Altered cerebral vessel innervation in the spontaneously hypertensive rat.

Abstract

SUMMARY. Autonomic innervation in the cerebral arterial walls of adult male spontaneously hypertensive rats and of normotensive Wistar-Kyoto rats was studied. When examined by fluorescence microscopy, dense catecholamine fluorescence was observed in anterior cerebral and middle cerebral arteries of both Wistar-Kyoto and spontaneously hypertensive rats. However, vertebral and basilar arteries and small pial arteries of Wistar-Kyoto rats received extremely sparse or no catecholamine fluorescence, whereas, in the respective regions of spontaneously hypertensive rats, catecholamine fluorescence was found to be significantly elevated. The endogenous norepinephrine content was also higher in cerebral arteries of spontaneously hypertensive than of Wistar-Kyoto rats. When examined ultrastructurally (potassium permanganate fixation), the incidence of granular vesicle-containing nerves, indicative of sympathetic nerves, was found to be significantly elevated in all cerebral arteries of spontaneously hypertensive rats examined. In contrast, the agranular vesicle-containing nerve, indicative of nonsympathetic nerves, with close synaptic cleft distance (<2 /im) was found to decrease or remain unchanged in the cerebral arteries of spontaneously hypertensive rats. These results suggest that cerebral sympathetic vasoconstriction may become more prominent than nonsympathetic vasodilation in spontaneously hypertensive rats. This finding lends further credence to the previous in vivo findings that cerebral sympathetic vasoconstrictor nerves become more functional and exhibit a protective effect against brain lesions during hypertension. The potential roles of neurogenic components involved in cerebral blood flow autoregulation are also discussed. (Circ Res 55: 392-403, 1984)

Noradrenergic Innervation of Gerbil Large Cerebral Arteries

“…Catecholamine fluorescence histochemis try has demonstrated that the major cerebral (extraparenchymal) arteries in mammals, in cluding man and a variety of laboratory ani mals, are innervated by noradrenergic nerves [Nelson and Rennels, 1970;Edvinsson et al, 1972;Owman et al, 1974], The present study has shown that in the gerbil, the ante rior cerebral circulation (internal carotid sys tem) receives a denser noradrenergic inner vation than the posterior circulation (vertebro-basilar system), and this has also been reported in other species [Nielsen and Ow man, 1967;Peerless and Yasargil, 1971;Ed vinsson et al, 1976;Kobayashi et al, 1981;Lee and Saito. 1984], A fluorescence histochemical study was undertaken in order to investigate the distri bution.…”

Analysis of cerebrovascular sympathetic nerve density in relation to stroke development in spontaneously hypertensive rats.

“…The cerebral 11 and noncerebral 12 vascular beds of SRSHR have greater densities of sympathetic nerves than those of Wistar-Kyoto normotensive rats. A quantitative increase in sympathetic innervation could protect the cerebrovasculature of SRSHR from hemorrhage during hypertension by either trophically influencing the vasculature to develop a thickened vascular wall.…”

Hypernoradrenergic Innervation: Its Relationship to Functional and Hyperplastic Changes in the Vasculature of the Spontaneously Hypertensive Rat

“…Ichijma [1969] increased area of NA fluorescent fibres in jejunal arteries from SHR (40-60 days and 4-6 months of age) Berkowitz and Spector [1976] increased NA content (chemical assay) in mesenteric arteries from SHR (10, 15 and 27 weeks of age) Head and Berkowitz [1979] increased NA content (radioenzymatic assay) in mesenteric and renal arteries from SHR (adult) Berkowitz et al [1980] increased NA content (radioenzymatic assay) in mesenteric arteries from SHR (5 and 16 weeks of age) Scott and Pang [1983] increased area of NA fluorescence in jejunal arteries from SHR (2, 4 and 12 weeks of age) Lee and Saito [1984] increased NA fluorescence, increased NA content (radioenzymatic assay) and increased granular vesicle-containing nerves in cerebral blood vessels from SHR (24 weeks of age) Lee et al [1983] increased nerve density in mesenteric arteriolar vessels from SHR (10-12 weeks of age) Head et al [1984] increased NA content (high performance liquid chromatography in conjunction with electrochemical detection HPLC-ECD) in mesenteric arteries from SHR (16-20 weeks of age) Featherston et al [1984] increased density of fluorescent fibres in superior mesenteric arteries from SHR (10 days, 3 weeks and 6 weeks of age) Head et al [1985] increased NA content (radioenzymatic and HPLC-ECD assay) in the mesenteric artery, abdominal aorta, inferior vena cava, kidney and vas deferentia from SHR (16-20 weeks of age) Lee[1985] increased nerve density (morphometric analysis) in large mesenteric arteries from the SHR (3-4 weeks of age) Cassis et al [1985] increased NA fluorescence, increased NA content (HPLC-ECD) and increased number of axon bundles in the caudal artery of the SHR (16 weeks of age) Shimamura et al [1987] increased NA content (HPLC-ECD) in mesenteric arteries from SHRSP and M-SHRSP rats (6 weeks of age) Donohue et al [1988] increased NA content (HPLC-ECD and radioenzymatic assay) in caudal and mes enteric arteries of the SHR (2 days to 17 weeks of age) Albert [1987] increased axonal volume, density of axons and varicositic vesicles in caudal arter ies of the SHR (adult animals) SHR is greater than that of WKY rats from birth [Gray, 1984], It should be cautioned, however, that the early appearance of hypemoradrenergic in nervation is not a characteristic of all blood vessels in the SHR. Donohue et al [1988] have provided evidence which shows that the onset of increased NA contents in the caudal artery of the SHR occurs during the time course of expression of hypertension.…”