Effects of cafeteria diet feeding on beta(3)-adrenoceptor expression and lipolytic activity in white adipose tissue of male and female rats

OBJECTIVE: To investigate the effects of short term (15 days) cafeteria die t feeding on the expression of beta (3)-AR in vivo and its association with lipolytic stimulation induced by beta (3)-AR agonist CGP12177A in isolated white adipocytes. ANIMALS: Six female and 6 male Wistar rats (at 4 weeks of age) were fed on a cafeteria diet plus standard diet for 15 days. The remaining 12 age- and sex-matched rats always received standard diet only. MEASUREMENTS: White gonadal adipose tissue was isolated and used for the de termination of beta (3)-AR and leptin expression, and for in vitro studies of lipolytic activity. RESULTS: Control male rats had higher levels of both beta (3)-AR and leptin mRNA in white adipose tissue than their female counterparts. Both male and female rats up-regulated the levels of both beta (3)-AR and leptin mRNA in response to 15 day cafeteria diet feeding. Noradrenaline- and isoprenaline -induced lipolysis were significantly increased in fat cells from control f emales compared to their male counterparts. CGP12177A stimulation resulted in significantly higher glycerol release in fat cells from cafeteria diet-f ed female rats, whereas there were no differences due to dietary treatment in male rats. The maximal lipolytic response of forskolin (stimulating aden ylyl cyclase) and dibutyryl cyclic AMP (cyclic AMP analogous) was not affec ted by sex or cafeteria diet feeding. CONCLUSION: Cafeteria diet feeding brings about higher excess body weight a nd impaired adipose tissue lipolytic activity in female rats compared to ma le rats. Thus, the higher levels of beta (3)-AR mRNA induced by cafeteria f eeding are not indicative per se of an increase of the lipolytic response o f the adipocytes. The changes seen in other adrenoceptor subtypes (beta (1) and beta (2)) may be more determinant of the overall lipolytic response of adipocytes.