Influence of corticosterone infusion on plasma levels of catecholamines, thyroid hormones, and certain metabolites in laying hens.

Corticosterone was infused continuously through subcutaneously implanted mini-osmotic pumps into laying White Leghorn hens at the rate of 30 micrograms/hr for 14 or 28 days. In both groups receiving corticosterone, plasma levels of glucose and triglycerides were not altered significantly. Circulating levels of cholesterol and free fatty acids increased significantly following both 14 and 28-day infusions of the hormone. Corticosterone treatment for 28 days produced significant increases in plasma levels of thyroxine (T4) and triiodothyronine (T3). However, following the 14-day corticosterone infusion, only T3 showed significant increase. The T3:T4 ratio in both groups of corticosterone-infused hens was significantly higher than in control hens. The concentration of plasma epinephrine showed no significant response to corticosterone treatment, while norepinephrine increased significantly following both periods of treatment.