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Lima LSD, Loyola V, Bicca JVML, Faro L, Vale CLC, Lotufo Denucci B, Mortari MR. Innovative treatments for epilepsy: Venom peptides, cannabinoids, and neurostimulation. J Neurosci Res 2022; 100:1969-1986. [PMID: 35934922 DOI: 10.1002/jnr.25114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/13/2022] [Accepted: 07/22/2022] [Indexed: 11/07/2022]
Abstract
Antiepileptic drugs have been successfully treating epilepsy and providing individuals sustained seizure freedom. However, about 30% of the patients with epilepsy present drug resistance, which means they are not responsive to the pharmacological treatment. Considering this, it becomes extremely relevant to pursue alternative therapeutic approaches, in order to provide appropriate treatment for those patients and also improve their quality of life. In the light of that, this review aims to discuss some innovative options for the treatment of epilepsy, which are currently under investigation, addressing strategies that go from therapeutic compounds to clinical procedures. For instance, peptides derived from animal venoms, such as wasps, spiders, and scorpions, demonstrate to be promising antiepileptic molecules, acting on a variety of targets. Other options are cannabinoids and compounds that modulate the endocannabinoid system, since it is now known that this network is involved in the pathophysiology of epilepsy. Furthermore, neurostimulation is another strategy, being an alternative clinical procedure for drug-resistant patients who are not eligible for palliative surgeries.
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Affiliation(s)
- Larissa Silva de Lima
- Laboratory of Neuropharmacology, Department of Physiological Sciences, Institute of Biological Sciences, University of Brasilia, Brasilia, Brazil
| | - Vinícius Loyola
- Laboratory of Neuropharmacology, Department of Physiological Sciences, Institute of Biological Sciences, University of Brasilia, Brasilia, Brazil
| | - João Victor Montenegro Luzardo Bicca
- Laboratory of Neuropharmacology, Department of Physiological Sciences, Institute of Biological Sciences, University of Brasilia, Brasilia, Brazil
| | - Lucas Faro
- Laboratory of Neuropharmacology, Department of Physiological Sciences, Institute of Biological Sciences, University of Brasilia, Brasilia, Brazil
| | - Camilla Lepesqueur Costa Vale
- Laboratory of Neuropharmacology, Department of Physiological Sciences, Institute of Biological Sciences, University of Brasilia, Brasilia, Brazil
| | - Bruna Lotufo Denucci
- Laboratory of Neuropharmacology, Department of Physiological Sciences, Institute of Biological Sciences, University of Brasilia, Brasilia, Brazil
| | - Márcia Renata Mortari
- Laboratory of Neuropharmacology, Department of Physiological Sciences, Institute of Biological Sciences, University of Brasilia, Brasilia, Brazil
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Tran HNT, McMahon KL, Deuis JR, Vetter I, Schroeder CI. Structural and functional insights into the inhibition of human voltage-gated sodium channels by μ-conotoxin KIIIA disulfide isomers. J Biol Chem 2022; 298:101728. [PMID: 35167877 PMCID: PMC8927997 DOI: 10.1016/j.jbc.2022.101728] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 02/08/2022] [Accepted: 02/11/2022] [Indexed: 12/13/2022] Open
Abstract
μ-Conotoxins are components of cone snail venom, well-known for their analgesic activity through potent inhibition of voltage-gated sodium channel (NaV) subtypes, including NaV1.7. These small, disulfide-rich peptides are typically stabilized by three disulfide bonds arranged in a ‘native’ CysI-CysIV, CysII-CysV, CysIII-CysVI pattern of disulfide connectivity. However, μ-conotoxin KIIIA, the smallest and most studied μ-conotoxin with inhibitory activity at NaV1.7, forms two distinct disulfide bond isomers during thermodynamic oxidative folding, including Isomer 1 (CysI-CysV, CysII-CysIV, CysIII-CysVI) and Isomer 2 (CysI-CysVI, CysII-CysIV, CysIII-CysV), but not the native μ-conotoxin arrangement. To date, there has been no study on the structure and activity of KIIIA comprising the native μ-conotoxin disulfide bond arrangement. Here, we evaluated the synthesis, potency, sodium channel subtype selectivity, and 3D structure of the three isomers of KIIIA. Using a regioselective disulfide bond-forming strategy, we synthetically produced the three μ-conotoxin KIIIA isomers displaying distinct bioactivity and NaV subtype selectivity across human NaV channel subtypes 1.2, 1.4, and 1.7. We show that Isomer 1 inhibits NaV subtypes with a rank order of potency of NaV1.4 > 1.2 > 1.7 and Isomer 2 in the order of NaV1.4≈1.2 > 1.7, while the native isomer inhibited NaV1.4 > 1.7≈1.2. The three KIIIA isomers were further evaluated by NMR solution structure analysis and molecular docking with hNaV1.2. Our study highlights the importance of investigating alternate disulfide isomers, as disulfide connectivity affects not only the overall structure of the peptides but also the potency and subtype selectivity of μ-conotoxins targeting therapeutically relevant NaV subtypes.
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Affiliation(s)
- Hue N T Tran
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Kirsten L McMahon
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Jennifer R Deuis
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Irina Vetter
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia; School of Pharmacy, The University of Queensland, Woolloongabba, Queensland, Australia.
| | - Christina I Schroeder
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia; Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland, USA.
