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Background: Millions of people struggle with alcohol use disorder (AUD). Abrupt abstinence after a period of chronic alcohol use can precipitate the alcohol withdrawal syndrome (AWS), which includes hyperexcitability and, potentially, seizures. We have shown that T‐type Ca2+ channels are novel, sensitive targets of alcohol, an effect that is dependent upon protein kinase C (PKC). The purpose of this study was to (1) understand midline thalamic neuronal hyperexcitability during alcohol withdrawal and its dependence on PKC; (2) characterize T channel functional changes using both current clamp and voltage clamp methods; and (3) determine which PKC isoform may be responsible for alcohol withdrawal (WD) effects. Methods: Whole‐cell patch clamp recordings were performed in midline thalamic neurons in brain slices prepared from C57bl/6 mice that underwent chronic intermittent alcohol exposure in a standard vapor chamber model. The recordings were compared to those from air‐exposed controls. T‐channel inactivation curves and burst responses were acquired through voltage‐clamp and current‐clamp recordings, respectively. Results: Whole‐cell voltage clamp recordings of native T‐type current exhibited a depolarizing shift in the voltage‐dependency of inactivation during alcohol withdrawal compared to air‐exposed controls. A PKCε translocation inhibitor peptide mitigated this change. Current clamp recordings demonstrated more spikes per burst during alcohol withdrawal. Consistent with voltage clamp findings, the PKCɛ translocation inhibitor peptide reduced the number of spikes per burst after WD. Conclusion: We found that alcohol WD produces T channel‐mediated hyperexcitability in the midline thalamus, produced in part by a shift in the inactivation curve consistent with greater availability of T current. WD effects on T current inactivation were reduced to control levels by blocking PKCε translocation. Our results demonstrate that PKCε translocation plays an important role in the regulation of alcohol withdrawal‐induced hyperexcitability in midline thalamic circuitry. [ABSTRACT FROM AUTHOR]

Background: Alcohol withdrawal syndrome (AWS) results from the sudden cessation of chronic alcohol use and is associated with high morbidity and mortality. Alcohol withdrawal‐induced central nervous system (CNS) hyperexcitability results from complex, compensatory changes in synaptic efficacy and intrinsic excitability. These changes in excitability counteract the depressing effects of chronic ethanol on neural transmission and underlie symptoms of AWS, which range from mild anxiety to seizures and death. The development of targeted pharmacotherapies for treating AWS has been slow, due in part to the lack of available animal models that capture the key features of human AWS. Using a unique optogenetic method of probing network excitability, we examined electrophysiologic correlates of hyperexcitability sensitive to early changes in CNS excitability. This method is sensitive to pharmacologic treatments that reduce excitability and may represent a platform for AWS drug development. Methods: We applied a newly developed method, the optogenetic population discharge threshold (oPDT), which uses light intensity response curves to measure network excitability in chronically implanted mice. Excitability was tracked using the oPDT before, during, and after the chronic intermittent exposure (CIE) model of alcohol withdrawal (WD). Results: Alcohol withdrawal produced a dose‐dependent leftward shift in the oPDT curve (denoting increased excitability), which was detectable in as few as three exposure cycles. This shift in excitability mirrored an increase in the number of spontaneous interictal spikes during withdrawal. In addition, Withdrawal lowered seizure thresholds and increased seizure severity in optogenetically kindled mice. Conclusion: We demonstrate that the oPDT provides a sensitive measure of alcohol withdrawal‐induced hyperexcitability. The ability to actively probe the progression of excitability without eliciting potentially confounding seizures promises to be a useful tool in the preclinical development of next‐generation pharmacotherapies for AWS. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We recently demonstrated that T-type calcium channels are affected by alcohol abuse and withdrawal. Treatment with ethosuximide, an antiepileptic drug that blocks T-type calcium channels, reduces seizure activity induced by intermittent ethanol exposures and withdrawals. Here, we expand on these findings to test whether ethosuximide can reduce the sensitivity to pentylenetetrazole-induced seizures during ethanol withdrawal.~Aims~Objective~We used an intermittent ethanol exposure model to produce withdrawal-induced hyperexcitability in DBA/2J mice.~Methods~Methods~Ethosuximide (250 mg/kg) reduced seizure severity in mice undergoing ethanol withdrawal with concurrent PTZ treatment (20 mg/kg). Importantly, ethosuximide did not produce rebound excitability and protected against ethanol withdrawal-induced mortality produced by concurrent PTZ treatment (40 mg/kg).~Results~Results~These results, in addition to previous preclinical findings, suggest that ethosuximide should be further evaluated as a safe, effective alternative to benzodiazepines for the treatment of alcohol withdrawal.~Conclusion~Conclusions [ABSTRACT FROM AUTHOR]

