Distribution and co-localization of immunoreactive helospectin with vasoactive intestinal polypeptide and peptide histidine methionine in human nasal mucosa, soft palate and larynx

Intrinsic neuroendocrine cells in the outer wall of the human pyriform recess

The extrinsic neural supply of the hypopharynx is well established. However, little is known about the intrinsic neurons and neuroendocrine cells (NECs) of the human hypopharynx that are under the influence of the extrinsic nerves. We aimed to identify and characterize such cell populations within the outer wall of the pyriform recess. We applied antibodies for neuron-specific enolase (NSE), calretinin (CR) and neurofilaments (NF) to autopsy samples from four donor cadavers. Within the lamina propria and the muscle layer of the pyriform recess outer wall, usually in perivascular areas, we found NSE-, CR- and NF-positive cells, mostly apolar, that were considered on a histological and immunohistochemical basis to be NECs. Although these cells have not, to our knowledge, been described previously in this anatomical location, their presence within the hypopharynx wall may explain the appearance of rare forms of local primary neuroendocrine carcinomas.

Hair-cycle-associated remodeling of the peptidergic innervation of murine skin, and hair growth modulation by neuropeptides

As the neuropeptide substance P can manipulate murine hair growth in vivo, we here further studied the role of sensory neuropeptides in hair follicle biology by determining the distribution and hair-cycle-dependent remodeling of the sensory innervation in C57BL/6 mouse back skin. Calcitonin-gene-related peptide, substance P, and peptide histidine methionine (employed as vasoactive intestinal peptide marker) were identified by immunohistochemistry. All of these markers immunolocalized to bundles of nerve fibers and to single nerve fibers, with distinct distribution patterns and major hair-cycle-associated changes. In the epidermis and around the distal hair follicle and the arrector pili muscle, only calcitonin-gene-related peptide immunoreactive nerve fibers were visualized, whereas substance P and peptide histidine methionine immunoreactive nerve fibers were largely restricted to the dermis and subcutis. Compared to telogen skin, the number of calcitonin-gene-related peptide, substance P, and peptide histidine methionine immunoreactive single nerve fibers increased significantly (p < 0.01) during anagen, including around the bulge region (the seat of epithelial stem cells). Substance P significantly accelerated anagen progression in murine skin organ culture, whereas calcitonin-gene-related peptide and a substance-P-inhibitory peptide inhibited anagen (p < 0.05). The inhibitory effect of calcitonin-gene-related peptide could be antagonized by coadministrating substance P. In contrast to substance P, calcitonin-gene-related peptide failed to induce anagen when released from subcutaneous implants. This might reflect a differential functional assignment of the neuropeptides calcitonin-gene-related peptide and substance P in hair growth control, and invites the use of neuropeptide receptor agonists and antagonists as novel pharmacologic tools for therapeutic hair growth manipulation.

Expression of vasoactive intestinal peptide, calcitonin gene-related peptide, substance P, and intermediate neurofilaments in nasal mucosal nerve fibers of horses without nasal disease

OBJECTIVE

To determine the distribution of nerve fibers containing calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal peptide (VIP), and intermediate neurofilaments in nasal mucosa of horses.

ANIMALS

6 horses without evidence of nasal disease.

PROCEDURE

Full-thickness nasal tissue specimens were obtained from the rostral portion of the nasal septum at necropsy, and fluorescence immunohistochemistry was performed to assess mucosal distribution of nerve fibers.

RESULTS

Nerve fibers with CGRP-like immunoreactivity (CGRP-Li) formed a dense subepithelial network, and a large number of fibers were found coursing between epithelial cells. Fibers with CGRP-Li were also associated with blood vessels and mucous glands. Fibers with SP-like immunoreactivity (SP-Li) had a similar distribution and density. In contrast, there were few fibers with VIP-like immunoreactivity. Fibers containing intermediate neurofilaments were prominent and appeared as large nerve fiber bundles mainly adjacent to the nasal septum but also close to mucous glands and within the lamina propria. Intermediate neurofilaments were also identified in single nerve fibers at all sites, but the density of fibers with intermediate neurofilaments did not match that of fibers with CGRP- or SP-Li.

CONCLUSIONS

The density and distribution of nerve fibers containing SP- or CGRP-Li in nasal mucosa of horses was similar to that reported for other species. However, expression of VIP in nerve fibers was low. Antibodies against intermediate neurofilaments identified many nerve fibers in nasal mucosa of horses but did not appear to identify small diameter fibers expressing SP or VIP.

