Innervation Of Cerebral Blood Vessels Research Articles

Inhibition of nNOS Changes Cerebrovascular Responses to Acute Hypertension

Interruption of parasympathetic nitroxidergic nerves to cerebral blood vessels or systemic administration of a nitric oxide synthase (NOS) inhibitor attenuates breakthrough of cerebrovascular autoregulation during acute hypertension. We hypothesized that neuronal NOS (nNOS) in parasympathetic fibers participated in the cerebrovascular effect and tested the hypothesis by administering the selective nNOS inhibitor propyl-L-arginine (PLA) or vehicle control into a cranial window. We first assessed the influence of PLA on cerebrovascular responses to acetylcholine (ACh; 10−5 M), which promotes synthesis of NO through endothelial NOS. We then increased mean arterial pressure (MAP) with intravenous phenylephrine (PE) while monitoring the diameter of cerebral arteries (41 ± 3 μm basal diameter). There was no significant change in dilatation in response to ACh before (7 ± 1 %) vs. after (5 ± 2 %) PLA. Basal MAP did not differ between groups. Vascular diameters increased significantly (p<0.05) less in animals that received the nNOS inhibitor (18 ± 6 μm) than in control rats (70 ± 15 μm) despite there being no significant difference in the change in MAP between groups. These findings further support our hypothesis that parasympathetic nitroxidergic innervation of cerebral blood vessels may participate in regulating cerebrovascular tone during hypertension. Support: VA Merit Review and NIH R01 HL59593.

Direct projections from the cardiovascular nucleus tractus solitarii to pontine preganglionic parasympathetic neurons: a link to cerebrovascular regulation.

Peripheral or central interruption of the baroreflex or the parasympathetic innervation of cerebral vessels leads to similar changes in regulation of cerebral blood flow. Therefore, we sought to test the hypothesis that the cardiovascular nucleus tractus solitarii, the site of termination of arterial baroreceptor nerves, projects to pontine preganglionic neurons whose stimulation elicits cerebral vasodilatation. The current study utilized both light and electron microscopic techniques to analyze anterograde tracing from the cardiovascular nucleus tractus solitarii to preganglionic parasympathetic neurons in the pons. We further used retrograde tracing from that same pontine region to the cardiovascular nucleus tractus solitarii and evaluated the confluence of tracing from the cardiovascular nucleus tractus solitarii to pontine preganglionic neurons labeled retrogradely from the pterygopalatine ganglia. The cardiovascular nucleus tractus solitarii projected to pontine preganglionic parasympathetic neurons, but more rostral and caudal regions of nucleus tractus solitarii did not. In contrast, all three regions of nucleus tractus solitarii projected to the nucleus ambiguus and dorsal motor nucleus of the vagus. Although not projecting to pontine preganglionic parasympathetic neurons, regions lateral, rostral, and caudal to cardiovascular nucleus tractus solitarii sent projections through the pons medial to the preganglionics. The study establishes the presence of a direct monosynaptic pathway from neurons in the cardiovascular nucleus tractus solitarii to pontine preganglionic parasympathetic neurons that project to the pterygopalatine ganglia, the source of nitroxidergic vasodilatory innervation of cerebral blood vessels. It provides evidence that activation of those preganglionic neurons can cause cerebral vasodilatation and increased cerebral blood flow. Finally, it demonstrates differential innervation of medullary and pontine preganglionic parasympathetic neurons by different regions of the nucleus tractus solitarii.

Innervation of cerebral blood vessels: morphology, plasticity, age-related, and Alzheimer's disease-related neurodegeneration.

The light microscopical and ultrastructural morphology of the innervation of the major cerebral arteries and pial vessels is described, including the origins of the different groups of nerve fibres and their characteristic neurotransmitter phenotype. Species and region specific variations are described and novel data regarding the parasympathetic innervation of cerebral vessels are presented. The dynamic nature, or plasticity, of cerebrovascular innervation is emphasized in describing changes affecting particular subpopulations of neurons during normal ageing and in Alzheimer's disease. The molecular controls on plasticity are discussed with particular reference to target-associated factors such as the neurotrophins and their neuronal receptors, as well as extracellular matrix related factors such as laminin. Hypotheses are presented regarding the principal extrinsic and intrinsic influences on plasticity of the cerebrovascular innervation.

