Effect of withania somnifera root extract against monocrotophos -induced altered responsiveness of chicken duodenum to acetylcholine

The contractile responses of isolated duodenal segments from chickens treated with monocrotophos (MCP) alone and in combination with Withania somnifera root extract (WRE) were studied using 4 channel polygraph (Biopac, USA). The study consisted of 5 groups with 12 birds in each group. Group I served as control. Monocrotophos (2 ppm in feed) was fed to chickens of group II to V and WRE (@ 100, 300 and 500mg/kg b. wt/day) was given in drinking water to birds of group III to V, respectively for 7 weeks. The cumulative doses of acetylcholine (0.01-300 μM) caused dosedependent contractions with significant increase in E_max and decrease in EC₅₀ values in MCP-exposed group II birds. Dose-response curve of ACh in group II birds was shifted to left. WRE significantly decreased responses of ACh in duodenum of chickens of group III to V. These findings demonstrated that MCP increased the responsiveness of muscarinic receptors in chicken duodenum and WRE had protective efficacy against MCP-induced alterations in responsiveness of cholinergic receptors to ACh in the tissue preparations.