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Qiang Y, Wu Y, Zhao D, Zhao B, Wang F, Ren S, Wen Y, Gu J, Zhang L, Liu K, Niu J, Wang L. Discovery and characterization of the novel conotoxin Lv1d from Conus lividus that presents analgesic activity. Toxicon 2021; 194:70-8. [PMID: 33610632 DOI: 10.1016/j.toxicon.2021.02.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 11/08/2020] [Accepted: 02/15/2021] [Indexed: 12/21/2022]
Abstract
Cone snails are predatory gastropod mollusks that are distributed in all tropical marine environments and contain small peptides (conotoxins) in their venom to capture prey. However, the biochemical and molecular aspects of conotoxins remain poorly understood. In this article, a novel α4/7-conotoxin, Lv1d, was obtained from the venom duct cDNA library of the worm-hunting Conus lividus collected from the South China Sea. The cDNA of Lv1c encodes a 65 residue conopeptide precursor, which consists of a 21 residue signal peptide, a 27 residue Pro region, and 17 residues of mature peptide. The mature peptide Lv1d was chemically synthesized according to the sequence GCCSDPPCRHKHQDLCG. It was found that 10 μM Lv1d can completely inhibit frog sciatic nerve-gastrocnemius muscle contractility within 60 min. Moreover, 100 μg/kg Lv1d showed good analgesic effects in mouse hot plate model and formalin test. Patch clamp experiments showed that 5 μM Lv1d can inhibit the cholinergic microexcitatory postsynaptic currents (mEPSCs) requency and amplitude of projection neurons in Drosophila. In conclusion, the synthesis of Lv1d and its biological and physiological data might contribute to the development of this peptide as a novel potential drug for therapeutic applications. This finding also expands the knowledge of the targeting mechanism of the α4/7-subfamily conotoxins.
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Metcalf CS, Huff J, Thomson KE, Johnson K, Edwards SF, Wilcox KS. Evaluation of antiseizure drug efficacy and tolerability in the rat lamotrigine-resistant amygdala kindling model. Epilepsia Open 2019; 4:452-463. [PMID: 31440726 PMCID: PMC6698678 DOI: 10.1002/epi4.12354] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 07/09/2019] [Accepted: 07/21/2019] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVE The lamotrigine-resistant amygdala kindling model uses repeated administration of a low dose of lamotrigine during the kindling process to produce resistance to lamotrigine, which also extends to some other antiseizure drugs (ASDs). This model of pharmacoresistant epilepsy has been incorporated into the testing scheme utilized by the Epilepsy Therapy Screening Program (ETSP). Although some ASDs have been evaluated in this model, a comprehensive evaluation of ASD prototypes has not been reported. METHODS Following depth electrode implantation and recovery, rats were exposed to lamotrigine (5 mg/kg, i.p.) prior to each stimulation during the kindling development process (~3 weeks). A test dose of lamotrigine was used to confirm that fully kindled rats were lamotrigine-resistant. Efficacy (unambiguous protection against electrically elicited convulsive seizures) was defined as a Racine score < 3 in the absence of overt compound-induced side effects. Various ASDs, comprising several mechanistic classes, were administered to fully kindled, lamotrigine-resistant rats. Where possible, multiple doses of each drug were administered in order to obtain median effective dose (ED50) values. RESULTS Five sodium channel blockers tested (eslicarbazepine, lacosamide, lamotrigine, phenytoin, and rufinamide) were either not efficacious or effective only at doses that were not well-tolerated in this model. In contrast, compounds targeting either GABA receptors (clobazam, clonazepam, phenobarbital) or GABA-uptake proteins (tiagabine) produced dose-dependent efficacy against convulsive seizures. Compounds acting to modulate Ca2+ channels show differential activity: Ethosuximide was not effective, whereas gabapentin was moderately efficacious. Ezogabine and valproate were also highly effective, whereas topiramate and levetiracetam were not effective at the doses tested. SIGNIFICANCE These results strengthen the conclusion that the lamotrigine-resistant amygdala kindling model demonstrates pharmacoresistance to certain ASDs, including, but not limited to, sodium channel blockers, and supports the utility of the model for helping to identify compounds with potential efficacy against pharmacoresistant seizures.
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Affiliation(s)
- Cameron S. Metcalf
- Anticonvulsant Drug Development Program, Department of Pharmacology and ToxicologyUniversity of UtahSalt Lake CityUTUSA
| | - Jennifer Huff
- Anticonvulsant Drug Development Program, Department of Pharmacology and ToxicologyUniversity of UtahSalt Lake CityUTUSA
| | - Kyle E. Thomson
- Anticonvulsant Drug Development Program, Department of Pharmacology and ToxicologyUniversity of UtahSalt Lake CityUTUSA
| | - Kristina Johnson
- Anticonvulsant Drug Development Program, Department of Pharmacology and ToxicologyUniversity of UtahSalt Lake CityUTUSA
| | - Sharon F. Edwards
- Anticonvulsant Drug Development Program, Department of Pharmacology and ToxicologyUniversity of UtahSalt Lake CityUTUSA
| | - Karen S. Wilcox
- Anticonvulsant Drug Development Program, Department of Pharmacology and ToxicologyUniversity of UtahSalt Lake CityUTUSA
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Loss CM, da Rosa NS, Mestriner RG, Xavier LL, Oliveira DL. Blockade of GluN2B-containing NMDA receptors reduces short-term brain damage induced by early-life status epilepticus. Neurotoxicology 2019; 71:138-149. [PMID: 30639357 DOI: 10.1016/j.neuro.2019.01.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 11/22/2018] [Accepted: 01/09/2019] [Indexed: 12/11/2022]
Abstract
Status epilepticus (SE) during developmental periods can cause short- and long-term consequences to the brain. Brain damage induced by SE is associated to NMDA receptors (NMDAR)-mediated excitotoxicity. This study aimed to investigate whether blockade of GluN2B-containing NMDAR is neuroprotective against SE-induced neurodegeneration and neuroinflammation in young rats. Forty-eight Wistar rats (16 days of life) were injected with pilocarpine (60 mg/kg; i.p.) 12-18 h after LiCl (3 mEq/kg; i.p.). Fifteen minutes after pilocarpine administration, animals received i.p. injections of saline solution (0.9% NaCl; SE + SAL group), ketamine (a non-selective and noncompetitive NMDAR antagonist; 25 mg/kg; SE + KET), CI-1041 (a GluN2B-containing NMDAR antagonist; 10 mg/kg; SE + CI group) or CP-101,606 (a NMDAR antagonist with great selectivity for NMDAR composed by GluN1/GluN2B diheteromers; 10 mg/kg; SE + CP group). Seven days after SE, brains were removed for Fluoro-Jade C staining and Iba1/ED1 immunolabeling. GluN2B-containing NMDAR blockade by CI-1041 or CP-101,606 did not terminate LiCl-pilocarpine-induced seizures. SE + SAL group presented intense neurodegeneration and Iba1+/ED1+ double-labeling in hippocampus (CA1 and dentate gyrus; DG) and amygdala (MePV nucleus). Administration of CP-101,606 did not alter this pattern. However, GluN2B-containing NMDAR blockade by CI-1041 reduced neurodegeneration and Iba1+/ED1+ double-labeling in hippocampus and amygdala similar to the reduction observed for SE + KET group. Our results indicate that GluN2B-containing NMDAR are involved in SE-induced neurodegeneration and microglial recruitment and activation, and suggest that stopping epileptic activity is not a condition required to prevent short-term brain damage in young animals.
