Galanin-immunoreactive Nerve Fibers Research Articles

Existence and co-existence of vasoactive substances in nerve fibres supplying the abdomino-pelvic arterial tree of the female pig and cow.

The occurrence and co-localization of several presumed vasoactive neuropeptides, serotonin, and catecholamine-synthesising enzymes--tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (D beta H) and phenylethanolamine-N-methyltransferase (PNMT)--were investigated in perivascular nerves supplying the systemic and distributing arteries of the abdomino-pelvic arterial tree of the female pig and certain arteries supplying female reproductive organs in the cow. As revealed by single immunofluorescence, perivascular axons immunoreactive for TH, D beta H, neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), substance P (SP), calcitonin gene-related peptide (CGRP) and Leu-enkephalin (LENK) occurred in both species examined, whereas galanin-immunoreactive (GAL-IR) nerve fibres were found exclusively in the pig. PNMT-, serotonin-, dynorphin A-, alpha-neoendorphin-, bombesin- or cholecystokinin-IR nerve terminals were not observed. The following classes of perivascular nerve fibres might be distinguished in the present study: 1) noradrenergic (i.e. TH/D beta H-IR), 2) NPY-, 3) GAL- (pig only), 4) LENK-, 5) VIP-, 6) SP-, 7) VIP/NPY-, 8) SP/CGRP-, 9) SP/GAL- (pig only), 10) SP/VIP- (cow only), 11) TH/D beta H/NPY- and 12) TH/D beta H/NPY/LENK-IR. Distinct differences in the distribution of LENK- and SP-IR axons around particular parts of the studied arterial tree in individual species were also observed. The present data indicate that the abdomino-pelvic arterial tree of the pig and cow receive perivascular nerve fibres that exhibit diverse chemical codes, and that different chemical coding of perivascular nerve fibres in individual species may depend on the target organ of the particular artery.

Distribution of galanin-immunoreactive nerve fibers in the carotid labyrinth of the bullfrog, Rana catesbeiana: comparison with substance P-immunoreactive fibers

Immunoreactivity of galanin (GAL) was detected in the nerve fibers distributed within the intervascular stroma of the bullfrog carotid labyrinth. GAL-immunoreactive fibers are numerous, and some are close to the sinusoidal plexus. Most GAL fibers appear as thin processes with some varicosities. A combination of indirect double immunofluorescence labelling and image processing clearly demonstrated that the distribution pattern of GAL fibers is different from that of SP fibers. This indicates that GAL and SP do not coexist in the same nerve fibers. The role of GAL fibers may be different from that of previously reported neuropeptides (substance P, calcitonin gene-related peptide, vasoactive intestinal polypeptide, neuropeptide Y, and others) as a neuromodulator in controlling vascular tone of the labyrinth.

Distribution of galanin-immunoreactive nerve fibers in the carotid labyrinth of the bullfrog,

Distribution of galanin-immunoreactive nerve fibers in the carotid labyrinth of the bullfrog,

Distribution, origin and plasticity of galanin-immunoreactivity in the rat carotid body

