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 GABA_A 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 (37^οC, 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 GABA_A receptor, the effect of parsley extract was assessed in the presence of muscimol (25 µM) and bicuculline (10 µM) as agonist and antagonist of GABA_A, 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 GABA_A both potentiated the spasmolytic effect of extract (0.2 mg/ml). Altogether, spasmolytic effect of extract was not attenuated in the presence of GABA_A antagonist.

Conclusion: It seems that GABA_A receptor is not involved in the antispasmodic effect of parsley seeds extract in rat ileum.