Regulation of regional cerebral blood flow by cholinergic fibers originating in the basal forebrain.

The intracranial neural vasodilative system of cholinergic fibers projecting from the basal forebrain to the cortex was discovered by Biesold, Inanami, Sato and Sato (Biesold, D., Inanami, O., Sato, A., Sato, Y., 1989. Stimulation of the nucleus basalis of Meynert increases cerebral cortical blood flow in rats. Neurosci. Lett. 98, 39-44) using laser Doppler flowmetry in anesthetized rats. This cholinergic vasodilative system, which operates by increasing extracellular ACh release, relies upon activation of both muscarinic and nicotinic cholinergic receptors in the parenchyma of the cortex. Further, the involvement of nitric oxide in this cholinergic vasodilation, indicates the necessity to this system of neurons, which contain nitric oxide synthase. The increase in cortical blood flow elicited by this cholinergic vasodilative system is independent of systemic blood pressure and is not coupled to cortical metabolic rates. This cholinergic vasodilative system may be activated by somatic afferent stimulation. Most of the data presented here were obtained in anesthetized animals.