Co-localisation of substance P-, bombesin- and peptide histidine isoleucine (PHI)-like peptides in gut endocrine cells of the dogfish Scyliorhinus stellaris

Autonomic control of gut motility: a comparative view

Gut motility is regulated to optimize food transport and processing. The autonomic innervation of the gut generally includes extrinsic cranial and spinal autonomic nerves. It also comprises the nerves contained entirely within the gut wall, i.e. the enteric nervous system. The extrinsic and enteric nervous control follows a similar pattern throughout the vertebrate groups. However, differences are common and may occur between groups and families as well as between closely related species. In this review, we give an overview of the distribution and effects of common neurotransmitters in the vertebrate gut. While the focus is on birds, reptiles, amphibians and fish, mammalian data are included to form the background for comparisons. While some transmitters, like acetylcholine and nitric oxide, show similar distribution patterns and effects in most species investigated, the role of others is more varying. The significance for these differences is not yet fully understood, emphasizing the need for continued comparative studies of autonomic control.

Observations favouring the occurrence of local production and marked effects of bombesin/gastrin-releasing peptide in the synovial tissue of the human knee joint--comparisons with substance P and the NK-1 receptor

We have previously shown that levels of the neuropeptides substance P (SP) and bombesin/gastrin-releasing peptide (BN/GRP) in blood and synovial fluid correlate with levels of pro-inflammatory cytokines in patients with rheumatoid arthritis (RA). It is well-established that SP is present in nerve endings in the synovium whilst the source of BN/GRP in human joints is completely unknown. Nor is it known whether GRP-receptors (GRP-R) are present in human synovial tissue. This study aimed to investigate the expression pattern of SP, BN/GRP and their receptors (NK-1R and GRP-R) in synovial tissue. Synovial tissue specimens from patients with RA or osteoarthritis (OA) were processed for immunohistochemistry, in situ hybridisation and ELISA. The results show the presence of BN/GRP, but not SP, in cells in the synovial tissue at both the protein and mRNA level. We did not find immunoreactive BN/GRP in nerve structures. NK-1R and GRP-R were also expressed at both protein and mRNA levels in cells associated with blood vessels and cells in the interstitial tissue. ELISA analyses revealed both SP and BN/GRP to be present in synovial tissue extracts and that synovial levels of SP were higher in RA patients than those with OA. Our results indicate that BN/GRP is produced by non-neuronal cells in the synovial tissue. Furthermore, both BN/GRP and SP may exert their effects on the synovial tissue through the respective receptors. These results suggest that BN/GRP and SP may modulate inflammation and vascular events, and possibly healing processes in the synovium. Finally, nerves should not be considered as the source of BN/GRP in synovial tissue although this peptide is presumably intimately involved functionally in synovial tissue, a previously unrecognised fact.

Are Neuropeptides Important in Arthritis?: Studies on the Importance of Bombesin/GRP and Substance P in a Murine Arthritis Model

Interference with the effects of neuropeptides may be of potential therapeutic value for the treatment of rheumatoid arthritis (RA). Two neuropeptides that can be discussed in this context are bombesin/gastrin-releasing peptide (BN/GRP) and substance P (SP). In order to obtain new information on the possible importance of these two peptides, the patterns of immunohistochemical expression of BN/GRP and SP and their related receptors in the mouse knee joint from healthy and arthritic mice were examined. Positive staining for GRP receptor and the SP preferred receptor (the neurokinin-1 receptor [NK-1 R]) was observed in articular chondrocytes. On the whole, there was a decrease in immunoreactions for both the GRP- and the NK-1 receptors in the articular chondrocytes in joints exhibiting severe arthritis. Staining for BN/GRP and GRP receptor was seen in the inflammatory infiltrates of the arthritic joints. New evidence for the occurrence of marked effects of BN/GRP concerning both the articular chondrocytes and the inflammatory process is obtained in this study. With these findings and previous observations of neuropeptide expression patterns and functions we discuss the possibility that interventions with the effects of BN/GRP, SP, and other neuropeptides might be worthwhile in RA.