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Affiliation(s)
- Cássio Morais Loss
- Cellular Neurochemistry Laboratory, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Cellular Biochemistry Laboratory, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
| | - Natã Sehn da Rosa
- Cellular Neurochemistry Laboratory, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Régis Gemerasca Mestriner
- Neurorehabilitation and Neural Repair Research Group, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Léder Leal Xavier
- Laboratory of Cell and Tissue Biology, School of Sciences, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Diogo Losch Oliveira
- Cellular Neurochemistry Laboratory, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
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Nôga DAMF, Brandão LEM, Cagni FC, Silva D, de Azevedo DLO, Araújo A, Dos Santos WF, Miranda A, da Silva RH, Ribeiro AM. Anticonvulsant Effects of Fractions Isolated from Dinoponera quadriceps (Kempt) Ant Venom (Formicidae: Ponerinae). Toxins (Basel) 2016; 9:toxins9010005. [PMID: 28025529 PMCID: PMC5308238 DOI: 10.3390/toxins9010005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 10/24/2016] [Accepted: 11/01/2016] [Indexed: 12/13/2022] Open
Abstract
Natural products, sources of new pharmacological substances, have large chemical diversity and architectural complexity. In this context, some toxins obtained from invertebrate venoms have anticonvulsant effects. Epilepsy is a neurological disorder that affects about 65 million people worldwide, and approximately 30% of cases are resistant to pharmacological treatment. Previous studies from our group show that the denatured venom of the ant Dinoponera quadriceps (Kempt) protects mice against bicuculline (BIC)-induced seizures and death. The aim of this study was to investigate the anticonvulsant activity of compounds isolated from D. quadriceps venom against seizures induced by BIC in mice. Crude venom was fractionated by high-performance liquid chromatography (HPLC) resulting in six fractions referred to as DqTx1-DqTx6. A liquid chromatography-mass spectrometry (LC/MS) analysis revealed a major 431 Da compound in fractions DqTx1 and DqTx2. Fractions DqTx3 and DqTx4 showed a compound of 2451 Da and DqTx5 revealed a 2436 Da compound. Furthermore, the DqTx6 fraction exhibited a major component with a molecular weight of 13,196 Da. Each fraction (1 mg/mL) was microinjected into the lateral ventricle of mice, and the animals were observed in an open field. We did not observe behavioral alterations when the fractions were given alone. Conversely, when the fractions were microinjected 20 min prior to the administration of BIC (21.6 nM), DqTx1, DqTx4, and DqTx6 fractions increased the latency for onset of tonic-clonic seizures. Moreover, all fractions, except DqTx5, increased latency to death. The more relevant result was obtained with the DqTx6 fraction, which protected 62.5% of the animals against tonic-clonic seizures. Furthermore, this fraction protected 100% of the animals from seizure episodes followed by death. Taken together, these findings indicate that compounds from ant venom might be a potential source of new anticonvulsants molecules.
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Affiliation(s)
| | | | - Fernanda Carvalho Cagni
- Physiology Department, University Federal of Rio Grande of Norte, Natal, RN 59078-970, Brazil.
| | - Delano Silva
- Physiology Department, University Federal of Rio Grande of Norte, Natal, RN 59078-970, Brazil.
| | | | - Arrilton Araújo
- Physiology Department, University Federal of Rio Grande of Norte, Natal, RN 59078-970, Brazil.
| | | | - Antonio Miranda
- Biophysics Department, Federal University of São Paulo, São Paulo, SP 04023-062, Brazil.
| | - Regina Helena da Silva
- Pharmacology Department, Federal University of São Paulo, São Paulo, SP 04023-062, Brazil.
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Zhu WY, Jiang P, He X, Cao LJ, Zhang LH, Dang RL, Tang MM, Xue Y, Li HD. Contribution of NRG1 Gene Polymorphisms in Temporal Lobe Epilepsy. J Child Neurol 2016; 31:271-6. [PMID: 26071373 DOI: 10.1177/0883073815589757] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/11/2015] [Indexed: 02/04/2023]
Abstract
The purpose of the present study was to investigate the possible association between temporal lobe epilepsy and NRG1 gene polymorphisms. A total of 73 patients and 69 controls were involved in this study. Genomic DNAs from the patients and controls were genotyped by polymerase chain reaction-ligase detection reaction method. There was an association of rs35753505 (T>C) with temporal lobe epilepsy (χ(2) = 6.730, P = .035). The frequency of risk allele C of rs35753505 was significantly higher (69.9%) in patients compared to controls (55.8%) (χ(2) = 6.023, P = .014). Interestingly, the significant difference of NRG1 genotype and allele frequency only existed among males, but not females. In addition, no statistically significant association was found between rs6994992, rs62510682 polymorphisms, and temporal lobe epilepsy. These data indicate that rs35753505 of NRG1 plays an important role in conferring susceptibility to the temporal lobe epilepsy in a Chinese Han population.
