Effect of hypophysectomy on weight gain and body composition in the genetically obese yellow (Ay/a) mouse

Abstract

In order to investigate the role of the pituitary in yellow obesity, genetically obese yellow mice (Aya) and normal nonyellow siblings (aa) were either shamoperated or hypophysectomized by a paraphyarngeal method at 45--50 days of age. The operated animals were weighed for 13 wk and their carcasses subsequently were analyzed for fat, water, and lean body mass content. Completeness of hypophysectomy was assessed by microscopic examination of stained serial sections of the brain and attached hypophyseal capsule. Completely hypophysectomized Aya mice still gained more weight than hypophysectomized nonyellow siblings and showed the excessive accumulation of fat characteristic of the yellow obesity. We conclude that the pituitary and the endocrine pathways it controls are not primarily involved in the expression of yellow obesity.