Calbindin distribution in male, female and lactating rat pituitary

Calcium binding proteins such as calbindin and calretinin have been studied in the pituitary gland, but information on them is still incomplete. To investigate the localization, distribution and role of calbindin in the pituitary, several antibodies to calbindin and to other pituitary markers, such as calretinin and tyrosine-hydroxylase, have been used in male, female and lactating rats. Calbindin has not been localised to a specific endocrine cell population unlike calretinin in the thyrotrophs. There was occasional localization in somatotrophs, thyrotrophs and luteotrophs, but not in corticotrophs or lactotrophs. However, there are sex differences in the expression of this protein as the number of calbindin-immunoreactive cells is higher in the male than in the female pituitary. Furthermore, the number of calbindin containing cells, not lactotrophs, increases in lactating rats and decreases after removal of the pups. It is concluded that calbindin expression may be altered by physiological and endocrine events such lactation, even though it is still unclear why the protein is not related to a specific cell type. The simultaneous use of monoclonal and polyclonal antisera to calbindin revealed that the rabbit antibody recognizes nuclear and cytoplasmic calbindin, while the monoclonal one binds only to the cytoplasmic calbindin. The suggestion is that calbindin may have a secondary role that is not simply to bind calcium.

Morphology of the air-breathing stomach of the catfish Hypostomus plecostomus

Histological and ultrastructural investigations of the stomach of the catfish Hypostomus plecostomus show that its structure is different from that typical of the stomachs of other teleostean fishes: the wall is thin and transparent, while the mucosal layer is smooth and devoid of folds. The epithelium lining the whole internal surface of the stomach consists of several types of cells, the most prominent being flattened respiratory epithelial cells. There are also two types of gastric gland cells, three types of endocrine cells (EC), and basal cells. The epithelial layer is underlain by capillaries of a diameter ranging from 6.1-13.1 microm. Capillaries are more numerous in the anterior part of the stomach, where the mean number of capillary sections per 100 microm of epithelium length is 4, compared with 3 in the posterior part. The cytoplasm of the epithelial cells, apart from its typical organelles, contains electron-dense and lamellar bodies at different stages of maturation, which form the sites of accumulation of surfactant. Small, electron-dense vesicles containing acidic mucopolysaccharides are found in the apical parts of some respiratory epithelial cells. Numerous gastric glands (2 glands per 100 microm of epithelium length), composed of two types of pyramidal cells, extend from the surface epithelium into the subjacent lamina propria. The gland outlets, as well as the apical cytoplasm of the cells are Alcian blue-positive, indicating the presence of acidic mucopolysaccharides. Zymogen granules have not been found, but the apical parts of cells contain vesicles of variable electron density. The cytoplasm of the gastric gland cells also contains numerous electron-dense and lamellar bodies. Gastric gland cells with electron-dense cytoplasm and tubulovesicular system are probably involved in the production of hydrochloric acid. Fixation with tannic acid as well as with ruthenium red revealed a thin layer of phospholipids and glycosaminoglycans covering the entire inner surface of the stomach. In regions of the epithelium where the capillaries are covered by the thin cytoplasmic sheets of the respiratory epithelial cells, a thin air-blood barrier (0.25-2.02 microm) is formed, thus enabling gaseous exchange. Relatively numerous pores closed by diaphragms are seen in the endothelium lining the apical and lateral parts of the capillaries. Between gastric gland cells, solitary, noninnervated endocrine cells (EC) of three types were found. EC are characterized by lighter cytoplasm than the surrounding cells and they contain dense core vesicles (DCV) with a halo between the electron-dense core and the limiting membrane. EC of type I are the most abundant. They are of an open type, reaching the stomach lumen. The round DCV of this type, with a diameter from 92-194 nm, have a centrally located core surrounded by a narrow halo. EC of type II are rarely observed and are of a closed type. They possess two kinds of DCV with a very narrow halo. The majority of them are round, with a diameter ranging from 88-177 nm, while elongated ones, 159-389 nm long, are rare. EC of type III are numerous and also closed. The whole cytoplasm is filled with large DCV: round, with a diameter from 123-283 nm, and oval, 230-371 nm long, both with a core of irregular shape and a wide, irregular halo. EC are involved in the regulation of digestion and probably local gas exchange. In conclusion, the thin-walled stomach of Hypostomus plecostomus, with its rich network of capillaries, has a morphology suggesting it is an efficient organ for air breathing.

