Galanin-immunoreactive Nerve Fibers Research Articles

Galanin - Immunoreactive Nerve Fibers in the Mucosal Layer of the Canine Gastrointestinal Tract During Inflammatory Bowel Disease

Abstract The effect of inflammatory bowel disease (IBD) on the density of galanin - immunoreactive (GAL-IR) nerve fibers was determined in the mucosa of canine duodenum, jejunum, and descending colon. Fiber density was evaluated by a single immunofluorescence method in biopsy specimens obtained from healthy dogs and patients with variable severity of the disease. The density of GAL-IR nerve fibers was determined by the semi-quantitative method by counting fibers in the field of view (0.l mm2). Fiber density was higher in dogs with moderate and severe IBD than in healthy animals. The results of the study suggest that GAL present in intestinal nerve fibers could play a role in the pathogenesis and development of canine IBD.

The distribution of galanin-immunoreactive nerve fibers in the rat pharynx

Galanin (GAL) consists of a chain of 29/30 amino acids which is widely distributed in the central and peripheral nervous systems. In this study, the distribution of GAL-immunoreactive (-IR) nerve fibers was examined in the rat pharynx and its adjacent regions. GAL-IR nerve fibers were located beneath the epithelium and taste bud-like structure of the pharynx, epiglottis, soft palate and larynx. These nerve fibers were abundant in the laryngeal part of the pharynx, and were rare in other regions. Mucous glands were mostly devoid of GAL-IR nerve fibers. In the musculature of pharyngeal constrictor muscles, many GAL-IR nerve fibers were also located around small blood vessels. However, intrinsic laryngeal muscles contained only a few GAL-IR nerve fibers. The double immunofluorescence method demonstrated that the distribution pattern of GAL-IR nerve fibers was partly similar to that of calcitonin gene-related peptide-IR nerve fibers in the pharyngeal mucosa and muscles. The present findings suggest that the pharynx is one of main targets of GAL-containing nerves in the upper digestive and respiratory systems. These nerves may have sensory and autonomic origins.

Galanin immunoreactivity in the brain of the desert lizard Uromastyx acanthinura during activity season

The distribution of galanin immunoreactive perikarya and nerve fibers in the brain of the desert lizard U. acanthinura was studied by means of immunofluorescence using an antiserum against rabbit galanin. The animals were captured during the activity season in March (wet season) just before reproduction period and in June (arid season) after ovulation period. Immunoreactive neurons were mostly detected in the mediobasal and the infundibular recess nuclei, the nucleus of the paraventricular organ, the paraventricular organ, the periventricular nucleus and in the anterior hypothalamus at the level of the periventricular nucleus, the paraventricular nucleus and the supraoptic nucleus. The differences in brain galanin expression between animals collected under both sets of environmental conditions indicated changes which occur during the annual and reproductive cycles. The wide hypothalamic and extrahypothalamic distribution of galanin immunoreactive fibers suggests that this peptide may have hypophysiotropic, neuromodulator and neurotransmitter roles in the lizard U. acanthinura.

Development of Galanin‐Containing Nerve Fibres in Rat Tibia

Galanin exerts tonic inhibition of nociceptive input to the central nervous system. Recently, this peptide was demonstrated in several neuronal and non-neuronal structures in bones and joints. In this study, the time of appearance and topographic localization of galanin-containing nerve fibres in bone were studied in rats from gestational day 16 (GD16) to postnatal day 21 (PD21). The tibia was chosen as a model of developing long bone and indirect immunofluorescence combined with confocal laser scanning microscopy was used to identify galanin-immunoreactive (GAL-IR) nerve fibres. The earliest, sparse GAL-IR fibres were observed on GD21 in the perichondrium of both epiphyses and in the periosteum of the diaphysis. From PD1 onwards, GAL-IR fibres were also seen in the bone marrow cavity and in the region of the inter-condylar eminence of the knee joint. Intramedullary GAL-IR fibres in proximal and distal metaphyses appeared around PD1. Some of them accompanied blood vessels, although free fibres were also seen. GAL-IR fibres located in the cartilage canals of both epiphyses were observed from PD7, in the secondary ossification centres from PD10 and in the bone marrow of both epiphyses from PD14. The time course and localization of galanin-containing nerve fibres resemble the development of substance P- and CGRP-expressing nerve fibres, thus suggesting their sensory origin.

