Involvement of GABAA receptors in the regulation of social preference and emotional behaviors by oxytocin in the central amygdala of female mandarin voles

The central nucleus of the amygdala (CeA) is the main output of the amygdala and plays an important role in behavioral and neuroendocrine responses to stress. Receptors for the neuropeptide oxytocin (OT) and GABA_A are found in high concentration in the CeA. The mechanisms underlying regulation of CeA OT in emotional and social behavior remain unclear. In this study we evaluated the effects of intra-CeA OT administration of different doses (0.1, 1 and 10 ng/side), OT receptor antagonist (OTR-A) (1, 10 and 100 ng/side) and OT plus OTR-A on social and emotional behavior using a social preference paradigm, open field test and elevated plus maze test in female monogamous mandarin voles (Microtus mandarinus). We then examined whether different doses of the GABA_A receptor antagonist bicuculline (5, 10 and 100 ng/side) affected the behavioral changes induced by intra-CeA microinjection of OT (1 ng/side). We found that administration of OT to the CeA increased social preference, central area investigation times in the open field test, and visits, transitions and time spent in the open arms in the elevated plus maze test; all responses were dose-dependent. Administration of OT plus OTR-A to the CeA produced no effects. Administration of bicuculline in combination with OT to the CeA decreased social preference, central area investigation times in the open field test, and visits, transitions and time spent in the open arms of the elevated plus maze test. These data suggest that OT in the CeA facilitates sociality and reduces levels of anxiety by interacting with local GABA_A receptors.