Pharmacological profile of the 5-hydroxytryptamine receptor of Fasciola hepatica body wall muscle.
5-HT is a candidate for the excitatory transmitter at the neuromuscular junction in trematodes including Fasciola hepatica. This study has determined the response of a muscle strip preparation from Fasciola hepatica to 5-HT and a range of agonists that distinguish between the vertebrate receptor 5-HT subtypes. 5-HT increased the resting tone and the rhythmic activity of the muscle strip. Of the 19 compounds tested, only 10 had an effect similar to 5-HT and all but 2 of these were tryptamine compounds. 5-HT was more potent than tryptamine whilst 4-OH-tryptamine had no effect, suggesting that the response is mediated by a 5-HT rather than a tryptamine receptor. 5-Fluorotryptamine and 5-carboxyamidotryptamine were the most potent agonists. 8-OH-DPAT also mimicked the effect of 5-HT, though less potently. Assuming that these agents elicit their response through a common receptor, this suggests the presence of a 5-HT receptor with similar properties in terms of agonist recognition as the vertebrate 5-HT1 class of receptor involved in controlling Fasciola muscle motility.
Tembe
E A
EA
Department of Physiology and Pharmacology, University of Southampton.
Holden-Dye
L
L
Smith
S W
SW
Jacques
P A
PA
Walker
R J
RJ
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D005210:Fasciola hepatica / Q000378:metabolism*; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects; D009132:Muscles / Q000187:drug effects* / Q000378:metabolism; D011985:Receptors, Serotonin / Q000145:classification / Q000187:drug effects*; D012701:Serotonin / Q000031:analogs & derivatives / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D014363:Tryptamines / Q000494:pharmacology
D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; D014363:Tryptamines; D012701:Serotonin; C034536:5-fluorotryptamine; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; C047087:5-carboxamidotryptamine