Colocalization of numerous immunoreactivities in endocrine cells of the chicken proventriculus at hatching

The colocalization of regulatory peptide immunoreactivities in endocrine cells of the chicken proventriculus at hatching has been investigated using the avidin-biotin technique in serial sections and double immunofluorescence in the same section for light microscopy, and double immunogold staining for electron microscopy. In addition to the eight immunoreactivities previously described in this organ, cells immunoreactive for peptide histidine isoleucine (PHI), peptide gene product 9.5 (PGP), and the amidating enzyme, peptidylglycine alpha-amidating monooxygenase (PAM) were observed. All the cells immunoreactive to glucagon were also immunostained by the PHI antiserum. In addition, all the glucagon-like peptide 1, avian pancreatic polypeptide, and some of the neurotensin-like cells costored also glucagon- and PHI-immunoreactive substances. PGP- and PAM-immunoreactivities were also found in the glucagon-positive cells. A small proportion of the somatostatin-containing cells were positive for PHI but not for other regulatory peptides. These results could suggest either the existence of a very complex regulatory system or that the endocrine system of the newborn chickens is not yet fully developed.

Short- and long-term effects of irradiation on laryngeal mucosa of the rat

Although radiotherapy is often used to treat laryngeal carcinoma, there is little information on the effects of this treatment on laryngeal structures. Rats were irradiated to the head and neck region and the larynges were studied by light- and electron-microscopy and immunohistochemistry. Ten days after irradiation, a change in the ultrastructural appearance of the granules of the subglottic glands was observed. Substance P-, bombesin- and enkephalin-like immunoreactivity was increased in local ganglionic cells and glandular nerve fibres. The mast cells were reduced in number. At examination 4 6 months after irradiation, there were no obvious differences compared with controls concerning mast-cell numbers and neuropeptide expression. The ultrastructural changes seen in the subglottic glands remained to some extent. The results show that structural changes in the subglottic glands occur concomitantly with an increased expression of certain neuropeptides in the innervation of these glands, which implies a relationship between these two parameters. The mast cells respond drastically to irradiation, but in the long run, regeneration of these cells occurs.

Ontogenetic and phylogenetic development of the endocrine pancreas (islet organ) in fish