Blood Pressure Lowering and Cerebral Blood Flow

The first part of this article concerns the general relation between blood pressure lowering and cerebral blood flow. Factors known to affect cerebral blood flow are reviewed, and recent advances in the field of innervation of cerebral blood vessels are outlined. Special emphasis is placed on the importance of the phenomenon of autoregulation and how this is disturbed in patients with hypertension. Not all antihypertensive drugs exert the same action on the cerebral circulation to produce the same blood pressure-lowering effect. In addition, the actions exerted by common antihypertensive drugs on the cerebral circulation are described. The second part of the article provides a comparison between the effect of carvedilol and that of propranolol on blood pressure reduction and cerebral blood flow. In a double-blind, crossover study involving 14 patients with mild-to-moderate hypertension, carvedilol was shown to have no effect on cerebral blood flow, whereas there was a slight tendency for lower flows to occur with the use of propranolol. Because of the small sample size, statistical significance was not reached. These results are consistent with other recently published findings.

Acetylcholine and vasoactive intestinal peptide in cerebral blood vessels: effect of extirpation of the sphenopalatine ganglion.

The innervation of cerebral blood vessels by nerve fibers containing acetylcholinesterase (AChE) and vasoactive intestinal peptide (VIP) and the vasomotor effects of the two neurotransmitters have been analyzed in the rat following the uni- or bilateral removal of the sphenopalatine ganglion (SPG), which is thought to be the major origin of this innervation. Histochemistry of AChE-positive nerve fibers and the immunoreactivity toward VIP revealed only a 30% reduction in the innervation pattern of the rostral part of the cerebral circulation following the operation. At approximately 4 weeks postoperatively, the original nerve network was restored. Quantitative measurements of cholineacetyltransferase activity and VIP revealed similar reductions in the levels of collected large cerebral arteries at the base of the brain and in small pial vessels overlying the cerebral cortex at the various postoperative times following uni- or bilateral removal of the SPG. The two techniques thus complemented each other. Vasomotor reactivity to acetylcholine (ACh) and VIP was examined in proximal segments of the middle cerebral artery at the various postoperative times. Generally, the removal of the SPG had no effect on the responses to ACh or VIP. The evidence indicates that only approximately one-third of the cholinergic/VIP innervation of the rostral part of the cerebral circulation originates in the SPG.

Autonomic innervation of cerebral blood vessels decreases in renal hypertensive rats.

The ultrastructural distribution of the autonomic nerves of brain arteries was investigated in renal (one-kidney, one clip) hypertensive and normotensive Wistar-Kyoto rats. Sympathetic and nonsympathetic nerve terminals were found only in the adventitial layer of brain arteries of renal hypertensive and normotensive rats. In both normotensive and renal hypertensive rats the total nerve endings were dense in anterior cerebral artery, moderately dense in middle cerebral artery, and sparse in basilar artery. In normotensive rats, nonsympathetic nerves outnumbered sympathetic nerves in anterior cerebral, middle cerebral, and basilar arteries. In renal hypertensive rats these two types of nerve terminals in close apposition to smooth muscle decreased in anterior cerebral and basilar arteries, while those in middle cerebral arteries remained unchanged. These results suggest that the potential neurogenic control of cerebral blood vessels as well as the trophic effect of sympathetic nerves on brain blood vessels may decrease in renal hypertensive rats. As this finding contrasts with that in spontaneously hypertensive rats, the pattern of innervation in brain arteries may differ in different types of hypertension.

Peptidergic innervation of cerebral blood vessels

Peptidergic innervation of cerebral blood vessels

Peptidergic innervation of cerebral blood vessels

Peptidergic innervation of cerebral blood vessels

A histochemical study on the innervation of cerebral blood vessels in the bullfrog