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Affiliation(s)
- Wen-Ye Zhu
- Institute of Clinical Pharmacy & Pharmacology, Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China School of Pharmaceutical Science, Central South University, Changsha, Hunan Province, China
| | - Pei Jiang
- Institute of Clinical Pharmacy & Pharmacology, Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China School of Pharmaceutical Science, Central South University, Changsha, Hunan Province, China
| | - Xin He
- Institute of Clinical Pharmacy & Pharmacology, Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China School of Pharmaceutical Science, Central South University, Changsha, Hunan Province, China
| | - Ling-Juan Cao
- Institute of Clinical Pharmacy & Pharmacology, Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China School of Pharmaceutical Science, Central South University, Changsha, Hunan Province, China
| | - Li-Hong Zhang
- Institute of Clinical Pharmacy & Pharmacology, Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China School of Pharmaceutical Science, Central South University, Changsha, Hunan Province, China
| | - Rui-Li Dang
- Institute of Clinical Pharmacy & Pharmacology, Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China School of Pharmaceutical Science, Central South University, Changsha, Hunan Province, China
| | - Mi-Mi Tang
- Institute of Clinical Pharmacy & Pharmacology, Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China School of Pharmaceutical Science, Central South University, Changsha, Hunan Province, China
| | - Ying Xue
- Institute of Clinical Pharmacy & Pharmacology, Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China School of Pharmaceutical Science, Central South University, Changsha, Hunan Province, China
| | - Huan-De Li
- Institute of Clinical Pharmacy & Pharmacology, Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China
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Abstract
The evolutionarily unique and ecologically diverse family Conidae presents fundamental opportunities for marine pharmacology research and drug discovery. The focus of this investigation is to summarize the worldwide distribution of Conus and their species diversity with special reference to the Indian coast. In addition, this study will contribute to understanding the structural properties of conotoxin and therapeutic application of Conus venom peptides. Cone snails can inject a mix of various conotoxins and these venoms are their major weapon for prey capture, and may also have other biological purposes, and some of these conotoxins fatal to humans. Conus venoms contain a remarkable diversity of pharmacologically active small peptides; their targets are an iron channel and receptors in the neuromuscular system. Interspecific divergence is pronounced in venom peptide genes, which is generally attributed to their species specific biotic interactions. There is a notable interspecific divergence observed in venom peptide genes, which can be justified as of biotic interactions that stipulate species peculiar habitat and ecology of cone snails. There are several conopeptides used in clinical trials and one peptide (Ziconotide) has received FDA approval for treatment of pain. This perspective provides a comprehensive overview of the distribution of cone shells and focus on the molecular approach in documenting their taxonomy and diversity with special reference to geographic distribution of Indian cone snails, structure and properties of conopeptide and their pharmacological targets and future directions.
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Affiliation(s)
| | - Dhanabalan Senthil Kumar
- Department of Zoology, Kandaswami Kandar College, Paramathi Velur-638 182, Namakkal, Tamil Nadu, India
| | - Sundaresan Umamaheswari
- Department of Environmental Biotechnology, Bharathidasan University, Tiruchurapalli, Tamil Nadu 620024, India
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Balsara R, Dang A, Donahue DL, Snow T, Castellino FJ. Conantokin-G attenuates detrimental effects of NMDAR hyperactivity in an ischemic rat model of stroke. PLoS One 2015; 10:e0122840. [PMID: 25822337 DOI: 10.1371/journal.pone.0122840] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 02/24/2015] [Indexed: 12/31/2022] Open
Abstract
The neuroprotective activity of conantokin-G (con-G), a naturally occurring antagonist of N-methyl-D-aspartate receptors (NMDAR), was neurologically and histologically compared in the core and peri-infarct regions after ischemia/reperfusion brain injury in male Sprague-Dawley rats. The contralateral regions served as robust internal controls. Intrathecal injection of con-G, post-middle carotid artery occlusion (MCAO), caused a dramatic decrease in brain infarct size and swelling at 4 hr, compared to 26 hr, and significant recovery of neurological deficits was observed at 26 hr. Administration of con-G facilitated neuronal recovery in the peri-infarct regions as observed by decreased neurodegeneration and diminished calcium microdeposits at 4 hr and 26 hr. Intact Microtubule Associated Protein (MAP2) staining and neuronal cytoarchitecture was observed in the peri-infarct regions of con-G treated rats at both timepoints. Con-G restored localization of GluN1 and GluN2B subunits in the neuronal soma, but not that of GluN2A, which was perinuclear in the peri-infarct regions at 4 hr and 26 hr. This suggests that molecular targeting of the GluN2B subunit has potential for reducing detrimental consequences of ischemia. Overall, the data demonstrated that stroke-induced NMDAR excitoxicity is ameliorated by con-G-mediated repair of neurological and neuroarchitectural deficits, as well as by reconstituting neuronal localization of GluN1 and GluN2B subunits in the peri-infarct region of the stroked brain.