The distribution, origin and plasticity of galanin immunoreactivity in the rat carotid body was examined using an indirect immunofluorescence method. Galanin-immunoreactive nerve fibers were observed around the blood vessels as well as around the clusters of glomus and sustentacular cells. A double-immunofluorescence method revealed the coexistence of galanin- and calcitonin gene-related peptide-immunoreactivities in these nerve fibers. In the jugular, petrosal and nodose ganglia which supply the sensory nerve fibers to the carotid body, subpopulations of neurons showed both galanin- and calcitonin gene-related peptide-immunoreactivities. In the superior cervical ganglion, a few neurons were immunoreactive for galanin but not calcitonin gene-related peptide. While the nerve fibers showing both galanin- and calcitonin gene-related peptide-immunoreactivities disappeared after transection of the carotid sinus nerve, many galanin-immunoreactive nerve fibers without calcitonin gene-related peptide-immunoreactivity appeared throughout the operated carotid body. In addition, galanin-immunoreactive glomus cells which were not observed in the normal carotid body, were apparent at one and three days after transection of the carotid sinus nerve. At seven days after the carotid sinus nerve transection, the galanin-immunoreactive glomus cells disappeared. In the superior cervical ganglion, the number of galanin-immunoreactive neurons increased from one day after transection of the carotid sinus nerve. Within three days after the carotid sinus nerve transection in combination with superior cervical ganglionectomy, all galanin-immunoreactive nerve fibers disappeared, while many galanin-immunoreactive glomus cells appeared in the operated carotid body. At seven days after this operation, the number of galanin-immunoreactive glomus cells decreased and a few galanin-immunoreactive nerve fibers with or without calcitonin gene-related peptide-immunoreactivities appeared. Transection of the vagus nerve had no effect on the number or distribution of galanin-immunoreactivity in the carotid body. Disappearance of galanin- and calcitonin gene-related peptide-immunoreactive nerve fibers after transection of the carotid sinus nerve suggests that the majority of those nerve fibers originate from petrosal neurons which colocalize galanin- and calcitonin gene-related peptide-immunoreactivity. In addition, the carotid sinus nerve transection may cause the acquisition of galanin-immunoreactivity in originally immunonegative glomus cells, and in nerve fibers which probably originate from the superior cervical ganglion.

Peptidergic innervation and endocrine cells in the human liver.

Histologically normal liver biopsy specimens from patients with Hodgkin's lymphoma were investigated with three immunohistochemical methods for the occurrence of peptidergic nerve fibers and endocrine cells. Numerous immunoreactive nerve fibers were seen with antisera against peripheral nerves markers (neuron-specific enolase, neurofilament protein, and S-100). These nerve fibers were localized in the tunica media of branches of both the hepatic artery and portal vein, around the bile ducts, and in the connective tissue of the interlobular septa. In the liver, 10 types of peptidergic nerve fibers were detected: glucagon-, glucagon-like peptide- (GLP), somatostatin-, neuropeptide Y- (NPY), vasoactive intestinal polypeptide-, neurotensin-, gastrin/cholecystokinin C-terminus-, substance P-, serotonin-, and galanin-immunoreactive nerve fibers. GLP-, somatostatin-, NPY-, neurotensin-, substance P-, and galanin-immunoreactive nerve fibers were abundant; the other nerve fibers were scarce. The nerve fibers showed two distinct patterns of distribution: they occurred in the blood vessel wall and in connective tissue of the interlobular septum. Pancreatic polypeptide- and NPY-immunoreactive cells were found among the lining epithelial cells of the bile ducts in the interlobular septum.

Neonatal capsaicin-treatment in mice: effects on pancreatic peptidergic nerves and 2-deoxy- d-glucose-induced insulin and glucagon secretion

It is not known whether sensory nerves are involved in the insulin, glucagon or glucose responses to autonomic nerve activation induced by 2-deoxy- d-glucose (2-DG). We therefore treated mice neonatally with capsaicin which permanently destroys sensory afferent nerve fibers. Immunohistochemistry of the pancreas at 13–14 weeks of age revealed a substantial reduction of calcitonin gene-related peptide (CGRP)-immunoreactive nerves and a partial reduction of substance P-immunoreactive nerves. In contrast, no effect was observed on galanin-immunoreactive nerves. At age 10–12 weeks, the mice were injected intravenously with 2-DG (500 mg/kg). In controls, 2-DG stimulated insulin and glucagon secretion and induced hyperglycemia ( P < 0.01). Capsaicin treatment partially reduced the glucose and glucagon responses to 2-DG ( P < 0.01). In contrast, the insulin response to 2-DG was not affected by capsaicin. It is concluded that the mouse pancreas contains capsaicin-sensitive sensory CGRP- and substance P-immunoreactive nerve fibers, whereas the galanin-immunoreactive nerve fibers are not sensitive to capsaicin. Furthermore, capsaicin-sensitive sensory nerve fibers are partially involved in 2-DG-induced glucagon secretion and hyperglycemia, whereas sensory nerves are not involved in 2-DG-induced insulin secretion.

