Adrenergic Nerve Fibers Research Articles

The autonomic innervation of rat brachial artery and vein.

The distribution pattern of quinacrine-positive, catecholamine-containing and acetylcholinesterase-positive nerve fibers was investigated in the rat brachial artery and vein using the quinacrine histofluorescence, the formal-dehyde-induced fluorescence and the acetylcholinesterase histochemical methods, respectively.Some animals were chemically sympathectomized using the neurotoxin 6-hydroxydopamine in order to ascertain the nature of the different kinds of nerve fibers visualized. The density of innervation between artery and vein as well as between the various portions of single blood vessels was studied using quantitative image analysis.No quinacrine-positive nerve fibers were found within rat brachial artery and vein. On the contrary both blood vessels were supplied by adrenergic and acetylcholinesterase-containing (likely cholinergic) nerve fibers. The pre-treatment of samples with quinacrine did not alter the intensity of the reaction neither the distribution pattern of nerve fibers, revealed with other histo-chemical techniques.The quantitative image analysis showed that the brachial artery is provided with an adrenergic innervation, richer of about 30% than corresponding vein. In the artery the adrenergic innervation was more developed of the cholinergic one of about 20% and in the vein of about 15%. The artery is provided with a cholinergic innervation richer than corresponding vein of about 25%. The density of nerve fibers decreases gradually proceeding towards the distal ends of studied blood vessels.

Catecholaminergic control of alpha-melanocyte-stimulating hormone (alpha MSH) release by frog neurointermediate lobe in vitro: evidence for direct stimulation of alpha MSH release by thyrotropin-releasing hormone.

The role of dopaminergic and adrenergic innervation of the intermediate lobe of amphibian pituitary in the release of alpha MSH has been studied in vitro. Neurointermediate lobes of frog (Rana ridibunda Pallas) have been perifused in amphibian culture medium (ACM) for 5-7 h. alpha MSH released in the effluent perifusate was measured by means of a sensitive and specific RIA. No significant morphological alteration of neurointermediate lobe cells was observed during the perifusion experiment, even at the electron microscopic level. The existence of dopaminergic receptors, responsible for an inhibition of frog melanotrophs, was shown using the dopaminergic agonists apomorphine (10(-6) M) and bromo-2-ergocryptine (10(-8) and 10(-7) M), which initiated a marked reduction of alpha MSH secretion. The effect of apomorphine was obliterated by the dopaminergic antagonist haloperidol. Haloperidol itself induced a dose-related stimulation, and the monoamine oxidase inhibitor nialamide (4 x 10(-3) M) inhibited alpha MSH secretion. In addition, haloperidol led to a complete reversal of the inhibitory effect of nialamide on alpha MSH secretion. These results demonstrate the existence, in the parenchyme of the intermediate lobe, of dopaminergic nerve fibers that are functionally active. The beta-adrenergic agonist isoproterenol was responsible for a dose-related stimulation of alpha MSH secretion; the stimulatory effect was reversed by the beta-adrenergic antagonist propranolol. TRH is a potent stimulator of alpha MSH secretion in amphibians. Since haloperidol and propranolol did not abolish the stimulation of alpha MSH release induced by TRH, it appeared that TRH action was not mediated via an inhibition of dopamine release or via a stimulation of adrenergic nerve fibers.

A morphologic study of the behavior of biogenic amines in experimental acetic acid gastric ulcer.

Morphological observations were made of the behavior of biogenic amines in the gastric wall of rats with acetic acid-induced ulcer. In the normal rat stomach, abundant adrenergic fibers were seen in the adventitia of arteries and arterioles, with frequently distributed mast cells in their environs, in all gastric wall layers. Mast cells had a more frequent distribution in the antral region than in the corpus ventriculi while enterochromaffin-like cells (EC-like cells) were found with greater frequencies in the latter region of gastric wall. Adrenergic fibers were abundant around blood vessels in perilesional area of the gastric wall of rats with acetic acid ulcer. Mast cells, seen more frequently in the antral region as in the normal rats, showed degranulation in these rats. The population of PAS-positive mucous cells reached its peak in 10 days after injection of acetic acid and subsequently declined with healing of the ulcer, thus remarkably concordant with the ulcer index. Local administration of serotonin produced angiospasm in the greater omentum. The finding indicates a possible participation of arteriospasm by adrenergic nerve fibers in the pathogenesis of gastric ulcer. The results of the present study strongly suggest that biogenic amines have bearing as an aggressive factor upon the angiospasm theory of ulcerogenesis.

