STRESS-INDUCED INCREASE IN BRAIN NEUROACTIVE STEROIDS - ANTAGONISM BYABECARNIL

Acute foot shock stress elicits a selective and time-dependent increas e of neuroactive steroid (pregnenolone, progesterone, allotetrahydrode oxycorticosterone) concentrations in rat brain cortex, accompanied by a marked increase of plasma corticosterone. The brain cortical neuroac tive steroid levels peaked between 10 and 30 min poststress and return ed to control values by 2 h. Abecarnil (0.3 mg/kg, IP), a beta-carboli ne derivative with anxiolytic properties, completely antagonized the e ffect of foot shock on brain cortical neuroactive steroids. A single a dministration of the anxiogenic beta-carboline FG 7142 (15 mg/kg, IP), in contrast, mimicked the effect of foot shock. These data support th e hypothesis for the existence of a functional relationship between br ain neuroactive steroid concentrations and GABA(A) receptor function/e motional state of the animal.