Abstract
Specific inhibition of glutamic acid decarboxylase (GAD, EC 4.1.1.15; the main enzyme involved in the synthesis of γ-aminobutyric acid) by mercaptopropionic acid interferes with the effect of dexamethasone on both the resting and stress-induced secretion of ACTH. It is postulated that dexamethasone may, at least in part, inhibit the secretion of ACTH via the induction of GAD, thereby raising the level of γ-aminobutyric acid in the central nervous system.