dementia, glaucoma, and severe neuropathic pain. Additionally, taking advantage of memantine's preferential binding to open channels and the fact that excessive NMDAR activity can be down-regulated by S-nitrosylation, we have recently developed combinatorial drugs called NitroMemantines. These drugs use memantine as a homing signal to target NO to hyperactivated NMDARs in order to avoid systemic side-effects of NO such as hypotension (low blood pressure). These second-generation memantine derivatives are designed as pathologically activated therapeutics, and in preliminary studies appear to have even greater neuroprotective properties than memantine.
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Affiliation(s)
- Huei-Sheng Vincent Chen
- Burnham Institute for Medical Research and the University of California-San Diego, La Jolla, California 92037, USA.
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Abstract
Human immunodeficiency virus-1 (HIV-1)-infected and immune-activated macrophages and microglia secrete neurotoxins. Two of these neurotoxins are the pro-inflammatory cytokines tumour necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta), which are thought to play a major role in inducing neuronal death. Both TNF-alpha and IL-1beta increase the permeability of the blood-brain barrier, through which subsequently HIV-infected monocytes can enter the brain. They both induce over-stimulation of the NMDA-receptor via several pathways, resulting in a lethal neuronal increase in Ca(2+) levels. Additionally, TNF-alpha co-operates with several other proinflammatory mediators to enhance their toxic effects. Although most research has focused on the neurotoxic effects of TNF-alpha and IL-1beta in HAD, there is also evidence that these cytokines can be neuroprotective. In this paper the effect of TNF-alpha and IL-1beta on neuronal life and death in HAD is discussed.
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Affiliation(s)
- N A C H Brabers
- Department of Virology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, the Netherlands
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Kaul M, Zheng J, Okamoto S, Gendelman HE, Lipton SA. HIV-1 infection and AIDS: consequences for the central nervous system. Cell Death Differ 2006; 12 Suppl 1:878-92. [PMID: 15832177 DOI: 10.1038/sj.cdd.4401623] [Citation(s) in RCA: 265] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Infection with the human immunodeficiency virus-1 (HIV-1) can induce severe and debilitating neurological problems that include behavioral abnormalities, motor dysfunction and frank dementia. After infiltrating peripheral immune competent cells, in particular macrophages, HIV-1 provokes a neuropathological response involving all cell types in the brain. HIV-1 also incites activation of chemokine receptors, inflammatory mediators, extracellular matrix-degrading enzymes and glutamate receptor-mediated excitotoxicity, all of which can trigger numerous downstream signaling pathways and disrupt neuronal and glial function. This review will discuss recently uncovered pathologic neuroimmune and degenerative mechanisms contributing to neuronal damage induced by HIV-1 and potential approaches for development of future therapeutic intervention.
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Affiliation(s)
- M Kaul
- Center for Neuroscience and Aging Research, The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
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Lipton SA. Paradigm shift in neuroprotection by NMDA receptor blockade: memantine and beyond. Nat Rev Drug Discov 2006; 5:160-70. [PMID: 16424917 DOI: 10.1038/nrd1958] [Citation(s) in RCA: 642] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Neuroprotective drugs tested in clinical trials, particularly those that block N-methyl-D-aspartate-sensitive glutamate receptors (NMDARs), have failed miserably in large part because of intolerable side effects. However, one such drug, memantine, was recently approved by the European Union and the US FDA for the treatment of dementia following our group's discovery of its clinically tolerated mechanism of action. Here, we review the molecular basis for memantine efficacy in neurological diseases that are mediated, at least in part, by overactivation of NMDARs, producing excessive Ca(2+) influx through the receptor's associated ion channel and consequent free-radical formation.
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Affiliation(s)
- Stuart A Lipton
- Burnham Institute for Medical Research, University of California at San Diego, 10901 North Torrey Pines Road, La Jolla, California 92037, USA.
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Guo L, Salt TE, Maass A, Luong V, Moss SE, Fitzke FW, Cordeiro MF. Assessment of neuroprotective effects of glutamate modulation on glaucoma-related retinal ganglion cell apoptosis in vivo. Invest Ophthalmol Vis Sci 2006; 47:626-33. [PMID: 16431960 PMCID: PMC2601027 DOI: 10.1167/iovs.05-0754] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
PURPOSE To assess the neuroprotective effects of different glutamate modulation strategies, with a nonselective (MK801) and a selective (ifenprodil) NMDA receptor antagonist and a metabotropic glutamate receptor agonist (mGluR Group II, LY354740), in glaucoma-related in vivo rat models of retinal ganglion cell (RGC) apoptosis. METHODS RGC apoptosis was induced in Dark Agouti (DA) rats by staurosporine (SSP) treatment. Single agents MK801, ifenprodil, or LY354740, or MK801 and LY354740 combined, were administrated intravitreally at different doses. Eyes were imaged in vivo using a recently established technique and the results confirmed histologically. The most effective combined therapy regimen of MK801 and LY354740 was then assessed in a chronic ocular hypertension (OHT) rat model with application at 0, 1, and 2 weeks after OHT surgery and the effects assessed as described before. RESULTS All strategies of glutamate modulation reduced SSP-induced-RGC apoptosis compared with the control, in a dose-dependent manner: MK801 (R2= 0.8863), ifenprodil (R2= 0.4587), and LY354740 (R2= 0.9094), with EC50s of 0.074, 0.0138, and 19 nanomoles, respectively. The most effective combination dose of MK801 and LY354740 was 0.06 and 20 nanomoles (P < 0.05), respectively, and the optimal timing of the therapy was 0 weeks after OHT surgery (P < 0.05). CONCLUSIONS This novel SSP model was validated as a useful tool for screening neuroprotective strategies in vivo. Group II mGluR modulation may be a useful treatment for RGC death. Combination therapy optimized to limit neurotoxic effects of MK801 may be an effective neuroprotective approach in retinal degenerative disease. Furthermore, treatments that minimize secondary RGC degeneration may be most useful in glaucoma.
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Affiliation(s)
- Li Guo
- Glaucoma and Optic Nerve Head Research Group, Department of Pathology, University College London Institute of Ophthalmology, London, United Kingdom
| | - Thomas E. Salt
- Department of Visual Science, University College London Institute of Ophthalmology, London, United Kingdom
| | - Annelie Maass
- Glaucoma and Optic Nerve Head Research Group, Department of Pathology, University College London Institute of Ophthalmology, London, United Kingdom
| | - Vy Luong
- Department of Visual Science, University College London Institute of Ophthalmology, London, United Kingdom
| | - Stephen E. Moss
- Department of Cell Biology, University College London Institute of Ophthalmology, London, United Kingdom
| | - Fred W. Fitzke
- Department of Visual Science, University College London Institute of Ophthalmology, London, United Kingdom
| | - M. Francesca Cordeiro
- Glaucoma and Optic Nerve Head Research Group, Department of Pathology, University College London Institute of Ophthalmology, London, United Kingdom
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