Galanin-immunoreactive nerves in the mouse and rat pancreas

Galanin-containing nerve fibers have previously been observed in the human, dog, and pig pancreas. Whether the mouse and rat pancreas also contain galanin nerve fibers has been a matter of debate. Therefore, we examined the distribution of galanin in the mouse and the rat pancreas. Further, the possible localization of galanin to adrenergic nerves was studied using sequential immunostaining for galanin and tyrosine hydroxylase (TH). In the mouse pancreas, numerous galanin-immunoreactive (GIR) nerve fibers occurred around blood vessels. They were less numerous in the exocrine parenchyma and in association with the islets. In contrast, in the rat pancreas, only a few GIR nerves were found. They were located around blood vessels and scattered in the exocrine parenchyma. Occasionally, GIR nerves were also observed in the islets. There was a dense distribution of TH-immunoreactive fibers in both the mouse and the rat pancreas. Sequential immunostaining revealed co-localization of galanin and TH immunoreactivity in nerve fibers in both the mouse and the rat pancreas. Following chemical sympathectomy using 6-hydroxydopamine (6-OHDA), not all GIR nerves disappeared. In the mouse pancreas a remaining population of galanin nerves was found around blood vessels, and occasionally in the islets. In the rat pancreas, a few GIR nerves were seen also after chemical sympathectomy. We conclude that intrapancreatic GIR nerves also occur in the mouse and the rat. These findings suggest that many of the GIR nerves are adrenergic but that non-adrenergic, possibly intrinsic or sensory GIR nerves exist as well in both the mouse and the rat pancreas.

Origin of galanin-immunoreactive nerve fibers in the rat paracervical autonomic ganglia and uterine cervix

Retrograde axonal tracing with fluorogold in conjunction with immunohistochemistry was used to examine the source of galanin-immunoreactive nerve fibers in the paracervical ganglia and uterine cervix of the female rat. Immunohistochemistry revealed galanin-immunoreactive neuron somata in lumbosacral dorsal root ganglia and around the central canal of the lumbosacral spinal cord (lamina X). Injection of fluorogold into the paracervical ganglia resulted in labelled cells in dorsal root ganglia and the sacral parasympathetic nucleus of the spinal cord; but fluorogold-labelled, galanin-immunoreactive cells were found only in dorsal root ganglia. Injection of the tracer in the cervix resulted in labelled cells in the paracervical ganglia and dorsal root ganglia; however, fluorogold-labelled, galanin-immunoreactive cells were again evident only in dorsal root ganglia. It is suggested that the galanin-immunoreactive nerve fibers and varicosities in the paracervical ganglia and uterine cervix are sensory fibers from spinal dorsal root ganglia. The galanin-immunoreactive varicosities in the ganglia could play a role in the modulation of pelvic visceral activity, while those in the musculature of the cervix could influence contractility.

Distribution of galanin-immunoreactive nerve fibers in the rat nasal mucosa

Galanin-like immunoreactivity was found in nerve fibers beneath and within the epithelium of the rat nasal mucosa by the use of immunohistochemical techniques. Immunoreactive fibers were also noted close to blood vessels and seromucous glands in the lamina propria. Fast blue applied to the nasal mucosa underwent retrograde transport to some immunoreactive neurons of the trigeminal ganglion. Thus, the rat nasal mucosa was shown to be innervated by galanin-containing sensory nerves.

