Modification of pituitary-adrenal feedback sensitivity in young rats by neonatal treatment with cortisol.
Neonatal exposure of rats to cortisol acetate was found to alter pituitary-adrenal feedback regulation at 20-25 days of age. Plasma levels of adrenocorticotrophin (ACTH) after ether stress were reduced in cortisol-treated rats pre-treated with 100 microgram corticosterone/100 g body weight, while rats given vehicle neonatally did not show suppression of the ACTH response below levels in animals given saline only or not injected as pre-treatments. Neonatal cortisol increased sensitivity to dexamethasone in inhibition of the stress response; cortisol-treated animals had a reduced plasma corticosterone response to stress 3 h after pre-treatment with 1.25, 2.5, 25, or 250 microgram dexamethasone/100 g body weight, while the stress response in animals given vehicle neonatally was not inhibited by the lowest dosage of dexamethasone. Neonatal cortisol treatment did not affect corticosteroid-binding globulin (CBG) binding capacity in plasma of 25-day-old animals. Thus, neonatal treatment with cortisol appears to increase feedback sensitivity to circulating corticosteroids at 20-25 days of age.
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D000831:Animals, Newborn; D003345:Corticosterone / Q000097:blood; D003907:Dexamethasone / Q000494:pharmacology; D005246:Feedback; D006854:Hydrocortisone / Q000494:pharmacology*; D010913:Pituitary-Adrenal System / Q000378:metabolism*; D051381:Rats; D014156:Transcortin / Q000378:metabolism
D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D014156:Transcortin; D003345:Corticosterone; D006854:Hydrocortisone