Immunoreactivities of gastrin (G-) cells. II. Non-specific binding of immunoglobulins to G-cells by ionic interactions

Pitfalls and Caveats in Applying Chromogenic Immunostaining to Histopathological Diagnosis

Chromogenic immunohistochemistry (immunostaining using an enzyme-labeled probe) is an essential histochemical technique for analyzing pathogenesis and making a histopathological diagnosis in routine pathology services. In neoplastic lesions, immunohistochemistry allows the study of specific clinical and biological features such as histogenesis, behavioral characteristics, therapeutic targets, and prognostic biomarkers. The needs for appropriate and reproducible methods of immunostaining are prompted by technical development and refinement, commercial availability of a variety of antibodies, advanced applicability of immunohistochemical markers, accelerated analysis of clinicopathological correlations, progress in molecular targeted therapy, and the expectation of advanced histopathological diagnosis. However, immunostaining does have various pitfalls and caveats. Pathologists should learn from previous mistakes and failures and from results indicating false positivity and false negativity. The present review article describes various devices, technical hints, and trouble-shooting guides to keep in mind when performing immunostaining.

Peripheral and central autonomic nervous system: does the sympathetic or parasympathetic nervous system bear the brunt of the pathology during the course of sporadic PD?

It is a well-established fact that the sympathetic, parasympathetic and enteric nervous systems are affected at early stages in Parkinson's disease (PD). However, it is not yet clarified whether the earliest pathological events preferentially occur in any of these three divisions of the autonomic nervous system (ANS). Significant involvement of the peripheral autonomic nervous system of the heart and gastrointestinal tract has been documented in PD. Accumulating evidence suggests that the PD pathology spreads centripetally from the peripheral to central nervous system through autonomic nerve fibers, implicating the ANS as a major culprit in PD pathogenesis and a potential target for therapy. This study begins with a brief overview of the structures of the central and peripheral autonomic nervous system and then outlines the major clinicopathological manifestations of cardiovascular and gastrointestinal disturbances in PD.

Label-Free Detection of Bacillus anthracis Spore Uptake in Macrophage Cells Using Analytical Optical Force Measurements

Understanding the interaction between macrophage cells and Bacillus anthracis spores is of significant importance with respect to both anthrax disease progression, spore detection for biodefense, as well as understanding cell clearance in general. While most detection systems rely on specific molecules, such as nucleic acids or proteins and fluorescent labels to identify the target(s) of interest, label-free methods probe changes in intrinsic properties, such as size, refractive index, and morphology, for correlation with a particular biological event. Optical chromatography is a label free technique that uses the balance between optical and fluidic drag forces within a microfluidic channel to determine the optical force on cells or particles. Here we show an increase in the optical force experienced by RAW264.7 macrophage cells upon the uptake of both microparticles and B. anthracis Sterne 34F2 spores. In the case of spores, the exposure was detected in as little as 1 h without the use of antibodies or fluorescent labels of any kind. An increase in the optical force was also seen in macrophage cells treated with cytochalasin D, both with and without a subsequent exposure to spores, indicating that a portion of the increase in the optical force arises independent of phagocytosis. These results demonstrate the capability of optical chromatography to detect subtle biological differences in a rapid and sensitive manner and suggest future potential in a range of applications, including the detection of biological threat agents for biodefense and pathogens for the prevention of sepsis and other diseases.

Fixation conditions affect the immunoreactivity of gustducin in rat vallate taste buds

This study aimed to examine gustducin immunoreactivities when adopting various immunostaining conditions in rat vallate taste buds. The occurrence and intensity of the immunoreactivities exhibited specific patterns in accordance with the fixation time. The immunoreactions were localized to only taste hairs, the upper part of the taste bud, after short fixation periods but then to the cell-body cytoplasm excluding the taste hairs after long fixation periods. These immunohistochemical data suggest that the staining protocols, especially the fixation time, cause discrepancies in gustducin immunoreactivities.

