Diazepam during prior ethanol withdrawals does not alter seizure susceptibility during a subsequent withdrawal

Proteomics and weighted gene correlated network analysis reveal glutamatergic synapse signaling in diazepam treatment of alcohol withdrawal

Background: Alcohol use disorder (AUD) is characterized by chronic excessive alcohol consumption, often alternating with periods of abstinence known as alcohol withdrawal syndrome (AWS). Diazepam is the preferred benzodiazepine for treatment of alcohol withdrawal syndrome under most circumstances, but the specific mechanism underlying the treatment needs further research. Methods: We constructed an animal model of two-bottle choices and chronic intermittent ethanol exposure. LC-MS/MS proteomic analysis based on the label-free and intensity-based quantification approach was used to detect the protein profile of the whole brain. Weighted gene correlated network analysis was applied for scale-free network topology analysis. We established a protein-protein interaction network based on the Search Tool for the Retrieval of Interacting Genes (STRING) database and Cytoscape software and identified hub proteins by CytoHubba and MCODE plugins of Cytoscape. The online tool Targetscan identified miRNA-mRNA pair interactions. Results: Seven hub proteins (Dlg3, Dlg4, Shank3, Grin2b, Camk2b, Camk2a and Syngap1) were implicated in alcohol withdrawal syndrome or diazepam treatment. In enrichment analysis, glutamatergic synapses were considered the most important pathway related to alcohol use disorder. Decreased glutamatergic synapses were observed in the late stage of withdrawal, as a protective mechanism that attenuated withdrawal-induced excitotoxicity. Diazepam treatment during withdrawal increased glutamatergic synapses, alleviating withdrawal-induced synapse inhibition. Conclusion: Glutamatergic synapses are considered the most important pathway related to alcohol use disorder that may be a potential molecular target for new interventional strategies.

Alcohol Withdrawal and the Associated Mood Disorders-A Review

Recreational use of alcohol is a social norm in many communities worldwide. Alcohol use in moderation brings pleasure and may protect the cardiovascular system. However, excessive alcohol consumption or alcohol abuse are detrimental to one's health. Three million deaths due to excessive alcohol consumption were reported by the World Health Organization. Emerging evidence also revealed the danger of moderate consumption, which includes the increased risk to cancer. Alcohol abuse and periods of withdrawal have been linked to depression and anxiety. Here, we present the effects of alcohol consumption (acute and chronic) on important brain structures-the frontal lobe, the temporal lobe, the limbic system, and the cerebellum. Apart from this, we also present the link between alcohol abuse and withdrawal and mood disorders in this review, thus drawing a link to oxidative stress. In addition, we also discuss the positive impacts of some pharmacotherapies used. Due to the ever-rising demands of life, the cycle between alcohol abuse, withdrawal, and mood disorders may be a never-ending cycle of destruction. Hence, through this review, we hope that we can emphasise the importance and urgency of managing this issue with the appropriate approaches.

Activation of neural stem cells from quiescence drives reactive hippocampal neurogenesis after alcohol dependence

Neural stem cell-driven adult neurogenesis contributes to the integrity of the hippocampus. Excessive alcohol consumption in alcoholism results in hippocampal degeneration that may recover with abstinence. Reactive, increased adult neurogenesis during abstinence following alcohol dependence may contribute to recovery, but the mechanism driving reactive neurogenesis is not known. Therefore, adult, male rats were exposed to alcohol for four days and various markers were used to examine cell cycle dynamics, the percentage and number of neural progenitor cell subtypes, and the percentage of quiescent versus activated progenitors. Using a screen for cell cycle perturbation, we showed that the cell cycle is not likely altered at 7 days in abstinence. As the vast majority of Bromodeoxyuridine-positive (+) cells were co-labeled with progenitor cell marker, Sox2, we then developed a quadruple fluorescent labeling scheme to examine Type-1, -2a, -2b and -3 progenitor cells simultaneously. Prior alcohol dependence indiscriminately increased all subtypes at 7 days, the peak of the reactive proliferation. An evaluation of the time course of reactive cell proliferation revealed that cells begin proliferating at 5 days post alcohol, where only actively dividing Type 2 progenitors were increased by alcohol. Furthermore, prior alcohol increased the percentage of actively dividing Sox2+ progenitors, which supported that reactive neurogenesis is likely due to the activation of progenitors out of quiescence. These observations were associated with granule cell number returning to normal at 28 days. Therefore, activating stem and progenitor cells out of quiescence may be the mechanism underlying hippocampal recovery in abstinence following alcohol dependence.

