Vol. 10, Issue 8 (2021)

Author(s):
Megha Madhusudhanan, Saranya C, Mery S John, Sanjay BM, Suraj SV, Suresh Narayanan Nair, Karapparambu Gopalan Ajithkumar, Nisha AR, Reghu Ravindran and Sanis Juliet

Abstract:
Histamine is a short-acting endogenous amine found abundant in the gastrointestinal tract. It is playing an important role in the inflammatory conditions of the intestine. Even though, many literature have described the complexity of its control on gastrointestinal motility, a clear interpretation of its involvement is lacking. Hence, the present study was undertaken to assess the role of histaminergic drugs in the normal propulsive motion of the intestine and modulation of acetylcholine induced contraction in rat ileum. The contractile responses to the agonist alone and in presence of antagonists were recorded using a Digital Dale’s Mono bath with isometric transducer connected to a recorder. The cumulative dose response of rat ileum to muscarinic and histaminergic drugs was determined. The median effective and inhibitory concentrations were calculated and the dose response curve was plotted. Histamine did not elicit any response in the rat ileal tissue even at the highest concentration added. The histamine receptor antagonists, chlorpheneramine maleate and ranitidine dihydrochloride didnot any effect on the rat ileum with prior exposure to histamine. However, pre-treatment with submaximal doses of atropine and histamine attenuated the contractile response to acetylcholine. On the other hand, the acetylcholine induced contraction was not altered by adding graded doses of histamine. The lack of response may be due to the absence of histaminergic receptors in the rat ileum. The modulation of response to acetylcholine indicates an involvement of H₃ receptor mediated pathway.