Studies on chemotherapy of parasitic helminths (VII). Effects of various cholinergic agents on the motility of Angiostrongylus cantonensis.

Effects of various cholinergic agents on the motility of Angiostrongylus cantonensis were studied to define the neuropharmacological properties of this worm. Stimulation of the motility and/or contraction were shown by eserine, ACh, carbachol, nicotine, DMPP, pyrantel, and Ba2+, but not by pilocarpine and McN-A-343. Contraction was similarly observed by these agents in the preparations paralyzed with praziquantel. Paralysis was caused remarkably by d-tubocurarine and slightly by succinylcholine, while the contraction induced by eserine and DMPP was little influenced by these drugs. Both the motility and the eserine-induced contraction were little influenced by hexamethonium, but stimulated remarkably by atropine. Though hemicholinium-3, morphine, and picrate showed little effect, guanidine stimulated remarkably the motility and also the eserine-induced contraction. The stimulatory action of guanidine was antagonized by strychnine. Strychnine paralyzed the motility, and the eserine-induced contraction was antagonized by the pre- and post-treatment with strychnine. From these results, it is suggested that the excitatory cholinergic mechanism in A. cantonensis is nicotinic, and it is basically similar to that reported in Ascaris suum.