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Wlaź P, Poleszak E, Serefko A, Wlaź A, Rundfeldt C. Anxiogenic- and antidepressant-like behavior in corneally kindled rats. Pharmacol Rep 2015; 67:349-52. [PMID: 25712662 DOI: 10.1016/j.pharep.2014.10.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Revised: 10/14/2014] [Accepted: 10/15/2014] [Indexed: 11/18/2022]
Abstract
BACKGROUND Anxiety and depression affect epileptic patients much more often than individuals from the general population. We were interested in whether corneal kindling in rats, which is a model of complex partial seizures with secondary generalization, would influence animal behavior in models of anxiety and depression. METHODS Kindling was achieved by transcorneal electric stimulation and fully kindled rats were used in this study. Kindled and sham-stimulated rats were subjected to the elevated plus maze and forced swim test which are believed to be predictive models for anxiety and depression in humans, respectively. RESULTS Kindling significantly decreased the percentage of time spent by the rats in open arms relative to time spent in open plus closed arms and it reduced immobility time in the swim test as compared with sham-stimulated rats. CONCLUSIONS Our results suggest that corneal kindling produces antidepressant- and anxiety-like effects in rats and it may be a useful model to study epilepsy-associated anxiety.
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Affiliation(s)
- Piotr Wlaź
- Department of Animal Physiology, Institute of Biology, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, Lublin, Poland.
| | - Ewa Poleszak
- Chair and Department of Applied Pharmacy, Medical University of Lublin, Lublin, Poland
| | - Anna Serefko
- Chair and Department of Applied Pharmacy, Medical University of Lublin, Lublin, Poland
| | - Aleksandra Wlaź
- Department of Pathophysiology, Medical University of Lublin, Lublin, Poland
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Amini E, Rezaei M, Mohamed Ibrahim N, Golpich M, Ghasemi R, Mohamed Z, Raymond AA, Dargahi L, Ahmadiani A. A Molecular Approach to Epilepsy Management: from Current Therapeutic Methods to Preconditioning Efforts. Mol Neurobiol 2014; 52:492-513. [PMID: 25195699 DOI: 10.1007/s12035-014-8876-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 08/25/2014] [Indexed: 01/16/2023]
Abstract
Epilepsy is the most common and chronic neurological disorder characterized by recurrent unprovoked seizures. The key aim in treating patients with epilepsy is the suppression of seizures. An understanding of focal changes that are involved in epileptogenesis may therefore provide novel approaches for optimal treatment of the seizure. Although the actual pathogenesis of epilepsy is still uncertain, recently growing lines of evidence declare that microglia and astrocyte activation, oxidative stress and reactive oxygen species (ROS) production, mitochondria dysfunction, and damage of blood-brain barrier (BBB) are involved in its pathogenesis. Impaired GABAergic function in the brain is probably the most accepted hypothesis regarding the pathogenesis of epilepsy. Clinical neuroimaging of patients and experimental modeling have demonstrated that seizures may induce neuronal apoptosis. Apoptosis signaling pathways are involved in the pathogenesis of several types of epilepsy such as temporal lobe epilepsy (TLE). The quality of life of patients is seriously affected by treatment-related problems and also by unpredictability of epileptic seizures. Moreover, the available antiepileptic drugs (AED) are not significantly effective to prevent epileptogenesis. Thus, novel therapies that are proficient to control seizure in people who are suffering from epilepsy are needed. The preconditioning method promises to serve as an alternative therapeutic approach because this strategy has demonstrated the capability to curtail epileptogenesis. For this reason, understanding of molecular mechanisms underlying brain tolerance induced by preconditioning is crucial to delineate new neuroprotective ways against seizure damage and epileptogenesis. In this review, we summarize the work to date on the pathogenesis of epilepsy and discuss recent therapeutic strategies in the treatment of epilepsy. We will highlight that novel therapy targeting such as preconditioning process holds great promise. In addition, we will also highlight the role of gene reprogramming and mitochondrial biogenesis in the preconditioning-mediated neuroprotective events.
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Affiliation(s)
- Elham Amini
- Department of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Cheras, Kuala Lumpur, Malaysia
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Srivastava AK, White HS. Carbamazepine, but not valproate, displays pharmacoresistance in lamotrigine-resistant amygdala kindled rats. Epilepsy Res 2012; 104:26-34. [PMID: 23158096 DOI: 10.1016/j.eplepsyres.2012.10.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 09/06/2012] [Accepted: 10/18/2012] [Indexed: 11/25/2022]
Abstract
The voltage gated sodium channel (VGSC) blocker lamotrigine (LTG), when administered during kindling acquisition, leads to the development of resistance to LTG. The present study aimed to assess whether LTG-resistant amygdala-kindled rats display subsequent resistance to the VGSC blocker carbamazepine (CBZ) and the broad-spectrum antiepileptic drug (AED) sodium valproate (VPA). Two groups of male Sprague Dawley rats received either 0.5% methylcellulose (MC) or LTG (5mg/kg, i.p.) 1h before each amygdala kindling stimulation. Treatments were stopped once both the groups were fully kindled. Two days later, both groups were challenged with a higher dose of LTG (15mg/kg, i.p.) to verify LTG-resistance in the experimental group (i.e., LTG-pretreated rats). The efficacy of CBZ and VPA was then evaluated in both groups. A higher dose of LTG blocked fully kindled seizures in the vehicle-treated rats but not seizures in the LTG-treated group. The mean seizure score, of the control group (1.2±0.3) was significantly lower (P<.05) than that of the LTG-treated population (3.5±0.7; n=8). A lower percent of the population in the control group was observed to display a generalized stage 4-5 seizure compared to the experimental group (i.e., those that received LTG during kindling acquisition) (28.5% vs. 62%, respectively). Interestingly, CBZ (10, 20, and 40mg/kg) displayed a dose-dependent anticonvulsant effect in the vehicle-kindled group, but was less effective in LTG-treated animals. In contrast, VPA (300mg/kg) effectively blocked the behavioral seizure and decreased the afterdischarge duration (ADD) in both vehicle and LTG groups. These findings suggest that the LTG-resistant, amygdala-kindled rat may represent a novel model of pharmacoresistant epilepsy.
