In vivo release of corticosterone in discrete brain areas of rats. A push-pull perfusion study

The spontaneous and depolarization-induced release of corticosterone was studied in the medial hypothalamus (MH) and the central amygdala (AC) in vivo, using a push-pull perfusion system. Significant variations in the spontaneous release of corticosterone could be observed over time (3-8 h). Corticosterone in the brain superfusates did not seem to stem from adrenocortical sites since a continuous release of the glucocorticoid could also be followed in bilateral adrenalectomized rats. Superfusion of MH and AC with depolarizing stimuli led to an enhanced release of corticosterone. Of greater general significance is the first demonstration that the release of a steroid hormone can be measured in discrete brain areas under in vivo conditions.