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Biomedical subjects

R Uddman

Publications and source records attributed to R Uddman.

At least 145 records · Page 8Linked to original sources

Cerebral veins: fluorescence histochemistry, electron microscopy, and in vitro reactivity.

Pial veins, choroid plexus veins, and the cerebri magna vein were investigated with regard to their ultrastructural organization, adrenergic nerve supply, and in vitro reactivity. The vessel walls consisted of a continuous layer of endothelial cells, large amounts of collagenous material, and occasional pericytes. Smooth muscle cells were observed only in a few specimens from the cerebri magna vein. All veins were surrounded by adrenergic nerve fibres. Potassium (124 mM) and noradrenaline (10(-5) - 10(-4) M) induced small contractions (0.2-0.5 mN) of isolated veins during in vitro conditions. The magnitude of these responses was less than one-tenth of that obtained in small pial arteries.

Animals↗

Nerve fibres containing gastrin-releasing peptide around pial vessels.

Nerve fibres containing immunoreactive gastrin-releasing peptide (GRP) were demonstrated around pial blood vessels of cat, guinea pig, rat, and mouse. A sparse supply was found around spinal cord blood vessels, whereas the choroid plexus seemed to be devoid of GRP fibres. Sympathectomy did not affect the number or distribution of the GRP fibres. The administration of neither GRP nor its closely related analogue, bombesin, contracted or dilated feline pial arteries in vitro.

Animals↗

Functional role for vasoactive intestinal polypeptide in the caudate nucleus: a 2-deoxy[14C]glucose investigation.

The quantitative autoradiographic 2-deoxy-[14C]glucose technique has been used with conscious rats to investigate the functional consequences (reflected as alterations in local rates of glucose utilization) of unilateral intrastriatal administration of vasoactive intestinal polypeptide. Intrastriatal administration of vasoactive intestinal polypeptide (20 pmol) significantly increased local glucose utilization in the injected striatum, where the increased use was localized in small punctate areas (100-500 microns wide in coronal sections) scattered throughout the nucleus at considerable distances (up to 4 mm) from the injection site. Significantly increased glucose utilization after intrastriatal injection of vasoactive intestinal polypeptide was observed in a number of regions (e.g., substantia nigra pars compacta, entopeduncular nucleus, lateral habenular nucleus, entorhinal, pyriform cortices, and amygdala) with known primary or secondary neuronal connections with the caudate nucleus. These alterations in glucose utilization were highly focal in nature, with the majority (40 of the 50 examined) of brain regions displaying unaltered rates of glucose utilization. The data provide evidence, obtained in conscious animals, that vasoactive intestinal polypeptide can modify functional processes in the caudate nucleus.

Animals↗

The feline carotid rete: vasomotor reactivity of isolated arteries.

Vasomotor responses of arteries from the feline carotid rete were examined using a sensitive in vitro system. The vessel segments constricted in response to several vasoactive agents and putative neurotransmitters. Sympathomimetic agents (noradrenaline, adrenaline, oxymetazoline, phenylephrine), 5-hydroxytryptamine, histamine, angiotensin II, and prostaglandin F2 alpha all induced concentration-dependent contractile responses. The contractions induced by noradrenaline, 5-hydroxytryptamine, and histamine could be antagonized by phentolamine, methysergide, and mepyramine, respectively. Cholinomimetics (acetylcholine, carbacholine), vasoactive intestinal peptide and papaverine induced potent dilatory responses. The effect of carbacholine was shifted towards higher agonist concentrations by atropine. Dilatations, though small in magnitude, were found by application of adenosine, isoproterenol, and histamine. These results correlate well with the recent demonstration of autonomic nerves and indicate the occurrence of corresponding receptor sites in the walls of the carotid rete arteries.

Acetylcholine↗

Neuropeptides in the thyroid gland: distribution of substance P and gastrin/cholecystokinin and their effects on the secretion of iodothyronine and calcitonin.

Previously, vasoactive intestinal polypeptide was localized to intrathyroidal nerve fibers. It stimulates iodothyronine secretion in mice. In the present study two populations of nerve fibers containing substance P and gastrin/cholecystokinin (CCK)-like immunoreactivity, respectively, were demonstrated in the thyroid gland of several mammals. The substance P fibers occurred around blood vessels and follicles, whereas the gastrin/CCK fibers occurred mainly around follicles. In the chicken thyroid and ultimobranchial glands only substance P-containing fibers could be demonstrated. Such fibers were particularly numerous in the ultimobranchial gland. CCK-4, CCK-8, and substance P did not increase thyronine secretion measured as release of radioiodine into the circulation of mice pretreated with Na125I and T4. The TSH-induced release of radioiodine was also unaffected. Calcitonin secretion in rats was stimulated by CCK-4, CCK-8, substance P, and vasoactive intestinal polypeptide.

Animals↗

Lack of vasoactive intestinal polypeptide nerves in esophageal achalasia.

