6-gingerol ameliorates weight gain and insulin resistance in metabolic syndrome rats by regulating adipocytokines.

Metabolic syndrome (MetS) can lead to increase of insulin resistance (IR) and visceral adipose tissue production of adipocytokines. 6-gingerol is known to have antioxidant and anti-inflammatory activities. Aim of this study is to investigate the effects of 6-gingerol on high-fat high-fructose (HFHF) diet-induced weight gain and IR in rats through modulation of adipocytokines. To induce MetS, male Sprague-Dawley rats were fed with a HFHF diet for 16 weeks and at Week 8, single-dose low-dose streptozotocin (22 mg/kg) were intraperitoneally injected. After 8 weeks of HFHF diet feeding, the rats were treated orally with 6-gingerol (50, 100, and 200 mg/kg/day) once daily for 8 weeks. At the end of the study, all animals were terminated, serum, liver, and visceral adipose tissues were harvested for biochemical analysis including the measurements of total cholesterol, triglycerides, HDL-cholesterol, fasting plasma glucose, insulin, leptin, adiponectin, proinflammatory cytokines (TNF-α and IL-6) and liver and adipose tissue histopathology. Biochemical parameters namely serum total cholesterol (243.7 ± 127.6 vs 72.6 ± 3 mg/dL), triglycerides (469.2 ± 164.9 vs 49.3 ± 6.3 mg/dL), fasting plasma glucose (334 ± 49.5 vs 121 ± 8.5 mg/dL), HOMA-IR (0.70 ± 0.24 vs 0.32 ± 0.06), and leptin (6.19 ± 1.24 vs 3.45 ± 0.33 ng/mL) were significantly enhanced, whereas HDL-cholesterol (26.2 ± 5.2 vs 27.9 ± 1.1 mg/dL) and adiponectin level (14.4 ± 5.5 vs 52.8 ± 10.7 ng/mL) were lowered in MetS vs normal control. Moreover, MetS were marked a significant increase in body weight and proinflammatory cytokines. Treatment with 6-gingerol dose-dependently restored all of those alterations towards normal values as well as the accumulation of lipid in liver and adipose tissues. These findings demonstrate that 6-gingerol, in a dose-dependent mode, showed capability of improving weight gain and IR in MetS rats through modulation of adipocytokines.