The morphology of the gastroenteropancreatic (GEP) system of fish was reviewed with the objective of providing the phylogenetic and ontogenetic development of the system in this vertebrate group, which includes agnathans and gnathostome cartilaginous, actinoptyerygian, and sarcopterygian fish. Particular emphasis is placed on the fish homolog of the endocrine pancreas of other vertebrates, which is referred to as the islet organ. The one-hormone islet organ (B cells) of larval lampreys is the most basic pattern seen among a free-living vertebrate, with the two-hormone islet organ (B and D cells) of hagfish and the three-hormone islet organ (B, D, and F cells) of adult lampreys implying a phylogenetic trend toward the classic four-hormone islet tissue (B, D, F, and A cells) in most other fish. An earlier stage in the development of this phylogenetic sequence in vertebrates may have been the restriction of islet-type hormones to the alimentary canal, like that seen in protochordates. The relationship of the islet organ to exocrine pancreatic tissue, or its equivalent, is variable among bony, cartilaginous, and agnathan fishes and is likely a manifestation of the early divergence of these piscine groups. Variations in pancreatic morphology between individuals of subgroups within both the lamprey and chondrichthyan taxa are consistent with their evolutionary distance. A comparison of the distribution and degree of concentration of the components of the islet organ among teleosts indicates a diffuse distribution of relatively small islets in the generalized euteleosts and the tendency for the concentration into Brockmann bodies of large (principal) islets (with or without secondary islets) in the more derived forms. The holostean actinopterygians (Amiiformes and Semiontiformes) share with the basal teleosts (osteoglossomorphs, elopomorphs) the diffuse arrangement of the components of the islet organ that is seen in generalized euteleosts. Since principal islets are also present in adult lampreys the question arises whether principal islets are a derived or a generalized feature among teleosts. There is a paucity of studies on the ontogeny of the GEP system in fish but it has been noted that the timing of the appearance of the islet cell types parallels the time that they appear during phylogeny; the theory of recapitulation has been revisited. It is stressed that the lamprey life cycle provides a good opportunity for studying the development of the GEP system. There are now several markers of cell differentiation in the mammalian endocrine pancreas which would be useful for investigating the development of the islet organ and cells of the remaining GEP system in fish.

Increase in bombesin-like peptides in the spinal cord after dexamethasone treatment of adrenalectomized rats

The potential influence of corticosteroids on the bombesin (BN)-like peptide family is unknown. Therefore, the effects of adrenalectomy (ADX) on the nervous system of Sprague-Dawley rats, some of them being treated with high doses of the synthetic glucocorticoid dexamethasone (DEX), were investigated. After 8-10 days of treatment, the rats were sacrificed and tissues were prepared for radioimmunoassay (RIA) and immunohistochemical examination. We found an increase in BN-like immunoreactivity in the superficial layers of the dorsal horn of the lumbar spinal cord in the ADX + DEX animals. This increase was confirmed by RIA (P < 0.05). The observations show that the expression of BN-like peptides is influenced by glucocorticoids. The altered levels of BN-like peptides may be related to the trophic and antinociceptive effects previously reported for these peptides.

Enhanced expression of neuropeptides in human breast cancer cell lines following irradiation

Previously, we have observed that the expression of the neuropeptides bombesin (BN-), the mammalian counterpart being gastrin-releasing peptide (GRP), and substance P (SP) in intact normal tissues, such as salivary and laryngeal glands, increases in response to irradiation. In the present study, the aim was to evaluate whether irradiation can have effects on individual cells that normally synthesize neuropeptides. In addition, since these neuropeptides are potentially mitogenic, we studied tumor cells. Therefore, the estrogen receptor-negative human breast cancer cell line MDA-MB-231 and its subline, with acquired doxorubicin resistance, MDA-MB-231 Dox were examined before irradiation and 4, 10, and 15 days after irradiation with 4 Gy (195 kV, 2 Gy fractions with 4 hours interval). Potential dose related changes were studied by delivering single doses of 2 or 9 Gy with the same technique. Immunohistochemical and radioimmunoassay (RIA) methods were used for detection of the SP and BN/GRP. Before, and at all time points following irradiation, a subpopulation in both cell lines displayed an intense immunostaining of SP and BN/GRP. A partial reorganization of the immunoreactive material was observed 10 days after irradiation. The RIA-analyses displayed signs of a dose-related increase, and a time-dependent transient and significant increase in the content of both peptides. The pattern of changes differed between the two peptides, and was especially pronounced in the doxorubicin resistant cells with regard to SP. Another neuropeptide, calcitonin gene related peptide (CGRP), was not detected in the cells used. The results suggest that irradiation has effects on a population of cultured neuropeptide-synthesizing cells. The occurrence and the specific changes obtained in the levels of neuropeptides, in response to irradiation, might imply an importance in the growth of breast cancer cells and in explaining repair processes following irradiation.

