LOCAL SYMPATHETIC DENERVATION OF WHITE ADIPOSE-TISSUE IN RATS INDUCESPREADIPOCYTE PROLIFERATION WITHOUT NOTICEABLE CHANGES IN METABOLISM

The direct influence of the sympathetic nervous system on white adipos e tissue was studied by performing a unilateral surgical denervation o f the retroperitoneal fat pad in rats, the contralateral pad being use d as a control. One week after surgery, the weight of the denervated p ad was significantly higher than that of the intact pad. In vivo, gluc ose utilization was not altered by denervation. The expression of GLUT 4 as well as the expression and activity of fatty acid synthase, lipop rotein lipase, and hormone-sensitive triglyceride lipase were similar in the two pads. Lipolysis in response to norepinephrine, determined i n vitro, was not modified by denervation although the ratio between al pha2- and beta-adrenergic receptors was changed. Denervation induced a n increase in DNA content without change in the number of mature adipo cytes. The expression of A2COL6/pOb24, a marker of the early step of a dipocyte differentiation, was significantly enhanced in the denervated pad, suggesting an increased number of preadipocytes. This was confir med by an increased cell number observed in the denervated fat pad 1 m onth after surgery. In conclusion, surgical denervation of the white f at pad does not alter the glucose and lipid metabolisms. By contrast, it accelerated adipocyte differentiation and led to the recruitment of new precursors.