Eicosapolyynoic acids, inhibitors of lipoxygenases, weaken the short-term plasticity of cholinoreceptors of neurons of the edible snail.

The influence of three polyacetylenic analogs of natural polyenoic acids which are inhibitors of their lipoxygenase oxidation on the dynamics of the extinction of the inward current induced by repeated iontophoretic applications of acetylcholine to the soma was investigated in identified RPa3 and LPa3 of the edible snail using the method of bielectrode recording of the potential on the membrane. It was found that eicosa-5,8,11,14-tetraynoic acid (30-60 mumole/liter) and eicosa-5,8,11,14,17-pentaynoic acid (4-50 mumole/liter) decrease the amplitude of the inward current induced by application of acetylcholine, and attenuate its extinction during repeated applications. The third analog, eicosa-8,11,14-triaynoic acid, does not exert a modulating influence on the magnitude of the current and its extinction. It was hypothesized that the lipoxygenase metabolites of the polyenoic acids regulate the plasticity of the cholinoreceptors of the neurons of the edible snail. Taking the nonidentical inhibition by the compounds used of the various lipoxygenases into account, the participation in the plasticity of the cholinoreceptors of those eicosanoids which are formed from arachidonic acid under the influence of 5-lipoxygenases is most probable. At the same time, a regulatory role of the eicosanoids formed under the influence of other lipoxygenases is not excluded.