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Intrathecal application of ethosuximide is highly efficient in suppressing seizures in a genetic model of absence epilepsy. Epilepsy Res 2022; 184:106967. [DOI: 10.1016/j.eplepsyres.2022.106967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 05/29/2022] [Accepted: 06/11/2022] [Indexed: 11/21/2022]
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Masicampo ML, Shan HQ, Xu V, Speagle M, Godwin DW. Selective Blockade of T-Type Ca2+ Channels is Protective Against Alcohol-Withdrawal Induced Seizure and Mortality. Alcohol Alcohol 2018; 53:526-531. [PMID: 29912275 DOI: 10.1093/alcalc/agy042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 06/04/2018] [Indexed: 11/13/2022] Open
Abstract
AIMS We have previously demonstrated that blockade of T-type calcium channels by the non-selective antagonist, ethosuximide (ETX), is effective at reducing electrographical and behavioral correlates of alcohol-withdrawal (WD) seizure. Here, we investigated whether blockade of these calcium channels with the selective antagonist TTA-P2 also reduces alcohol-WD seizure. SHORT SUMMARY The non-specific T-type calcium channel antagonist, ETX, is protective against alcohol-WD seizure. However, the mechanism of this effect is unclear. Here, we provide evidence that further suggests selective blockade of T-type calcium channels are protective against alcohol-WD seizure and WD-related mortality. METHODS We used an intermittent ethanol exposure model to produce WD-induced hyperexcitability in DBA/2 J mice. Seizure severity was intensified with the chemoconvulsant pentylenetetrazole (PTZ). RESULTS TTA-P2 (10 mg/kg) reduced seizure severity in mice undergoing alcohol WD with concurrent PTZ treatment (20 mg/kg). Moreover, TTA-P2 (20 and 40 mg/kg) was also protective against PTZ-induced (40 mg/kg) seizure and mortality. CONCLUSIONS These results are consistent with prior results using ETX, and suggest that the protective effects of ETX and TTA-P2 against EtOH WD seizures are mediated by T-type calcium channels.
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Affiliation(s)
- Melissa L Masicampo
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, 1 Medical Center Boulevard, Winston-Salem, NC, USA.,Department of Physiology and Pharmacology, Wake Forest School of Medicine, 1 Medical Center Boulevard, Winston-Salem, NC, USA
| | - Hong Qu Shan
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, 1 Medical Center Boulevard, Winston-Salem, NC, USA
| | - Victoria Xu
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, 1 Medical Center Boulevard, Winston-Salem, NC, USA
| | - Merritt Speagle
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, 1 Medical Center Boulevard, Winston-Salem, NC, USA
| | - Dwayne W Godwin
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, 1 Medical Center Boulevard, Winston-Salem, NC, USA.,Department of Physiology and Pharmacology, Wake Forest School of Medicine, 1 Medical Center Boulevard, Winston-Salem, NC, USA
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Galvan A, Devergnas A, Pittard D, Masilamoni G, Vuong J, Daniels JS, Morrison RD, Lindsley CW, Wichmann T. Lack of Antiparkinsonian Effects of Systemic Injections of the Specific T-Type Calcium Channel Blocker ML218 in MPTP-Treated Monkeys. ACS Chem Neurosci 2016; 7:1543-1551. [PMID: 27596273 DOI: 10.1021/acschemneuro.6b00186] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Dopaminergic medications ameliorate many of the motor impairments of Parkinson's disease (PD). However, parkinsonism is often only partially reversed by these drugs, and they can have significant side effects. Therefore, a need remains for novel treatments of parkinsonism. Studies in rodents and preliminary clinical evidence have shown that T-type calcium channel (TTCC) antagonists have antiparkinsonian effects. However, most of the available studies utilized nonselective agents. We now evaluated whether systemic injections of the specific TTCC blocker ML218 have antiparkinsonian effects in MPTP-treated parkinsonian Rhesus monkeys. The animals were treated chronically with MPTP until they reached stable parkinsonism. In pharmacokinetic studies, we found that ML218 reaches a peak CSF concentration 1-2 h after s.c. administration. In electrocardiographic studies, we found no effects of ML218 on cardiac rhythmicity. As expected, systemic injections of the dopamine precursor L-DOPA dose-dependently increased the movements in our parkinsonian animals. We then tested the behavioral effects of systemic injections of ML218 (1, 10, or 30 mg/kg) or its vehicle, but did not detect specific antiparkinsonian effects. ML218 (3 or 10 mg/kg) was also not synergistic with L-DOPA. Using recordings of electrocorticogram signals (in one animal), we found that ML218 increased sleep. We conclude that ML218 does not have antiparkinsonian effects in MPTP-treated parkinsonian monkeys, due at least in part, to the agent's sedative effects.
