Adiponectin and resistin response in the onset of obesity in male and female rats

Objective: Studying the sex-dependent response of adiponectin and resistin adipose tissue expression and circulating levels in the onset of dietary obesity. Methods and Procedures: Male and female 4-week-old Wistar rats were fed a control or cafeteria ( CAF) diet for 15 days. Body weight and energy intake were monitored. Gonadal ( visceral), retroperitoneal ( visceral) and inguinal ( subcutaneous) white adipose tissue ( WAT) depots were collected. Serum adiponectin and resistin and tissue mRNA levels were analyzed by western blot and reverse transcription - PCR, respectively. Serum levels of insulin, tumor necrosis factor-alpha ( TNF alpha), and glucose were measured by enzyme-linked immunosorbent assay and by a glucose sensor. Insulin resistance was assessed by the homeostasis model assessment ( HOMA). Results: Energy intake and adipose-tissue weight were significantly increased in the CAF rats, with higher increase in visceral than in subcutaneous fat, especially in females. The effective production of adiponectin and resistin ( total levels adjusted per WAT weight) was decreased in the CAF groups, more markedly in females for adiponectin. This decrease was associated with the tendency to lower WAT mRNA levels for resistin, but not for adiponectin. Insulin levels were not significantly altered. Fasting glucose was slightly increased in CAF females. HOMA score was not significantly increased by CAF feeding, although it tended to be increased in a few CAF females. Discussion: Decrease of WAT adiponectin and resistin-effective production seems an early response to obesity development under a high-fat ( CAF) diet, with sex-associated differences. This can probably be related to a physiological role of both adipokines modulating the insulin signaling system.