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Affiliation(s)
- Ajay K Srivastava
- Anticonvulsant Drug Development (ADD) Program, Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, Salt Lake City, UT, USA
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Hanada T, Hashizume Y, Tokuhara N, Takenaka O, Kohmura N, Ogasawara A, Hatakeyama S, Ohgoh M, Ueno M, Nishizawa Y. Perampanel: A novel, orally active, noncompetitive AMPA-receptor antagonist that reduces seizure activity in rodent models of epilepsy. Epilepsia 2011; 52:1331-40. [DOI: 10.1111/j.1528-1167.2011.03109.x] [Citation(s) in RCA: 278] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Corcoran ME, Kroes RA, Burgdorf JS, Moskal JR. Regional changes in gene expression after limbic kindling. Cell Mol Neurobiol 2011; 31:819-34. [PMID: 21424270 DOI: 10.1007/s10571-011-9672-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 03/02/2011] [Indexed: 11/24/2022]
Abstract
Repeated electrical stimulation results in development of seizures and a permanent increase in seizure susceptibility (kindling). The permanence of kindling suggests that chronic changes in gene expression are involved. Kindling at different sites produces specific effects on interictal behaviors such as spatial cognition and anxiety, suggesting that causal changes in gene expression might be restricted to the stimulated site. We employed focused microarray analysis to characterize changes in gene expression associated with amygdaloid and hippocampal kindling. Male Long-Evans rats received 1 s trains of electrical stimulation to either the amygdala or hippocampus once daily until five generalized seizures had been kindled. Yoked control rats carried electrodes but were not stimulated. Rats were euthanized 14 days after the last seizures, both amygdala and hippocampus dissected, and transcriptome profiles compared. Of the 1,200 rat brain-associated genes evaluated, 39 genes exhibited statistically significant expression differences between the kindled and non-kindled amygdala and 106 genes exhibited statistically significant differences between the kindled and non-kindled hippocampus. In the amygdala, subsequent ontological analyses using the GOMiner algorithm demonstrated significant enrichment in categories related to cytoskeletal reorganization and cation transport, as well as in gene families related to synaptic transmission and neurogenesis. In the hippocampus, significant enrichment in gene expression within categories related to cytoskeletal reorganization and cation transport was similarly observed. Furthermore, unique to the hippocampus, enrichment in transcription factor activity and GTPase-mediated signal transduction was identified. Overall, these data identify specific and unique neurochemical pathways chronically altered following kindling in the two sites, and provide a platform for defining the molecular basis for the differential behaviors observed in the interictal period.
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Affiliation(s)
- M E Corcoran
- Neural Systems and Plasticity Research Group and Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, SK S7N 3R2, Canada.
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Alex AB, Saunders GW, Dalpé-Charron A, Reilly CA, Wilcox KS. CGX-1007 prevents excitotoxic cell death via actions at multiple types of NMDA receptors. Neurotoxicology 2011; 32:392-9. [PMID: 21396956 DOI: 10.1016/j.neuro.2011.03.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Revised: 02/17/2011] [Accepted: 03/02/2011] [Indexed: 11/16/2022]
Abstract
Glutamate induced excitotoxic injury through over-activation of N-methyl-D-aspartate receptors (NMDARs) plays a critical role in the development of many neurodegenerative diseases. The present study was undertaken to evaluate the role of CGX-1007 (Conantokin G) as a neuroprotective agent against NMDA-induced excitotoxicity. Conantokin G, a cone snail peptide isolated from Conus geographus is reported to selectively inhibit NR2B containing NMDARs with high specificity and is shown to have potent anticonvulsant and antinociceptive effects. CGX-1007 significantly reduced the excitotoxic cell death induced by NMDA in organotypic hippocampal brain slice cultures in a concentration-dependent manner. In contrast, ifenprodil, another NR2B specific antagonist failed to offer neuroprotection against NMDA-induced excitotoxicity. We further determined that the neuroprotection observed is likely due to the action of CGX-1007 at multiple NMDA receptor subtypes. In a series of electrophysiology experiments, CGX-1007 inhibited NMDA-gated currents in human embryonic kidney (HEK) 293 cells expressing NMDA receptors containing either NR1a/NR2B or NR1a/NR2A subunit combinations. CGX-1007 produced a weak inhibition at NR1a/NR2C receptors, whereas it had no effect on NR1a/NR2D receptors. Further, the inhibition of NMDA receptors by CGX-1007 was voltage-dependent with greater inhibition seen at hyperpolarized membrane potentials. The voltage-dependence of CGX-1007 activity was also observed in recordings of NMDA-gated currents evoked in native receptors expressed in cortical neurons in culture. Based on our results, we conclude that CGX-1007 is a potent neuroprotective agent that acts as an antagonist at both NR2A and NR2B containing receptors.
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Affiliation(s)
- Anitha B Alex
- Department of Pharmacology & Toxicology,Anticonvulsant Drug Development Program, University of Utah, 417 Wakara Way, Salt Lake City, UT 84108, USA
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Traynelis SF, Wollmuth LP, McBain CJ, Menniti FS, Vance KM, Ogden KK, Hansen KB, Yuan H, Myers SJ, Dingledine R. Glutamate receptor ion channels: structure, regulation, and function. Pharmacol Rev 2010; 62:405-96. [PMID: 20716669 PMCID: PMC2964903 DOI: 10.1124/pr.109.002451] [Citation(s) in RCA: 2530] [Impact Index Per Article: 180.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The mammalian ionotropic glutamate receptor family encodes 18 gene products that coassemble to form ligand-gated ion channels containing an agonist recognition site, a transmembrane ion permeation pathway, and gating elements that couple agonist-induced conformational changes to the opening or closing of the permeation pore. Glutamate receptors mediate fast excitatory synaptic transmission in the central nervous system and are localized on neuronal and non-neuronal cells. These receptors regulate a broad spectrum of processes in the brain, spinal cord, retina, and peripheral nervous system. Glutamate receptors are postulated to play important roles in numerous neurological diseases and have attracted intense scrutiny. The description of glutamate receptor structure, including its transmembrane elements, reveals a complex assembly of multiple semiautonomous extracellular domains linked to a pore-forming element with striking resemblance to an inverted potassium channel. In this review we discuss International Union of Basic and Clinical Pharmacology glutamate receptor nomenclature, structure, assembly, accessory subunits, interacting proteins, gene expression and translation, post-translational modifications, agonist and antagonist pharmacology, allosteric modulation, mechanisms of gating and permeation, roles in normal physiological function, as well as the potential therapeutic use of pharmacological agents acting at glutamate receptors.