Specific histochemical techniques for the demonstration of catecholamine and acetylcholinesterase have been used to study the distribution of adrenergic and cholinergic nerves on the cerebral blood vessels of bullfrog, Rana catesbeiana. The adrenergic nerve meshworks on the cerebral arteries of bullfrog were less dense, had a more elongate appearance along the arterial axis as compared with those of mammals and were rather similar to those of snakes. The nerve plexuses on the cerebral carotid artery and its main branches were somewhat denser than those on the basilar artery. The most characteristic feature of innervation in the bullfrog cerebral vessels was that no acetylcholinesterase-positive fibres were observed on the extraparenchymal arteries, whereas, in all higher vertebrates investigated so far, the cerebral arteries have been found to be dually innervated although differences in the density of innervation of the two nerves may exist. This suggests that the peripheral adrenergic innervation on the cerebral blood vessels appeared earlier than the cholinergic one in the evolution of vertebrates. On the other hand, both adrenergic and acetylcholinesterase-positive fibres were observed in close contact with parenchymal arterioles and capillaries suggesting the possible existence of a dual central innervation. This feature, however, was by no means common. Thus, the central neurons have a significant influence on the cerebral circulation in the bullfrog is somewhat equivocal. Most of the pial and the parenchymal small vessels and the parenchymal capillaries exhibited a heavy acetylcholinesterase activity on the vascular walls. Although the significance of the enzyme is obscure as yet, this has to be considered in relation to the regulatory mechanism of the cerebral circulation.

Do vasomotor nerves significantly regulate cerebral blood flow?

HomeCirculation ResearchVol. 43, No. 4Do vasomotor nerves significantly regulate cerebral blood flow? Free AccessAbstractPDF/EPUBAboutView PDFSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyRedditDiggEmail Jump toFree AccessAbstractPDF/EPUBDo vasomotor nerves significantly regulate cerebral blood flow? M J Purves M J PurvesM J Purves Search for more papers by this author Originally published1 Oct 1978https://doi.org/10.1161/01.RES.43.4.485Circulation Research. 1978;43:485–493 Previous Back to top Next FiguresReferencesRelatedDetailsCited ByLevine B, Giller C, Lane L, Buckey J and Blomqvist C (1994) Cerebral versus systemic hemodynamics during graded orthostatic stress in humans., Circulation, 90:1, (298-306), Online publication date: 1-Jul-1994.Dodge J, Bevan R and Bevan J (1994) Comparison of density of sympathetic varicosities and their closeness to smooth muscle cells in rabbit middle cerebral and ear arteries and their branches., Circulation Research, 75:5, (916-925), Online publication date: 1-Nov-1994.Saito A and Lee T (1985) Autonomic innervation of cerebral blood vessels decreases in renal hypertensive rats., Hypertension, 7:4, (514-518), Online publication date: 1-Jul-1985.Briggs L, Garcia J, Conger K, Pinto de Moraes H, Geer J and Hollander W (1985) Innervation of brain intraparenchymal vessels in subhuman primates: ultrastructural observations., Stroke, 16:2, (297-301), Online publication date: 1-Mar-1985.Crystal G, Downey H, Adkins T and Bashour F (1983) Regional blood flow in canine brain during nicotine infusion: effect of autonomic blocking drugs., Stroke, 14:6, (941-947), Online publication date: 1-Nov-1983.Bevan J, Buga G, Jope C, Jope R and Moritoki H (1982) Further evidence for a muscarinic component to the neural vasodilator innervation of cerebral and cranial extracerebral arteries of the cat., Circulation Research, 51:4, (421-429), Online publication date: 1-Oct-1982.Nakai K, Imai H, Kamei I, Itakura T, Komari N, Kimura H, Nagai T and Maeda T (1981) Microangioarchitecture of rat parietal cortex with special reference to vascular "sphincters". Scanning electron microscopic and dark field microscopic study., Stroke, 12:5, (653-659), Online publication date: 1-Sep-1981.Sadoshima S, Busija D, Brody M and Heistad D (1981) Sympathetic nerves protect against stroke in stroke-prone hypertensive rats. A preliminary report., Hypertension, 3:3_pt_2, (I124), Online publication date: 1-May-1981. (1980) Report of the Hypertension Task Force of the National Heart, Lung, and Blood Institute. Current research and recommendations from the Subgroup on Local Hemodynamics., Hypertension, 2:3, (342-369), Online publication date: 1-May-1980.Busija D, Heistad D and Marcus M (1980) Effects of sympathetic nerves on cerebral vessels during acute, moderate increases in arterial pressure in dogs and cats., Circulation Research, 46:5, (696-702), Online publication date: 1-May-1980.Heistad D and Marcus M (1979) Effect of sympathetic stimulation on permeability of the blood-brain barrier to albumin during acute hypertension in cats., Circulation Research, 45:3, (331-338), Online publication date: 1-Sep-1979. October 1, 1978Vol 43, Issue 4Article InformationMetrics Copyright © 1978 by American Heart Associationhttps://doi.org/10.1161/01.RES.43.4.485 Originally publishedOctober 1, 1978 PDF download Advertisement

A histochemical study of the innervation of cerebral blood vessels in the turtle.

