Trigonella foenum-graecum water extract improves insulin sensitivity and stimulates PPAR and γ gene expression in high fructose-fed insulin-resistant rats

Insulin resistance is the main defect associated with the metabolic syndrome. In obesity, the decreased adiponectin levels and elevation of plasma-free fatty acids are the main factors associated with insulin resistance. In this study, we evaluated the effect of trigonella foenum-graecum (TFG) extract on insulin sensitivity in high fructose-fed insulin-resistant rats.

Experimental rats were fed with a high fructose diet for eight weeks. After the first six weeks, the animals were treated with trigonella foenum-graecum extract or pioglitazone for two weeks. Serum glucose, triglycerides, cholesterol, and HDL-c were measured. The insulin and adiponectin levels were assayed by the enzyme-linked immunosorbent assay (ELISA), and Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) was calculated. The plasma-free fatty acid profile was obtained by gas chromatography. PPARγ and GLUT4 gene expression were assessed by real-time polymerase chain reaction (PCR) and western blotting.

In the trigonella foenum-graecum-extract treated group the following results were obtained: Insulin (49.02 ± 6.93 pmol/L), adiponectin (7.1 ± 0.64 μg/ml), and triglycerides (110.3 ± 16.7 mg/dl), which were significantly different and improved compared to the control group (insulin (137 ± 34 pmol/l), adiponectin (3.9 ± 0.15 μg/ml), glucose (187 ± 15 mg/dl), and triglycerides (217 ± 18 mg/dl). Also the PPARγ gene expression was significantly increased compared to the control group.

This study demonstrates the beneficial effects of trigonella foenum-graecum extract on insulin resistance in rats fed on a high-fructose diet. At least three mechanisms are involved, including direct insulin-like effect, increase in adiponectin levels, and PPARγ protein expression.