Type 2 Neural Progenitor Cell Activation Drives Reactive Neurogenesis after Binge-Like Alcohol Exposure in Adolescent Male Rats

Excessive alcohol consumption during adolescence remains a significant health concern as alcohol drinking during adolescence increases the likelihood of an alcohol use disorder in adulthood by fourfold. Binge drinking in adolescence is a particular problem as binge-pattern consumption is the biggest predictor of neurodegeneration from alcohol and adolescents are particularly susceptible to the damaging effects of alcohol. The adolescent hippocampus, in particular, is highly susceptible to alcohol-induced structural and functional effects, including volume and neuron loss. However, hippocampal structure and function may recover with abstinence and, like in adults, a reactive burst in hippocampal neurogenesis in abstinence may contribute to that recovery. As the mechanism of this reactive neurogenesis is not known, the current study investigated potential mechanisms of reactive neurogenesis in binge alcohol exposure in adolescent, male rats. In a screen for cell cycle perturbation, a dramatic increase in the number of cells in all phases of the cycle was observed at 7 days following binge ethanol exposure as compared to controls. However, the proportion of cells in each phase was not different between ethanol-exposed rats and controls, indicating that cell cycle dynamics are not responsible for the reactive burst in neurogenesis. Instead, the marked increase in hippocampal proliferation was shown to be due to a twofold increase in proliferating progenitor cells, specifically an increase in cells colabeled with the progenitor cell marker Sox2 and S-phase (proliferation) marker, BrdU, in ethanol-exposed rats. To further characterize the individual subtypes of neural progenitor cells (NPCs) affected by adolescent binge ethanol exposure, a fluorescent quadruple labeling technique was utilized to differentiate type 1, 2a, 2b, and 3 progenitor cells simultaneously. At one week into abstinence, animals in the ethanol exposure groups had an increase in proliferating type 2 (intermediate progenitors) and type 3 (neuroblast) progenitors but not type 1 neural stem cells. These results together suggest that activation of type 2 NPCs out of quiescence is likely the primary mechanism for reactive hippocampal neurogenesis following adolescent alcohol exposure.

GABA withdrawal syndrome: GABAA receptor, synapse, neurobiological implications and analogies with other abstinences

The sudden interruption of the increase of the concentration of the gamma-aminobutyric acid (GABA), determines an increase in neuronal activity. GABA withdrawal (GW) is a heuristic analogy, with withdrawal symptoms developed by other GABA receptor-agonists such as alcohol, benzodiazepines, and neurosteroids. GW comprises a model of neuronal excitability validated by electroencephalogram (EEG) in which high-frequency and high-amplitude spike-wave complexes appear. In brain slices, GW was identified by increased firing synchronization of pyramidal neurons and by changes in the active properties of the neuronal membrane. GW induces pre- and postsynaptic changes: a decrease in GABA synthesis/release, and the decrease in the expression and composition of GABAA receptors associated with increased calcium entry into the cell. GW is an excellent bioassay for studying partial epilepsy, epilepsy refractory to drug treatment, and a model to reverse or prevent the generation of abstinences from different drugs.

Acupuncture Reduces Alcohol Withdrawal Syndrome and c-Fos Expression in Rat Brain

Acupuncture as a therapeutic intervention is widely practiced in the treatment of many functional disorders including alcohol abuse. In the present study, the effects of acupuncture on alcohol withdrawal syndrome (AWS) and Fos-like immunoreactivity (FLI) in the striatum and the nucleus accumbens (NAC) of rats were investigated. During 3 days of cessation following chronic administration of ethanol (3 g/kg, i.p. for 3 weeks), rats showed a significant increase in AWS, such as hypermotility, tail rigidity, grooming and tremor, and an increase in FLI in the dopamine terminal areas of the brain. Treatment with acupuncture at zusanli (ST36) or sanyinjiao (SP6) during the withdrawal period inhibited both AWS and FLI of rats undergoing ethanol injection. These results suggest that acupuncture may be useful in the treatment of alcoholism by modulating post-synaptic neural activation in the striatum and NAC.