Innervation of bovine mesenteric lymphatics: From the histochemical point of view

Histochemical studies were carried out on the distribution of adrenergic and cholinergic nerves in bovine mesenteric lymphatics. Most of the catecholamine-specific fluorescent nerve fibers demonstrated by the glyoxylic acid method encircled these vessels, although a few of them ran spirally or longitudinally. The fluorescent nerve fibers were present not only in the adventitia but also in the smooth muscle layers. The peak wavelengths of excitation and emission spectra of the fluorescence analyzed by means of a microepifluorescence spectrophotometer were about 415 and 465 nm, respectively. Both the values agreed with those of norepinephrine. Most of the cholinesterase-positive fibers stained by the copper thiocholine method were longitudinal in direction. The pattern of their distribution was similar to that of the catecholamine-containing nerve fibers, though the distribution density of the former fibers was less than the latter. Labeling was not affected by 10 −4 M iso-OMPA in the presence of acetylthiocholine iodide as a substrate—an indication that the staining of these fibers is specific for cholinesterase activity. These results suggest that the adrenergic and cholinergic nerve fibers are distributed in the smooth muscle layers as well as in the adventitia of bovine mesenteric lymphatics.

Innervation pattern of inferior vena cava in mouse and rat.

The innervation pattern of rat and mouse inferior vena cava was studied using catecholamine fluorescence and cholinesterase histochemical methods. Adrenergic nerve fibers innervate only abdominal portions of the inferior vena cava, while cholinergic nerves are chiefly distributed to the thoracic inferior vena cava and show a gradual decrease in the abdomen. Chemical sympathectomy performed with the neurotoxin 6-hydroxydopamine does not alter the pattern of cholinergic innervation of the inferior vena cava, suggesting the parasympathetic nature of cholinergic nerves.

Intrinsic innervation of porcine semilunar heart valves.

In order to provide additional information on the morphology and the functional performance of semilunar valves, the presence of nerve fibers was investigated in the aortic and pulmonary leaflets by AChE techniques, formaldehyde-induced fluorescence methods, en block silver nitrate and gold chloride impregnation and electron microscopy. The results show that AChE positive and adrenergic nerve fibers are constantly present in every leaflet of all the animals examined. The pattern of innervation is similar in aortic and pulmonary valves and no differences exist between coronary and non coronary aortic leaflets. Nerve networks extend over the inferior two-thirds of the leaflets: they are composed of myelinated and non-myelinated axons and are mainly located in the ventricular side of the leaflets. Structures resembling free sensory endings can be shown both by light and electron microscopy. The presence in the leaflets of blood vessels and of an intrinsic smooth muscle system suggests that these two components are the most probable targets of the nerve fibers.

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.

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.

Autonomic innervation of the urogenital system: adrenergic and cholinergic elements

The major organs of the male urogenital (UG) system have been examined in various mammals, including man, using light and electron microscopic (EM) histochemical methods. For the light microscopic study, the urinary bladder, the vas deferens and the penis (corpora cavernosa and corpus spongiosum) were studied in the rat, cat, dog, monkey and man using a glyoxylic acid (GA) method modified for peripheral adrenergic nerve fibers, and a thiocholine method for acetylcholinesterase (AChE). Fine structural analysis was done on the vasa of rat, cat, monkey and man, and on the bladder and penis of cat, dog, monkey and man. Tissue was fixed in glutaraldehyde (GMO) as a control or in glutaraldehyde-dichromate (GDC) for the specific localization of norepinephrine (NE). All organs studied demonstrated numerous adrenergic nerve fibers throughout the muscular layers, in the connective tissue, and in the adventitia of most blood vessels. These fibers had a brilliant fluorescence when visualized with the GA method, and demonstrated many varicosities with small (400–600 A) and/or large (800–1200 A) granular vesicles in both control and GDC-fixed tissue examined with the EM. Evaluation of the vesicles with the analytical electron microscope (AEM) verified that those in the GDC-fixed tissue were chrome-positive, and, therefore, NE-containing. In the vas and penis, acetylcholinesterase(AChE)-positive nerve fibers were encountered less frequently at the light microscopic level than adrenergic fibers, and few typical cholinergic varicosities were seen in these organs with the EM. In the bladder, cholinergic nerves were seen with about the same frequency as adrenergic fibers in both light microscopic and EM preparations. Also observed frequently in each of the viscera were varicosities with large to very large (800–2000 A) granular vesicles of the kind presently hypothesized to be peptidergic or purinergic. Few varicosities of the type considered sensory, with large (800–1200 A) clear vesicles and numerous mitochondria, were observed in this tissue. Evidence from this study suggests that mammalian UG organs are innervated extensively by adrenergic nerves, and, excepting the bladder, have a limited cholinergic innervation; in the bladder, numerous fibers of each type can be found. In addition, another type of nerve fiber, perhaps peptidergic or purinergic, is found in large numbers in each of the organs studied and thus may represent a significant effector of autonomie regulation.