Galanin modulates vagally induced contractions in the mouse oesophagus

Nitrergic myenteric neurons co-innervating motor endplates were previously shown to inhibit vagally induced contractions of striated muscle in the rodent oesophagus. Immunohistochemical demonstration of putative co-transmitters, e.g. galanin, in enteric neurons prompted us to study a possible role of galanin in modulating vagally mediated contractions in an in vitro vagus nerve-oesophagus preparation of the mouse. Galanin (1-16) (1-100 nmol L(-1)), in the presence of the peptidase inhibitor, phenanthroline monohydrate, inhibited vagally induced contractions in a concentration-dependent manner (control: 100%; galanin 1 nmol L(-1): 95.6 +/- 1.6%; galanin 10 nmol L(-1): 57.3 +/- 6.5%; galanin 100 nmol L(-1): 31.2 +/- 8.1%, n = 5). The non-selective galanin receptor antagonist, galantide (100 nmol L(-1)), blocked the inhibitory effect of galanin (10 nmol L(-1)) while the selective non-galanin receptor 1 and galanin receptor 3 antagonists, M871 (1 micromol L(-1)) and SNAP37889 (100 nmol L(-1)), respectively, and the nitric oxide synthase inhibitor, NG-nitro-l-arginine methyl ester (L-NAME) (200 micromol L(-1)), failed to affect this galanin-induced response. Simultaneous application of galantide (100 nmol L(-1)) and L-NAME (200 micromol L(-1)) significantly reduced the inhibitory effect of capsaicin (30 mumol L(-1)) on vagally induced contractions when compared with its effect in the presence of L-NAME alone or in combination with the selective galanin receptor 2 or 3 antagonists. An inhibitory effect of piperine on vagally induced contractions was reduced neither by galantide nor by L-NAME. Immunohistochemistry revealed galanin immunoreactive myenteric neurons and nerve fibres intermingling with cholinergic vagal terminals at motor endplates. These data suggest that galanin from co-innervating enteric neurons co-operates with nitric oxide in modulating vagally induced contractions in the mouse oesophagus.

Re-innervation pattern of the ‘neovagina’ created from the bladder flap in patients with Mayer-Rokitanski-Kistner-Hauser syndrome: An immunochemical study

Background. Cystovaginoplasty (CVP) is a method of vaginal reconstruction in women with Mayer-Rokitansky-Kistner-Hauser Syndrome (MRKHS). The neo-vagina allows normal sexual intercourses, but after CVP, the sexual life of patients with MRKHS does not differ significantly from normal females. Therefore, we decided to elucidate the pattern of sensory re-innervation of the bladder flap used for the surgery.Methods. Biopsies were taken from vaginal vestibule and urinary bladder during the CVP and 1 year later in four patients with MRKHS. The following neurotransmitters were studied calcitonin gene-related peptide (CGRP), galanin (GAL), vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP).Results. CGRP and PACAP nerve fibres were sparse under the urothelium and in submucosal layer of the neovagina, they were more numerous around blood vessels and in the vicinity of smooth muscles. This was similar to the pattern observed in the urinary bladder. VIP- and GAL-positive nerve fibres were most numerous in the submucosa around blood vessels and in smooth muscle bundles of neovagina. They were distinctly less numerous beneath the epithelium. This innervation pattern mimicked that seen in normal vagina and in vaginal vestibule of patients with MRKHS.Conclusions. Our findings demonstrate considerable nervous system plasticity in the bladder flap. Distribution of presumably sensory CGRP and PACAP immunoreactive nerve fibers was similar to the pattern observed within the intact bladder wall, and VIP or GAL immunoreactive nerve fibers (vasomotor functions) were distributed in a manner similar to that observed in the intact vaginal wall.