Upregulated vimentin suggests new areas of neurodegeneration in a model of an alcohol use disorder

Excessive alcohol intake, characteristic of an alcohol use disorder (AUD), results in neurodegeneration as well as cognitive deficits that may recover in abstinence. Neurodegeneration in psychiatric disorders such as AUDs is due to various effects on tissue integrity. Several groups report that alcohol-induced neurodegeneration and recovery include a role for adult neurogenesis. Therefore, the initial purpose of this study was to investigate the effect of alcohol on the temporal profile of neural progenitor cells using the radial glia marker, vimentin, in a model of an AUD. However, striking vimentin expression throughout corticolimbic regions led, instead, to the discovery of a significant gliosis response in this model. Adult male rats were subjected to a 4-day binge model of an AUD and brains harvested for immunohistochemistry at 0, 2, 4, 7, 14, and 28 days following the last dose of ethanol. A prominent increase in vimentin immunoreactivity was apparent at 4 and 7 days post binge that returned to control levels by 14 days in the corticolimbic regions examined. Vimentin-positive cells co-labeled with glial fibrillary acidic protein (GFAP), which suggested that cells were reactive astrocytes. A second experiment supported that increased vimentin was not primarily due to alcohol withdrawal seizures and is more likely due to alcohol-induced cell death. As this gliosis was remarkably distinct in regions where cell death had not previously been reported in this model, adjacent tissue sections were processed for FluoroJade B staining for cell death. FluoroJade B-positive cells were evident immediately following the last ethanol dose as expected, but were significantly elevated in the hippocampal dentate gyrus and CA3 regions and corticolimbic regions from 2 to 7 days post binge. Intriguingly, vimentin labeling of astrogliosis is more widespread than FluoroJade B labeling of cell death, which suggests that 4-day binge ethanol consumption is more damaging than originally realized.

Disrupted thalamic T-type Ca2+ channel expression and function during ethanol exposure and withdrawal

Chronic ethanol exposure produces profound disruptions in both brain rhythms and diurnal behaviors. The thalamus has been identified as a neural pacemaker of both normal and abnormal rhythms with low-threshold, transient (T-type) Ca(2+) channels participating in this activity. We therefore examined T-type channel gene expression and physiology in the thalamus of C57Bl/6 mice during a 4-wk schedule of chronic intermittent ethanol exposures in a vapor chamber. We found that chronic ethanol disrupts the normal daily variations of both thalamic T-type channel mRNA levels and alters thalamic T-type channel gating properties. The changes measured in channel expression and function were associated with an increase in low-threshold bursts of action potentials during acute withdrawal periods. Additionally, the observed molecular and physiological alterations in the channel properties in wild-type mice occurred in parallel with a progressive disruption in the normal daily variations in theta (4-9 Hz) power recorded in the cortical electroencephalogram. Theta rhythms remained disrupted during a subsequent week of withdrawal but were restored with the T-type channel blocker ethosuximide. Our results demonstrate that a key ion channel underlying the generation of thalamic rhythms is altered during chronic ethanol exposure and withdrawal and may be a novel target in the management of abnormal network activity due to chronic alcoholism.

Alcohol withdrawal-induced hippocampal neurotoxicity in vitro and seizures in vivo are both reduced by memantine

BACKGROUND

The ethanol withdrawal (EWD) syndrome is typically treated using benzodiazepines such as diazepam. However there is concern that benzodiazepines may not prevent neurotoxicity associated with EWD. Antagonists of glutamate/N-Methyl-D-Aspartate receptors (NMDARs) such as MK801 have been shown to be effective against both EWD-induced neurotoxicity in vitro and seizures in vivo. However, most of these agents have adverse side effects. An exception is the moderate affinity NMDAR channel blocker memantine, used in Alzheimer's dementia. The present studies examined the ability of memantine to protect against EWD-related toxicity in vitro and seizures in vivo.

METHODS

Organotypic hippocampal slice cultures from neonatal rat pups were treated starting at 15 days in vitro with 100 mM ethanol for 10 days followed by a 24-hour EWD period. During the 24-hour EWD period cultures were treated with memantine (15 or 30 microM). MK801 (10 microM) was utilized as a positive control. For the in vivo studies, the ability of memantine (2, 5, 10, and 15 mg/kg) to reduce convulsions was analyzed in Swiss-Webster mice using the handling induced convulsion test paradigm.

