EFFECTS OF NEONATAL HYDROCORTISONE TREATMENT ON PITUITARY AND ADRENOCORTICAL-RESPONSE TO STRESS IN YOUNG-RATS

Administration of corticosteroids to rat pups within the first several days of life results in retardation of several behavioral, neurophysiological, and biochemical developmental patterns. At 25 days of age, animals treated neonatally with 1.0, 0.5, or 0.1 mg hydrocortisone acetate showed dose-dependent decreases in plasma ACTH following 2.5 min continuous exposure to ether. On day 20, plasma corticosterone values did not differ between these groups 15 min after ether stress, but lower values were seen 60 min after ether in animals treated at birth with 0.5 mg hydrocortisone. At 45-48 days of age, hydrocortisone-treated animals exposed to one of 2 different stressors showed decreased plasma corticosterone response to stress; females had lower corticosterone levels following both stressors, while males showed suppressed corticosterone levels following exposure to the mild (novelty) but not to the intense (ether) stress. These data demonstrate that neonatal exposure to hydrocortisone results in decreased CNS-pituitary responsivity to stress at 20-25 days of age, and that the adrenocortical response to stress is impaired at 45-48 days of age. © 1979 S. Karger AG, Basel.