Bombesin-like peptide is present in duct cells in salivary glands: studies on normal and irradiated animals

Bombesin (BN) and its mammalian counterpart gastrin-releasing peptide act as neuroregulatory hormones and tissue-specific growth factors, and have been implicated as peripheral and central satiety-inducing agents. In the present study, the immunohistochemical expression of BN in submandibular, sublingual and parotid glands of rats was examined 10 days after 5 consecutive days with daily doses of 6-8 Gy irradiation. Radioimmunoassay (RIA) methods were also used. Immunoreactive granular structures were observed within duct cells of both controls and irradiated animals. In the parenchyma of irradiated animals, very few nerve fibres showing BN-like immunoreactivity were observed. The RIA analysis showed that the content of BN-like material significantly increased in submandibular and parotid glands in response to irradiation. The results suggest that mainly a non-neural form of BN is detected in the salivary glands in the immunohistochemical analysis. Thus, the immunohistochemical observations suggest that BN-like peptides may be present in the duct system, where they may be constituents of the saliva. The observations of an increase in BN content in response to irradiation are of interest as BN has mitogenic effects, may stimulate secretion and contributes to satiety.

Ultrastructure of fetal alimentary organs: stomach and spiral intestine in the southern stingray, Dasyatis americana

In the fetal southern stingray, Dasyatis americana, both the stomach and spiral intestine function early in development to digest and absorb nutrient histotroph elaborated by uterine villi termed trophonemata. The gastric mucosa consists of a surface columnar mucous epithelium that is confluent with gastric pits or foveolae. Gastric glands are populated by oxynticopeptic and enteroendocrine cells. The surface mucous cells are pyramidal with apical microvilli. Oxynticopeptic cells are low columnar with a distinct and elaborate tubulovesicular system in the apical cytoplasm. Microvilli line the lumen of the gastric glands and cells have elaborate interdigitating lateral folds. Enteroendocrine cells are characterized by basal granules and a prominent rough endoplasmic reticulum. The fetal intestine is filled with bile-tinged viscous fluid. A core of submucosa supports spiral intestinal plicae that form the spiral valve from which villi project. The most prominent characteristic of the cells are enormous supranuclear vesicles formed by coalescence of smaller endocytotic vesicles. The apical cytoplasm has a profusion of smooth tubules, endoplasmic reticulum, and lysosomes. The large vesicles are interpreted as storage depots for continually ingested histotroph. Small vesicles may then bud off to be digested via the lysosomal system.

Bombesin-like immunoreactivity in the rat larynx: increase in response to irradiation

It is previously well known that bombesin has effects as growth factor and that changes in bombesin content in air-way structures occur in various patho-physiological conditions. In the present study, the effects of radiotherapy on bombesin expression in the rat larynx were studied. Irradiation was given for five days, 6 or 8 gray daily. Ten days after cessation of irradiation, the subglottic part of the larynx from irradiated and control animals was dissected out, and processed for immunohistochemistry or radioimmunoassay. The radioimmunoassay analysis showed that the content of bombesin-like material increased 2-fold after irradiation. The immunohistochemical analysis displayed an increased bombesin-like immunoreactivity in local ganglionic cells and in nerve fibers in the submucosal glands. These nerve fibers are likely to be derived from the local ganglionic cells. On the other hand, there was no change in the pattern of immuno-reactivity in the innervation of the epithelium and the lamina propria, including the blood vessels. The observations show that radiotherapy can be added to the list of factors that influence bombesin expression in airway structures.