Galanin in the porcine pancreas

Galanin, a 29 amino acid neuropeptide, was recently isolated from pig intestine. We studied the localization, nature and effect of galanin in pig pancreas. Galanin immunoreactive nerve fibers were regularly found in the pancreas. A peptide chromatographically similar to synthetic galanin was identified in pancreas extracts. The effect of galanin on the endocrine and exocrine secretion was studied in isolated pancreases, perfused with a synthetic medium containing 3.5, 5 or 8 mmol/l glucose and synthetic galanin (10 −10–10 −8 mol/l). There was no effect on the basal exocrine secretion. The output of insulin, glucagon, somatostatin and pancreatic polypeptide (PP) was measured in the effluent. There was no effect on PP secretion. At a perfusate glucose concentration of 5 mmol/l, galanin at 10 −9 mol/l increased insulin secretion by 55 ± 14% (mean ±S.E.M., n = 5) of basal secretion, and at 10 −8 mol/l by 58 ± 27% ( n = 6). At 8 mmol/l glucose, insulin secretion increased by 25 ± 10% ( n = 6) and 62 ± 17% ( n = 8). At 5 mmol/l glucose glucagon secretion was increased by 15 ± 3% ( n = 5) by galanin at 10 −9 mol/l and by 29 ± 11% ( n = 5) by galanin at 10 −8 mol/l, and at 8 mmol/l glucose by 66 ± 27% and 41 ± 25%. Somatostatin secretion was inhibited to 72 ± 2% ( n = 5) of basal secretion by galanin at 10 −9 mol/l and to 65 ± 7% ( n = 7) at galanin at 10 −8 mol/l, both at 5 mmol/l glucose. At 8 mmol/l the figures were 83 ± 6% and 70 ± 10%. Insulin secretion in response to square wave increases in glucose concentration from 3.5 to 11 mmol/l ( n = 5) increased 2-fold during simultaneous perfusion with galanin (10 −8 mol/l). The present results contrast to results obtained with porcine galanin in other species, emphasizing the importance of avoiding species incongruity in the evaluation of effects of regulatory peptides.

Effect of Diabetes in the BB Wistar Rat on the Peptidergic Component of the Enteric Innervation

Whole mount preparations of the small intestine from Wistar, normoglycemic 90-day diabetic BB, hyperglycemic 90-day diabetic BB and age-matched nondiabetic BB rats were immunostained to determine the extent of the peptidergic innervation. The neuropeptides examined were vasoactive intestinal peptide, neuropeptide Y, substance P. calcitonin gene-related peptide, galanin and somatostatin. The extent of the peptidergic innervation in the submucous and myenteric plexuses from the control Wistar, nondiabetic BB and normoglycemic diabetic BB rats was identical. In the submucous plexus of the hyperglycemic diabetic BB rats there was a marked reduction in the number of somatostatin-immunoreactive neurons and nerve fibres. Substance P and calcitonin gene-related peptide which are colocalized in a proportion of the somatostatin neurons were unaffected. In the myenteric plexus of the hyperglycemic diabetic BB rats the number and intensity of staining of the galanin-immunoreactive nerve fibers was markedly increased. Galanin has not been observed to colocalize with any of the other neuropeptides examined.

Galanin-immunoreactive nerves in the female rat paracervical ganglion and uterine cervix: distribution and reaction to capsaicin

The presence and distribution of galanin-immunoreactivity was examined in the uterine cervix and paracervical autonomic ganglia of the female rat. Some animals were treated with capsaicin to determine if galanin-immunoreactivity was present in small-diameter primary afferent nerves. Other animals were treated with the noradrenergic neurotoxin 6-hydroxydopamine to ascertain if galanin-immunoreactivity was present in sympathetic noradrenergic nerves. Galanin-immunoreactive nerve fibers were sparse in the cervical myometrium and vasculature, but numerous in the paracervical ganglion where they appeared to innervate principal neurons. Immunoreactivity was also present in dorsal root ganglia, dorsal horn of spinal cord, and inferior mesenteric ganglia. Capsaicin treatment resulted in a marked reduction of galanin-immunoreactivity in the spinal cord dorsal horn, but not in the dorsal root ganglia, paracervical ganglia, or cervix (although there was a substantial reduction of substance P-, neurokinin A-, and calcitonin gene-related peptide-immunoreactivity in the dorsal horn. dorsal root ganglia, and uterine cervix). 6-Hydroxydopamine treatment did not cause any appreciable change in the galanin-immunoreactivity in any tissues. We conclude that galanin-like immunoreactivity is expressed in nerve fibers innervating the paracervical ganglia and uterine cervix of the female rat. This immunoreactivity is probably present in afferent nerves and could play a role in neuroendocrine reflexes and in reproductive function.

