The Role of GABAA Receptor in Antispasmodic Activity of Hydroalcholic Extract of Petroselinum Crispum (Parsley) Seed in Rat Ileum

Abstract Background: Parsley is one of the medicinal herbs used for gastrointestinal disorders. However, spasmolytic activity of Petroselinum crispum (parsley) extract has been reported, there is a lack of information to support the mechanism of this antispasmodic activity. Taking this into account, the purpose of the present work was to investigate the role of GABAA receptor on antispasmodic activity of the hydroalcoholic extract of parsley seed in isolated rat ileum. Materials and Methods: In this study, terminal portion of ileum (2 cm) was dissected out and mounted in an organ bath containing air bubbled Tyrode solution (37οC, pH=7.4). Under 1gr resting tension, ileal contraction was induced by KCl (60 mM) and recorded isotonically. The effects of non-cumulative (0.1-0.5 mg/ml) concentrations of extract on KCl-induced contractions were examined. After evaluating the effect of agonist and antagonist GABAA receptor, the effect of parsley extract was assessed in the presence of muscimol (25 µM) and bicuculline (10 µM) as agonist and antagonist of GABAA, respectively. Results: Parsley seed extract reduced the KCl-induced ileal contraction in a concentration-dependent manner (n=7, p<0.001). Both muscimol and bicuculline exerted relaxant effect on ileal contraction (n=7, p<0.05, p<0.01, respectively). Surprisingly, agonist and antagonist of GABAA both potentiated the spasmolytic effect of extract (0.2 mg/ml). Altogether, spasmolytic effect of extract was not attenuated in the presence of GABAA antagonist. Conclusion: It seems that GABAA receptor is not involved in the antispasmodic effect of parsley seeds extract in rat ileum.