AJP - Regulatory, Integrative and Comparative Physiology, Vol 250, Issue 2 313-R317, Copyright © 1986 by American Physiological Society
Ontogeny of epinephrine-induced anorexia in rats
A. M. Rodriguez-Zendejas, G. Chambert, M. C. Lora-Vilchis, A. N. Epstein and M. Russek
Intraperitoneal or intraportal epinephrine elicits a strong inhibition of
food intake in adult rats and dogs but has no effect when injected
intramuscularly or intrajugularly, in spite of production of larger
hyperglycemia and cardiovascular changes. These facts suggest that the
effect of epinephrine on feeding is elicited via the liver. Ontogeny of
this adrenergic control of food intake was studied in newborn and weanling
rats. Anorexic effect of intraperitoneal epinephrine was clearly observed
in dam-deprived 3-day-old neonatal rats (youngest in which it was tested),
both when they were offered enriched milk through an anterior oral cannula
while they were isolated from their dam and when they were allowed to
suckle from her. However, anorectic effect was less in neonatal rats (day
3-13) than in adults. Weanling rats, 21-26 days old, were as sensitive to
intraperitoneal epinephrine as adults. In 3- to 4-day-old rats it also
reduced water intake, but this effect disappeared by day 12 and was not
observed in mildly water-deprived adults. Peripheral adrenergic control of
intake appears very early in ontogeny of rats. First, it affects food and
water intake equally, but by day 12 it affects only food intake. Increase
in sensitivity to epinephrine after weaning is probably due to an increase
in number of hepatocytic adrenergic receptors and/or increase in enzymes
necessary for hepatic effects of epinephrine.
