Covington, H. E. | bioRxiv Science

bioRxiv2025

Repeated Binge-Like Alcohol Drinking Heightens Aggression in Mice

RationaleIn humans, alcohol drinking is a significant driver of violent behaviors such as assaults and homicides. While acute intoxication is known to produce heightened aggression, little is known about alcohols long-term effects. Emerging evidence, however, suggests that chronic alcohol intake can promote heightened aggression, including during abstinence and may also sensitize individuals to alcohols acute aggression-heightening effects. ObjectivesThe goal of this study was to test the effects of chronic binge-like ethanol drinking on both alcohol-involved and alcohol-uninvolved aggression in male CFW mice. We aimed to model individual differences in binge drinking and assess changes in aggression during both acute and protracted abstinence. ResultsAfter 5 weeks of Drinking in the Dark (DID), CFW mice that showed higher levels of EtOH drinking ( high drinkers, 1.33 g/kg/h) became more aggressive than low drinkers (0.45 g/kg/h) and H2O controls, as measured via frequency of attack bites during resident-intruder fighting. In the first aggressive encounter following 1 week of abstinence, animals with an alcohol drinking history initiate a fight more rapidly and with greater consistency than H2O controls. We also found that a single session of binge-like alcohol drinking acutely heightened aggression regardless of drinking history. ConclusionsThese results suggest that repeated binge-like alcohol drinking causes escalations in alcohol-uninvolved aggression during acute (in high drinkers) and protracted abstinence (in all alcohol drinkers). However, chronic alcohol intake does not appear to sensitize animals to alcohol-involved aggression. These findings support the utility of genetically heterogeneous CFW mice for modeling individual variability in alcohol-related aggression.

neuroscience↗

bioRxiv2023

Histone H3 serotonylation dynamics in dorsal raphe nucleus contribute to stress-induced gene expression and behavior

BackgroundMajor depressive disorder (MDD), along with related mood disorders, is a debilitating illness that affects millions of individuals worldwide. While chronic stress increases incidence levels of mood disorders, stress-mediated disruptions in brain function that precipitate these illnesses remain elusive. Serotonin-associated antidepressants (ADs) remain the first line of therapy for many with depressive symptoms, yet low remission rates and delays between treatment and symptomatic alleviation have prompted skepticism regarding precise roles for serotonin in the precipitation of mood disorders. Our group recently demonstrated that serotonin epigenetically modifies histone proteins (H3K4me3Q5ser) to regulate transcriptional permissiveness in brain. However, this phenomenon has not yet been explored following stress and/or AD exposures. MethodsWe employed a combination of genome-wide and biochemical analyses in dorsal raphe nucleus (DRN) of male and female mice exposed to chronic social defeat stress to examine the impact of stress exposures on H3K4me3Q5ser dynamics, as well as associations between the mark and stress-induced gene expression. We additionally assessed stress-induced regulation of H3K4me3Q5ser following AD exposures, and employed viral-mediated gene therapy to reduce H3K4me3Q5ser levels in DRN and examine the impact on stress-associated gene expression and behavior. ResultsWe found that H3K4me3Q5ser plays important roles in stress-mediated transcriptional plasticity. Chronically stressed mice displayed dysregulated H3K4me3Q5ser dynamics in DRN, with both AD- and viral-mediated disruption of these dynamics proving sufficient to rescue stress-mediated gene expression and behavior. ConclusionsThese findings establish a neurotransmission-independent role for serotonin in stress-/AD-associated transcriptional and behavioral plasticity in DRN.

neuroscience↗