RESUMEN
The sex steroid hormone estrogen is a key modulator of numerous physiological processes and adaptive behaviors, but it may also be co-opted to drive maladaptive behaviors. While many behavioral roles for estrogen signaling have been shown to occur through canonical genomic signaling mechanisms via nuclear receptors, estrogen can also act in a neurotransmitter-like fashion at membrane-associated estrogen receptors to rapidly regulate neuronal function. Early alcohol drinking confers greater risk for alcohol use disorder in women than men, and binge alcohol drinking is correlated with high circulating estrogen but a causal role for estrogen in alcohol drinking has not been established. Here, we demonstrate that gonadally intact female mice consume more alcohol and display an anxiolytic phenotype when they have elevated levels of ovarian-derived estrogen across the estrous cycle. We found that rapid, nongenomic estrogen signaling at membrane-associated estrogen receptor alpha in the bed nucleus of the stria terminalis (BNST) is necessary and sufficient for the pro-alcohol drinking effects of ovarian estrogen signaling, regardless of the transcriptional program of a high ovarian estrogen state. We further show that a population of corticotropin-releasing factor (CRF) BNST neurons (BNSTCRF) is a critical mediator of these effects, as high estrogen rapidly enhances synaptic excitation of BNSTCRF neurons and promotes their role in driving binge alcohol drinking. These findings show a causal role for endogenous, ovarian-derived estrogen in hormonal modulation of risky alcohol consumption and provide the first demonstration of a purely rapid, nongenomic signaling mechanism of ovarian estrogen in the brain controlling behavior in gonadally intact females.