The presence and possible role of a galanin-like peptide in the mudpuppy heart

A correlated histochemical and pharmacological study was undertaken to establish the presence, origin, and possible function of nerve fibers containing a galanin-like peptide in the mudpuppy ( Necturus maculosus) heart. Whole mount preparations of septum-sinus venosus or atria and sections of ventricular muscle were prepared for immunocytochemistry. Galanin-immunoreactive fibers were found coursing diffusely across the septum-sinus venosus to form complex networks over cardiac muscle strands. Individual atrial muscle strands were densely innervated by galanin-immunoreactive fibers and galaninimmunoreactive fibers were also observed in the epicardial and myocardial layers of the ventricle. Most of the parasympathetic postganglionic neurons in the cardiac ganglion and many of the small intensely fluorescent-like cells exhibited galanin immunoreactivity. Galanin-immunoreactive fibers were present in the nerve trunks connecting clusters of parasympathetic postganglionic neurons. Close associations between galanin-positive fibers and individual parasympathetic postganglionic neurons were also observed. The presence of the galanin-immunoreactive fibers was similar in preparations taken from animals pretreated with 6-hydroxydopamine to that seen in preparations taken from control animals, indicating that the galanin-positive fibers were not sympathetic postganglionic axons. Moreover, the galaninimmunoreactive nerve fibers were separate from fibers containing substance P and/or calcitonin gene-related peptide that have previously been shown to be processes of afferent fibers. In twitch-tension experiments, galanin in the range 1 × 10 −7 to 1 × 10 −6M caused cardioinhibition of spontaneously beating isolated septal-sinus venosus preparations. Galanin also produced a concentrationdependent 1 × 10 −7 to 1 × 10 −6M decrease in the twitch-tension development of electrically stimulated atrial or ventricular preparations. Local application of galanin produced hyperpolarization of cardiac muscle fibers in both isolated septal-sinus venosus preparations and atrial preparations. The response of individual parasympathetic ganglion cells to local application of galanin varied between neurons; some neurons were depolarized whereas others were hyperpolarized. We conclude that a galanin-like peptide is contained in both the parasympathetic postganglionic neurons and small intensely fluorescent-like cells and their processes. Further, we hypothesize that in the case of the parasympathetic postganglionic neurons, the galanin-like peptide may work in conjunction with acetylcholine to regulate cardiac activity.

Galanin-immunoreactive nerves in the rat iris: alterations induced by denervations

The iris and choroid membrane of the adult rat contain nerve fibers expressing immunoreactivity to the neuropeptide galanin. The density and distribution of galanin-positive nerve fibers varied from iris to iris and, particularly, among animals. Smooth, non-terminal axons were seen running in nerve bundles consisting of otherwise negative fibers. From the choroid membrane these bundles reached the iris via the ciliary body. Axons were frequently seen to branch giving rise to a sparse system of varicose, single fibers in the dilator plate and sphincter area. Galanin-positive fibers were sometimes also seen outlining blood vessels. Capsaicin, in a dose that causes permanent depletion of substance P- and cholecystokinin-immunoreactive fibers in the iris, caused no change in amount of galanin-positive fibers. Removal of the superior cervical ganglion caused a rapid and pronounced increase in the number of galanin-immunoreactive nerve fibers. Similarly, removal of the ciliary ganglion appeared to increase galanin immunoreactivity, while removal of the pterygopalatine ganglion was less effective. Lesioning of the trigeminal ganglion caused a disappearance of galanin immunoreactivity. The sympathectomy-induced increase was counteracted by capsaicin. Galanin-positive nerve cell bodies were present in both the superior cervical and the trigeminal ganglia. In the superior cervical ganglion, immunoreactive galanin did not seem to coexist with neuropeptide Y-positive cells; in the trigeminal ganglion, some galanin-positive cells also contained calcitonin gene-related peptide (CGRP) immunoreactivity, while most cells did not. In the iris, double-staining suggested that CGRP and galanin immunoreactivities were contained in different fiber populations.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution of galanin immunoreactivity in the genitourinary tract of man and rat

