2022 Volume 59 Issue 1 Pages 83-87
This article reviews basic studies of the effects of acupuncture stimulation on cerebral cortical blood flow and the involvement of the cholinergic vasodilator system in these responses, focusing on comparisons between forelimb and auricular stimulation, and age-related changes. In anesthetized adult rats, manual acupuncture stimulation of a forepaw increases cortical cerebral blood flow (CBF) and mean arterial pressure (MAP), while stimulation of the auricular region increases CBF without altering MAP. The afferent pathways of these responses are somatic afferent nerves innervating the forepaw, or the auricular regions. The increase in CBF induced by forepaw stimulation is accompanied by an increase in cortical acetylcholine (ACh) release, which mediates ACh receptors of both the muscarinic and nicotinic subtypes. These findings suggest the contribution of the cholinergic cerebral vasodilator system. In aged rats, although vasodilation mediating the alpha-4 beta-2 type nicotinic receptors declines, that of the muscarinic receptors is maintained, and increased CBF resulting from forepaw acupuncture is also maintained. Because of its lesser effect on MAP, auricular stimulation might be more appropriate for clinical applications.
