Influence of age and splanchnic nerve on glucagon-induced changes of adrenomedullary catecholamine content and blood glucose level in the avian group

Abstract

Glucagon (0.1 mg·100 g body wt^-1) increased norepinephrine (NE) content in adult pigeon (31%) and parakeet (58%), decreased NE content in the adrenal medulla of newly-hatched pigeon (36%), parakeet (52%), and crow (44%) 0.5 h after treatment. Epinephrine (E) content decreased to 26% and 59% of control values, respectively, in newly-hatched pigeon and parakeet 0.5 h after treatment. Glucagon produced hyperglycemia irrespective of age and species. The results indicate that aging modulates glucagon-induced changes of catecholamine (CA) content. In the innervated (I) adrenal gland of pigeon, glucagon caused a 31% increase of NE content 0.5 h after injection, a 46% decrease of NE content 12 h after injection, and a 192% increase of NE 24 h after injection. In the I gland of pigeons, glucagon also caused a 61% decrease of E content 4 h after injection, and brought about a 100% increase of E 24 h after injection. Glucagon-induced changes of CA content differ significantly between the I and denervated (D) glands. The results indicate that the splanchnic nerve regulates release and/or resynthesis of CA induced by glucagon.