Galanin has been shown to be present in substantial quantities in the human and rat genitourinary tract by radioimmunoassay and immunocytochemistry. The highest concentrations measured by radioimmunoassay were found in the human vas deferens, corpus cavernosum and spongiosum and in the vagina and cervix. In man gel chromatographic analysis showed two molecular forms. The earlier eluting peak was different from porcine galanin standard. There was only one molecular form in the rat which emerged in an earlier position than the porcine standard. Galanin immunoreactive nerve fibres demonstrated in the genitourinary tract were found both in man and rat. They were found within smooth muscle and in close relationship to blood vessels. The presence and distribution of galanin in the genitourinary system suggest the possibility that this neuropeptide could play a role in the regulation of smooth muscle tone, blood flow and motility.

Distribution of galanin immunoreactivity in the respiratory tract of pig, guinea pig, rat, and dog.

Galanin, a newly discovered peptide isolated from porcine intestine, is known to cause contraction in rat smooth muscle preparations and to induce hyperglycaemia in dogs. By the use of radioimmunoassay and immunohistochemical techniques the concentration and distribution of galanin immunoreactivity were determined in several areas of the respiratory tract of five dogs, five guinea pigs, five rats, and two pigs. Antibodies were raised in rabbits to whole unconjugated natural porcine galanin. The highest galanin concentrations were found in the bronchus and the trachea of the dog, guinea pig, rat (2 pmol/g in each case), and pig (less than 1 pmol/g). The lowest galanin concentrations were found in the lung parenchyma. Gel chromatographic analysis in the pig showed one molecular form of galanin coeluting with the porcine galanin standard. By means of the indirect immunofluorescence technique on sections of tissues fixed in benzoquinone solution, galanin was found to be confined to nerve fibres in different regions of the respiratory tract. In the nasal mucosa of the pig nerve fibres containing galanin were distributed around seromucous glands and blood vessels and beneath the epithelium. In the trachea, bronchus, and major intrapulmonary airways of the pig, dog, and guinea pig galanin immunoreactive fibres were detected predominantly in smooth muscle, as well as around seromucous glands and in the adventitia of blood vessels. Rarely, galanin immunoreactive nerve fibres were found in the lung parenchyma. A few galanin immunoreactive ganglion cells also containing vasoactive intestinal polypeptide were found in the adventitia of the tracheobronchial wall of the pig and dog. The distribution of galanin suggests that it may have some influence on airway, vascular, and secretory functions in the mammalian respiratory tract.

Galanin nerve fibers in the rat gut: Distribution, origin and projections

Galanin, a 29 amino acid peptide, was recently isolated from the porcine gut. Immunocytochemistry revealed a dense network of galanin-immunoreactive nerve fibers in the submucosa, smooth muscle layers and intramural ganglia throughout the rat gastrointestinal tract. In the smooth muscle the density of innervation was lower in the colon than in the small intestine. In the mucosa galaninimmunoreactive fibers were quite numerous in the small intestine, less numerous in the large intestine and rare in the stomach. A moderate number of galanin-immunoreactive nerve cell bodies could be detected in the myenteric ganglia throughout the digestive tract and in the submucous ganglia of the intestines. Enteric galanin-immunoreactive fibers seem to be intrinsic to the gastrointestinal tract since their distribution and frequency were unaffected after extrinsic denervation (chemical sympathectomy, vagal denervation or clamping of nerves running within the mesenterium). Myectomy at the mid-jejunal level resulted in a total loss of galanin-immunoreactive nerve fibers 5 mm anally to the lesion with a gradual return of galanin-immunoreactive fibers up to 15–20 mm further anally; there was no overt loss of fibers orally. The findings indicate that myenteric galanin-immunoreactive neurones issue long descending projections that terminate either within the myenteric ganglia or in the smooth muscle.