Neurogenic Regulation of Cerebral Blood Flow

Abstract

The brain has a well-developed vascular network, which allows it to consume up to 15% of the cardiac output with a low mass relative to the whole-body weight. Normally, the metabolic demands of the brain depend considerably on the intensity of functioning of its different departments, which requires constant regulation of the local blood flow level. On the other hand, the state of systemic hemodynamics can have a significant impact on the organ blood flow. Complex and multilevel mechanisms of the regulation of organ cerebral blood flow are aimed at minimizing the possible adverse effects of systemic hemodynamics impairment. The importance of precise and prompt regulation of cerebral blood flow is reinforced by the absence of energy reserves or substrates for its autonomous production in the nervous tissue. The main mechanisms of cerebral blood flow regulation include: myogenic regulation, influence of local humoral influences and vasoactive substances (hormones, metabolites) of systemic blood flow, changes in blood gas composition (increase or decrease in blood oxygen or carbon dioxide tension). In addition, endothelium-dependent mechanisms of regulation are distinguished. Finally, one more level of cerebral arterial tone regulation is represented by the effect of neurotransmitters released from vasomotor fibers terminals of sympathetic and parasympathetic sections of autonomic nervous system, as well as from subcortical neurons and cortical interneurons terminals. In the present review, the principles of neurogenic regulation of cerebral blood flow are considered. The neurogenic regulation of vascular tone is the most complex regulatory circuit. The autonomic innervation of cerebral vessels has significant features that distinguish it from that in most other organs of the great circulatory circle. In addition to the autonomic innervation proper, the vessels of the brain receive sensory innervation, and the small intracerebral arterioles are also innervated -directly by subcortical neurons and cortical interneurons. In this connection, a deeper understanding of the molecular mechanisms of the neurogenic regulation of cerebral blood flow may serve as a basis for the development of new methods of treatment of severe brain diseases based on neuromodulation in the long term.