SEX-DIFFERENCES IN GABA BENZODIAZEPINE RECEPTOR CHANGES AND CORTICOSTERONE RELEASE AFTER ACUTE STRESS IN RATS

Since many hormonal indices of stress responsiveness are sexually dimo rphic in rats, we examined sex differences and the effects of gonadect omy on the stress-related changes in GABA(A)/benzodiazepine receptors in rats. Intact or ovariectomized female rats displayed a markedly gre ater corticosterone response and a more pronounced increase in benzodi azepine receptors than males (intact or orchidectomized) after acute h andling or swim stress. Swim stress increased benzodiazepine receptor density without modifying affinity in cortex, hippocampus, and hypotha lamus. Corticosterone treatment induced benzodiazepine receptor levels comparable to those seen after swim stress in all hormone groups. Han dling stress also enhanced cortical low-affinity GABA(A) receptor leve ls in males and ovariectomized females. Both GABA and benzodiazepine r eceptor levels were positively correlated with circulating corticoster one levels in female, but not male, groups. GABA/benzodiazepine coupli ng was unaffected by stress or hormonal status. These sexual dimorphis ms in hormonal responses to stress may help elucidate the causes and c onsequences of stress-induced changes in the GABA(A)/benzodiazepine re ceptor complex.