Suitability of muscarinic acetylcholine receptor antibodies for immunohistochemistry evaluated on tissue sections of receptor gene-deficient mice

Acetylcholine (ACh) is a major regulator of visceral function exerting pharmacologically relevant effects upon smooth muscle tone and epithelial function via five types of muscarinic receptors (M1R-M5R). In this paper, we assessed the specificity of muscarinic receptor (MR) antibodies in immunohistochemical labelling on tissue sections by analysing specimens from wild-type and respective gene-deficient mice. Of 24 antibodies evaluated in this study, 16 were tested at 18 different conditions each, and eight of them in 21 different protocols, resulting in a total number of 456 antibody/protocol combinations. Each of them was tested at four antibody dilutions at minimum, so that finally, at least 1,824 conditions were evaluated. For each of them, dorsal root ganglia, urinary bladder and cross-sections through all thoracic viscera were investigated. In all cases where the antigen was available, at least one incubation condition was identified in which only select cell types were immunolabelled in the positive control but remained unlabelled in the pre-absorption control. With two exceptions (M2R antibodies), however, all antibodies produced identical immunohistochemical labelling patterns in tissues taken from corresponding gene-deficient mice even when the pre-absorption control in wild-type mice suggested specificity. Hence, the present data demonstrate the unpleasant fact that reliable immunohistochemical localisation of MR subtypes with antibodies is the exception rather than the rule. Immunohistochemical detection of MR subtype localisation in tissue sections of peripheral organs is limited to the M2R subtype utilising the most commonly used methodological approaches.

Immuno-laser capture microdissection of frozen prolactioma sections to prepare proteomic samples

Laser capture microdissection (LCM) technology combined with immunohistochemistry (immuno-LCM) is a valuable tool to obtain specific target cell populations and therefore this technique enables more accurate proteomic profile. In this study, we optimized the regular immuno-LCM technique to isolate and stain pure prolactin cells from either normal human pituitary (n=6) or prolactioma (n=11). Compared with the routine procedure, more intense and specific staining could be obtained when sections were pretreated with 0.2% Triton X-100 for 4 min. Interestingly, longer pretreatment (0.2% Triton X-100 for 10 min) or higher concentration (2% Triton X-100 for 4 and 10 min) greatly impaired labeling intensity and cell shape. Further scanning electron microscope study revealed that the component extracted from the cell surface by Triton X-100 was lipid. Using the optimized immuno-LCM technique, more pure prolactin cells could be isolated and prepared for further proteomic analysis. Taken together, we reported an optimized immuno-LCM technique that could effectively dissect pure target cells in different type pituitary adenomas for further proteomics analysis.

Triton X-100 pretreatment of LR-white thin sections improves immunofluorescence specificity and intensity

The staining of intracellular antigenic sites in postembedded samples is a challenging problem. Deterioration of antigenicity and limited antibody accessibility to the antigen are commonly encountered on account of processing steps. In this study preservation of the antigen was achieved by fixing the tissues with mild fixatives, performing partial dehydration, and embedding in a low crosslinked hydrophilic acrylic resin, LR-White. Permeabilization of cell membranes with Triton X-100 is well documented but can affect some antigen conformations. We tested the effect of Triton X-100 on the ED1 antigen present in the lysosomal membrane of the macrophage in cell culture. The ED1 antigen in the lysosome was resistant to extraction by Triton X-100. Interestingly pretreating the LR-White sections of macrophage pellets with Triton X-100 improved the staining intensity of ED1. The most intense and clear specific fluorescent staining was observed when sections were pretreated with 0.2% Triton X-100 for 2 min. Longer exposure of sections to 0.2% Triton or 2 min exposure to 2% Triton lead to reduced ED1 labeling. SEM observations indicated that the detergent extracted a component from the cells and not the resin and was determined to be lipid. This novel technique could be applied in many research areas where postembedding fluorescent immunolabeling with higher labeling intensity is desired.

Age-related changes in the gastrointestinal tract: a functional and immunohistochemical study in guinea-pig ileum

It is known that there is an age-related increase in gastrointestinal diseases. However, there is a lack of studies dealing with the correlation between age-related changes in function and intrinsic innervation in the gastrointestinal tract. The purpose of this work was to study this subject in the guinea pig ileum, whose functional and structural features are well known in the young age. Ileal longitudinal muscle -- myenteric plexus (LMMP) preparations were obtained from 3-to 24-month-old guinea pigs. Both functional and immunohistochemical techniques were applied. The force of the contraction elicited by excitatory stimuli (electrical stimulation, acetylcholine, substance P, and opioid withdrawal) increased in parallel with an age-dependent reduction in the density of excitatory motor neurones to the longitudinal muscle, whereas other subpopulations of neurones, including inhibitory motor neurones, decreased much more slowly. Although the increase in responsiveness could be related to the age/weight-related increment in muscle bulk, some compensatory modifications to the lowered density of excitatory neurones could also be involved. On the other hand, the acute inhibitory response to morphine remained unaltered in old animals, whilst in vitro tolerance was lower. These results suggest that although age-dependent neuronal loss does not cause dramatic changes in intestinal motility, it is a factor that could contribute to disturbing normal responsiveness and, perhaps, underlie the higher frequency of gastrointestinal diseases encountered in the elderly.