Morphological and physiological factors involved in the contractility of the spermatic cord and ductus deferens of the opossum (Didelphis albiventris).

The opossum spermatic cord is characterized by a thick skeletal muscle coat, provided by the great development of the cremasteric muscle. Acetylcholine induced a powerful contraction of the spermatic cord placed in an organ bath containing Heller's solution. This contraction was blocked by curare but not completely by atropine as is usual for skeletal muscle. However, the ductus deferens did not respond to acetylcholine or catecholamines under the same conditions. Specific histochemical methods for both catecholamines and acetylcholinesterases revealed that the ductus deferens musculature, composed mainly of circular fibres, is richly innervated by adrenergic and presumed cholinergic nerve fibres. The lack of responsiveness to the neurotransmitters could be explained by the absence of longitudinally arranged muscle. It is suggested that in the opossum the cremaster could participate in the mechanism of sperm transport.

Sensory components in the terminal innervation of the ovine cardiac conduction system

AbstractNeuromuscular relationships in the cardiac conduction system of the ovine heart were studied by means of light and electron microscopy. Fluorescence microscopy was used to demonstrate the distribution of adrenergic nerves. Histochemical methods demonstrated sites of acetylcholinesterase and nonspecific cholinesterase activity at both light and electron microscopic levels. Surgical denervation was used in an attempt to support the identification of different types of nerve endings. A dense plexus of nerves strongly positive for acetylcholinesterase was present in all parts of the conduction system. Nonspecific cholinesterase was found to be limited to large nerve bundles which were presumed to be preganglionic. A dense plexus of adrenergic nerve fibers was identified in both the SA and AV nodes, but such fibers were very sparsely distributed along the AV bundle and its branches.On the basis of morphology as demonstrated by electron microscopy, three types of nerve endings or varicosities associated with the specialized cells of the conduction system were identified. Cholinergic endings, presumably post‐ganglionic parasympathetic, contained many nongranulated synaptic vesicles. Adrenergic or post‐ganglionic sympathetic endings or varicosities contained granulated synaptic vesicles. Axonal enlargements containing numerous mitochondria and varying numbers of pleomorphic dense bodies were identified as sensory endings on the basis of their morphologic similarity to such endings found elsewhere in the animal body. These were found in 22% of the blocks examined by electron microscopy, were present in all parts of the conduction tissue, and were acetylcholinesterase positive. They did not show obvious signs of degeneration following vagotomies or thoracic sympathectomy, suggesting the possibility that they were endings of neurons intrinsic to the heart. No signs of degeneration were noted in the endomysial plexus following vagotomy either proximal or distal to the distal (nodose) ganglion. Degeneration of small fibers of the plexus was noted following thoracic sympathectomy.This study provides evidence suggesting a significant sensory innervation to the cardiac conduction system, with the cell bodies of the sensory neurons located in or near the heart.

Dual effects of catecholamines on pre- and post-junctional membranes in the dog trachea.

