Sympathetic nerve terminals in the tunica media of human superficial temporal and middle cerebral arteries: wet histofluorescence

Effect of Adventitial Dissection of Superficial Temporal Artery on the Outcome of Superficial Temporal Artery-Middle Cerebral Artery Bypass in Moyamoya Disease

Superficial temporal artery-middle cerebral artery (STA-MCA) has been used for the treatment of occlusive cerebrovascular disease including moyamoya disease. The effect of STA-MCA bypass depends not only on the patency of anastomosis, but also on integrity and functional capacity of the donor artery. In the present prospective study, we investigated the effect of extensive stripping STA adventitia and fasciae on hemodynamic function in STA-MCA bypass of moyamoya disease patients. Twenty patients (n=8 in control group, n=12 in stripping group) of moyamoya disease were subjected to STA-MCA end-to-side direct anastomosis. Perfusion unit (PU) values of the cortex were measured and recorded using a Laser Doppler flowmetry (LDF) for 5 days. Computed tomography perfusion was performed to determine blood flow before and after bypass. No patient experienced significant neurologic deficits associated with neurosurgical complications. LDF demonstrated that adventitial stripping group had higher cerebral blood flow increase than control group. The adventitia stripping group tends to have higher rate of increased cerebral perfusion after bypass than non-stripping group. Furthermore, the ultrasound examination at 3 days after bypass demonstrated that the adventitial stripping group has a tendency of bigger STA and higher peak systolic velocity than control group. Our result suggests that stripping adventitia of STA improves hemodynamics of STA-MCA bypass in moyamoya disease.

Perivascular nerves of the human basal cerebral arteries: I. Topographical distribution

In the present study the topographical distribution of the intrinsic nerve plexuses of the basal cerebral arteries in humans was quantified and the relation between vessel diameter and nerve density was investigated. Whole-mount preparations of various segments of the basal cerebral arteries from middle-aged patients were stained for protein gene product (PGP) 9.5. The deep nerve plexuses, located at the adventitial-medial border, were quantified by image analysis. Confocal scanning laser microscopy was used to study nerve plexuses throughout the adventitia. Transverse cryostat sections were stained for PGP 9.5, tyrosine hydroxylase and neurofilament, and quantified. The results showed a three-layered configuration of the adventitial nerves. Measurements on whole-mounts demonstrated that nerve densities were highest in the posterior communicating artery (PCom), and next highest in the proximal parts of the posterior cerebral artery (PCA) and anterior choroidal artery. There appeared to be no clear relation between nerve density and vessel diameter. The measurements on sections confirmed the high nerve densities in the PCom and PCA. Tyrosine hydroxylase- and neurofilament-immunoreactivities appeared to demonstrate separate subpopulations of the overall nerve plexuses, representing sympathetic and, possibly, sensory fibers, respectively. Densities of both subgroups generally followed those of PGP 9.5-immunoreactive nerves. Transmission electron microscopy suggested motor function of the deep nerve plexuses. The results indicate a stronger neuronal influence on this part of the cerebral circulation than hitherto reported. It is concluded that human basal cerebral arteries display a topographical distribution of deep perivascular nerves, and that nerve density is determined by locality rather than by vascular diameter.

Innervation of cerebral arteries by nerves containing 5-hydroxytryptamine and noradrenaline

Noradrenaline (NA)-containing nerves, mainly originating in the sympathetic superior cervical ganglia, supply large and small cerebral arteries. In large cerebral arteries, nerves containing serotonin (5-hydroxytryptamine, 5-HT) may represent neuronal uptake of circulating 5-HT by sympathetic nerves. 5-HT-containing nerves supplying small pial vessels probably have a central origin in the dorsal raphe nucleus. In most species, NA is a weak vasoconstrictor (alpha 1- or alpha 2-adrenoceptors), while 5-HT is a potent vasoconstrictor (5-HT2 or 5-HT1-like receptors) of large cerebral arteries. In contrast, both NA and 5-HT tend to cause vasodilatation in small pial vessels and arterioles. Adrenergic and serotonergic transmission can be modulated by pH, a range of putative neurotransmitters and neuromodulators, and by the endothelium. Sumatriptan, a 5-HT1-like receptor agonist, has been shown to be effective in the treatment of migraine. Changes in NA- or 5-HT-containing nerves and/or in the responses of cerebral vessels to NA and 5-HT have been observed in a variety of vascular disorders, including cerebral vasospasm following subarachnoid haemorrhage, hypertension, and atherosclerosis.

