Reactive changes in adrenal innervation of cerebral arteries in conditions of the activation of cholinergic mechanisms.

Abstract

The arterial vessels of the brain are characterized by efferent innervation which is abundant and diverse with respect to sources and morphobiological organization [4, 7,15]. At the same time, the functional significance of the neurogenic influences on the tonus of cerebral vessels and the permeability of the blood-brain barrier, as well as the character of the interrelationships between various components of the vascular innervation which are diverse in their mediator nature, are unclear in many respects [1, 10, 11, 14, 17]. The questions of interaction of the adrenergic and cholinergic portions of the nervous apparatus of the main-line arteries and the arteries of the pia mater which are morphologically most distinctly manifest are a constituent of this problem. The adrenergic innervation of the cerebral vessels has been studied in relatively great detail [4, 15]. The architectonics of the nerve plexi has been investigated, its sympathetic and brainstem sources have been identified, and the constrictor reactions of both the main-line and pial arteries in response to stimulation of the cervical sympathetic ganglia and the noradrenergic structures of the pons have been described [1, 10, 15]. On the other hand, information regarding the cholinergic innervation comes down in essence to a description of the elements of the nerve plexi and the dilator endothelium-dependent effects of the intravascular administration of acetylcholine [13, 14, 18]. The sources and functional purpose of the cholinergic fibers and terminals in the walls of the cerebral arteries have not been investigated [4, 7], although it may be considered proven that the neurogenic regulation of the cerebral circulation is mainly determined by the interrelationship of the adrenergic and cholinergic influences [10, 17]. The purpose of the present study is the investigation of the reaction of the adrenergic neural apparatus of the cerebral arteries to the prolonged pharmacological activation of the cholinergic mechanisms of the brain.