AJP - Endocrinology and Metabolism, Vol 254, Issue 2 E162-E166, Copyright © 1988 by American Physiological Society
Effect of hypophysectomy on energy balance and brown fat activity in obese Zucker rats
S. Holt, N. J. Rothwell, M. J. Stock and D. A. York
Department of Human Nutrition, School of Biochemical and Physiological Sciences, University of Southampton, United Kingdom.
Hypophysectomy (HYPX) in genetically obese (fa/fa) Zucker rats
significantly reduced body weight and energy gains and stimulated energy
expenditure (by 34%), the thermic response to food (by 144%), and brown
adipose tissue (BAT) mitochondrial GDP-binding capacity (by 190%) compared
with pair-fed, sham-operated obese rats. These changes in energy balance in
obese HYPX rats were reversed by corticosterone replacement (1 mg/day), but
the increased BAT activity was only partly restored to normal. HYPX had
only small effects on energy balance in lean Zucker rats compared with
pair-fed, sham-operated lean controls but increased the acute thermic
response to food and BAT mitochondrial GDP-binding capacity; these effects
were inhibited by replacement of HYPX rats with corticosterone. The results
suggest that alterations in the hypothalamic-pituitary-adrenal axis play a
fundamental role in the development and maintenance of genetic obesity.