Monoamine oxidase-containing nerve fibers in the major cerebral arteries of rats

The localization of monoamine oxidase (MAO) in nerve fibers associated with the major cerebral arteries in rats was studied using a new coupled peroxidation method modified by adding nickel ammonium sulfate at the electron microscopic level. MAO was, localized in some unmyelinated axons, both in the adventitia and in the periadventitial nerve bundles. Schwann cell cytoplasm encircling myelinated axons in the periadventitial nerve bundles also contained a MAO-reactive substance. The incidences of MAO-containing axons in the adventitial layer of the anterior cerebral, middle cerebral, internal carotid and basilar arteries were 32.3%, 29.5%, 29.6% and 21.1%, respectively. In the periadventitial nerve bundles, MAO activity was also demonstrated in 10.8% among unmyelinated axons. Preincubation with clorgyline, a specific inhibitor of MAOA, suppressed staining in the axons, both in adventitia and in periadventitial nerve bundles, but not in the Schwann cell cytoplasm. Conversely, preincubation with deprenyl, a specific inhibitor of MAOB, suppressed staining in the Schwann cell cytoplasm, but not in the axons. Therefore, MAO in the axons is regarded as MAOA and MAO in the Schwann cell cytoplasm as MAOB. In immunosympathectomized rats (anti-NGF-treated rats), MAO reactivity was suppressed in axons associated with cerebral arteries, but was retained in some Schwann cell cytoplasm. The results indicate that the MAO-containing unmyelinated axons coincide with the postganglionic noradrenergic ones. Thus, histochemical MAO staining may be utilized to study postganglionic sympathetic nerve fibers presumably innervating the major cerebral arteries at the electron microscopic level.

Neuronal pathways to the rat middle meningeal artery revealed by retrograde tracing and immunocytochemistry

The origin of nerve fibers to the middle meningeal artery of rat was studied by retrograde tracing in combination with immunocytochemistry. Application of the retrograde tracer, True blue (TB), to the middle meningeal artery labeled nerve cell bodies in the ipsilateral superior cervical ganglion, the otic ganglion, the sphenopalatine ganglion, the jugular-nodose ganglionic complex, the trigeminal ganglion and the cervical dorsal root ganglion at level C2. A few nerve cell bodies were labeled in the contralaterally placed ganglia. Judging from the number of labeled nerve cell bodies, the ipsilateral superior cervical ganglion, the otic ganglion, the sphenopalatine and the trigeminal ganglia contribute most to its innervation. A moderate supply of labeled nerve cell bodies was seen in the cervical dorsal root ganglion at level C2 whereas there were only few in the jugular-nodose ganglionic complex. The TB-labeled nerve cell bodies were further examined for the presence of neuropeptides. For that purpose antibodies against neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP) and substance P (SP) were used. Most of the TB-labeled nerve cell bodies in the superior cervical ganglion exhibited NPY-immunoreactivity. In the sphenopalatine and otic ganglia the majority of the TB-labelled neurons were VIP-immunoreactive whereas in the trigeminal and dorsal root ganglion at level C2 the majority of labeled nerve cell bodies displayed CGRP-immunofluorescence and a minority of the labeled nerve cell bodies were substance P-immunoreactive. Together the findings indicate that several ganglia project to the middle meningeal artery of the rat and that many neuropeptides are involved in vasomotor control and in mediation of afferent information.

Origin and distribution of cerebral vascular innervation from superior cervical, trigeminal and spinal ganglia investigated with retrograde and anterograde WGA-HRP tracing in the rat

Peripheral sources of cerebral vascular innervation have been investigated with retrograde and anterograde neuronal tracing of wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP) in the rat. For retrograde identification of sources of innervation, WGA-HRP was applied to the exposed basilar artery through a fine slit in the overlying meninges, and sections of brain and peripheral ganglia were reacted with tetramethylbenzidine for detection of the tracer. A high density of tetramethylbenzidine reaction product was observed around the basilar artery and in the surrounding pial tissue, but the application sites were not completely selective since some tracer always had spread into the ventral brain stem. Retrogradely labelled cell bodies were identified in the superior cervical, stellate, first and second spinal, and trigeminal ganglia, i.e. these ganglia may represent origins of basilar artery innervation. In a second series of experiments, microinjections of WGA-HRP were placed into the indicated ganglia to obtain anterograde labelling of nerve fibres on whole-mounts of the cerebral vessels. Injections into trigeminal ganglia labelled nerve fibres on the ipsilateral half of the circle of Willis, as well as the contralateral anterior cerebral artery and the rostral part of the basilar artery. The first and second spinal ganglia projected to the vertebrobasilar arteries, while the ipsilateral part of the internal carotid (outside the circle of Willis) received fibres from the second spinal ganglion. Nerve fibres originating in trigeminal and spinal ganglia were organised in bundles, and between these a sparse plexus of thin single fibres appeared. Injection of WGA-HRP into superior cervical ganglion labelled a plexus of nerve fibres on the ipsilateral circle of Willis and the (rostral) basilar artery. These experiments demonstrated the origin and distribution of sympathetic and sensory innervation to major cerebral arteries in the rat.