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Affiliation(s)
| | | | | | | | | | - J. Scott Daniels
- Department
of Pharmacology and Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Ryan D. Morrison
- Department
of Pharmacology and Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Craig W. Lindsley
- Department
of Pharmacology and Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
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Ghamkhari Nejad G, Shahabi P, Alipoor MR, Ghaderi Pakdel F, Asghari M, Sadighi Alvandi M. Ethosuximide Affects Paired-Pulse Facilitation in Somatosensory Cortex of WAG\Rij Rats as a Model of Absence Seizure. Adv Pharm Bull 2016; 5:483-9. [PMID: 26819920 DOI: 10.15171/apb.2015.066] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 06/28/2015] [Accepted: 07/27/2015] [Indexed: 11/09/2022] Open
Abstract
PURPOSE The interaction between somatosensory cortex and thalamus via a thalamocortical loop is a theory behind induction of absence epilepsy. Inside peri-oral somatosensory (S1po) and primary somatosensory forelimb (S1fl) regions, excitatory and inhibitory systems are not balanced and GABAergic inhibitory synapses seem to play a fundamental role in short-term plasticity alterations. METHODS We investigated the effects of Ethosuximide on presynaptic changes by utilizing paired-pulse stimulation that was recorded from somatosensory cortex in 18 WAG\Rij rats during epileptic activity. A twisted tripolar electrode including two stimulating electrodes and one recording electrode was implanted into the S1po and S1FL according to stereotaxic landmarks. Paired-pulses (200 µs, 100-1000 µA, 0.1 Hz) were applied to somatosensory cortex at 50, 100, 400, 500 ms inter-pulse intervals for 50 min period. RESULTS The results showed that paired-pulse facilitation was significantly reduced at all intervals in all times, but compared to the control group of epileptic WAG/Rij rats (p<0.05), it was exceptional about the first 10 minutes after the injection. At the intervals of 50 and 100 ms, a remarkable PPD was found in second, third, fourth and fifth 10-min post injection. CONCLUSION These experiments indicate that Ethosuximide has effects on presynaptic facilitation in somatosensory cortex inhibitory loops by alteration in GABA levels that leads to a markedly diminished PPF in paired-pulse stimulation.
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Affiliation(s)
| | - Parviz Shahabi
- Neurosciences Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mohamad Reza Alipoor
- Neurosciences Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Firouz Ghaderi Pakdel
- Department of Physiology, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, Iran
| | - Mohammad Asghari
- Road Traffic Injury Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mina Sadighi Alvandi
- Drug Applied Research Center, Tabriz University of Medical Sciences,Tabriz, Iran
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Ethosuximide reduces electrographical and behavioral correlates of alcohol withdrawal seizure in DBA/2J mice. Alcohol 2014; 48:445-53. [PMID: 24933286 DOI: 10.1016/j.alcohol.2014.01.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 01/24/2014] [Accepted: 01/24/2014] [Indexed: 11/20/2022]
Abstract
Chronic alcohol abuse depresses the nervous system and, upon cessation, rebound hyperexcitability can result in withdrawal seizure. Withdrawal symptoms, including seizures, may drive individuals to relapse, thus representing a significant barrier to recovery. Our lab previously identified an upregulation of the thalamic T-type calcium (T channel) isoform CaV3.2 as a potential contributor to the generation and propagation of seizures in a model of withdrawal. In the present study, we examined whether ethosuximide (ETX), a T-channel antagonist, could decrease the severity of ethanol withdrawal seizures by evaluating electrographical and behavioral correlates of seizure activity. DBA/2J mice were exposed to an intermittent ethanol exposure paradigm. Mice were treated with saline or ETX in each withdrawal period, and cortical EEG activity was recorded to determine seizure severity. We observed a progression in seizure activity with each successive withdrawal period. Treatment with ETX reduced ethanol withdrawal-induced spike and wave discharges (SWDs), in terms of absolute number, duration of events, and contribution to EEG power in the 6-10 Hz frequency range. We also evaluated the effects of ETX on handling-induced convulsions. Overall, we observed a decrease in handling-induced convulsion severity in mice treated with ETX. Our findings suggest that ETX may be a useful pharmacological agent for studies of alcohol withdrawal and treatment of resulting seizures.
