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

Abstract

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.

Neurons of a Limited Subthalamic Area Mediate Elevations in Cortical Cerebral Blood Flow Evoked by Hypoxia and Excitation of Neurons of the Rostral Ventrolateral Medulla

“…ZI-SVA projects further to the BF (Ricardo, 1981;Jones 1995) and makes it a good candidate to mediate cerebrovasodilator effects of SVA excitation. Electrical or chemical stimulation of the BF produces global and independent of metabolism increase in rCBF (Biesold et al, 1989;Lacombe et al, 1989;Kimura et al, 1990;Sato and Sato, 1992). However, failure of electrolytic lesion of BF to reverse the vasodilator effect of SVA stimulation refuted a possible relay role of the BF.…”

“…The rCBF increase evoked from BF is independent of metabolism (Kimura et al, 1990) and mediated by cholinergic mechanisms (Dauphin et al, 1991;Scremin et al, 1991;Sato and Sato, 1992;Zhang et al, 1995). We hypothesized that the BF might mediate the vasodilation evoked by the stimulation of the SVA.…”

Effect of Acupuncture-Like Stimulation on Cortical Cerebral Blood Flow in Anesthetized Rats.

“…The intracranial cholinergic vasodilative system, discovered by Sato and his colleagues in 1989 [15,16] and reviewed by Sato and Sato in 1992 [14], have the following characteristic properties: (1) There are diffuse projections from the NBM to the frontal, parietal and occipital cortices. (2) Extracellular ACh is released in the cortex and activates the muscarinic and nicotinic ACh receptors.…”

“…Recent studies in our laboratory have shown that cortical CBF is regulated by intracranial nerves (see review by Sato and Sato [14]). Particularly, excitation of cholinergic nerve fibers originating in the basal forebrain nucleus (the nucleus basalis of Meynert) releases extracellularly acetylcholine (ACh) in the cortex [15], resulting in an increase in cortical CBF [16], independent of metabolic vasodilation [17].…”

Interpretation of Microdialysis Data

“…If we stretch the limits of this schematic even further to include mechanisms, it could be envisaged that the induction of behaviors with appropriate physiological components of appropriate magnitude is attained by regulating the influence of the lateral connections between neural circuits that facilitate related behaviors. As an example, neural regulation of hippocampal blood flow by septal mechanisms (Osborne, 1996) may be associated with septally derived cortical arousal (Buzsaki et al, 1983), which may be associated with active memory or learning (Hagan et al, 1988;Chrohack and Napier, 1992;Givens and Olton, 1994;Osborne, 1994), all of which may be associated with an increase in content of hippocampal ACh (Decker et al, 1988;Cao et al, 1990;Sato and Sato, 1992). Furthermore, the neuroarchitecture suggested above is not homogeneous but varies as the influence of lateral connections alters as one anatomical brain region merges with the adjacent histologically defined brain region.…”