Effects of stress and betamethasone on the production of corticosterone by the rat adrenal gland in vitro.

1. Production of corticosterone in vitro was studied using adrenal glands from rats which had been subjected to stress or treated with betamethasone.2. An increase in corticosterone production occurred in the first but not the second hour of incubation in adrenals removed immediately after stress. When the interval between stress and adrenalectomy was longer, the increased corticosterone production persisted.3. Betamethasone had no effect on corticosteroidogenesis in vitro when added directly to the incubation medium or when administered to rats shortly before removal of their adrenal glands.4. Corticosteroidogenesis in vitro was considerably reduced in the adrenals of rats given prolonged treatment with betamethasone.5. The significance of the results and the reliability of in vitro corticosteroid production as an index of hypothalamo-pituitary-adrenal activity is discussed.