Effects of Cold and Intracerebroventricular Injection of Glucagon on Plasma Catecholamines in Muscovy Ducklings

The aim of the present study was to understand the effect of cold and i. c. v glucagon administration on plasma catecholamine. Cold exposure (+4C) induces a 42 % increase of arteriel plasma norepinephrine (NE) in thermoneutral (TN) ducklings. Thus, cold has a stimulatory effect on the sympathetic nervous system (SNS).15min after i. c. v glucagon injection plasma epinephrine (E) increase in TN ducklings, (74 %) whereas NE concentration decrease (23 %) only in TN. Plasma NE remained in glucagon treated (GT). Injection of glucagon causes a decrease in heart rate (HR) in TN duckling whereas it has no effect on GT ducklings. In conclusion, large increase in E levels in TN ducklings may be due to a massive release of adrenal catecholamine in response to cold and i. c. v glucagon administration. Treatment with glucagon twice daily rendered ducks possibly insensitive to the effect of i. c. v glucagon injection.