Ileal myenteric plexus in aged guinea-pigs: loss of structure and calretinin-immunoreactive neurones

Myenteric plexus controls gastrointestinal motility by means of well organized circuits which are comprised of sensory neurones, interneurones and motor neurones to the muscular layers. Calretinin (CR) is a calcium-binding protein that, in guinea-pig ileum, has only been found in ascending interneurones, which also express neurofilament triplet proteins (NFT), and excitatory longitudinal muscle motor neurones, which do not. In spite of some evidence that age affects both function and structure of the myenteric plexus, little is known about the possible selectivity of the process regarding specific myenteric neuronal phenotypes. The influence of age on both the structure of the myenteric plexus and the presence of CR-immunoreactive (CR-IR) neurones was studied using conventional immunohistochemical procedures applied to ileal whole-mount preparations from guinea-pigs. Both a reduction in ganglionic size and changes in the distribution of neurones inside and outside the ganglia, together with a general neuronal loss were found in preparations from aged guinea-pigs. More interestingly, a relatively more pronounced age-related loss of CR-IR neurones, especially those lacking of NFT expression, was found. Specific myenteric neuronal phenotypes may show differential sensitivity to ageing, and this could, under certain circumstances, alter the functional balance of gastrointestinal motility in aged individuals.

Immunohistochemical demonstration of the small GTPase RhoA on epoxy-resin embedded sections

The purpose of the present study was to establish a method for light microscopical immunohistochemical localization of the small G protein RhoA on specimens treated and embedded for routine transmission electron microscopy. There are advantages in antigen immunolocalization on resin semi-thin sections compared to cryostat or paraffin sections: the preservation of morphological details, the well-defined immunoprecipitate localization and the possibility to correlate the immunohistochemical results with those obtained by electron microscope on neighbouring sections. These advantages are particularly useful for the subcellular localization of low molecular weight proteins such as RhoA, a small G protein able to cycle from the inactive cytoplasmic form to the plasma membrane-bound active form.

Constants and variables in immunohistochemistry

Many efforts have been made to develop reliable methods for the quantification of immunohistochemical reaction products. Most of the corresponding studies have dealt with problems related to the development of adequate hardware and software, while fewer investigations have focused on variables of histotechnical or immunohistochemical methods. The present paper summarizes findings and experience obtained over many years in this latter field, and a total of 14 corresponding parameters were considered. The studies were performed with methods well established in the author's laboratory; namely immunohistochemistry for various pancreatic hormones and chromogranin A applying the peroxidase anti-peroxidase method on serial semithin sections from the mammalian endocrine pancreas. Optical densities of immunoreactivities were determined using an appropriate measuring program by the interactive image analysis system IBAS. All parameters investigated were found to influence densities of immunoreactivities, and those with major significance were: 1) the thickness of histologic sections; 2) the dilution range of the antisera used as first layers; 3) the type or composition of the buffers used for dilution of the antisera and of the chromogen di-aminobenzidine or as the rinsing solution. All these variables could be standardized in appropriate ways. It was not possible, however, to prevent batch-to-batch (inter-assay) variations. Finally, the results of the present investigations served to increase the efficiency of immunohistochemical staining by the applied methods.

Intralobular ducts of human major salivary glands contain leptin and its receptor

Leptin, a 16-kDa hormone, plays an important role in the control of food intake and in energy homeostasis both in rodents and in man. Leptin is mainly produced and secreted by adipocytes, but other tissues and gastric glands have also recently been shown to produce it in a dual (endocrine and exocrine) mode. In addition, a leptin receptor has been detected in taste cells of mouse circumvallate papillae and in rat intestinal epithelium. These data prompted us to carry out a detailed study of human salivary glands as potential leptin-producing organs. Biopsies of salivary glands (submandibular and parotid) obtained from male and female patients during surgery for different clinical indications were subjected to immunohistochemical study for the presence of leptin, its functional receptor, insulin and glucagon. The presence and cellular distribution of glucocorticoid receptor in leptin-secreting cells were also investigated. Double immunohistochemical staining (silver-gold intensification and avidin-biotin-peroxidase) was used for the visualization of glucocorticoid receptor and leptin labelling, respectively. The results show that intralobular duct cells of submandibular and parotid glands are immunoreactive for leptin, leptin receptor and glucagon but not for insulin. Leptin was also detected in some microglobules in whole saliva obtained from four healthy volunteers. Co-localization for leptin, leptin receptor and glucocorticoid receptor in the same cell type suggested a functional relationship between glucocorticoid hormone and leptin secretion also at the level of the salivary glands.

