Role of tryptaminergic system in regulating the motility of Gastrothylax crumenifer

Tryptaminergic system plays a specific role in different animals. Its presence has also been established in different trematodes. In the present study, the effect of different tryptaminergic agents on the spontaneous muscular activity of Gastrothylax crumenifer was assessed. 5-hydroxytryptamine caused concentration-dependent (10⁻⁷–10⁻³ M) increase in the amplitude and baseline tension of spontaneous muscular activity of rumen fluke, whereas its precursor, 5-hydroxytryptophan also induced a significant increase in the amplitude at 10⁻⁵–10⁻³ M concentrations and baseline tension at 10⁻⁴ and 10⁻³ M concentrations, without affecting the frequency of spontaneous contractions. Cyproheptadiane, a 5-HT receptor antagonist (10⁻⁵–10⁻³ M) elicited significant decrease in the amplitude and baseline tension, as compared to the controls and did not affect the frequency of spontaneous muscular activity of rumen fluke. These findings indicate the presence of well developed tryptaminergic system and its stimulatory role in regulating the spontaneous muscular activity of rumen fluke.