Role of acetylcholine in regulation of interaction between axon and Schwann cell during rhythmic excitation of nerve fibers

Axon excitation increases the number of acetylcholine receptors (ACR) of th e Schwann cell (SC) depending on the frequency of rhythmic excitation (RE) and on intercellular concentrations of K+, Ca2+, and acetylcholine. During RE, activity of axonal acetylcholine esterase is decreased, thus providing for high intercellular acetylcholine concentration. Increased intercellular concentration of acetylcholine activates phosphoinositide-specific phospho lipase C (PIPLC) of the myelin nerve fiber. During RE, K+ depolarization an d acetylcholine exocytosis can activate Ca2+ entry via Ca2+ channels, thus inducing SC ACR phosphorylation mediated by PIPLC stimulation.