AJP - Regulatory, Integrative and Comparative Physiology, Vol 239, Issue 3 337-R343, Copyright © 1980 by American Physiological Society
Effect of lateral hypothalamic lesions on regulation of body weight and adiposity in rats
K. M. Milam, J. S. Stern, L. H. Storlien and R. E. Keesey
Obese and lean Zucker rats received bilateral electrolytic lesions of the
lateral hypothalamus (LH) at 10 wk of age; control obese and lean rats were
sham lesioned. After lesioning the body weights of both obese and lean
animals were first reduced and then maintained until being killed (32 wk)
at a stable percentage of the nonlesioned control levels (74.5 and 78.3%,
respectively). Carcass analysis revealed that the adipose tissue mass was
significantly lowered by LH lesions in both the obese and lean animals.
Percent carcass fat of lesioned lean rats was less than that of controls
(15.0 vs. 23.5%) due to the presence of slightly, but not significantly,
smaller and fewer adipocytes. Though absolute levels of fat were likewise
lowered in obese rats, their percent carcass fat remained at control levels
(52.0 vs. 53.0%) due to equivalent decreases in other body compartments. In
the lesioned rats the reduced levels of adipose tissue were associated with
a significant reduction in adipocyte number; adipocyte size was unchanged.
It is concluded that the lateral hypothalamus of obese Zucker rats
participates in the regulation of body weight in the same manner as in lean
rats. The differences noted in percent carcass fat between LH lesioned lean
and obese Zucker rats are apparently related to the obese animal's known
propensity to sequester energy in the form of lipid.