An immunohistochemical study of endocrine cells in the abomasum of vagotomized calf

The effect of thoraco-vagotomy on the distribution and frequency of chromogranin-, serotonin-, somatostatin- and gastrin-immunoreactive cells in the abomasum of the calf were investigated by immunohistochemistry. Calves were vagotomized at 1 week old and sampled 2 and 4 weeks later. The endocrine cells generally decreased in number in vagotomized calves as compared to non-operated control calves. However, the detailed responses of endocrine cells to vagotomy varied depending on the endocrine cell type, region of gastric mucosa, and period after vagotomy. The present result suggests that the vagus nerve has an influence on the intrinsic regulatory system by endocrine cell control in the ruminant abomasum.

Evidence of the participation of peribiliary mast cells in regulation of the peribiliary vascular plexus along the intrahepatic biliary tree

Our pilot study disclosed that tryptase-positive mast cells (MC) were densely distributed around the intrahepatic bile ducts (peribiliary MC). In this study, the pathophysiologic roles of these MC were examined with respect to the microcirculation around the bile duct in 71 cases of histologically normal liver, 24 cases of chronic hepatitis, and 45 cases of liver cirrhosis. The tryptase-positive MC were very close to the microvessels of the peribiliary vascular plexus (PVP), which supply the intrahepatic biliary tree. The tryptase-positive MC were frequently found adjacent to vascular smooth muscle cells, including pericytes. The location of the tryptase-positive MC was confirmed by ultrastructural analysis. In cirrhosis, the numbers of both microvessels of PVP and peribiliary MC increased in parallel. Peribiliary MC were immunoreactive for endothelin 1 (ET-1), and were variably immunoreactive for histamine, chymase, inducible nitric oxide synthase (iNOS), and endothelin A and B (ET(A) and ET(B)) receptors, particularly in cirrhotic livers. On vascular endothelial cells of PVP, endothelial nitric oxide synthase (eNOS) and ET-1 were consistently detectable, and ET(A) receptors, ET(B) receptors, and iNOS were variably detectable. Pericytes of PVP expressed ET(A) and ET(B) receptors in addition to ET-1 and iNOS. Biliary epithelial cells also focally expressed iNOS, ET-1, and ET(A) and ET(B) receptors. These vasoactive substances were strongly expressed on the cellular components in cirrhotic liver. By in situ hybridization, iNOS mRNA signals were observed on iNOS-immunoreactive cell components, including peribiliary MC. These morphologic and immunohistochemical findings suggest that the cellular components displaying vasoactive substances in the milieu of the intrahepatic biliary tree are very dynamic in the vasoregulation of PVP in normal livers, even more so in cirrhosis, and that peribiliary MC exert local effects on the microcirculation of PVP, directly and indirectly.

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.

Vasodilation of swimbladder vessels in the european eel (Anguilla anguilla) induced by vasoactive intestinal polypeptide, nitric oxide, adenosine and protons

The effects of β-adrenergic stimulation, vasoactive intestinal polypeptide (VIP), adenosine, the nitric oxide (NO)-releasing agent sodium nitroprusside and of metabolic end-products of gas gland cell metabolism on swimbladder blood flow were investigated using saline- or blood-perfused swimbladder preparations of the freshwater European eel Anguilla anguilla. While β-adrenergic vasodilation was not detectable, a bolus injection of adenosine (100 microl, 10(−)7 mol l-1) and application of VIP (10(−)7 mol kg-1) caused a significant decrease in perfusion pressure in saline-perfused swimbladder preparations. Immunohistochemical analysis revealed the presence of VIP-immunoreactive nerve fibres in the swimbladder artery and in the swimbladder vein (seawater-adapted eels were used for immunohistochemical studies). Application of sodium nitroprusside also elicited a small, but significant, decrease in perfusion pressure in saline-perfused swimbladder preparations, while preincubation of swimbladder tissue with N(ω)nitro-l-arginine, a non-selective inhibitor of nitric oxide synthase, significantly enhanced the flow-induced increase in perfusion pressure. Lactate, the major metabolic end-product of gas gland cell metabolism, had no effect on perfusion pressure. In contrast, an increase in proton concentration in both saline- and blood-perfused preparations induced a vasodilation, as indicated by a significant decrease in perfusion pressure. The results demonstrate that VIP, NO, adenosine and protons may induce a vasodilation of swimbladder blood vessels. None of these effects, however, compares in time span with the previously described immediate, short-lasting vasodilation of swimbladder vessels elicited by pulse stimulation of the vagus nerve.