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Affiliation(s)
- Stephen F Traynelis
- Department of Pharmacology, Emory University School of Medicine, Rollins Research Center, 1510 Clifton Road, Atlanta, GA 30322-3090, USA.
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Mortari MR, Cunha AOS, Ferreira LB, dos Santos WF. Neurotoxins from invertebrates as anticonvulsants: From basic research to therapeutic application. Pharmacol Ther 2007; 114:171-83. [PMID: 17399793 DOI: 10.1016/j.pharmthera.2007.01.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Revised: 01/19/2007] [Accepted: 01/19/2007] [Indexed: 12/21/2022]
Abstract
Invertebrate venoms have attracted considerable interest as a potential source of bioactive substances, especially neurotoxins. These molecules have proved to be extremely useful tools for the understanding of synaptic transmission events, and they have contributed to the design of novel drugs for the treatment of neurological disorders and pain. In this context, as epilepsy involves neuronal substrates, which are sites of action of many neurotoxins; venoms may be particularly useful for antiepileptic drug (AED) research. Epilepsy is a chronic disease whose treatment consists of controlling seizures with antiepileptics that very often induce strong undesirable side effects that may limit treatment. Here, we review the vast, but yet unexplored, world of neurotoxins from invertebrates used as probes in pharmacological screening for novel and less toxic antiepileptics. We briefly review (1) the molecular basis of epilepsy, as well as the sites of action of commonly used anticonvulsants (we bring a comprehensive review of the elements from invertebrate venoms which are mostly studied in neuroscience research and may be useful for drug development); (2) peptides from conus snails; (3) peptides and polyamine toxins from spiders and wasps; and (4) peptides from scorpions.
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Affiliation(s)
- Márcia Renata Mortari
- Neurobiology and Venoms Laboratory, Department of Biology, School of Philosophy, Sciences and Literature, University of São Paulo Ribeirão Preto, Brazil
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Abstract
Pharmacoresistance remains a major challenge in epilepsy management. The availability of ten new antiepileptic drugs since the late 1980s has not dramatically improved the outcome of refractory epilepsy. This article provides an overview of the contemporary understanding of epilepsy and the limitation of current treatment modalities, discusses putative biological mechanisms of medical intractability and reviews some of the novel strategies under investigation to overcome the challenge of pharmacoresistance.
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Affiliation(s)
- Patrick Kwan
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong.
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Lu XCM, Williams AJ, Wagstaff JD, Tortella FC, Hartings JA. Effects of delayed intrathecal infusion of an NMDA receptor antagonist on ischemic injury and peri-infarct depolarizations. Brain Res 2005; 1056:200-8. [PMID: 16112094 DOI: 10.1016/j.brainres.2005.07.041] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2005] [Revised: 07/18/2005] [Accepted: 07/21/2005] [Indexed: 11/28/2022]
Abstract
The potent NMDA receptor antagonist, Conantokin-G (CGX-1007), a snail peptide, has an 8-h therapeutic window in rat focal cerebral ischemia. We hypothesized that the mechanism of neuroprotection is the inhibition of 'secondary phase' peri-infarct depolarizations (PIDs), recently shown to recur 6--24 h post-reperfusion. Rats were implanted with intrathecal (i.t.) catheters for drug delivery and DC-compatible electrodes for continuous PID monitoring and subjected to transient (2 h) middle cerebral artery occlusion. Four groups were studied. In two groups (C(40)C and C(20)C), continuous infusion of CGX--1007 was administered over 8--24 h post-occlusion at 0.1 microg/h (0.04 nmol/h) following either a 40- or 20-nmol bolus dose at 8 h. Another group (C(40)S) received the 40-nmol bolus followed by saline infusion, and a control group received saline. Intrathecal drug treatment reduced infarct volumes relative to controls by 61%, 31%, and 10% in C(40)C, C(40)S, and C(20)C groups, respectively, but also induced dose-dependent paralysis and elevated mortality. All rats had PID rates similar to the control group prior to treatment, but following treatment secondary phase PIDs were reduced by 47--57% in each drug group compared to controls. Because several animals exhibited PID inhibition but no neuroprotection, there was no significant correlation between these endpoints across groups. However, drug-treated animals that did not exhibit secondary phase PIDs prior to treatment had significantly smaller infarcts and reduced subsequent PID activity than corresponding control rats. Results suggest that post-reperfusion PIDs play a substantial, though still undefined pathogenic role in delayed maturation of cerebral infarction and NMDA receptor-targeted neuroprotection.
