Role of 5-HT in cholera toxin-induced mucin secretion in the rat small intestine

The activation of a 5-hydroxytryptamine(sub 4)-like (5-HT) receptors controls the cholera toxin-induced mucin secretion in the proximal and distal parts of the rat small intestine. Mucin secretion induced by 5-HT-administration follows two processes based on differences in sensitivities to capsaicin and tetrodotoxin. Both processes meet at a cholinergic pathway. The 5-HT(sub 2) receptor antagonist ketanserin and the cyclooxygenase inhibitor indomethacin are incapable of inhibiting the secretion. Partial blocking is affected by the mixed 5-HT(sub 3/4) receptor antagonist tropisetron.