AJP - Regulatory, Integrative and Comparative Physiology, Vol 248, Issue 2 172-R180, Copyright © 1985 by American Physiological Society
Effects of intragastric hyperalimentation on pair-fed rats with ventromedial hypothalamic lesions
M. C. Walgren and T. L. Powley
The present study was undertaken to determine the relative contributions of
altered metabolic responses and excess food intake to the obesity and
hyperinsulinemia of the ventromedial hypothalamic (VMH) syndrome. This
experiment, employing an intragastric hyperalimentation protocol, was also
designed to address the related issue of whether altered energy utilization
serves as a compensatory strategy for reducing energy retention in the face
of excess intake. Separate groups of VMH-lesioned and sham-lesioned female
rats were fed, either orally or intragastrically, up to 200% of the
calories ingested by a normally feeding intact rat. Both VMH-lesioned and
intact rats became obese and hyperinsulinemic when hyperalimented for 30
days, but rats with lesions deposited 25% more fat than intact animals
receiving an identical number of calories. Estimates of total carcass
energy indicated that rats with lesions required 11% less calories than
intact rats to retain identical levels of energy. Furthermore, intact
hyperalimented rats failed to evidence the caloric wastage that has been
reported to occur in orally fed rats that overeat cafeteria diets.
