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Pathological impairments in the regulation of affect (i.e., emotion) and flexible decision-making are commonly observed across numerous neuropsychiatric disorders and are thought to reflect dysfunction of cortical and subcortical circuits that arise in part from imbalances in excitation and inhibition within these structures. Disruptions in GABA transmission, in particular, that from parvalbumin-expressing interneurons (PVI), has been highlighted as a likely mechanism by which this imbalance arises, as they regulate excitation and synchronization of principle output neurons. G protein-gated inwardly rectifying potassium ion (GIRK/Kir3) channels are known to modulate excitability and output of pyramidal neurons in areas like the medial prefrontal cortex and hippocampus; however, the role GIRK plays in PVI excitability and behavior is unknown. Male and female mice lacking GIRK1 in PVI (Girk1flox/flox:PVcre) and expressing td-tomato in PVI (Girk1flox/flox:PVCre:PVtdtom) exhibited increased open arm time in the elevated plus-maze, while males showed an increase in immobile episodes during the forced swim test (FST). Loss of GIRK1 did not alter motivated behavior for an appetitive reward or impair overall performance in an operant-based attention set-shifting model of cognitive flexibility; however it did alter types of errors committed during the visual cue test. Unexpectedly, baseline sex differences were also identified in these tasks, with females exhibiting overall poorer performance compared to males and distinct types of errors, highlighting potential differences in task-related problem-solving. Interestingly, reductions in PVI GIRK signaling did not correspond to changes in membrane excitability but did increase action potential (AP) firing at higher current injections in PVI of males, but not females. This is the first investigation on the role that PVI GIRK-signaling has on membrane excitability, AP firing, and their role on affect and cognition together increasing the understanding of PVI cellular mechanisms and function.

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AbstractWomen transition to addiction faster and experience greater difficulties remaining abstinent; however, what drives this is unknown. Although poorly understood, loss of cognitive control following chronic drug use has been linked to decreased activation of frontal cortical regions. We show that self-administration of the opioid, remifentanil, causes a long-lasting decrease in ex vivo excitability but augments firing capacity of pyramidal neurons in the prelimbic cortex. This phenomenon occurs faster in females, manifests from sex-specific changes in excitatory and inhibitory synaptic regulation and aligns with impairments in cognitive flexibility. Further, chemogenetic induction of a hypoactive pyramidal neuron state in drug-naïve mice produces deficits, while compensating for this hypoactive state protects against cognitive inflexibility resulting from opioid self-administration. These data define cellular and synaptic mechanisms by which opioids impair prefrontal function and cognitive control and indicate that interventions aimed at treating opioid addiction must be tailored based on biological sex.