Galanin Expression in a Murine Model of Allergic Contact Dermatitis

Galanin is a neuropeptide widely distributed in the nervous system. The expression of galanin was investigated in murine contact allergy using immunohistochemistry, radioimmunoassay and in situ hybridization. Female BALB/c mice were sensitized with oxazolone and 6 days later challenged on the dorsal surface of ears, while control mice received vehicle. After 24 h, one ear was processed for immunostaining using a biotinylated fluorescence technique, while the other ear was frozen and processed for radioimmunoassay or in situ hybridization. Galanin immunoreactive nerve fibres were more numerous (p < 0.01) in the eczematous compared with control ears. Double-staining with antibody to the nerve fibre marker PGP (protein gene product) 9.5 revealed colocalization of PGP 9.5 and galanin in nerve fibres. Radioimmunoassay demonstrated a decrease (p < 0.04) in galanin concentration in eczematous compared with control ears. Our results suggest a role for galanin in murine contact allergy.

Distribution of calcitonin gene-related peptide (CGRP), substance P (SP) and galanin (GAL) immunoreactive nerve fibers in the seminal vesicle and prostate of the male sheep

Double immunohistochemistry was used to determine the occurrence and distribution pattern of nerve fibres immunoreactive to calcitonin gene-related peptide (CGRP), substance P (SP) and galanin (GAL) in seminal vesicles and prostate of the male sheep. Numerous CGRP- and SP-immunoreactive (IR) nerve fibres were found in the mucosal layer and smooth musculature of the seminal vesicles and prostate. In both glands nerve terminals immunoreactive to CGRP were more numerous than SP-IR ones. The majority of CGRP-IR nerve fibers showed colocalization of this peptide and SP. In both layers of the seminal vesicle and prostate, rare nerve terminals immunoreactive to GAL were also found. Immunoreactivity to SP was also found in all GAL-IR nerve fibers. The presence of numerous CGRP- and SP-IR nerve fibers in the seminal vesicle and prostate of the male sheep suggests that these neuropeptides may be involved in the sensory transmission and/or control of smooth muscle contractility. On the other hand, a relatively low number of GAL-IR nerve fibers of the seminal vesicle and prostate suggest that this peptide may act as an anti-nociceptive agent. It cannot be excluded that, in the seminal vesicle, GAL may also be involved in the control of the smooth muscle fiber activity. The possible role of CGRP, SP and GAL in the regulation of functions of the accessory sexual glands needs to be determined in further physiological studies.

Galanin-immunoreactive nerve fibers in the periodontal ligament during experimental tooth movement.

Neuropeptides have been suggested to play a role in pain transmission during orthodontic tooth movement. We examined this hypothesis by examining the effect of orthodontic tooth movement on the expression of galanin (GAL)-immunoreactive (ir) nerve fibers in the periodontal ligament (PDL) of one mesial root (MR) and two distal roots (DRs) of the rat maxillary first molar. In control rats, GAL-ir fibers were very rare in the PDL. One day after the insertion of the elastic band, the number of GAL-ir fibers increased, becoming most numerous at 3 days. From 5 to 28 days, GAL-ir fibers tended to decrease. Electron microscopic observation showed that all of the GAL-ir fibers were unmyelinated. These findings suggest that GAL-containing nerve fibers in the PDL may play an important role in the response of the tissue to experimental tooth movement.

Localization of the neuropeptide galanin in nerve fibers and epithelial keratinocytes of the rat molar gingiva.

Knowledge of the histochemical substrates of cellular and neurovascular connections in the gingiva is essential in order to understand the initial mechanisms of inflammation in the periodontium. Since the localization of the neuroendocrine peptide galanin in the gingiva is still unclear, we used immunohistochemical, in situ hybridization and immunoblot techniques to assess the localization of galanin in the gingiva of rat molars. Galanin-immunoreactive nerve fibers were located around blood vessels in the lamina propria, beneath the epithelium, in the epithelial-proprial junction and in the basal layer of the epithelium. Galanin was highly expressed in the suprabasal keratinocytes of the gingival epithelium. The localization of galanin in gingival nerve fibers and the expression of galanin in keratinocytes of the gingival epithelium indicate that galanin may be a possible regulator of different cellular functions in the gingiva.

