Resistin mediates tomato and broccoli extract effects on glucose homeostasis in high fat diet-induced obesity in rats

Background: Resistin is an adipocyte hormone that regulates glucose metabolism. Elevated levels of resistin may cause insulin resistance. This may link obesity, and increased fat mass to type II diabetes and insulin resistance. We hypothesized that treatment with tomato and broccoli extracts regulates glucose homeostasis via modulation of resistin levels in high fat diet-induced obesity rats (HFD). Methods: Forty-eight male albino rats were divided into 8 groups as follows: control, HFD, stop fat diet (SD), Tomato 200 mg/kg (T200), Tomato 400 mg/kg (T400), Broccoli 200 mg/kg (B200), Broccoli 400 mg/kg (B400), and Chromax (CX). Treatment continued for 1 month. Serum levels of resistin, leptin, adiponectin, glucose and insulin were measured using ELISA and spectrophotometry. Results: Serum levels of resistin were significantly reduced in the T 200, T 400, B 200, B 400 and CX groups to: 4. 13 +/- 0.22 ng/ml, 1.51 +/- 0.04 ng/ml, 4.13 +/- 0.22 ng/ml, 2.32 +/- 0.15 ng/ml and 1.37 +/- 0.03 ng/ml, respectively, compared to HFD group and SD group (P value < 0.0001). Non-significant differences were found between T 400, B 400 and CX groups. Serum levels of leptin were significantly reduced in the T 400 (22.7 +/- 0.84 pg/ml) group compared to the B 400 (41 +/- 2.45 Pg/ml) and CX groups (45.7 +/- 2.91 Pg/ml), P value < 0.001. Serum levels of adiponectin were significantly increased in the T 400 group (131 +/- 3.84 pg/ml) compared to the CX group (112 +/- 4.77 pg/ml), P value < 0.01. Conclusions: Our results demonstrate that tomato and broccoli extract treatment regulates glucose homeostasis via reduction of serum resistin and may be a useful non-pharmacological therapy for obesity.