Effect of hypophysectomy on energy balance and brown fat activity in obese Zucker rats.
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.
Holt
S
S
Department of Human Nutrition, School of Biochemical and Physiological Sciences, University of Southampton, United Kingdom.
Rothwell
N J
NJ
Stock
M J
MJ
York
D A
DA
D002001:Adipose Tissue, Brown / Q000378:metabolism*; D000818:Animals; D001831:Body Temperature; D001835:Body Weight; D004734:Energy Metabolism; D007016:Hypophysectomy; D008297:Male; D009765:Obesity / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D011924:Rats, Zucker