Role of Hippocampal Neurogenesis in Alcohol Withdrawal Seizures

Anticonvulsant Role of Adenosine is Blunted During Alcohol Withdrawal Syndrome in an Adult Zebrafish Model

Alcohol (ethanol) dependence and related disorders are life-threatening conditions and source of suffering for the user, family members and society. Alcohol withdrawal syndrome (AWS) is a little-known dynamic process associated with a high frequency of relapses. A state of hyperglutamatergic neurotransmission and imbalanced GABAergic function is related to an increased susceptibility to seizures during alcohol withdrawal. Adenosine signaling display an important role in endogenous response to decrease seizure and related damages. Here, an intermittent alcohol exposure regimen (1 h daily of 0.5% ethanol solution) for 16 days or 8 days of the same ethanol exposure regimen followed by 1 or 8 days of ethanol withdrawal was used to assess adenosine signaling in the context of seizure susceptibility using adult zebrafish. In both abstainer groups, a sub-convulsant dose of pentylenetetrazol (2.5 mM) was able to increase the frequency of animals reaching a clonic seizure-like state, while continuous-treated animals had no seizure, as did control animals. The total brain mRNA expression of A1 adenosine receptor was decreased in animals with 1 day of ethanol withdrawal. The agonism of A1 adenosine receptor induced an anticonvulsant effect in animals with 1 day of ethanol withdrawal after the injection of the specific agonist (N6-cyclopentyladenosine, 10 mg.Kg- 1; i.p.). These findings reinforce A1 adenosine receptor as a key target in acute alcohol withdrawal syndrome and zebrafish as an excellent platform to study biological mechanism of AWS.

Hippocampal ceRNA networks from chronic intermittent ethanol vapor-exposed male mice and functional analysis of top-ranked lncRNA genes for ethanol drinking phenotypes

The molecular mechanisms regulating the development and progression of alcohol use disorder (AUD) are largely unknown. While noncoding RNAs have previously been implicated as playing key roles in AUD, long-noncoding RNA (lncRNA) remains understudied in relation to AUD. In this study, we first identified ethanol-responsive lncRNAs in the mouse hippocampus that are transcriptional network hub genes. Microarray analysis of lncRNA, miRNA, circular RNA, and protein coding gene expression in the hippocampus from chronic intermittent ethanol vapor- or air- (control) exposed mice was used to identify ethanol-responsive competing endogenous RNA (ceRNA) networks. Highly interconnected lncRNAs (genes that had the strongest overall correlation to all other dysregulated genes identified) were ranked. The top four lncRNAs were novel, previously uncharacterized genes named Gm42575, 4930413E15Rik, Gm15767, and Gm33447, hereafter referred to as Pitt1, Pitt2, Pitt3, and Pitt4, respectively. We subsequently tested the hypothesis that CRISPR/Cas9 mutagenesis of the putative promoter and first exon of these lncRNAs in C57BL/6J mice would alter ethanol drinking behavior. The Drinking in the Dark (DID) assay was used to examine binge-like drinking behavior, and the Every-Other-Day Two-Bottle Choice (EOD-2BC) assay was used to examine intermittent ethanol consumption and preference. No significant differences between control and mutant mice were observed in the DID assay. Female-specific reductions in ethanol consumption were observed in the EOD-2BC assay for Pitt1, Pitt3, and Pitt4 mutant mice compared to controls. Male-specific alterations in ethanol preference were observed for Pitt1 and Pitt2. Female-specific increases in ethanol preference were observed for Pitt3 and Pitt4. Total fluid consumption was reduced in Pitt1 and Pitt2 mutants at 15% v/v ethanol and in Pitt3 and Pitt4 at 20% v/v ethanol in females only. We conclude that all lncRNAs targeted altered ethanol drinking behavior, and that lncRNAs Pitt1, Pitt3, and Pitt4 influenced ethanol consumption in a sex-specific manner. Further research is necessary to elucidate the biological mechanisms for these effects. These findings add to the literature implicating noncoding RNAs in AUD and suggest lncRNAs also play an important regulatory role in the disease.

New Insights Into the Role of Aberrant Hippocampal Neurogenesis in Epilepsy

Data accumulated over the past four decades have confirmed that adult hippocampal neurogenesis (HN) plays a key role in the wide spectrum of hippocampal pathology. Epilepsy is a disorder of the central nervous system characterized by spontaneous recurrent seizures. Although neurogenesis in persistent germinative zones is altered in the adult rodent models of epilepsy, the effects of seizure-induced neurogenesis in the epileptic brain, in terms of either a pathological or reparative role, are only beginning to be explored. In this review, we described the most recent advances in neurogenesis in epilepsy and outlooked future directions for neural stem cells (NSCs) and epilepsy-in-a-dish models. We proposed that it may help in refining the underlying molecular mechanisms of epilepsy and improving the therapies and precision medicine for patients with epilepsy.