Structural and Functional Denervation of Human Detrusor after Spinal Cord Injury

The bladder receives an extensive nerve supply that is predominantly cholinergic, but several putative transmitters are present, some of which are colocalized. Previous studies have shown increased levels of sensory nerves, reduced inhibitory transmitters, and structural and functional changes in the excitatory input in unstable bladder conditions. The present study compared the end-organ nerve supply to the bladder in spinal cord injury (SCI) with uninjured controls. Acetylcholinesterase histochemistry and double-label immunofluorescence were used to investigate neurotransmitter content, with confocal laser scanning microscopy to assess colocalization. Organ bath studies provided functional correlates for the structural changes in the excitatory innervation. Control samples had dense innervation of the detrusor containing a diverse range of transmitters. Hyperreflexic SCI samples showed patchy denervation, and areflexic SCI samples were diffusely denervated. Vasoactive intestinal polypeptide-, neuropeptide Y-, neuronal nitric oxide synthase-, and galanin-immunoreactive nerve fibers were reduced from frequent or moderately frequent to infrequent or very infrequent in SCI. Calcitonin gene-related peptide-immunoreactive fibers were infrequent in controls and SCI samples. Patterns of colocalization were unchanged, but significantly fewer fibers expressed more than one transmitter. The subepithelial plexus was markedly reduced and several of the smaller coarse nerve trunks showed no immunoreactivity to the transmitters assessed. There was no reduction in sensitivity to electrical field stimulation of intrinsic nerves in SCI, but the maximum force generated by each milligram of bladder tissue and the peak force as a proportion of the maximum carbachol contraction were significantly reduced and the responses were protracted. There was no significant functional atropine-resistant neuromuscular transmission in controls or SCI. The reported findings have clinical implications in the management of chronic SCI and development of new treatments.

Distinct localization and target specificity of galanin-immunoreactive sympathetic preganglionic neurons of a teleost, the filefish Stephanolepis cirrhifer

Immunoreactivity for galanin was examined in the sympathetic preganglionic neurons in the spinal cord, adrenal glands, sympathetic ganglia, and some sensory ganglia of the filefish Stephanolepis cirrhifer. Galanin-immunoreactive neurons were found only in the rostral part, but not in the caudal part of the central autonomic nucleus (a column of sympathetic preganglionic neurons of teleosts). Many galanin-immunoreactive nerve terminals were found in contact with neurons in the celiac ganglia and the cranial sympathetic ganglia on both sides of the body. Most neurons encircled by galanin-immunoreactive nerve fibers were negative for tyrosine hydroxylase. Galanin-immunoreactive nerve fibers were very sparse in the spinal sympathetic paravertebral ganglia. No galanin-immunoreactive nerve fibers were found in the adrenal glands. No sensory neurons of the trigeminal, vagal, or spinal dorsal root ganglia were positive for galanin-immunoreactivity. These results suggest that galanin-immunoreactive sympathetic preganglionic neurons have distinct segmental localization and might project specifically to a population of non-adrenergic sympathetic postganglionic neurons in the celiac and cranial sympathetic ganglia.

Ontogeny of galanin‐immunoreactive elements in the intrinsic nervous system of the chicken gut