Glucagon- and NPY-related peptide-immunoreactive cells in the gut of sea bass (Dicentrarchus labrax L.): a light and electron microscopic study

Glucagon and peptide of the neuropeptide Y (NPY) family immunoreactivities were studied in the gut of sea bass (Dicentrarchus labrax) using antisera against bovine/porcine glucagon, porcine glucagon, glicentin (10-30), bovine pancreatic polypeptide (PP), peptide tyrosine tyrosine (PYY), salmon PYY (sPYY), and NPY. Glucagon-, glicentin-, PYY-, and NPY-immunoreactive (ir) cells were detected in the stomach, and glucagon-, PP-, PYY-, sPYY-, and NPY-ir cells in the intestine. PP, PYY, and NPY immunoreactivities coexisted in intestinal endocrine cells (NPY-like peptide containing cells), in some of which there was also glucagon immunoreactivity. Preabsorption tests indicated that different products of the glucagon gene(s) are probably expressed in the stomach and intestine of sea bass and that the peptides belonging to the NPY family in the endocrine cells of the intestine are more similar to NPY than to other peptides of this family. Glucagon-ir cells in the stomach, and glucagon/NPY-like containing cells in the intestine, were characterized by conventional and immunogold electron-microscopic techniques. The glucagon cells had secretory granules with a clotted content, the gold particles being observed in both the core and the halo. Glucagon/NPY-like cells showed two types of secretory granules differing in size, both of which were immunogold labeled with anti-NPY and anti-sPYY; the smaller granules were weakly immunogold labeled with anti-glucagon.

Glial fibrillary acidic protein (GFAP) immunoreactivity in enteric ganglia of the chick embryo

We examined by immunohistochemistry the expression of glial fibrillary acidic protein (GFAP) in enteric ganglia of the chick embryo, using a polyclonal antibody. The morphology of enteric ganglion cells was examined by electron microscopy. Faint GFAP immunoreactivity was detected in ganglion cells and cell processes from around day 7 in ovo. Later in development the intensity of the immunofluorescence increased and it became more evident that immunoreactive small ganglion cells (interpreted as primitive glial cells), and their processes, surrounded larger negative cell profiles (interpreted as primitive neuronal cells); GFAP immunofluorescence was also evident in intramuscular and mucosal nerve trunks. In colocalization experiments, GFAP immunoreactivity was detected in a proportion of HNK-1/N-CAM immunoreactive ganglion cells, in both the myenteric and submucosal plexus. In addition, we observed GFAP immunoreactive nerves in wholemount preparations of chick gut from as early as day 4.5 in ovo. In the ganglionated nerve of Remak, GFAP immunoreactive satellite and Schwann cells were in evidence from day 5 of incubation. Neuronal markers, such as neurofilament, have been detected very early in development in neural crest cell populations in chick enteric ganglia. In contrast, the expression of markers of the glial phenotype has previously been observed only in the late stages of embryonic development. From our experiments, we conclude that neuronal and glial phenotypes are immunohistochemically distinct from as early as day 4.5 of incubation, even if by ultrastructural criteria glial cells are clearly distinguishable from neurons only after day 16 in ovo.

Immunohistochemical study of normal and mange (S. scabiei var. rupicaprae) infested chamois (Rupicapra rupicapra L.) skin

The immunohistochemical study of chamois (Rupicapra rupicapra L.) skin showed that a limited number of available monoclonal and polyclonal antibodies expressed reactivity with skin cell components. These included cytokeratins, vimentin, desmin, neuron-specific enolase and S-100 protein with almost the same distribution pattern as already described in the skin of humans and animals. Antibodies used for labelling skin-associated lymphoid tissues and other cells with the immunologic function in human skin failed to demonstrate these cells in the chamois skin with the exception of LCA and OKT6 antibodies. Epidermal Langerhans cells were reliably demonstrated only by the enzyme histochemical method for adenosine triphosphatase, while the majority of mononuclear cells in dermal infiltrates showed a strong immunoreaction with OKT6 antibody. The histologic and histochemical analysis showed that the dermal infiltrations in infested skin consisted of macrophages, lymphocytes, granulocytes, mastocytes and fibroblasts. The chamois skin affected with sarcoptes mange showed a significant loss of cytokeratins in the epidermis and its derivatives. Particular keratinocytes showing nonspecific staining with several antibodies were also described and discussed in this paper.

