[The effect of leukotrienes B4, C4, 12-hydroxyeicosatetraenoic acid and of the threo- and erythro-epimers of hepoxilin B3 on the plasticity of the neuronal cholinoreceptors in the snail].

Effects of several acyclic eicosanoids (which are formed from arachidonic acid under the action of 5- and 12-lipoxygenases) on desensitization of somatic cholinoreceptors of Helix lucorum RPa3 and LPa3 neurons were studied by means of two-electrode voltage clamp technique. The substances under study were: leukotrienes B4, C4, 12(S)-hydroxy-(5Z,8Z,10E,14Z)-eicosatetraenoic acid (12-HETE), threo- and erythro-epimers of hepoxilin B3. Cholinoreceptor plasticity was evaluated by a degree of depression of inward current, induced by rhythmical local ACh applications on the soma with intervals 55-180 sec. Leukotrienes B4 and C4 intensified cholinoreceptor plasticity. Inhibitor of inositol-1,4,5-trisphosphate-dependent (IP3-d) mobilization of deposited Ca2+, TMB-8, prevented the effect of leukotriene C4. 12-HETE, threo- and erythro-epimers of hepoxilin B3 did not change plasticity. A conclusion is made that cholinoreceptor plasticity is controlled by leukotrienes B4 and C4. One of the regulatory pathways includes IP3-d Ca-mobilization. Eicosanoids from 12-lipoxygenase pathway (12-HETE, threo- and erythro-epimers of hepoxilin B3) do not participate in this intracellular regulatory mechanism.