Characterizing estrogen regulation of neuronal excitability in the extended amygdala - Project Summary/ Abstract Alcohol use disorder poses a monumental public health challenge in society, but the mechanisms behind this disease are not fully understood. Estrogen (17β-estradiol, E2) is a steroid hormone that coordinates sex differences in brain architecture, neuronal circuitry, and behavior and has been implicated in addiction and other psychological disorders. E2 can regulate behavioral function by to binding estrogen receptors (ERs) in the brain and initiating genomic and/or rapid signaling mechanisms. Our lab has shown that female rodents in a high ovarian E2-state (proestrus) consume more alcohol compared to males and when they are in a low E2-state (metestrus). In addition, we have found that mice in proestrus exhibit decreased avoidance than those metestrus and males. In vivo infusion of ERα-specific E2 into the bed nucleus of the stria terminalis (BNST) of metestrus mice increases drinking levels to proestrus levels but does not change avoidance behaviors. These data suggest that E2 signaling in the BNST modulates neuronal activity in different ways during binge drinking compared to during anxiety. We have also demonstrated that corticotropin-releasing factor (CRF) neurons from the BNST (BNSTCRF) are critical for modulating anxiety behaviors and alcohol consumption, and robustly express ERs. Initial ex vivo electrophysiology experiments indicate that BNSTCRF neurons are a heterogeneous population, and persistently firing neurons have a more excitable phenotype present in proestrus animals compared to those in metestrus. We have also found evidence that their passive and kinetic properties exhibit E2-state dependent changes that may be contributing to higher excitability. We hypothesize that persistent firing BNSTCRF neuron excitability is being mediated through different E2 signaling mechanisms, and this is contributing to our observed behavioral effects. In Aim 1, I will use electrophysiology to parse out whether these neurons’ excitability properties are stimulated in response to rapid E2 and if there is ER-specificity in these effects. I will also test whether EtOH alters the excitability of these neurons, and if so, whether E2 status or sex plays a role in the sensitivity. In Aim 2, I will use snRNAseq to probe whether genes are differentially regulated depending on E2- state or sex, which would indicate a genomic mechanism at play. If the genes for voltage-gated ion channel genes that control excitability are differentially regulated, the effects on their corresponding currents will be queried through electrophysiology. In doing these experiments, diverse mechanisms of E2 signaling present in BNSTCRF neurons will be revealed.
