The role of nitric oxide and prostaglandins in the effect of alcoholic Trigonella foenum-graecum seed extract on aortic reactivity in streptozotocin-diabetic rats

Background and the purpose of the study: Trigonella foenum-graecum (TFG) has demonstrated beneficial effects in both Insulin-dependen and non- Insulin-dependen diabetic animals. This study was conducted to evaluate the effects of the alcoholic seed extract of this plant on aortic reactivity and underlying mechanisms in streptozotocin-diabetic rats. Male Wistar rats were divided into control, extract-treated control, diabetic, and extract-treated diabetic groups. Diabetes was induced by a single i.p. injection of streptozotocin (STZ; 60 mg/kg). Treatment groups received TFG extract (200 mg/kg; i.p.) every other day for 1 month. Then, contractile responsiveness of thoracic aorta to KCl and noradrenaline (NA) and relaxation to acetylcholine (ACh) and sodium nitroprusside (SNP) was determined. For determination of the involvement of NO and prostaglandins in relaxation response to ACh, rings were incubated 30 min before the experiment with N(ω)-nitro-L-arginine methyl ester)L-NAME(and/or indomethacin (INDO). Diabetic state significantly increased maximum contractile responses to KCl and NA (p<0.01-0.005) and reduced maximum relaxation due to ACh (p<0.01) as compared to controls and treatment with TFG extract in diabetic group significantly improved these changes relative to untreated diabetic group (p<0.05). Meanwhile, pretreatment with L-NAME did not produce any significant change between diabetic and extract-treated diabetic groups. On the other hand, there was a significant difference in both of these two groups following pretreatment with INDO (p<0.01). Major Intraperitoneal administration of alcoholic seed extract of TFG for one month could improve some functional indices of the vascular system in diabetic state and endothelium-derived prostaglandins are involved in this response.