AJP - Regulatory, Integrative and Comparative Physiology, Vol 270, Issue 4 738-R743, Copyright © 1996 by American Physiological Society
Chronically altered body protein levels following lateral hypothalamic lesions in rats
M. D. Hirvonen and R. E. Keesey
University of Wisconsin, Madison 53706, USA.
Rats maintaining reduced body weights after lesions of the lateral
hypothalamus (LH; LH rats) are characterized by smaller body protein
masses. Two experiments were conducted to determine whether this reduced
protein mass is actively defended. In the first, it was found that LH rats
induced to overeat and restore body weight to the level of nonlesioned
controls markedly increased their body fat without significantly increasing
body protein. That is, LH rats at normal body weights were notably obese.
In the second experiment, body protein losses produced by food restriction
in LH rats were both relatively small and proportionally the same as those
seen in similarly restricted nonlesioned controls. These observations
demonstrate that LH rats retain the capacity for preserving body protein
when challenged by either under- or overnutrition. The apparently
irreversible reduction in the body protein mass thus appears to be the
result of a specific lean tissue downregulation induced by LH damage.
