Addiction is viewed as maladaptive glutamate-mediated neuroplasticity that is regulated, in part, by calcium-permeable AMPA receptor (CP-AMPAR) activity. However, the contribution of CP-AMPARs to alcohol-seeking behavior remains to be elucidated. We evaluated CP-AMPAR activity in the basolateral amygdala (BLA) as a potential target of alcohol that also regulates alcohol self-administration in C57BL/6J mice. Operant self-administration of sweetened alcohol increased spontaneous EPSC frequency in BLA neurons that project to the nucleus accumbens as compared to behavior-matched sucrose controls indicating an alcohol-specific upregulation of synaptic activity. Bath application of the CP-AMPAR antagonist NASPM decreased evoked EPSC amplitude only in alcohol self-administering mice indicating alcohol-induced synaptic insertion of CP-AMPARs in BLA projection neurons. Moreover, NASPM infusion in the BLA dose-dependently decreased the rate of operant alcohol self-administration providing direct evidence for CP-AMPAR regulation of alcohol reinforcement. Since most CP-AMPARs are GluA1-containing, we asked if alcohol alters the activation state of GluA1-containing AMPARs. Immunocytochemistry results showed elevated GluA1-S831 phosphorylation in the BLA of alcohol as compared to sucrose mice. To investigate mechanistic regulation of alcohol self-administration by GluA1-containing AMPARs, we evaluated the necessity of GluA1 trafficking using a TET-ON AAV encoding a dominant-negative GluA1 c-terminus (GluA1ct) that blocks activity-dependent synaptic delivery of native GluA1-containing AMPARs. GluA1ct expression in the BLA reduced alcohol self-administration with no effect on sucrose controls. These results show that CP-AMPAR activity and GluA1 trafficking in the BLA mechanistically regulate the reinforcing effects of sweetened alcohol. Pharmacotherapeutic targeting these mechanisms of maladaptive neuroplasticity may aid medical management of alcohol use disorder.

150-250 words)The United States is experiencing an opioid epidemic of significant proportions, imposing enormous fiscal and societal costs. While prescription opioid analgesics are essential for treating pain, the cessation of these drugs can induce a withdrawal syndrome, and thus opioid use often persists to alleviate or avoid these symptoms.Therefore, it is essential to understand the neurobiology underlying this critical window of withdrawal from opioid analgesics to prevent continued usage. To model this, we administered a low dose of morphine, and precipitated withdrawal with naloxone to investigate the behavioral and cellular responses in C57BL/6J male and female mice. Following 3 days of administration, both male and female mice sensitized to the repeated bouts of withdrawal, as evidenced by their composite global withdrawal score. Female mice exhibited increased withdrawal symptoms on some individual measures, but did not show characteristic weight loss observed in male mice. Because of its role in mediating withdrawal-associated behaviors, we examined neuronal excitability and inhibitory synaptic transmission in the bed nucleus of the stria terminalis (BNST) 24 hours following the final precipitated withdrawal. In male mice, morphine withdrawal increased spontaneous GABAergic signaling compared to controls. In contrast, morphine withdrawal decreased spontaneous GABAergic signaling, and increased BNST projection neuron excitability in female mice. Intriguingly, these opposing GABAergic effects were dependent on within slice excitability. Our findings suggest that male and female mice manifest divergent cellular responses in the BNST following morphine withdrawal, and alterations in BNST inhibitory signaling may be a significant factor contributing to the expression of behaviors following opioid withdrawal.