The Effect of M-Cholinoreceptor Blockade on Functional Activity of Somatomotor, Cardiovascular and Respiratory Systems in Newborn Rats upon Activation of Cholinoreactive Structures

Resumo

Activities of the somatomotor, cardiovascular and respiratory systems were investigated in conditions of impaired cholinergic regulation in rat pups aged 1 and 16 days. Acetylcholinesterase (AChE) inhibition by physostigmine (eserine), which leads to activate cholinoreactive structures, is accompanied by a unidirectional impairment of the cardiac sinus rhythm in newborn and, to a lesser extent, 16-day-old rats. Activation of cholinoreactive structures decreases the rate and regularity of breathing and also alters the pattern and parameters of motor activity. Physostigmine injection potentiates motor activity in 1-day-old and depresses it in 16-day-old rats. The blockade of muscarinic cholinoreceptors in rats of both age groups largely affects functional activity of the cardiovascular system, preventing severe cardiac arrhythmias caused by injection of the AChE inhibitor. It was shown that the formation of the definitive level of cholinergic regulation, including the maturation of the mechanisms underlying reciprocal interactions within the cholinergic system itself, is completed in the early period of rat postnatal ontogenesis. Age-related differences in responses of the somatomotor, cardiovascular and respiratory systems to changes in the level of activation of cholinoreactive structures are associated with these processes.