Background T-type calcium channels (T-channels) are widely distributed in the central and peripheral nervous system, where they mediate calcium entry and regulate the intrinsic excitability of neurons. T-channels are dysregulated in response to alcohol administration and withdrawal. We therefore investigated acute ethanol ( Et OH) effects and the underlying mechanism of action in human embryonic kidney ( HEK) 293 cell lines, as well as effects on native currents recorded from dorsal root ganglion ( DRG) neurons cultured from Long-Evans rats. Methods Whole-cell voltage-clamp recordings were performed at 32 to 34°C in both HEK cell lines and DRG neurons. The recordings were taken after a 10-minute application of Et OH or protein kinase C ( PKC) activator (phorbol 12-myristate 13-acetate [ PMA]). Results We recorded T-type Ca2+ currents (T-currents) from 3 channel isoforms ( Ca V3.1, Ca V3.2, and Ca V3.3) before and during administration of Et OH. We found that only 1 isoform, Ca V3.2, was significantly affected by EtOH. Et OH reduced current density as well as producing a hyperpolarizing shift in steady-state inactivation of both Ca V3.2 currents from HEK 293 cell lines and in native T-currents from DRG neurons that are known to be enriched in Ca V3.2. A myristoylated PKC peptide inhibitor ( MPI) blocked the major Et OH effects, in both the cell lines and the DRG neurons. However, PMA effects were more complex. Lower concentration PMA (100 nM) replicated the major effects of Et OH, while higher concentration PMA (1 μM) did not, suggesting that the Et OH effects operate through activation of PKC and were mimicked by lower concentration of PMA. Conclusions Et OH primarily affects the CaV3.2 isoform of T-type Ca2+ channels acting through PKC, highlighting a novel target and mechanism for Et OH effects on excitable membranes. [ABSTRACT FROM AUTHOR]

Background Chronic ethanol ( EtOH) leads to disruptions in resting electroencephalogram ( EEG) activity and in sleep patterns that can persist into the withdrawal period. These disruptions have been suggested to be predictors of relapse. The thalamus is a key structure involved in both normal brain oscillations, such as sleep-related oscillations, and abnormal rhythms found in disorders such as epilepsy and Parkinson's disease. Previously, we have shown progressive changes in mouse thalamic T-type Ca2+ channels during chronic intermittent EtOH exposures that occurred in parallel with alterations in theta (4 to 8 Hz) EEG patterns. Methods Two groups of 8-week-old male C57 BL/6 mice were implanted with wireless EEG/electromyogram ( EMG) telemetry and subjected to 4 weeks of chronic, intermittent EtOH vapor exposure and withdrawal. During the week after the final withdrawal, mice were administered ethosuximide ( ETX; 200 mg/kg) or saline. EEG data were analyzed via discrete Fourier transform, and sleep-scored for further analysis. Results Chronic intermittent EtOH exposure produced changes in the diurnal rhythms of the delta (0.5 to 4 Hz) and theta bands that persisted into a subsequent week of sustained withdrawal. These disruptions were restored with the T-channel blocker ETX. Repeated EtOH exposures preferentially increased the relative proportion of lower frequency power (delta and theta), whereas higher frequencies (8 to 24 Hz) were decreased. The EtOH-induced decreases in relative power for the higher frequencies continued into the sustained withdrawal week for both groups. Increases in absolute delta and theta power were observed in averaged nonrapid eye movement and rapid eye movement sleep spectral data during withdrawal in ETX-treated animals, suggesting increased sleep intensity. Conclusions These results suggest that persistent alterations in delta and theta EEG rhythms during withdrawal from chronic intermittent EtOH exposure can be ameliorated with ETX and that this treatment might also increase sleep intensity during withdrawal. [ABSTRACT FROM AUTHOR]

Introduction: Chronic alcohol abuse is associated with neurophysiological changes in brain activity; however, these changes are not well localized in humans. Non-human primate models of alcohol abuse enable control over many potential confounding variables associated with human studies. The present study utilized high-resolution magnetoencephalography (MEG) to quantify the effects of chronic EtOH self-administration on resting state (RS) brain function in vervet monkeys.Methods: Adolescent male vervet monkeys were trained to self-administer ethanol (n=7) or an isocaloric malto-dextrin solution (n=3). Following training, animals received 12 months of free access to ethanol. Animals then underwent RS magnetoencephalography (MEG) and subsequent power spectral analysis of brain activity at 32 bilateral regions of interest associated with the chronic effects of alcohol use.Results: demonstrate localized changes in brain activity in chronic heavy drinkers, including reduced power in the anterior cingulate cortex, hippocampus, and amygdala as well as increased power in the right medial orbital and parietal areas.Discussion: The current study is the first demonstration of whole-head MEG acquisition in vervet monkeys. Changes in brain activity were consistent with human electroencephalographic studies; however, MEG was able to extend these findings by localizing the observed changes in power to specific brain regions. These regions are consistent with those previously found to exhibit volume loss following chronic heavy alcohol use. The ability to use MEG to evaluate changes in brain activity following chronic ethanol exposure provides a potentially powerful tool to better understand both the acute and chronic effects of alcohol on brain function. [ABSTRACT FROM AUTHOR]