Vasoactive intestinal polypeptide-containing nerves were examined in the lower esophagus of control and achalasia patients. The smooth muscle in patients with achalasia had conspicuously fewer vasoactive intestinal polypeptide-immunoreactive nerve fibers than specimens from control patients. Also the concentration of vasoactive intestinal polypeptide in the lower esophagus was much reduced in achalasia. In view of the potent smooth muscle relaxing effects of vasoactive intestinal polypeptide, it is suggested that the reduced number of vasoactive intestinal polypeptide fibers in the achalasic esophagus causes or at least contributes to the incomplete relaxation and the increased resting tone of the lower esophageal sphincter characteristic of this disease.

Adult↗

VIP (vasoactive intestinal polypeptide)--immunoreactive innervation of the portal vein.

Nerve fibres displaying immunoreactivity for vasoactive intestinal polypeptide (VIP) were found in the wall of the portal vein in cats, guinea pigs, rats and mice. In whole-mount preparations a sparse network of VIP fibres was seen in the vessel wall. Electrical field stimulation of the rat portal vein in vitro caused a significant release of VIP. The results suggest that VIP ergic nerve fibres play a role in the regulation of portal blood flow.

Animals↗

Perivascular nerves in the feline carotid rete.

Numerous nerve fibres containing acetylcholinesterase and noradrenaline, as well as avian pancreatic polypeptide-, vasoactive intestinal peptide-, or substance P-like immunoreactivity are observed around arteries in the external carotid rete of the cat. The nerves are located in the adventitial layer close to the media. It is possible that adrenergic, cholinergic and peptidergic nerve fibres may have a strong neurogenic influence on the rete blood vessels.

Acetylcholinesterase↗

Adrenergic and peptidergic innervation of cochlear blood vessels.

Guinea pig cochlear blood vessels were investigated with regard to their supply of adrenergic and peptidergic nerve fibers. Using the glyoxylic acid histofluorescence technique, numerous adrenergic fibers were seen around the labyrinthine artery, whereas the spiral modiolar artery contained only few such fibers. Immunocytochemistry revealed nerve fibers containing immunoreactive avian pancreatic polypeptide, vasoactive intestinal peptide, substance P, or gastrin-releasing peptide around the labyrinthine and spiral modiolar arteries. Adrenergic or peptidergic nerve fibers were not seen around the blood vessels of the stria vascularis. Upon removal of the superior cervical ganglion, adrenergic fibers disappeared and fibers displaying avian pancreatic polypeptide immunoreactivity were reduced in number. These data suggest co-occurrence of catecholamines and immunoreactive avian pancreatic polypeptide in a population of adrenergic nerves.

Adrenergic Fibers↗

Somatostatin and VIP neurons in the retina of different species.

Neurons displaying somatostatin or vasoactive intestinal polypeptide (VIP) immunoreactivity were detected among the amacrine cells in the retina of baboon, cynomolgus monkey, squirrel monkey, cow, pig, cat, rabbit, guinea-pig, rat, mouse, frog and goldfish. Generally, immunoreactive cell bodies were located in the inner nuclear layer with processes ramifying in three more or less well-defined sublayers in the inner plexiform layer. The density of the sublayers and their location varied with the peptide and species investigated. In most cases there was a sublayer in the outermost part (Ramon y Cajal's sublamina 1) of the inner plexiform layer and this sublayer was usually the best developed. In some species a few somatostatin fibres were also detected in the outer plexiform layer, suggesting that some interplexiform cells contain somatostatin. In the baboon VIP was found exclusively in interstitial amacrine cells which have their cell bodies and processes entirely within the inner plexiform layer.

Animals↗

Neuronal substance P in the esophagus. Distribution and effects on motor activity.

Substance P-immunoreactive nerve fibres were fairly numerous in the lower esophagus of the guinea-pig and cat but few in the pig. They were particularly numerous in the myenteric and submucosal plexuses but could be detected also in the circular and longitudinal smooth muscle and in the muscularis mucosae. Only in the cat were SP-immunoreactive cell bodies detected, albeit in low number, in the myenteric plexus. Radioimmunoassay showed that the lower part of the cat esophagus contained approximately 10 times more immunoreactive SP than the upper part and that the muscle layer contained more SP than the mucosa. Motor effects of synthetic SP were studied on segments from circular smooth muscle of cat esophagus. SP contracted the smooth muscle and enhanced the response to electrical stimulation. These effects of SP could be blocked by the specific SP antagonist (D-Pro2, D-Trp7, 9)-SP. The contractile response to electrical stimulation could be blocked by the cholinergic muscarinic blocker atropine and the opiate receptor agonist leu-enkephalin but not by the SP antagonist or by adrenergic blockers. Hence, the results suggest that cholinergic neurons innervate the circular smooth muscle, and that opiate receptor agonists suppress transmission in these neurons. Neuronal SP in the esophagus may serve to enhance the contractile responses of esophageal smooth muscle.

Animals↗

Antagonism by (D-Pro2, D-Trp7,9)-substance P of the cerebrovascular dilatation induced by substance P.

