Effect of somatotropin and feed restriction on body composition and
adipose tissue metabolism in obese zucker rats.
Azain, M. J., D. B. Hausman, T. R. Kasser, and R. J. Martin.
Animal and Dairy Science Department, Department of Foods and
Nutrition, University of Georgia, Athens, 30602 and Animal Sciences
Division, Monsanto Company, St. Louis, MO 63198
APStracts 2:0043E, 1995.
The objective of the present study was to determine if exogenous
somatotropin (STH) administration in conjunction with feed
restriction could alter the composition of gain in the obese rat.
Five-week old female lean and obese Zucker rats were assigned to the
following treatments for 6 weeks: Ad libitum fed (AL), restricted
(approx. 75% of ad libitum lean), and restricted with STH (2 mg
STH/d). Growth rate was decreased in restricted groups and was
normalized to that of the AL lean group in restricted rats treated
with STH. In lean rats, restriction decreased protein accretion.
Restriction plus STH treatment decreased lipid accretion, but
increased protein accretion and body weight gain to that of the AL
lean group. As expected, feed restriction reduced body size in obese
rats, but carcass lipid was maintained at 44%; a level similar to
that of the AL obese rats. Lipid accretion rate was decreased with
restriction in obese rats and was further reduced, to a level similar
to that of the lean group, in the obese rats that were restricted and
treated with STH. Protein accretion was decreased in the restricted
obese group but was normalized in those treated with STH to a level
similar to that in the AL lean group. Basal rates of lipolysis in
isolated adipocytes were not affected by STH. However, STH treatment
normalized the responsiveness of cells from the obese rats to
stimulation of lipolysis by isoproterenol. The results demonstrate
that a combination of caloric restriction and STH was effective at
normalizing body weight and composition of gain in the obese Zucker
rat.
Received 1 August 1994; accepted in final form 24 February 1995.
APS Manuscript Number E299-4.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 March 1995.