Brain histone methylation mechanisms in adulthood after adolescent alcohol exposure

University Of Illinois At Chicago, Chicago IL

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Abstract

? DESCRIPTION (provided by applicant): Alcohol use disorder (AUD) and alcohol addiction are significant public health concerns with serious effects on society and individuals. Adolescent binge drinking is common and contributes to anxiety and other psychiatric disorders in adulthood. Recent research shows that epigenetic mechanisms are responsible for the development of brain structures and are modified by alcohol exposure. The amygdala, known as a regulator of emotion, fear, and anxiety, undergoes epigenetic changes in response to adolescent alcohol use that leads to increased anxiety-related behaviors and abnormal synaptic plasticity in adulthood. However, the crosstalk between epigenetic enzymes and chromatin is enormously complex, and many of the mechanisms of adolescent alcohol exposure have yet to be elucidated. The discovery of novel epigenetic effectors of alcohol in the adolescent brain may lead to new treatment targets for adolescent alcohol exposure-induced adult psychopathology. Our previous studies suggest that adolescent intermittent ethanol (AIE) exposure in rats increases anxiety-like behaviors and decreases synaptic plasticity associated events in the amygdala in adulthood. Lysine demethylase 1 (LSD1; also known as Kdm1a) and its neuron- specific splice variant Lsd1+8a are histone demethylases that may be responsible for altering chromatin around important synaptic plasticity-associated genes in the adult amygdala following AIE. Additionally, microRNA-137 (miR-137) may be responsible for regulating Lsd1+8a and thereby affecting downstream histone methylation mechanisms and spinogenesis. This proposal is based on the hypotheses that AIE produces a persistent increase in miR-137 expression in the amygdala, decreasing LSD1+8a expression and increasing H3K9me2 at crucial synaptic plasticity-related genes leading to anxiety-like behaviors in adulthood. We will perform a series of experiments to test these hypotheses. We will dose AIE adult rats with acute ethanol to determine if this challenge will rescue the alterations in anxiety-like behaviors, gene expression, histone methylation, and dendritic spines in the amygdala of AIE adult rats. We will inhibit Lsd1+8a in the central nucleus of the amygdala (CeA) using shRNA in control rats to determine if Lsd1+8a inhibition alone can recapitulate the behavioral and epigenetic deficits of AIE in adulthood. Finally, we will determine if miR-137 inhibition in the CeA can rescue the alterations in anxiety-like behaviors, gene expression, histone methylation, and dendritic spines in AIE adult rats. Taken together, this proposal will increase the understanding of chromatin remodeling by adolescent alcohol and may identify novel pharmacological targets for the treatment of adult psychopathology-related adolescent drinking.