The effects of (D-Pro2, D-Trp7,9)-substance P, a structural analogue of substance P, were examined in two models on cerebrovascular responses to substance P(SP) in cats; in vitro using segments of the middle cerebral artery and in situ by microapplication of the peptides close to pial arterioles. (D-Pro2, D-Trp7,9)-SP in concentrations up to 6.6 x 10(-6) M was without significant effect upon isolated middle cerebral arteries under normal conditions and in arteries contracted with prostaglandin F2 alpha. SP caused concentration-dependent relaxations of middle cerebral arteries contracted by prostaglandin F2 alpha (mean +/- SE; EC50: 2.0 +/- 1.6 x 10(-9) M). The presence of (D-Pro2, D-Trp7,9)-SP shifted the concentration-response curve of SP towards higher concentrations without significantly effecting the maximum response of the arteries to SP. A relaxation by 24.2 +/- 4.0% (n = 6) was obtained in prostaglandin F2 alpha contracted arteries by increasing the potassium concentration with 2 mM in the buffer solution. This response to potassium was unaltered in the presence of 6.6 x 10(-6)M of (D-Pro2, D-Trp7,9)-SP (25.0 +/- 7.1%, n = 5). Perivascular microapplication of SP around individual pial arterioles in situ effected dose-dependent increases in vascular calibre (mean response 14.5 +/- 2% with SP, 10(-7)M). The concomitant perivascular administration of (D-Pro2, D-Trp7,9)-SP (6.6 x 10(-6)M), which alone did not alter the arteriolar calibre, attenuated significantly the cerebrovascular response to SP (mean response 1.5 +/- 3.2%). On the basis of the agonist-antagonist relation found, these observations point to the possibility of a specific SP receptor site in cerebral arteries and arterioles.

Animals↗

Feline cerebral veins and arteries: comparison of autonomic innervation and vasomotor responses.

1. The innervation of feline cerebral (pial) vessels by nerve fibres containing noradrenaline, substance P or vasoactive intestinal polypeptide (VIP) has been examined using the Falck-Hillarp histo-fluorescence method and immunohistochemical techniques. Cerebral veins were shown to be innervated by nerve fibres containing noradrenaline, substance P or VIP. Nerve fibres containing noradrenaline were the most numerous, while fibres containing substance P were observed least frequently in both types of vessel. For each putative neurotransmitter, the density of the innervation of the cerebral veins was less than that of cerebral arteries.2. The vasomotor responses of individual pial arteries and veins on the convexity of the cerebral cortex to perivascular micro-injection of noradrenaline, substance P and VIP were examined in twenty-five cats anaesthetized with alpha-chloralose.3. The perivascular micro-application of noradrenaline resulted in pronounced dose-dependent reductions in the diameter of pial veins (maximum calibre reduction: 32+/-3% noradrenaline 10(-5) M) and arteries (22+/-3% noradrenaline 10(-5) M). Pial veins were more sensitive to noradrenaline than were pial arteries tested under similar conditions. The reductions in the diameter of cerebral veins and arteries resulting from the administration of noradrenaline could be attenuated by the concomitant micro-application of phentolamine (10(-6) M).4. The perivascular micro-application of substance P effected significant dose-dependent increases in the calibre of pial veins (maximum calibre increase: 16+/-4% substance P 10(-7) M) which were of a similar magnitude to those observed in pial arteries in response to this peptide (21+/-4% substance P 10(-6) M).5. The perivascular micro-application of VIP resulted in small increases in the calibre of pial veins (maximum calibre increase: 9+/-2% VIP 10(-8) M) which were proportionately smaller than those observed in pial arteries in response to this peptide (23+/-5% VIP 10(-7) M).

Animals↗

Perivascular substance P: occurrence and distribution in mammalian pial vessels.

Nerve fibres containing immunoreactive substance P (SP) were demonstrated in the wall of cerebral blood vessels of several mammalian species. Pial arteries of cat and guinea-pig were richly supplied with SP nerve fibres, while those of rat, rabbit, pig, and man had a moderate number. SP fibres were more numerous in pial vessels belonging to the rostral parts of the circle of Willis as compared to more caudally located blood vessels. In cat and guinea-pig, blood vessels in the choroid plexus were surrounded by few SP nerve fibres; also spinal cord blood vessels of cat contained few such fibres.

Animals↗

Adrenergic, cholinergic and peptidergic nerve fibres in dura mater--involvement in headache?

Nerve fibres containing noradrenaline, acetylcholinesterase, vasoactive intestinal polypeptide and substance P were demonstrated in the dura mater of guinea-pigs using histochemical and immunohistochemical methods. These fibres accompanied blood vessels of all size, indicating a vasomotor role. In addition, some nerve fibres were observed without any obvious relation to the blood vessels. The rich supply of nerve fibres to the various parts of the dura mater may possibly be of importance in the pathogenesis of some types of headache.

Acetylcholinesterase↗