Neurotransmitters and neuromodulators involved in laryngeal innervation

The distribution and role of neurotransmitters and neuromodulators in laryngeal innervation are reviewed, and our recent findings regarding the nitrergic innervation of the larynx are demonstrated for the better understanding of the complexity of the laryngeal innervation system. Noradrenergic innervation of the larynx was studied with fluorescence histochemistry and electron microscopy after application of 5-hydroxydopamine. These studies confirmed the existence of noradrenergic innervation for the submucosal glands and blood vessels, and the origin and course of noradrenergic nerve fibers contained in the laryngeal nerves and their destinations in the larynx. Cholinergic innervation of the larynx has not been clarified in detail. Many kinds of neuropeptides have been demonstrated to be involved in laryngeal innervation. Vasoactive intestinal polypeptide originating from intralaryngeal ganglionic neurons participates in laryngeal vasodilation and reduction of laryngeal seromucous secretion. Neuropeptide Y nerve fibers are few in the larynx, and most originate from the superior cervical ganglion. They are distributed around the large or medium-sized blood vessels, especially arteries. They are also associated with excretory structures. Substance P was the first neuropeptide found to be a sensory neurotransmitter in the laryngeal afferent system. It is also involved in regulation of laryngeal blood flow and secretion. Calcitonin gene-related peptide is associated with the sensory, autonomic, and motor innervation of the larynx. The majority of enkephalin nerve fibers are located close to excretory structures, although no information on the physiological significance of enkephalin is available. In addition to the above neuropeptides, the peptides histidine isoleucine, histidine methionine, and helospectin have been shown to exist in the larynx. The nitrergic innervation of the larynx has been recently studied with NADPH-diaphorase histochemistry and immunohistochemistry using antiserum against nitric oxide synthase. Nitric oxide originates from the neurons in the intralaryngeal ganglia and is believed to modulate blood flow and secretion of the larynx. It controls the laryngeal exocrine secretion in cooperation with intrinsic vasoactive intestinal polypeptide and/or extrinsic calcitonin gene-related peptide. Nitric oxide from the nodose ganglion may modulate nociception of the larynx. The existence of nitrergic neurons located in the intrinsic laryngeal muscles has been demonstrated. Many of them are bipolar or pseudounipolar, so they might be sensory in nature. The effect of injury of the recurrent laryngeal nerve on the induction of nitric oxide synthase in the laryngeal motoneurons is also discussed.

Distribution of two VIP-related peptides, helospectin and pituitary adenylate cyclase activating peptide (PACAP), in the human upper respiratory system

Helospectin (HS) and pituitary adenylate cyclase activating peptide (PACAP) are newly discovered peptides isolated from the salivary gland venom of the lizard Heloderma horridum and the ovine hypothalamus, respectively. They show chemical similarities to vasoactive intestinal polypeptide (VIP), appear to have similar functions and are present in gut, brain, lung, male and female genitourinary tract. In the present study, the distribution of the helospectin and PACAP-27 in the human upper respiratory system was investigated using indirect immunofluorescence and electron-microscopical ABC-pre-embedding methods. Immunohistochemistry revealed helospectin-like (HS-LI) and PACAP-like (PACAP-LI) immunoreactivity in nerve fibers in human nasal, the larynx (vocal cord, ventricular fold, epiglottis), the tongue and the soft palate mucosa. Helospectin-LI and PACAP-LI containing nerve fibers were mainly found in close association to blood vessels and glandular structures. Colocalization studies carried out by application of double immunofluorescence showed that HS and/(or) PACAP-LI coexist with VIP in apparently the same nerve fibers in the upper respiratory system, although single nerve fibers seem to exclusively express helospectin. The localization patterns of helospectin and PACAP-LI in the human upper respiratory system suggests their possible involvement in the regulation of secretory activities and local blood flow.

Regulatory peptides in the human soft palate

The distributions of vasoactive intestinal polypeptide, peptide, histidine methionine, helospectin, neuropeptide Y and its C-flanking peptide, substance P and calcitonin gene-related peptide were studied in the human soft palate using immunocytochemical techniques. Peptide-containing nerve fibers were found to form a dense network around glandular acini, excretory ducts and blood vessels, as well as beneath and within the epithelium. Chromogranin A, bombesin-flanking peptide and calcitonin gene-related peptide immunoreactivities were detected in endocrine-like cells located in excretory ducts.

