Effects of intracerebroventricular injections of des-His1 (Glu9) glucagon amide on the regulatory thermogenesis in muscovy ducklings.

Recent investigations have demonstrated a modulatory action of glucagon on shivering via the central nervous system in ducklings. Such an action could be mediated by glucagon receptors that have been recently detected in several brain areas involved in the central control of the involuntary motricity in this avian species. The present study using des-His1 (Glu9) glucagon amide, was performed to investigate the central mechanisms of glucagon on shivering.

Inhibition of shivering thermogenesis by centrally applied glucagon in muscovy ducklings.

Glucagon has marked thermogenic and lipolytic effects in birds but could also be involved in the central modulation of neural activity on the basis of the recently discovered glucagon receptors in several areas of the brain in ducklings. The aim of this work was to investigate the possible role of these receptors in the modulation of thermogenic processes. Glucagon was infused into the lateral ventricle of the brain in ducklings after an acute cold exposure (4 degrees C, 2 h) or at thermoneutrality (25 degrees C).

Radioautographic demonstration and localization of glucagon receptors in duck brain.

The discovery of glucagon biosynthesis and receptors within mammalian brain has led one to suspect a neurotransmitter role for glucagon. In order to address this hypothesis in birds, we investigated the existence of glucagon receptors in duck brain by radioligand binding on fresh tissue sections and radioautography. Specific high-affinity [125I]glucagon binding sites similar to those in the liver were demonstrated in the avian brain.