RESULTS

In vitro studies demonstrated that memantine is effective at blocking EWD-induced neurotoxicity. In vivo experiments showed that memantine also significantly reduced convulsions induced by EWD in mice.

CONCLUSIONS

Memantine may be of therapeutic value during alcohol detoxification by virtue of its having neuroprotective effects in addition to anti-seizure activity. The potential role of memantine in treatment of alcoholism is deserving of further study.

Addiction: the clinical interface

This review gives an overview of what we see as the key issues in the human pharmacology of drugs of addiction. We review evidence of efficacy and mechanisms by which treatments act and point out areas where further work is needed. The role of agonist, partial agonist and antagonist treatments for opioid addiction is detailed and current issues relating to the mechanisms of actions at the receptor level and how to improve on compliance are discussed. The role of the brain dopamine and GABA-A systems in drug dependence is considered in relation to the growing pharmacology of these receptor systems, and the current status of novel preclinical targets reviewed. In addition, the different roles of dynamic and kinetic factors in both addiction and its treatment are discussed in relation to the underlying neuropharmacology of the disorders as defined from human and preclinical studies. Finally, some pointers to future research and especially to drug development by pharma are elaborated.

A Five-Day Gradual Reduction Regimen of Chlormadinone Reduces Premenstrual Anxiety and Depression: A Pilot Study

BACKGROUND

Anxiety and depression commonly occur in premenstrual dysphoric disorder (PMDD). The PMDD symptomatology disappears once the menstrual cycle reinitiates, resembling a withdrawal syndrome.

METHODS

The present study is a pilot, controlled, double-blind study exploring the effectiveness of a premenstrual 5-day gradual reduction regimen of chlormadinone acetate on PMDD. Volunteers received an initial dose of 10 mg (five 2-mg tablets) on the 24(th) day of the menstrual cycle and one-fifth of the dose less (one tablet) each day until a dose of 2 mg (one 2-mg tablet) was reached on the 28(th) day of the menstrual cycle. The control group received placebo with a similar regimen.

RESULTS

The 5-day gradual reduction regimen of chlormadinone significantly improved (F(3.76) = 3.29, p <0.02) the daily symptoms report (DSR) scores by the third month of treatment. The resulting relative risk was 4.09 (confidence interval: 1.15-14.57, p <0.005, 95% CI). Compared to placebo, chlormadinone clinically and statistically reduced the severity of depression, anxiety, food cravings, mood swings and cramps. A statistical reduction of symptoms such as poor coordination, irritability, feeling out of control, hopelessness, decreased interest and headache was detected but was not clinically relevant. No changes occurred in concentration difficulties, tiredness, insomnia, swelling, breast tenderness and aches. As side effects, 30% of the volunteers showed changes in the length of the menstrual cycle, and 15% experienced dyspepsia.

CONCLUSIONS

A 5-day gradual reduction regimen of chlormadinone improves some of the discomforting ailments associated with PMDD, namely, depression and anxiety.

Lorazepam and MK-801 effects on behavioral and electrographic indices of alcohol withdrawal sensitization

Repeated cycles of chronic ethanol exposure and withdrawal result in sensitization of withdrawal-related CNS hyperexcitability that generally reflects an imbalance in activity of GABA and glutamate systems. Many pharmacological treatments for ethanol withdrawal target neuroadaptive changes in GABA and glutamate neurotransmission. The present study utilized a mouse model of repeated withdrawals to evaluate the ability of lorazepam and MK-801 treatments to antagonize behavioral and electroencephalographic (EEG) measures of sensitized withdrawal seizure activity. Adult male C3H/He mice received chronic intermittent ethanol vapor exposure in inhalation chambers (16 h/day) and during each withdrawal cycle, separate groups of mice were evaluated for handling-induced convulsions (HIC) or abnormal EEG (high-voltage "brief spindle episodes" (BSE)) activity. Lorazepam (0.5-1.0 mg/kg) or MK-801 (0.1-0.3 mg/kg) treatment at 1 h into each of three withdrawal cycles reduced behavioral (HIC) and electrographic (BSE) signs of seizure activity in a dose-related fashion compared to vehicle-treated mice. During a subsequent untreated withdrawal, mice previously treated with lorazepam or MK-801 for earlier withdrawals exhibited reduced HIC activity during the acute phase but exacerbated HIC activity during the protracted phase of this final (fourth) withdrawal cycle. Both lorazepam and MK-801 treatment conditions resulted in enhanced BSE activity during the entire fourth (untreated) withdrawal episode. Collectively, these results suggest that while treatment of repeated ethanol withdrawals with a benzodiazepine (lorazepam) or an NMDA receptor antagonist (MK-801) may have some initial benefits in ameliorating the development of sensitized withdrawal excitability, such treatment may also render subjects more vulnerable to seizure activity at later time points.

