Effects of stimulated adrenocortical activity on the concentration of thyroxine and triiodothyronine in blood serum of piglets.
The effects of elevated adrenocortical activity, induced by cold exposure, weaning or starvation, or exogenous adrenocorticotrophin (ACTH) on the concentrations of thyroxine (T4) and triiodothyronine (T3) in blood serum were investigated in 99 sucking piglets and weaners, divided into five experiments. No changes in concentrations of circulating iodothyronines were recorded during a 3-hour exposure of 3- to 4-day-old piglets to ambient temperature of 8-12 degrees C. Two days after weaning of 4-week-old piglets the concentration of T4 increased. At the same time a decrease of the concentration of T3 was observed in their starving littermates. Two hours after the administration of ACTH, the concentration of both iodothyronines decreased, that of T4 nonsignificantly. 17 hours after the administration of the second of two doses of ACTH, i.e. at the time when the concentration of corticosteroids approached initial values, the blood concentration of iodothyronines both in sucking piglets and in weaners was elevated, that of T4 nonsignificantly. We suggest that for the changes of T4 and T3 concentrations in blood sera of stressed animals both specific stressor effects and circulating corticosteroids are responsible. The suppressive action of corticosteroids seems to be limited to the period of adrenocortical stimulation only.
D015062:11-Hydroxycorticosteroids / Q000097:blood; D000302:Adrenal Cortex / Q000187:drug effects / Q000502:physiology*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D000833:Animals, Suckling; D003080:Cold Temperature; D013217:Starvation; D013552:Swine; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*; D014886:Weaning
D015062:11-Hydroxycorticosteroids; D014284:Triiodothyronine; D000324:Adrenocorticotropic Hormone; D013974:Thyroxine