REGULATION OF ANXIETY BY GABA(A) RECEPTORS IN THE RAT AMYGDALA

Blockade of GABAergic inhibition in the region of the anterior basolat eral amygdala (BLA) of rats elicits physiologic changes associated wit h a defense reaction. The present study was undertaken to determine wh ether GABA receptors in the BLA might be involved in regulating experi mental anxiety using the social interaction (SI) and conflict test. Gu ide cannulae were stereotaxically implanted bilaterally in the BLA of rats for intracerebral microinjections. In the BLA, injection of the G ABA, receptor antagonists bicuculline methiodide (BMI) and picrotoxin (PIG) produced anxiogenic-like effects in the SI paradigm, as did BMI injection using the conflict paradigm. Injection of the GABA, agonist muscimol (MUS) into the central nucleus of the amygdala (Ce) produced anxiolytic-like effects in the SI test. Microinjection of MUS, baclofe n (GABA, agonist), 20H-saclofen (GABA, antagonist) or strychnine (glyc ine antagonist) into the BLA or BMI into the Ce elicited no change in experimental anxiety as measured by the SI test. These results suggest that endogenous GABA acts tonically at GABA, receptors in the BLA to inhibit anxiety responses.