Project Summary Sex differences in fast-spiking interneurons promote AUD-related PFC dysfunction: remediation by modulating mGlu1 and mGlu5. Alcohol use disorder (AUD) affects both men and women, however women are disproportionately harmed by several disease outcomes. A key brain region dysregulated by alcohol is the prefrontal cortex (PFC), which exhibits significant sexual dimorphism and is essential for managing appropriate drinking. PFC output is mediated by pyramidal cells, glutamatergic neurons that course onto the limbic system, each one typically projecting to a single subcortical structure. Pyramidal cell activity is dynamically regulated by fast-spiking parvalbumin-expressing interneurons (PV-INs). Increasing evidence suggests that excitatory transmission onto PV-INs regulates sex differences in drinking behaviors, therefore pharmacological modulation of PV-INs provides a promising means to ameliorate AUD-related symptomology. PFC PV-INs express several druggable receptors, notably including metabotropic glutamate (mGlu) receptor subtypes 1 and 5. Our preliminary data indicate that mGlu1 and mGlu5 modulate PV-INs in a sex-specific manner, and further, that intermittent voluntary drinking induces sex-specific alterations to several mGlu1- and mGlu5-related PV-IN physiology. Our central hypothesis is that sex differences in PFC PV-IN function underlie AUD- related pathophysiology, and that modulating mGlu1 and mGlu5 can ameliorate maladaptive changes induced by binge-like alcohol consumption. This hypothesis will be tested through two specific aims. Aim 1 (K99): To test the hypothesis that mGlu1 and mGlu5 modulation can ameliorate sex-specific alcohol- induced pathophysiology through actions on PFC PV-INs. PV-IN synaptic physiology and plasticity will be interrogated in an ex vivo slice preparation. In addition, PV-IN function will be examined in vivo with fiber photometry while female and male mice seek alcohol and perform other PFC-dependent behaviors. Aim 2 (R00): To test the hypothesis that sex-specific alcohol-induced dysregulation of distinct PFC outputs can be remediated through mGlu1 and mGlu5 modulation of inhibitory transmission. A viral approach will be used to label PFC pyramidal cells based on projection target in female and male transgenic optogenetic mice (PV- ChR2). We will assess how PV-INs control specific PFC output pathways following intermittent alcohol exposure, and how these phenomena are regulated by sex and mGlu1/mGlu5. Training: I will gain extensive experience with drinking models and in vivo cell type-specific Ca2+ imaging. Training in alcohol models and fiber photometry will allow me to apply my interest in mGlu synaptic plasticity and PFC circuitry to unanswered questions about how sex differences are manifested in AUD. I will also receive essential career development training to facilitate a transition to an independent junior faculty position within the alcohol research community.