Galanin is a brain-gut peptide that is present in the central and peripheral nervous systems. In the gut, it is contained exclusively in intrinsic and extrinsic nerve supplies, and it is involved overall in the regulation of gut motility. To obtain information about the ontogeny of galanin, we undertook an immunohistochemical study of chicken embryos. The time of first appearance and the distribution patterns of galanin were investigated with fluorescence and streptavidin-biotin-peroxidase (ABC) immunohistochemical protocols by using a galanin polyclonal antiserum. The various regions of the gut and the pancreas were obtained from chicken embryos aged from 3 days of incubation to hatching. All specimens were fixed in buffered picric acid-paraformaldehyde, frozen, and cut with a cryostat. Galanin-immunoreactive neuroblasts were first detected at 4 days in the mesenchyme of the proventriculus/gizzard primordium and within the Remak ganglion. They then extended cranially and caudally, reaching all of the other gut regions at 6.5 days. Galanin-immunoreactive nerve elements mainly occupied the sites of myenteric and submucous plexuses. From day 15, galanin-immunoreactive nerve fibers tended to invade the circular muscular layer and part of the lamina propria of the mucosa. In the pancreas, weak galanin-immunoreactive nerve elements were detected at 5.5 days. They tended to be distributed among the glandular lobules according to the organ differentiation. The widespread distribution during the earlier embryonic stages represents evidence indicating that the neuropeptide galanin may have a role as a differentiating or growth factor. From late embryonic life, its predominant presence in sympathetic nerves and in muscular layers fits with the functions demonstrated previously in adults of other vertebrates for galanin as a modulator of intestinal motility. Anat Rec 254:28–38, 1999. © 1999 Wiley-Liss, Inc.

Ontogeny of galanin-immunoreactive elements in the intrinsic nervous system of the chicken gut.

Galanin is a brain-gut peptide that is present in the central and peripheral nervous systems. In the gut, it is contained exclusively in intrinsic and extrinsic nerve supplies, and it is involved overall in the regulation of gut motility. To obtain information about the ontogeny of galanin, we undertook an immunohistochemical study of chicken embryos. The time of first appearance and the distribution patterns of galanin were investigated with fluorescence and streptavidin-biotin-peroxidase (ABC) immunohistochemical protocols by using a galanin polyclonal antiserum. The various regions of the gut and the pancreas were obtained from chicken embryos aged from 3 days of incubation to hatching. All specimens were fixed in buffered picric acid-paraformaldehyde, frozen, and cut with a cryostat. Galanin-immunoreactive neuroblasts were first detected at 4 days in the mesenchyme of the proventriculus/gizzard primordium and within the Remak ganglion. They then extended cranially and caudally, reaching all of the other gut regions at 6.5 days. Galanin-immunoreactive nerve elements mainly occupied the sites of myenteric and submucous plexuses. From day 15, galanin-immunoreactive nerve fibers tended to invade the circular muscular layer and part of the lamina propria of the mucosa. In the pancreas, weak galanin-immunoreactive nerve elements were detected at 5.5 days. They tended to be distributed among the glandular lobules according to the organ differentiation. The widespread distribution during the earlier embryonic stages represents evidence indicating that the neuropeptide galanin may have a role as a differentiating or growth factor. From late embryonic life, its predominant presence in sympathetic nerves and in muscular layers fits with the functions demonstrated previously in adults of other vertebrates for galanin as a modulator of intestinal motility.

Role of galanin in the gastrointestinal sphincters.

Galanin was present and exerted potent effects in all the gastrointestinal sphincters examined. Galanin-immunoreactive nerve fibers and neurons are present in both the myenteric and submucosal plexuses of sphincters. The neuropeptide exerts diverse effects in different sphincteric smooth muscles that may be species specific. For example, in the lower esophageal sphincter, it may cause an increase in basal tone and suppression of nonadrenergic noncholinergic (NANC) nerve-mediated relaxation. On the contrary, in the internal anal sphincter (IAS), the predominant effect of galanin is to cause smooth muscle relaxation and augmentation of NANC nerve-mediated relaxation. In other sphincters, galanin may either have no effect or cause either an increase or a decrease in basal tone. Most of the actions of galanin on basal smooth muscle sphincteric tone are due to its actions directly on smooth muscle cells. However, some of the relaxant actions of the peptide may also be due to activation of NANC inhibitory neurons. The basic mechanism/s responsible for sphincteric smooth muscle contraction or relaxation in response to galanin have not been investigated. The suppressive as well as the augmentatory effects of galanin on NANC nerve-mediated sphincteric smooth muscle relaxation may be due to inhibition or facilitation, respectively, of the release of NANC inhibitory neurotransmitters such as nitric oxide and vasoactive intestinal polypeptide. Diverse effects in different gastrointestinal sphincters suggest a neuromodulatory rather than a neurotransmitter role of galanin and a significant role of the neuropeptide and putative antagonists in the pathophysiology and potential therapy of gastrointestinal motility disorders especially those affecting sphincteric function.

