Article date: November 1987
By: A.W. Baird, A.W. Cuthbert in Volume 92, Issue 3, pages 647-655
Using a number of 5‐hydroxytryptamine (5‐HT)‐antagonists we have compared their activity against the chloride‐secretory response in guinea‐pig ileal and colonic epithelia when challenged with 5‐HT or antigen. Guinea‐pigs sensitized to β‐lactoglobulin (βLG) were used throughout; these were obtained by providing animals with cows' milk for drinking.
Of methysergide, ketanserin, cyproheptadine and ICS 205–930, only the latter inhibited both the response to 5‐HT and to antigen challenge. Methysergide caused a minor, significant effect on 5‐HT but not on βLG responses. Ketanserin had no effect on the responses to 5‐HT, but both ketanserin and cyproheptadine inhibited the challenge to βLG.
The data are considered in relation to the current views of receptor subtypes for 5‐HT. Some of the reported inhibitors may be non‐specific, while we consider there is evidence to support the view that 5‐HT3‐receptors (neuronal receptors) are involved both in the responses to 5‐HT and to antigen challenge.
Tetrodotoxin mimicked the effect of ICS 205–930 on both the response to 5‐HT and to antigen challenge in sensitized tissues, confirming a neuronal involvement for both types of stimuli.
Using a number of 5‐hydroxytryptamine (5‐HT)‐antagonists we have compared their activity against the chloride‐secretory response in guinea‐pig ileal and colonic epithelia when challenged with 5‐HT or antigen. Guinea‐pigs sensitized to β‐lactoglobulin (βLG) were used throughout; these were obtained by providing animals with cows' milk for drinking.
Of methysergide, ketanserin, cyproheptadine and ICS 205–930, only the latter inhibited both the response to 5‐HT and to antigen challenge. Methysergide caused a minor, significant effect on 5‐HT but not on βLG responses. Ketanserin had no effect on the responses to 5‐HT, but both ketanserin and cyproheptadine inhibited the challenge to βLG.
The data are considered in relation to the current views of receptor subtypes for 5‐HT. Some of the reported inhibitors may be non‐specific, while we consider there is evidence to support the view that 5‐HT3‐receptors (neuronal receptors) are involved both in the responses to 5‐HT and to antigen challenge.
Tetrodotoxin mimicked the effect of ICS 205–930 on both the response to 5‐HT and to antigen challenge in sensitized tissues, confirming a neuronal involvement for both types of stimuli.
DOI: 10.1111/j.1476-5381.1987.tb11368.x
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