Adenosine cyclic 3',5'-monophosphate in the liver fluke, Fasciola hepatica. I. Activation of adenylate cyclase by 5-hydroxytryptamine

Abrahams, S.L.; Northup, J.K.; Mansour, T.E.

Molecular Pharmacology 12(1): 49-58


ISSN/ISBN: 0026-895X
PMID: 176567
Accession: 068523104

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5-Hydroxytryptamine AMP in the liver fluke F. hepatica, especially in the anterior end head of the organism. The accumulation of the cyclic neuclotide and the accompanying increase in motility of the isolated fluke head were dependent on 5-HT concentration. Adenylate cyclase in particles from fluke heads showed a greater activation by 5-HT than did particles from the posterior end of the fluke. The ability of indoleamine analogues of 5-HT to stimulate fluke motility and to activate adenylate cyclase dimished with decreasing structural similarity of the analogue to 5-HT. Both the free amino and 5-OH groups of 5-HT appear important for its recognition by adenylate cyclase. c-AMP seems to act as a second messenger for 5-HT in invertebrates. No direct relationship between the elevation of the cyclic nucleotide and the stimulation of motility is suggested. Both amphetamine and D-LSD stimulated fluke motility but did not cause an increase in endogenous levels of the cyclic nucleotide. Moreover, D-LSD antagonized the 5-HT activation of adenylate cyclase; this antagonism may be related to the high affinity of D-LSD for its site on adenylate cyclase.