Adrenalectomy reduces adiposity by decreasing food efficiency, not direct effects on white adipose tissue.

OBJECTIVE

This study was conducted to establish the effects of adrenalectomy (ADX) on adipose tissue metabolism in male Sprague-Dawley rats fed a standard chow diet.

RESEARCH METHODS AND PROCEDURES

The effects of adrenalectomy on adipose cell size, lipoprotein lipase activity, and basal and insulin-stimulated glucose conversion to lipid and lipolysis were measured.

RESULTS

ADX decreased body weight gain during the post-operative period in the absence of changes in food intake; feed efficiency was decreased significantly. ADX decreased adipocyte size by 30%. ADX increased adipocyte response to the effect of submaximal concentrations of insulin on lipid synthesis and lipolysis. ADX decreased maximally insulin-stimulated lipid synthesis, but this effect was accounted for by decreased adipocyte size. In contrast, ADX had no effect on maximally insulin-inhibited lipolysis. ADX did not affect heparin-releasable LPL. The small effect of ADX on residual extractable adipose tissue LPL activity was accounted for by decreased fat cell size.

DISCUSSION

ADX decreased adiposity in the absence of changes in food intake, lipoprotein lipase activity, and adipocyte lipid metabolism. The effect is best attributed to decreased feed efficiency.