Regulatory peptides in gastric endocrine cells of the rainbow trout Oncorhynchus mykiss: general distribution and colocalizations

The endocrine cells of the rainbow trout (Oncorhynchus mykiss) stomach have been investigated using the immunocytochemical techniques of peroxidase-anti-peroxidase and avidin-biotin-peroxidase complexes on paraffin sections. 33 antisera were tested and eight immunoreactivities were detected: somatostatin-, glucagon- bombesin-, substance P-, serotonin-, met-enkephalin-, CCK/gastrin-, and chromogranin-like containing cells. All of them were present throughout the gastric mucosa except CCK/gastrin-like containing cells that were restricted to the pyloric epithelium. Somatostatin 25 and chromogranin immunoreactive cells are described for the first time in fish stomach. Serotonin immunoreactive cells were also positive for the Grimelius technique and some of them were immunoreactive to anti substance P or anti CCK/gastrin. Immunoreactivities for gastrin 17, gastrin 34 and CCK appeared in the same cells and the absorption controls showed that a molecule containing the carboxi-terminal pentapeptide of this family was present in trout stomach.

Irradiation-induced effects on the innervation of rat salivary glands: changes in enkephalin- and bombesin-like immunoreactivity in ganglionic cells and intraglandular nerve fibers

When treating head and neck for cancer with the use of radiotherapy the salivary glands are usually within the treatment volume with ensuing dryness and discomfort. Since the autonomic nervous system is of pivotal importance for the salivary gland function and integrity, the irradiation-induced effects may involve an influence on the innervation of salivary glands. Therefore, the rat submandibular gland, including the submandibular ganglionic cells, has been subjected to immunohistochemical examination with respect to expression of neuropeptides following fractionated irradiation with high energy photons. A markedly enhanced expression of bombesin- and leu-enkephalin-(ENK)-like immunoreactivities (LI) in the ganglionic cells and a pronounced increase in the number of nerve fibers showing these immunoreactivities in the submandibular gland tissue following irradiation were observed 10 days after treatment. On the other hand, no changes in the patterns of VIP (vasoactive intestinal polypeptide)- and NPY (neuropeptide Y)-immunoreactivities occurred. Thus, the present study shows that alterations in the expression of certain neuropeptides take place in the submandibular gland and its associated ganglionic cells in response to irradiation of the head and neck region. These changes may add further explanation to the inherent radiosensitivity of salivary glands.

Some peptide-like colocalizations in endocrine cells of the pyloric caeca and the intestine of Oncorhynchus mykiss (Teleostei)

The coexistence of immunoreactivities to cholecystokinin, glucagon, glucagon-like peptide 1, salmon pancreatic polypeptide, neuropeptide tyrosine, and peptide tyrosine tyrosine was studied immunocytochemically, revealing for the first time in fish intestine the existence in the same cell of immunoreactivities to cholecystokinin-glucagon/glucagon-like peptide 1, cholecystokinin-salmon pancreatic polypeptide, glucagon/glucagon-like peptide 1-salmon pancreatic polypeptide, glucagon/glucagon-like peptide 1-neuropeptide tyrosine, salmon pancreatic polypeptide tyrosine tyrosine, and glucagon/glucagon-like peptide 1-peptide tyrosine tyrosine. Colocalization of cholecystokinin-salmon pancreatic polypeptide was observed only in the pyloric caeca of the rainbow trout Oncorhynchus mykiss, while the other colocalizations also occurred in proximal and middle intestinal segments. In all cases, endocrine cells immunoreactive to only one of the paired antisera were detected except for anti-glucagon and anti-glucagon-like peptide 1, which always immunostained the same cells.

Neuropeptide Y-like immunoreactivity in the dogfish gastroenteropancreatic tract: light and electron microscopical study

The 36 amino acid neuropeptide Y (NPY) has been examined in mammals and is mainly located in the nerves. Its distribution in nonmammalian vertebrate and in some invertebrate nervous systems has been confirmed. Using antisera raised to porcine NPY, NPY immunoreactivity has been localized in endocrine cells of the pancreas and gastrointestinal tract of two dogfish, Scyliorhinus stellaris and Scyliorhinus canicula. Immunostained serial sections and cross-absorption experiments with related peptides, including avian and bovine pancreatic polypeptide and peptide tyrosine tyrosine, excluded any cross-reactivity. The fine structure of the cells containing NPY-like substance is described.