Free fatty acids are involved in the inverse relationship between hormone-sensitive lipase (HSL) activity and expression in adipose tissue after high-fat feeding or beta(3)-adrenergic stimulation

Objective: The hormone-sensitive lipase (HSL) is the rate-limiting enzyme i n adipose tissue lipolysis. The aim of this experimental trial was to study the effects of a beta(3)-adrenergic agonist (Trecadrine) on plasma fatty a cids, adipocyte HSL activity, and gene expression in control and cafeteria- induced obese animals. Research Methods and Procedures: Control and cafeteria-fed rats were treate d with a placebo or Trecadrine during 35 days. Plasma fatty acids were meas ured by an enzymatic method, whereas HSL activity was assessed by using lab eled triolein as substrate. Finally, HSL gene expression from white adipose tissue (WAT) was determined using a reverse transcription-polymerase chain reaction method. Results: Trecadrine administration reduced plasma fatty acids and HSL mRNA levels in abdominal WAT, whereas HSL activity was significantly higher in t he Trecadrine-treated obese rats than in the obese nontreated rats. Also, a bdominal WAT HSL activity significantly increased, whereas WAT HSL gene exp ression fell in control rats treated with beta(3)-adrenergic agonist as com pared with control untreated animals. Discussion: In situations of fat accumulation (high-fat feeding) or lipid m obilization (beta(3)-adrenergic stimulation), changes in HSL activity and H SL gene expression seem to follow a trend related to plasma fatty acids lev els, as indicated by the positive correlation (r = 0.39, p < 0.05) between HSL mRNA levels and plasma fatty acids, and the negative correlation (r = - 0.38, p < 0.05) between plasma fatty acids and HSL activity. Furthermore, a highly negative correlation (r = -0.59, p < 0.001) between HSL activity an d HSL mRNA expression was found, in which plasma-free fatty acids are appar ently involved.