Update on the neurobiology of alcohol withdrawal seizures

Abrupt cessation of alcohol intake after prolonged heavy drinking may trigger alcohol withdrawal seizures. Generalized tonic-clonic seizures are the most characteristic and severe type of seizure that occur in this setting. Generalized seizures also occur in rodent models of alcohol withdrawal. In these models, the withdrawal seizures are triggered by neuronal networks in the brainstem, including the inferior colliculus; similar brainstem mechanisms may contribute to alcohol withdrawal seizures in humans. Alcohol causes intoxication through effects on diverse ion channels and neurotransmitter receptors, including GABA(A) receptors--particularly those containing delta subunits that are localized extrasynaptically and mediate tonic inhibition--and N-methyl-D-aspartate (NMDA) receptors. Alcohol dependence results from compensatory changes during prolonged alcohol exposure, including internalization of GABA(A) receptors, which allows adaptation to these effects. Withdrawal seizures are believed to reflect unmasking of these changes and may also involve specific withdrawal-induced cellular events, such as rapid increases in alpha4 subunit-containing GABA(A) receptors that confer reduced inhibitory function. Optimizing approaches to the prevention of alcohol withdrawal seizures requires an understanding of the distinct neurobiologic mechanisms that underlie these seizures.

Temporally specific burst in cell proliferation increases hippocampal neurogenesis in protracted abstinence from alcohol

Adult neurogenesis is a newly considered form of plasticity that could contribute to brain dysfunction in psychiatric disease. Chronic alcoholism, a disease affecting over 8% of the adult population, produces cognitive impairments and decreased brain volumes, both of which are partially reversed during abstinence. Clinical data and animal models implicate the hippocampus, a region important in learning and memory. In a model of alcohol dependence (chronic binge exposure for 4 d), we show that adult neurogenesis is inhibited during dependence with a pronounced increase in new hippocampal neuron formation after weeks of abstinence. This increase is attributable to a temporally and regionally specific fourfold increase in cell proliferation at day 7 of abstinence, with a majority of those cells surviving and differentiating at percentages similar to controls, effects that doubled the formation of new neurons. Although increases in cell proliferation correlated with alcohol withdrawal severity, proliferation remained increased when diazepam (10 mg/kg) was used to reduce withdrawal severity. Indeed, those animals with little withdrawal activity still show a twofold burst in cell proliferation at day 7 of abstinence. Thus, alcohol dependence and recovery from dependence continues to alter hippocampal plasticity during abstinence. Because neurogenesis may contribute to hippocampal function and/or learning, memory, and mood, compensatory neurogenesis and the return of normal neurogenesis may also have an impact on hippocampal structure and function. For the first time, these data provide a neurobiological mechanism that may underlie the return of human cognitive function and brain volume associated with recovery from addiction.

Enhanced alcohol self-administration after intermittent versus continuous alcohol vapor exposure

BACKGROUND

Ethanol self-administering rats exhibit enhanced responding during withdrawal from continuous exposure to ethanol vapor. This study compared self-administration of ethanol during withdrawal from continuous versus intermittent ethanol vapor.

METHODS

Experiment 1 examined self-administration of ethanol in rats trained to self-administer ethanol after continuous, intermittent (14 hr on and 10 hr off), or no (i.e., controls) ethanol vapor exposure. Exposure time was equalized such that the intermittent group received 4 weeks of exposure and the continuous group received 2 weeks of exposure. Four self-administration tests were conducted 2 hr after removal from vapor, and each test was separated by 3 to 4 days of ethanol vapor. Experiment 2 examined self-administration of ethanol after 2 weeks of intermittent vapor either 2 or 8 hr after removal from vapor. Experiment 3 addressed the specificity of the increased responding for ethanol by examining saccharin self-administration after 2 weeks of intermittent vapor.