The relationship of galanin immunoreactive nerve fibers to glandular cells in the anterior pituitary in the monkey

The anterior pituitary is known to be regulated by hypothalamic hormones via the portal system. However, our recent studies have demonstrated the presence of a substantial amount of substance P (SP)-, calcitonin gene-related peptide (CGRP)- and galanin (GAL)- immunoreactive (ir) nerve fibers with numerous varicosities in the anterior pituitaries of the Macaca mulatta monkey. The present study investigated the relationship of the GAL-ir nerve fibers to the glandular cells. The M. mulatta monkeys were used and the sections of the anterior pituitary were double immunostained. GAL-ir nerve fibers and/or varicosities were found in proximity to contact directly with corticotropes, somatotropes, lactotropes, gonadotropes and thyrotropes without any exception. These findings indicate that a direct neural factor may be involved in the regulation of adenohypophyseal secretion.

Peptidergic innervation of the human gallbladder.

The human gallbladder was investigated by means of immunohistochemical methods for the occurrence of peptidergic nerve fibres. In the gallbladder 11 types of peptidergic nerve fibres were observed. These were somatostatin-, pancreatic polypeptide (PP)-, peptide YY (PYY)-, neuropeptide Y (NPY)-, vasoactive intestinal peptide (VIP)-, gastric inhibitory peptide (GIP)-, neurotensin-, cholecystokinin (CCK)/gastrin C-terminus, substance P-, galanin- and serotonin-immunoreactive nerve fibres. NPY- and GIP-containing neurones were occasionally observed in the ganglionated plexus in the fibromuscular coat. Somatostatin-, NPY-, neurotensin-, and galanin-immunoreactive nerve fibres were abundant. The other nerve fibres were few. Peptidergic nerve fibres occurred in the lamina propria mucosae around and in close contact with the basement membrane of the epithelial cells. In the fibromuscular coat, they lied mainly around the muscle bundles. They showed no special arrangement in the perimuscular connective tissue. In both arteries and veins somatostatin-, neurotensin, and galanin nerve fibres were detected in both tunica media and tunica adventitia. NPY-nerve fibres were found in tunica media and substance P- and GIP- nerve fibres in tunica adventitia. The peptidergic nerve fibres observed in the gallbladder outnumbered those observed with the peripheral nerve markers used in this study. It has been speculated that this might be due to the coexistence of several neuropeptides in the same nerve fibre and/or the coexistence of these neuropeptides with a classical neurotransmitter.

Immunohistochemical localization of galanin in bovine reproductive organs.

The vagina, uterus and oviduct were shown to receive galanin immunoreactive (GAL-IR) nerve fibres, the number of which varied between particular organs. In the ovary, GAL-IR nerves were absent. A small number of these nerves were located in the layers of the oviduct. A moderate number of GAL-IR nerves were situated in the body and uterine horns, whereas the uterine cervix and vagina wall contained a large number of GAL-IR nerve fibres, evenly distributed throughout particular membranes of the organs. GAL-IR nerves were found to contain, simultaneously, either vasoactive intestinal polypeptide (VIP), substance P (SP) or Leu5-enkephalin (ENK). Many of the GAL-IR nerves contained tyrosine hydroxylase (TH). A group of GAL-IR nerves that did not possess immunoreactivity to VIP, SP, ENK or TH was also observed.

