RESUMO
Background The antidiabetic and antioxidant effects of Trigonella foenum-graceum have been suggested. The effects of hydroalcoholic extract of the plant seeds and metformin against the diabetes-induced memory impairment were investigated. Materials and methods The rats were treated: (1) control, (2) diabetic (3-6) and diabetic rats treated by 50, 100 and 200 mg/kg of the plant extract or metformin. The rats were diabetic by streptozotocin (STZ, 55 mg/kg). After the passive avoidance test, malondialdehyde (MDA), nitric oxide (NO) metabolites, total thiol (SH), catalase (CAT) and superoxide dismutase (SOD) were determined in the brain. Results In the diabetic group, at 3, 24 and 48 h after receiving a shock, the latency to enter the dark room was lower than for the controls (p < 0.001). All doses of the extract and metformin increased the latencies to enter the dark at 3 and 24 h after the shock treatment (p < 0.05-p < 0.001). Additionally, the two higher doses of the extract and metformin increased the latency at 48 h after the shock (p < 0.05-p < 0.001). Diabetes also elevated MDA and NO metabolites, while it reduced thiol, SOD and CAT in the hippocampal and cortical tissues (p < 0.001). Treatment of the diabetic animals by the highest dose of the extract and also metformin reduced the MDA and NO metabolites, while it improved thiols, SOD and CAT (p < 0.01-p < 0.001). Conclusions Based on our findings, metformin and the hydro-alcoholic extract from the T. foenum-graceum seed prevented memory deficits resulting from diabetes. Preventing oxidative damage in the brain may at least, in part, be responsible for the positive effects of the extract and metformin.