1 Effects of noradrenaline or isoprenaline on the membrane and contractile properties of the smooth muscle cell, or on the excitatory neuro-effector transmission in the dog trachea, in vitro, were observed by use of microelectrodes and double sucrose gap methods.2 Noradrenaline (<5 x 10(-6) M) or isoprenaline (<5 x 10(-7) M) modified neither the membrane potential nor the membrane resistance. Increased concentrations of noradrenaline (>5 x 10(-5) M) depolarized and isoprenaline (>5 x 10(-7) M) hyperpolarized the membrane, and these actions were suppressed by phentolamine and propranolol respectively. Both catecholamines reduced the membrane resistance.3 Noradrenaline (5 x 10(-6) M) or isoprenaline (5 x 10(-7) M) reduced the resting tension, raised the mechanical threshold required to produce the contraction and suppressed the amplitude of phasic contractions evoked by electrical depolarization of the membrane.4 The action potential evoked by an outward current pulse in the presence of tetraethylammonium (TEA) was not affected by 5 x 10(-6) M isoprenaline, while the mechanical response was markedly suppressed.5 The excitatory junction potential (e.j.p.) evoked by electrical field stimulation was blocked by atropine. Noradrenaline (5 x 10(-7) M) or isoprenaline (5 x 10(-8) M) suppressed the amplitude of e.j.p. with no change in the membrane potential or input membrane resistance. Depression in the amplitude of e.j.ps produced by noradrenaline or isoprenaline reduced the amplitude of phasic contractions evoked by e.j.ps.6 These inhibitory actions of the catecholamines on mechanical responses and on e.j.ps were suppressed by pretreatment with propranolol (4 x 10(-6) M).7 Dog tracheal smooth muscles are innervated by cholinergic excitatory and adrenergic inhibitory systems. Electrical field stimulation produced excitation of both cholinergic and adrenergic nerve fibres, and propranolol (4 x 10(-6) M) enhanced the amplitude of e.j.p. generated by excitation of cholinergic nerves when repetitive stimulation (10 stimuli at 20 Hz) was used, but not the amplitude of the e.j.p. evoked by a single stimulus.8 5-Hydroxytryptamine (6 x 10(-6) M) produced a tonic contracture of the dog trachea. After pretreatment with atropine (4 x 10(-6) M), field stimulation (50 mus in duration and repetitive stimuli at 20 Hz) induced reversal of the contracture induced by 5-hydroxytryptamine and this was abolished by propranolol (5 x 10(-6) M).9 These results indicate that endogenous or exogenous catecholamines, in relatively low concentrations, predominantly activate beta-adrenoceptors in the pre- and post-junctional membrane in the dog trachea, and induce muscle relaxation.

The autonomic innervation of rat jugular vein.

The autonomic innervation of rat jugular vein was studied using glyoxylic acid fluorescence and acetylcholinesterase histochemical methods. The rat jugular vein is provided with both adrenergic and cholinergic nerve fibers organized in plexuses located at the adventitial-medial border. The existence of these nerve plexuses does not seem to support biochemical findings that suggests a lack of innervation in the rat jugular vein and which propose this blood vessel as a model for the analysis of drug-smooth muscle cell interaction without the interference of neuronal uptake mechanisms.

Effects of nifedipine on potassium-induced contraction and noradrenaline release in cerebral and extracranial arteries from rabbit.

The present study was designed to evaluate the effects of the calcium antagonist nifedipine on potassium-evoked contractions and release of noradrenaline from sympathetic nerves in rabbit basilar and facial arteries. Contractions were measured isometrically in a small volume organ bath. While noradrenaline (NA) produced strong contractions in facial arteries, the majority of the basilar arteries responded only to the highest concentrations of NA employed (greater than 10 microM) with weak contraction. Prazosin (1 microM) and phentolamine (1-10 microM) effectively antagonized the responses to NA in both types of vessel. In contrast, contractions evoked by potassium (K+, 124 mM) were only slightly reduced by the alpha-adrenoceptor blocking agents, indicating that the participation of endogenous NA in maintaining the contractile response to K+ is either small or negligible in the vessel types studied. Nifedipine concentration-dependently inhibited K+-induced contractions in basilar and facial arteries, the former being significantly more affected as evidenced by the maximum inhibitions (approximately 80% compared to approximately 60%) and IC50 values (approximately 10 nM vs. approximately 30 nM). A combination of nifedipine (0.3 microM) and prazosin (1 microM) or phentolamine (1 microM) further suppressed the K+-evoked contractile response in facial arteries, but failed to do so in basilar arteries, when compared with the effect of nifedipine alone. The depressant effect of the alpha-adrenoceptor blockers was, however, still obtainable after reserpine treatment of the facial artery in vitro. Fluorescence histochemical demonstration of noradrenaline revealed a dense network of adrenergic nerve fibres in the walls of the basilar and facial artery. The vessels were also shown to accumulate 3H-NA and release it upon depolarization with K+. The uptake and subsequent release of 3H-NA were significantly reduced by desipramine (10 microM). Nifedipine (0.3-3.0 microM) failed to alter the K+-evoked 3H-NA efflux from sympathetic nerves in neither of the two vessel types. It may be concluded that nifedipine effectively inhibits K+-evoked contractions in isolated basilar and facial arteries from rabbit without interfering with nerve-mediated NA release. Possible explanations for this selective effect of nifedipine on muscle contraction are discussed.