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Sondossi K, Majdzadeh M, Ghaeli P, Ghahremani MH, Shafaroodi H, Paknejad B, Ostad SN. Analysis of the antiepileptic, ethosuximide impacts on neurogenesis of rat forebrain stem cells. Fundam Clin Pharmacol 2014; 28:512-8. [PMID: 24354536 DOI: 10.1111/fcp.12061] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 11/18/2013] [Accepted: 12/10/2013] [Indexed: 12/01/2022]
Abstract
Specific GABAergic interneurons in the hilus are lost in animal models with temporal-lobe epilepsy (TLE). Some preclinical evidence has indicated that GABAergic cells may provide relief from seizures in these models. This study was aimed to examine the ability of ethosuximide, an anticonvulsant drug, to promote neurogenesis in 3-day-old rat forebrain cortex stem cells. Most of the cells were found to be nestin-positive undifferentiated neural stem cells prior to their exposure to ethosuximide. It was noted that the number and percentage of tubulin β-III immunopositive neurons were increased after 6 days treatment with ethosuximide. Upon bFGF withdrawal, exposure to ethosuximide differentiated the stem cells to MAP2 positive neural cells (7.18 ± 0.43, 21.766 ± 0.55 and 41.57 ± 0.5 for control, 0.1 and 1 μM, respectively). GABA immunofluorescence images illustrated that ethosuximide increased GABAergic neurons (7.19 ± 0.32, 23.23 ± 0.55, and 46.30 ± 0.44 for control, 0.1 and 1 μM, respectively). Additionally, BrdU immunofluorescence assay showed that ethosuximide-enhanced nucleus proliferation in the neuronal stem cells. Therefore, the results of this study suggest that ethosuximide may compensate damage caused by seizure attacks and possibly other neuronal loss disorders.
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Affiliation(s)
- Kiana Sondossi
- Department of Pharmacology, Pharmaceutical Sciences Branch, Islamic Azad University (IAU), Tehran, Iran
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Greenhill SD, Chamberlain SEL, Lench A, Massey PV, Yuill KH, Woodhall GL, Jones RSG. Background synaptic activity in rat entorhinal cortex shows a progressively greater dominance of inhibition over excitation from deep to superficial layers. PLoS One 2014; 9:e85125. [PMID: 24454801 PMCID: PMC3893176 DOI: 10.1371/journal.pone.0085125] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 11/22/2013] [Indexed: 11/21/2022] Open
Abstract
The entorhinal cortex (EC) controls hippocampal input and output, playing major roles in memory and spatial navigation. Different layers of the EC subserve different functions and a number of studies have compared properties of neurones across layers. We have studied synaptic inhibition and excitation in EC neurones, and we have previously compared spontaneous synaptic release of glutamate and GABA using patch clamp recordings of synaptic currents in principal neurones of layers II (L2) and V (L5). Here, we add comparative studies in layer III (L3). Such studies essentially look at neuronal activity from a presynaptic viewpoint. To correlate this with the postsynaptic consequences of spontaneous transmitter release, we have determined global postsynaptic conductances mediated by the two transmitters, using a method to estimate conductances from membrane potential fluctuations. We have previously presented some of this data for L3 and now extend to L2 and L5. Inhibition dominates excitation in all layers but the ratio follows a clear rank order (highest to lowest) of L2>L3>L5. The variance of the background conductances was markedly higher for excitation and inhibition in L2 compared to L3 or L5. We also show that induction of synchronized network epileptiform activity by blockade of GABA inhibition reveals a relative reluctance of L2 to participate in such activity. This was associated with maintenance of a dominant background inhibition in L2, whereas in L3 and L5 the absolute level of inhibition fell below that of excitation, coincident with the appearance of synchronized discharges. Further experiments identified potential roles for competition for bicuculline by ambient GABA at the GABAA receptor, and strychnine-sensitive glycine receptors in residual inhibition in L2. We discuss our results in terms of control of excitability in neuronal subpopulations of EC neurones and what these may suggest for their functional roles.
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Affiliation(s)
- Stuart David Greenhill
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, United Kingdom
| | | | - Alex Lench
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, United Kingdom
| | - Peter Vernon Massey
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, United Kingdom
| | - Kathryn Heather Yuill
- School of Biomedical & Healthcare Sciences, Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth, United Kingdom
| | - Gavin Lawrence Woodhall
- Aston Brain Centre, School of Life and Health Sciences, Aston University, Birmingham, United Kingdom
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