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Affiliation(s)
- X-C May Lu
- Division of Psychiatry and Neurosciences, Walter Reed Army Institute of Research, 503 Robert Grant Ave., Silver Spring, MD 20910, USA
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Slamberová R, Mares P. Cortical epileptic afterdischarges in immature rats are differently influenced by NMDA receptor antagonists. Eur J Pharmacol 2005; 516:10-7. [PMID: 15904917 DOI: 10.1016/j.ejphar.2005.04.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2004] [Revised: 03/21/2005] [Accepted: 04/14/2005] [Indexed: 10/25/2022]
Abstract
Epileptic afterdischarges elicited by stimulation of sensorimotor cortex were chosen to test anticonvulsant effects of NMDA receptor antagonists in developing rats (12, 18 and 25 days old) with implanted electrodes. Afterdischarges were elicited four times with 10-min intervals in the experiments with dizocilpine and 20 min with the other two drugs. Dizocilpine (0.5 or 1 mg/kg), CGP 40116 (0.1, 0.5 or 1 mg/kg) or 2-amino-7-phosphonoheptanoic acid (AP7, 30 or 60 mg/kg) was injected intraperitoneally between the first and second stimulation. Intensity of movements accompanying stimulation was diminished regularly only by CGP 40116. Duration of afterdischarges was reduced and intensity of clonic seizures was decreased by CGP 40116 in all age groups; dizocilpine exhibited similar action in 25- and 18-day-old rats, AP7 only in 25-day-old animals. Anticonvulsant action of the three NMDA antagonists exhibited different developmental profiles in our model; this difference might be due to developmental changes of NMDA receptors.
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Affiliation(s)
- Romana Slamberová
- Institute of Physiology, Academy of Sciences of the Czech Republic, Vídenská 1083, CZ-142 20 Prague 4, Czech Republic
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23
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Abstract
RATIONALE L: -Glutamate is the major excitatory neurotransmitter in the central nervous system (CNS) and mediates its actions via activation of both ionotropic and metabotropic receptor families. The development of selective ligands, including competitive agonists and antagonists and positive and negative allosteric modulators, has enabled investigation of the functional roles of glutamate receptor family members. OBJECTIVE In this review we describe the subunit structure and composition of the ionotropic and metabotropic glutamate receptors and discuss their pharmacology, particularly with respect to selective tools useful for investigation of their function in the CNS. RESULTS A large number of ligands are now available that are selective either for glutamate receptor subfamilies or for particular receptor subtypes. Such ligands have enabled considerable advances in the elucidation of the physiological and pathophysiological roles of receptor family members. Furthermore, efficacy in animal models of neurological and psychiatric disorders has supported the progression of several glutamatergic ligands into clinical studies. These include ionotropic glutamate receptor antagonists, which have entered clinical trials for disorders including epilepsy and ischaemic stroke, alpha-amino-3-hydroxy-5-methyl-4-isoazolepropionic acid (AMPA) receptor positive allosteric modulators which are under evaluation as cognitive enhancers, and metabotropic glutamate receptor 2 (mGluR2) agonists which are undergoing clinical evaluation as anxiolytics. Furthermore, preclinical studies have illustrated therapeutic potential for ligands selective for other receptor subtypes in various disorders. These include mGluR1 antagonists in pain, mGluR5 antagonists in anxiety, pain and drug abuse and mGluR5 positive allosteric modulators in schizophrenia. CONCLUSIONS Selective pharmacological tools have enabled the study of glutamate receptors. However, pharmacological coverage of the family is incomplete and considerable scope remains for the development of novel ligands, particularly those with in vivo utility, and for the their use together with existing tools for the further investigation of the roles of receptor family members in CNS function and as potentially novel therapeutics.
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Affiliation(s)
- James N C Kew
- Psychiatry Centre of Excellence for Drug Discovery, GlaxoSmithKline, New Frontiers Science Park, Harlow, Essex CM19 5AW, UK.
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Barton ME, White HS, Wilcox KS. The effect of CGX-1007 and CI-1041, novel NMDA receptor antagonists, on NMDA receptor-mediated EPSCs. Epilepsy Res 2004; 59:13-24. [PMID: 15135163 DOI: 10.1016/j.eplepsyres.2003.12.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2003] [Accepted: 12/24/2003] [Indexed: 11/20/2022]
Abstract
The N-methyl-D-aspartate (NMDA) receptor-gated ion channel is comprised of at least one NR1 subunit and any of four NR2 subunits (NR2A-D). The NR2 subunit confers different pharmacological and kinetic properties to the receptor. CGX-1007 (Conantokin G), a 17-amino acid polypeptide isolated from the venom of Conus geographus, is a novel NMDA receptor antagonist that is thought to be selective for the NR2B subunit. CGX-1007 has been reported to have highly potent, broad-spectrum anticonvulsant activity in animal seizure models. CI-1041 is an investigational compound, which also possesses anticonvulsant activity and has been shown to be highly selective for NR2B containing NMDA receptors. Although both CI-1041 and CGX-1007 are reportedly NR2B specific antagonists, they differ in their ability to block amygdala-kindled seizures, suggesting that the mechanism of action of these compounds differs. The present study was designed to test the hypothesis that CI-1041 and CGX-1007 would differentially modulate the function of NMDA receptors at excitatory synapses. Using the whole cell patch clamp technique, CGX-1007 and CI-1041 were found to block CA1 pyramidal cell, NMDA receptor-mediated excitatory postsynaptic currents (N-EPSCs) in a concentration-dependent manner in hippocampal slices from P4-P6 animals. In contrast, only CGX-1007 decreased NMDA receptor-mediated EPSC peak amplitude in slices from adult animals. The CGX-1007 block of peak amplitude was accompanied by a similar concentration-dependent decrease in decay kinetics of NMDA receptor-mediated EPSCs. These results suggest that while CI-1041 may be selective for NMDA receptors containing the NR2B subunit, CGX-1007 appears to be less selective than previously reported.
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Affiliation(s)
- Matthew E Barton
- Anticonvulsant Drug Development Program, Department of Pharmacology and Toxicology, University of Utah, 20 S 2030 E, RM 408, Salt Lake City, UT 84112, USA
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