GABA-A receptor signaling in the anterior cingulate cortex modulates aggression and anxiety-related behaviors in socially isolated mice

Dysfunctional modulation of brain circuits that regulate the emotional response to potentially threatening stimuli is associated to an inappropriate representation of the emotional salience. Reduced top-down control by cortical areas is assumed to underlie several behavioral abnormalities including aggression and anxiety related behaviors. Previous studies have identified disrupted GABA signaling in the anterior cingulate cortex (ACC) as a possible mechanism underlying the top-down regulation of aggression and anxiety. In this study, we investigate a role for GABA-A receptor in the ACC in the regulation of aggression and anxiety related behaviors in socially isolated mice. We evaluated the effects of site directed injections of the GABA-A receptor agonist, muscimol or the GABA-A receptor antagonist, bicuculline into the ACC on these behaviors. Results showed that hyper-aggressive behavior, the anxiety and avoidance behavior in socially isolated mice were increased by muscimol microinfusion into ACC, while the sociability was not affected. In contrast, hyper-aggressive behavior in socially isolated mice was inhibited following bicuculline microinfusion without affecting anxiety. Furthermore, microinfusion of bicuculline into ACC decreased avoidance intensity and significantly reinforced social behavior, suggesting that GABA-A receptor inhibition in ACC specifically regulated aggression and sociability. Together, our results confirm a role for GABA-A receptor signaling in the ACC in the regulation of aggressive, social and anxiety related behaviors in socially isolated mice.