Evidence for sex steroid inhibition of lipoprotein lipase in men: comparison of abdominal and femoral adipose tissue.

Plasma estradiol has been suggested to suppress adipose tissue lipoprotein lipase (LPL) activity in women. The present study explores the regulation of LPL by sex steroids in sedentary obese men (N = 24) at their usual weight. Femoral adipose tissue LPL activity, eluted with serum and heparin or extracted with detergent, showed significant inverse correlations with plasma levels of testosterone, bioavailable testosterone, dihydrotestosterone, and estradiol. Both measures of femoral LPL activity were also correlated with the weight change occurring despite efforts to maintain a constant weight. Abdominal LPL activity showed significant but weaker inverse correlations with bioavailable testosterone only. Multivariate analysis of potential predictors for eluted femoral LPL activity showed that plasma testosterone, dihydrotestosterone, and estradiol were interdependent, whereas the rate of weight change was an independent variable. In the regression equation, only bioavailable testosterone and weight change were retained, explaining 63% of the variability (R = .79, P = .0002). These results suggest that sex steroids suppress adipose tissue LPL activity in men, and more so in the thigh than in the abdomen, thereby possibly contributing to a central fat accumulation. The data are compatible with a model from male animals suggesting that testosterone effects on adipose tissue LPL are mediated by estradiol formed locally.