RESULTS

Four weeks of intermittent exposure produced an increase in ethanol self-administration during the first withdrawal relative to controls and relative to animals receiving 2 weeks of continuous exposure. The continuous group was indistinguishable from controls on the first test and gradually increased their responding across tests. Two weeks of intermittent exposure also increased ethanol self-administration, and there was no difference in this effect 2 or 8 hr after removal from vapor. There was no difference in saccharin self-administration in control rats and those given 2 weeks of intermittent exposure.

CONCLUSIONS

The finding that intermittent exposure produces more rapid increases in self-administration of ethanol relative to continuous exposure suggests that intermittent exposure may be associated with a more rapid escalation of the allostatic processes responsible for excessive ethanol self-administration. The mechanisms that drive the increases in drinking during withdrawal are similar after 2 and 8 hr of withdrawal and seem to be specific to ethanol.

Integrative Neurobiology of the Alcohol Withdrawal Syndrome???From Anxiety to Seizures

This article represents the proceedings of a symposium presented at the 2003 Research Society on Alcoholism meeting in Ft. Lauderdale, Florida, organized and chaired by Carl L. Faingold. The presentations were (1) Overview, by Carl L. Faingold; (2) Stress, Multiple Alcohol Withdrawals, and Anxiety, by Darin Knapp; (3) Relationship Between Genetic Differences in Alcohol Drinking and Alcohol Withdrawal, by Julia Chester; (4) Neuronal Mechanisms in the Network for Alcohol Withdrawal Seizures: Modulation by Excitatory Amino Acid Receptors, by Carl L. Faingold; and (5) Treatment of Acute Alcohol Withdrawal and Long-Lasting Alterations in Hippocampal Neuronal Networks, by Larry P. Gonzalez. The presentations emphasized the importance of using intact behaving animals to advance the understanding of the human alcohol withdrawal syndrome. This involves applying and amplifying the neurophysiological and neurotransmitter findings observed in vitro to the network-based neurobiological mechanisms that are involved in several important aspects of the specific behaviors observed clinically. The symposium provided evidence that the organizational aspects of neuronal networks in the intact nervous system add another nexus for the action of alcohol and drugs to treat alcohol withdrawal that may not be readily studied in isolated neural elements used in in vitro approaches.

Alcohol and withdrawal: from animal research to clinical issues

The withdrawal syndrome in alcohol-dependent patients appears to be a major stressful event whose intensity increases with repetition of detoxifications according to a kindling process. Disturbances in the balance between excitatory and inhibitory neural processes are reflected in a perturbed physical state while disturbances in the balance between positive and negative reinforcements are reflected in a perturbed mood state. Our purpose is to link the different behavioral outcomes occurring during withdrawal with specific biological brain mechanisms from the animal to the human being. Better understanding of the various biological mechanisms underlying withdrawal from alcohol will be the key to design and to apply appropriate pharmaceutical management, together with appropriate therapy aimed at inducing protracted abstinence.

ERK regulation in chronic ethanol exposure and withdrawal

The extracellular signal regulated protein kinases (ERKs), also known as mitogen-activated protein kinases (MAPK) of 42 and 44 kd, play a crucial role in the induction of various forms of neural plasticity. Ethanol induces long-lasting functional changes that are more severe following repeated exposure and may involve intracellular signal transduction mechanisms. Therefore, we investigated the regulation of the ERK signal transduction pathway in models of continuous and intermittent ethanol exposure and withdrawal. Moderate blood alcohol levels (BALs) reduced ERK activation in most of the brain regions studied. Conversely, during withdrawal, activation of ERK was increased in most areas with some regional variations in the levels and kinetics of induction. The most dramatic effects were observed in the amygdala, the cerebellum, the striatum and the hippocampus. In the amygdala and the cerebellum, the activation of ERK observed during withdrawal was significantly higher after intermittent ethanol exposure than after continuous exposure, suggesting the establishment of a form of sensitization to the effects of withdrawal on ERK regulation. Thus the dysregulation of the ERK pathway could contribute to escalation of withdrawal symptoms induced by repeated withdrawal and possibly to the neuroadaptative changes believed to underlie progression towards addiction.