Effects of Murraya koenigii leaf extract on impaired gastrointestinal motility in streptozotocin-induced diabetic rats.

Objective: The present study was to investigate the effects of Murraya koenigii leaf (MKL), an Indian herb, on glucose homeostasis, intestinal transit time, response to exogenous acetylcholine of smooth muscles of distal colon, and intestinal thiobarbituric acid reactive substance (TBARS) level in streptozotocin (STZ)-induced diabetic rats.

Methods: Male adult Wistar rats were used in this study. Diabetes was induced in the rats by STZ (70 mg/kg, intravenously). The treatments of MKL extract (300 and 500 mg/kg) and glibenclamide were started after stabilization of blood glucose level (13 d after single dose of STZ), while the standard drug cisapride or vitamin E was given from the last week (8th week) of experimentation. At the end of the study, the rats were sacrificed and evaluated for gastrointestinal motility, the contractile response of distal colons and the TBARS content. The gastrointestinal motility was evaluated by measuring the intestinal transit rate of charcoal meal. The contractile response of distal colon was measured in terms of evaluating the dose-response curve with increasing doses of acetylcholine, and the TBARS content was measured by calculating the level of polyunsaturated fatty acid in homogenates of intestines of the diabetic rats.

Results: MKL significantly decreased the blood glucose level at the 30th (P<0.05) and 60th (P<0.01) day of MKL administration (300 and 500 mg/kg). The gastrointestinal motility significantly (P<0.05) reduced after 9 weeks in diabetic rats and it was correlated to the decrease of the percent response of acetylcholine on distal colons (P<0.01) and the increase of TBARS (as an index of oxidative stress) in intestines (P<0.05), while prior treatment with MKL (300 and 500 mg/kg) up to 9 weeks increased the gastrointestinal motility demonstrated by the increase in the activation of cholinergic response to acetylcholine on distal colons (P<0.05). The TBARS also decreased after 9-week treatment with MKL (P<0.05).

Conclusion: The present study suggested that MKL had protective effect against gastrointestinal disturbances in diabetes by controlling glucose level as well as defending against peripheral damage of cholinergic neurons by providing antioxidant shelter, so it may be helpful in diabetic patients with impaired gastrointestinal motility.