AJP - Regulatory, Integrative and Comparative Physiology, Vol 255, Issue 6 908-R913, Copyright © 1988 by American Physiological Society
Ontogeny of alpha- and beta-adrenergic anorexia in rats
M. C. Lora-Vilchis, G. Chambert, A. M. Rodriguez-Zendejas, L. M. Soto-Mora, M. Russek and A. N. Epstein
Department of Physiology, National School of Biological Sciences, National Polytechnic Institute, Mexico, D.F., Mexico.
The anorectic action of alpha- (phenylephrine) and beta- (isoproterenol)
adrenergic agonists was studied in mildly deprived neonatal, weanling,
prepubescent, and adult rats. Intraperitoneal phenylephrine produced a
reduction of food intake at all ages but with reduced potency and with a
maximum of 50% in neonates. Contrary to intramuscular epinephrine that has
no effect on feeding at any age, intramuscular phenylephrine was as
effective as intraperitoneal in neonates, probably because it is not as
rapidly destroyed in tissues as epinephrine. However, in weanlings and
adults intramuscular phenylephrine was much less anorectic than
intraperitoneal, suggesting that this effect is exerted via the liver.
Isoproterenol did not reduce milk intake at any age before adulthood.
Lactate had no effect on milk intake before the age of 40 days. Thus
catecholamine anorexia is a purely alpha-adrenergic effect in young rats
and appears before the metabolic effect of lactate. beta-Adrenergic
anorexia, on the other hand, can be obtained only after puberty, suggesting
that the mechanism mediating it matures after the preparatory action of the
sexual hormones.