Sympathetic Nerve Stimulation on the perfused rat heart. Affinities of N-methylatropine and pirenzepine at pre- and postsynaptic muscarine receptors.

Rat isolated hearts with the sympathetic nerves attached were perfused with (-)-3H-noradrenaline in order to label the storage vesicles of the adrenergic nerves. Release was induced either by electrical stimulation of the nerves (3 Hz, 1 min) or by perfusion with high K+ solution (54 mM). The overflow of 3H-noradrenaline and its metabolites was determined by liquid scintillation counting after separation of the compounds by column chromatography. The experimental conditions ensured a minor contribution of 3H-metabolites to the evoked total tritium overflow. The release of 3H-noradrenaline evoked by nerve stimulation or high K+ solution was decreased in the presence of the muscarinic agonist, methacholine, N-methylatropine reversed the inhibition completely. Thus, the rat heart contains inhibitory muscarine receptors modulating noradrenaline release from adrenergic nerve fibres. In order to compare the presynaptic muscarine receptors with postsynaptic muscarine receptors in one and the same organ, the pA2 values of N-methylatropine and pirenzepine at both of these sites were measured. The antagonism of methacholine-induced inhibition of 3H-noradrenaline overflow was determined as the presynaptic parameter. pA2 values of 9.61 for N-methylatropine and 6.63 for pirenzepine were found. The methacholine-induced inhibition of the atrial tension development of isolated left rat atria paced at 2Hz was measured as a postsynaptic parameter. pA2 values of 9.90 for N-methylatropine and 6.69 for pirenzepine were found. The postsynaptic pA2 values did not differ from the presynaptic affinity constants indicating that neither substance revealed differences in structure between neuronal and myocardial muscarine receptors in the rat heart.

Electrical and mechanical properties and neuro-effector transmission in the smooth muscle layer of the guinea-pig ileocecal junction.

Electrical and mechanical properties and neuroeffector transmission were studied in circular strips of smooth muscle taken from the ileocecal junction of guinea-pigs in relation to sphincter action, using the microelectrode, and tension recording methods. The membrane potential of the smooth muscle was low (-43mV) compared with the membrane potential of circular muscle cells of the ileum or caecum (-58 mV or 62 mV). Only small populations of the muscle cells (about 5%) generated spontaneous action potentials. Field stimulation of the tissue produced an initial slight relaxation followed by a contraction, and the mechanical responses were accompanied by membrane hyperpolarization (i.j.p.) followed by repolarization with rebound spikes. Treatment with atropine increased the amplitude of i.j.p.s and decreased the amplitude of the rebound repolarization. Propranolol or phentolamine did not affect the amplitude of i.j.p., however, phentolamine slightly reduced the amplitude of the rebound repolarization. These results indicate that the ileocecal junction is predominantly controlled by non-adrenergic, non-cholinergic inhibitory nerve fibres and that the distribution of adrenergic and cholinergic excitatory nerve fibres is sparse.

Nerve Fibers with a Selective Affinity for Quinacrine in the Cornea

The existence of a limited population of neither adrenergic nor cholinergic nerve fibers was observed in the rat cornea. These nerve fiber-like structures have a selective affinity for quinacrine and are not altered by chemical sympathectomy. The findings are discussed.

Acetylcholinesterase containing nerve fibers in guinea pig ovary.

The distribution of acetylcholine esterase (AChE) in the ovary of normal as well as of sympathectomized guinea pigs was studied. In normal animals AChE-positive nerve fibres were found organized in a perivascular plexus. Some nerve fibres reach the corpus luteum and the follicular wall. Chemical sympathectomy performed with he neurotoxin 6-hydroxydopamine caused an almost complete disappearance of AChE positive nerve fibres suggesting that most of the AChE activity of ovarian nerves is localized in adrenergic nerve fibres. Enzyme activity was also present in smooth muscle cells of the vascular tree.

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.

Circadian rhythm of adrenergic nerve fiber activity in the rat dura mater

Circadian rhythm of adrenergic nerve fiber activity in the rat dura mater