Neurotransmitters for the Canine Inferior Pharyngeal Constrictor Muscle

The inferior pharyngeal constrictor muscle plays an important role at the pharyngeal phase of deglutition and is anatomically composed of the thyropharyngeal muscle and cricopharyngeal muscle. In this study we investigated the distribution pattern of neuropeptidergic and catecholaminergic nerve fibers in the thyropharyngeal muscle and cricopharyngeal muscle of seven puppies by immunohistochemistry. Some of the calcitonin gene‐related peptide–, substance P–, vasoactive intestinal polypeptide–, and tyrosine hydroxylase–immunoreactive nerve fibers were found to lie parallel to the muscle fibers in both the thyropharyngeal muscle and cricopharyngeal muscle. Nerve fibers with immunoreactivity to all substances examined were found to be associated with blood vessels in both the thyropharyngeal muscle and cricopharyngeal muscle, and the number of calcitonin gene‐related peptide, neuropeptide Y, and tyrosine hydroxylase nerve fibers was higher than the number of substance P, vasoactive intestinal polypeptide, and galanin nerve fibers. Motor end plate‐like structures with calcitonin gene‐related peptide immunoreactivity were found in both the thyropharyngeal muscle and cricopharyngeal muscle. These structures in the cricopharyngeal muscle were clearly less than those in the thyropharyngeal muscle. Some clusters of neurons were detected only in the cricopharyngeal muscle of all dogs examined. Substance P–, vasoactive intestinal polypeptide–, galanin–, and neuropeptide Y–immunoreactive neurons were found in this ganglion, and the vasoactive intestinal polypeptide–immunoreactive neurons were the most abundant. Abundant calcitonin gene‐related peptide– and vasoactive intestinal polypeptide–immunoreactive nerve fibers, and some substance P– and galanin‐immunoreactive nerve fibers were distributed in the ganglion. A few neuropeptide Y– and tyrosine hydroxylase‐immunoreactive nerve fibers were also found in the ganglion. These findings suggest the complex participation of neuropeptides in the innervation of the inferior constrictor muscle.

Neurotransmitters for the canine inferior pharyngeal constrictor muscle

The inferior pharyngeal constrictor muscle plays an important role at the pharyngeal phase of deglutition and is anatomically composed of the thyropharyngeal muscle and cricopharyngeal muscle. In this study we investigated the distribution pattern of neuropeptidergic and catecholaminergic nerve fibers in the thyropharyngeal muscle and cricopharyngeal muscle of seven puppies by immunohistochemistry. Some of the calcitonin gene-related peptide - , substance P - , vasoactive intestinal polypeptide - , and tyrosine hydroxylase - immunoreactive nerve fibers were found to lie parallel to the muscle fibers in both the thyropharyngeal muscle and cricopharyngeal muscle. Nerve fibers with immunoreactivity to all substances examined were found to be associated with blood vessels in both the thyropharyngeal muscle and cricopharyngeal muscle, and the number of calcitonin gene-related peptide, neuropeptide Y, and tyrosine hydroxylase nerve fibers was higher than the number of substance P, vasoactive intestinal polypeptide, and galanin nerve fibers. Motor end plate-like structures with calcitonin gene-related peptide immunoreactivity were found in both the thyropharyngeal muscle and cricopharyngeal muscle. These structures in the cricopharyngeal muscle were clearly less than those in the thyropharyngeal muscle. Some clusters of neurons were detected only in the cricopharyngeal muscle of all dogs examined. Substance P - , vasoactive intestinal polypeptide - , galanin-, and neuropeptide Y - immunoreactive neurons were found in this ganglion, and the vasoactive intestinal polypeptide - immunoreactive neurons were the most abundant. Abundant calcitonin gene-related peptide - and vasoactive intestinal polypeptide - immunoreactive nerve fibers, and some substance P - and galanin-immunoreactive nerve fibers were distributed in the ganglion. A few neuropeptide Y - and tyrosine hydroxylase - immunoreactive nerve fibers were also found in the ganglion. These findings suggest the complex participation of neuropeptides in the innervation of the inferior constrictor muscle. (OTOLARYNGOL HEAD NECK SURG 1995;113:755-9.)