[The role of adenylate cyclase and phosphoinositide second messenger systems in regulation of acetylcholine secretion in synapses of the cerebral hemispheres and brain stem in rats]

Abstract

Changes in acetylcholine secretion in the cholinergic synapses of the rat cerebral hemispheres and brain stem were studied in in vivo experiments against the background of modulation of the activity of the adenylate cyclase and phosphoinositide secondary messenger systems by injection of caffeine and lithium chloride. The level of mediator secretion was determined according to the content of bound acetylcholine fractions in the homogenate of the indicated parts of the animal's brain. It was established that secretion of the mediator in the rat hemispheres is regulated by postsynaptic N-cholinoceptors located on the body of cholinergic neurons which have a phosphoinositide system actiung as secondary mediators and, possibly are related to subtype M1. It is also possible that the secretion is also regulated by presynaptic autoreceptors connected with the adenylate cyclase system, which function according to the mechanism of negative feedback and is related to subtype M2. Acetylcholine secretion in the brain stem synapses is regulated according to the negative feedback mechanism by muscarine receptors linked with the adenylate cyclase system and probably related to subtype M4.