AJP - Regulatory, Integrative and Comparative Physiology, Vol 241, Issue 5 330-R335, Copyright © 1981 by American Physiological Society
Metabolic concomitants of glucagon-induced suppression of feeding in the rat
N. Geary, W. Langhans and E. Scharrer
The suppression of food intake elicited in rats by injection of pancreatic
glucagon and the accompanying changes in energy metabolite flux were
investigated. Glucagon injections, 120-360 micrograms ip, were made as rats
began the first meal of the dark phase after food deprivation during the
light phase. Glucagon-injected rats terminated their meals sooner and ate
smaller meals than vehicle-injected rats. For metabolic assays, rats were
identically treated and killed just at meal onset or 15 min later. Portal
vein blood glucose increased similarly in all rats allowed to feed, whereas
plasma nonesterified fatty acid and D-(-)-3-hydroxybutyrate levels
decreased during feeding. In contrast, hepatic vein and aorta blood glucose
levels increased more after glucagon than after vehicle injections. Liver
glycogen content decreased after glucagon injections. The highest glucagon
dose only had slight lipolytic and ketogenic effects. It was concluded the
glycogenolytic and hyperglycemic action of glucagon may generate a satiety
signal sufficient to cause premature termination of meals. Changes in
ketone and lipid fluxes do not appear necessary for this behavioral effect.