Distribution and seasonal variation of vasoactive intestinal (VIP)-like peptides in the nervous system of Helix pomatia

The distribution of neuropeptides immunologically related to vasoactive intestinal peptide (VIP) and its precursor peptide preproVIP(111-122), as well as to other peptides of the VIP-family, was studied in the central and peripheral nervous and sensory system of the snail, Helix pomatia, by use of immunocytochemical methods. VIP and preproVIP immunoreactivity was present in somata and nerve fibres of all central ganglia. Hibernating snails contained on average a total of 670 VIP- and 763 preproVIP-immunoreactive neurons. The number of immunoreactive cells was substantially reduced by more than 50% in active snails during summer with an average of 289 VIP- and 356 preproVIP-immunoreactive neurons. Antiserum against VIP labelled nerve fibres next to blood vessels and smooth muscle cells, whereas preproVIP-like material was localized in nerve fibres and endocrine-like cells among dorsal body cells and in the connective tissue along fiber tracts. VIP-immunoreactive material was also found in accessory ganglia of small and large tentacles, ganglia of the lips, the sensory epithelium of the tentacles, free nerve endings between skin epithelial cells, neuronal cells in the retina and in the sensory epithelium of statocysts. The cell-specific distribution and the seasonal variation of VIP- and preproVIP-like peptides suggest that they may act as transmitters or modulators in the nervous and sensory system and may be involved in the physiological adaptation of central neurons during long-term resting periods of snails.

Helospectin and pituitary adenylate cyclase activating polypeptide in the human vagina

Helospectin and pituitary adenylate cyclase activating polypeptide (PACAP), both recently isolated from the poisonous saliva of the American lizard or from ovine hypothalamus respectively, belong to the same peptide family as vasoactive intestinal polypeptide (VIP), peptide histidine methionine (PHM) and glucagon. In the present study, occurrence and distribution patterns of nerve fibers containing helospectin- and PACAP-like immunoreactivity in the human vagina were investigated by immunohistochemistry. Double immunofluorescent labeling showed that helospectin or PACAP are co-expressed with VIP and PHM within subpopulations of VIP-immunoreactive nerve fibers. Nervous structures containing helospectin and VIP were particularly numerous in the internal mucous lining of the vagina and in free epithelial nerve endings, and an abundant network of nerve fibers surrounding blood vessels was detected. Nerve fibers co-expressing PACAP and VIP were more numerous than those expressing helospectin and VIP and were mainly found in close association with blood vessels as well as beneath and within the epithelium. Due to the lack of non-rabbit helospectin or PACAP antibodies, possible co-localizations between these two peptides could not be investigated at this time. The localizations demonstrated suggest possible roles of the two peptides in the regulation of local blood flow and lubrication of the vagina.

Helospectin-like immunoreactivity in the rat eye and pterygopalatine ganglion

Helospectin I and II, nearly identical peptides isolated from lizard venom, show close sequence homology with vasoactive intestinal peptide (VIP). In mammals, the helospectins have been localized immunohistochemically to neurons of the brain, digestive tract and respiratory system, commonly co-existing with VIP. Using an antiserum that recognizes both forms of the peptide, we localized helospectin-like immunoreactivity in the rat eye and pterygopalatine ganglion. In the eye, helospectin-positive nerve fibers were evident mostly in the choroid, associated with small arterial vessels or distributed diffusely in the stroma; they were only occasionally seen in the anterior uvea. All of the helospectin nerve fibers also appeared to be immunoreactive for VIP. In the pterygopalatine ganglion, the principal source of VIP-containing innervation of the posterior uvea, approximately 25% of ganglion cells were helospectin-positive; all helospectin-reactive cells were also strongly positive for VIP. This immunohistochemical localization of helospectin indicates possible involvement in ocular autonomic functions, particularly regulation of blood flow.

Regulatory peptides in the human larynx and recurrent nerves

We studied the peptide-innervation of the human larynx (vocal cord, ventricular folds, epiglottis, subglottic region and the recurrent nerves) using immunocytochemical and radioimmunological methods. In the tissues of the larynx investigated, the following regulatory peptides were detected: vasoactive intestinal polypeptide (VIP), peptide histidine methionine (PHM), helospectin, neuropeptide Y (NPY), C-flanking peptide of NPY (C-PON), calcitonin gene-related peptide (CGRP), substance P and neurokinin. In the recurrent nerves only small numbers of peptide-immunoreactive nerve fibers were found. Most of them showed positive immunoreactivities with antibodies to PHM, NPY and C-PON, but only rare and scattered nerve fibers were positive for VIP-, CGRP- and substance P.