Sex-dependent dietary obesity, induction of UCPs, and leptin expression inrat adipose tissues

Objective: The aim of this study was to determine the sex-dependent differe nces in the response of key parameters involved in thermogenesis and contro l of body weight in brown adipose tissue (BAT) and white adipose tissue (WA T) in postcafeteria-fed rats, a model of dietary obesity. Research Methods and Procedures: BAT and WAT were obtained from male and fe male control and postcafeteria-fed Wistar rats. Postcafeteria-fed rats were initially fed with cafeteria diet from day 10 of life until day 110 (cafet eria period) and with standard chow diet from then until day 180 of life (p ostcafeteria period). Body mass and energy intake were evaluated. Biometric parameters were analyzed in interscapular BAT (IBAT). Levels of uncoupling protein 1 (UCP1), alpha (2)-adrenergic receptor (AR), and beta (3)-AR prot eins and UCP1, UCP2, UCP3, beta (3)-AR, and leptin mRNAs, in IBAT or WAT, w ere studied by Western blot and Northern blot analyses, respectively. Results: Rats attained 59% (females) and 39% (males) increase in body weigh t at the end of the cafeteria period. During the postcafeteria period, the rats showed a loss of body weight, which was higher in females. Postcafeter ia-fed female rats also presented higher activation of thermogenic paramete rs in IBAT, including UCP1, UCP2, and UCP3 mRNAs. Female control rats showe d lower levels of both alpha (2) and beta (3)-ARs in BAT compared with male rats, but these levels in postcafeteria-fed female and male rats were the same, because males tended to down-regulate them. Levels of leptin mRNA in response to the postcafeteria state depended on gender and the specific WAT depot studied. Discussion: It is suggested that in postcafeteria-fed female rats, BAT ther mogenic capacity becomes more efficiently activated than in males. Female r ats also showed a bigger weight loss. The parallel regulation of the levels of UCP2 and UCP3 mRNAs, with respect to UCP1 mRNA, with higher activation in female postcafeteria-fed rats, suggests a possible role of both UCP2 and UCP3 in the regulation of energy expenditure and in the control of body we ight. The distinct responses to overweight of alpha (2) and beta (3)-ARs-wh ich were sex dependent-and leptin mRNA-which depended on both sex and WAT d epot-also support the different response of thermogenesis-related parameter s between overweight males and females.