Specific histochemical techniques for the demonstration of noradrenaline and of acetylcholinesterase have been used to study the distribution of adrenergic and cholinergic nerves to the cerebral blood vessels of turtle, Geoclemys reevesii. The major and medium-sized cerebral arteries were supplied with dense adrenergic nerve plexuses, the plexuses were particularly dense in the medium-sized pial arteries of very thick vascular wall, indicating the functional significance of these arteries in the cerebral circulation. The parenchymal arterioles and capillaries were also supplied with adrenergic nerves. On the other hand, the cholinergic innervation was less dense than the adrenergic one and the acetylcholinesterase activity of the nerve fibres was remarkably weak. By contrast, the parenchymal small arterioles and capillaries exhibited heavy acetylcholinesterase activity on the vascular wall and, in addition, the capillaries were supplied with the well-stained acetylcholinesterase-positive nerve fibres. These fibres and also the adrenergic fibres associating with the capillaries appear to be of central origin. It is suggested that the cholinergic mechanisms in the parenchymal small vessels also play an important role in the cerebral circulation. The basophil leucocytes observed abundantly in the blood of turtle emitted an intensive greenish yellow fluorescence after formaldehyde gas-treatment.

A histochemical study of the innervation of cerebral blood vessels in the snake.

Dual innervation of snake cerebral blood vessels by adrenergic and cholinergic fibres was demonstrated with the use of histochemical methods. Although the nerve plexuses are somewhat less dense, the essential features of innervation of the blood vessels are similar to those of mammals with the exception that the adrenergic plexuses are more prominent than the cholinergic plexuses. The major arteries of the cerebral carotid system have a rich nerve supply. However, the innervation is less rich in the basilar and poor in the spinal (vertebral) arteries. Although the arteries supplying the right side of head are poorly developed, three pairs of arteries, cerebral carotids, ophthalmics and spinals, supply the snake brain. The carotids and ophthalmics are densely innervated and are accompanied by thick nerve bundles, suggesting that the nerves preferentially enter the skull along those arteries. Some parenchymal arterioles are also dually innervated. Connection between the brain parenchyma and intracerebral capillaries via both cholinergic and adrenergic fibres was observed. In addition cholinergic nerve fibers, connecting capillaries and the intramedullary nerve fibre bundles, were noticed. Capillary blood flow may be influenced by both adrenergic and cholinergic central neurons. The walls of capillaries also exhibit heavy acetylcholinesterase activity. This may indicate an important role for the capillary in the regulation of intracerebral blood flow.

The innervation of cerebral blood vessels by central noradrenergic neurons

Publisher Summary This chapter describes a study analyzing the innervation of cerebral blood vessels by central noradrenergic neurons. Bilateral superior cervical ganglionectomised rats and sham operated controls were examined using the immunofluoresence technique for dopamine-β-hydroxylase (DBH) localization. The brains were examined for 7 days, 14 days and 2 months after surgery. Sham operated controls showed the typical dense noradrenergic innervation of pial vessels. Bilateral ganglionectomy resulted in the disappearance of DBH-containing fibers on pial blood vessels. The absence of the sympathetic innervation throughout the pial system was used as the criterion of complete removal of both superior cervical ganglia. By 7 days all traces of the pial vessel innervation had disappeared and in no case was there any apparent regeneration of sympathetic fibers even after 2 months. Within the brain parenchyma, superior cervical ganglionectomy resulted in no detectable decrease in the presence of noradrenergic fibers or terminals associated with small arteries and arterioles. The chapter shows small vessels as observed in the brains of superior cervical ganglionectomised rats. Varicose DBH-containing fibers were seen in close association with these small vessels.