AJP - Regulatory, Integrative and Comparative Physiology, Vol 250, Issue 4 676-R681, Copyright © 1986 by American Physiological Society
Dose-related suppression of feeding by intraportal glucagon infusion in the rat
B. G. Weick and S. Ritter
Continuous intraportal infusion of pancreatic glucagon during a feeding
test conducted in the dark phase of the circadian photoperiod produced a
dose-related suppression of feeding in rats. At the end of the 30 min of
infusion, food intake was suppressed 10% at the infusion rate of 0.33
micrograms X kg-1 X min-1 and 45% at the highest infusion rate studied (100
micrograms X kg-1 X min-1). At infusion rates of 33 and 100 micrograms X
kg-1 X min-1, the suppression of cumulative intake persisted for 30 min
after the termination of the infusion, but no effect on 24-h intake was
observed. Glucagon's glycemic effects were measured for two glucagon doses
(1 and 10 micrograms X kg-1 X min-1) in the absence of food using a
paradigm similar to that used for the feeding tests. In contrast to the
suppression of food intake, the hyperglycemic effects of glucagon were not
dose related for the two doses tested. The hyperglycemia was similar in
magnitude 5 min after the start of the infusion at both infusion rates.
Subsequently, plasma glucose concentrations declined more rapidly at the
higher than at the lower glucagon dose. This difference in the effect of
glucagon on glucose disposal may be important for glucagon's satiating
effect.