Nonspecific labeling of myelin with secondary antisera and high concentrations of Triton X-100

Triton X-100 is used in immunohistochemistry to make tissue permeable, to present certain antigens to antisera, and to prevent certain nonspecific interactions. This detergent is routinely dissolved in buffers at concentrations of 0.01-0.2%. Using high concentrations of Triton X-100 (0.2-2%) and anti-immunoglobulins G (anti-IgGs), labeling of myelin and microglia was detected in fixed brain tissue by indirect fluorescence and avidin-biotin-immunoperoxidase techniques. Differences were found between the species studied (mouse and rat), the type of anti-IgG (anti-mouse, anti-rabbit, anti-sheep, anti-rat, or anti-guinea pig), the detergent concentration, and whether Triton X-100 was included in the incubation media or applied as a pretreatment. Mouse brain displayed strong myelin labeling with all anti-IgGs but rat brain only with anti-rabbit or anti-sheep IgGs. Staining of ramified microglia occurred only in mouse tissue when anti-mouse IgG was used. Nonspecific staining of myelin was also intense in paraffin-embedded tissue and in human brain frozen sections. These results are significant for the prevention of undesirable staining in routine immunolabeling and they also provide a comparatively inexpensive, easy to perform strong labeling of myelin. In addition, the double marker signal (peroxidase and fluorescence) is useful for double labeling studies. (J Histochem Cytochem 46:109-117, 1998)

Nitric oxide synthase- and neuropeptide Y-containing subpopulations of sympathetic neurons in the coeliac ganglion of the Atlantic cod, Gadus morhua, revealed by immunohistochemistry and retrograde tracing from the stomach

In this study retrograde tracing was used to locate sympathetic ganglion cells innervating the stomach of a teleost fish, Gadus morhua. A subpopulation of small neurons in the coeliac ganglion was retrogradely labelled after Fast Blue injection in the stomach wall. Neurons projecting to the myenteric plexus and muscle layers contained tyrosine hydroxylase immunoreactivity, and neurons projecting to submucosal layers and blood vessels contained neuropeptide Y immunoreactivity in addition to being tyrosine hydroxylase immunoreactive. A population of nitric oxide synthase containing tyrosine hydroxylase immunoreactive neurons was also found in the coeliac ganglion. These neurons were not frequently labelled after injection in any layer of the stomach. The presence of entero-enteric pathways was also surveyed, but too few enteric neurons were labelled with Fast Blue after injection in the coeliac ganglion to indicate a presence of an entero-enteric reflex. We conclude that in teleost fish, as previously reported in a variety of mammals, a pattern of target specific chemical coding of sympathetic neurons exists, but that all reflex systems of mammalian vertebrates are perhaps not present in fish.

Cytogenetic and immunohistochemical analysis of an adult anaplastic neuroblastoma

Neuroblastomas in children are common tumors and are characterized by a number of recurrent cytogenetic and molecular changes. Adult neuroblastomas are rare, and their relationship to pediatric neuroblastomas is not clear. We report an anaplastic neuroblastoma presenting in a 28-year-old man. Histopathologic identification of the tumor as a neuroblastoma was problematic, and the initial diagnosis was poorly differentiated sarcoma. Tumor cells expressed immunoreactivity for tyrosine hydroxylase in addition to generic neuroendocrine markers, consistent with catecholamine-synthesizing ability. They also extended long, branching neurites in vitro. The tumor was positive for immunoreactive trkA. The karyotype after 6 days in culture was found to be 42,XY with multiple chromosomal abnormalities. The only abnormality shared with pediatric neuroblastomas was a rearrangement of chromosome 17q. Double minute chromosomes or homogeneously staining regions associated with N-myc amplification were not present. To our knowledge, this is the first reported karyotype of an adult neuroblastoma. The cytogenetic findings, together with expression of trkA, suggest that the tumor was more closely related to the favorable prognosis neuroblastomas of infancy than to the poor prognosis tumors that occur in older children, despite its unfavorable histology.

Merkel cells are absent in basal cell carcinomas but frequently found in trichoblastomas. An immunohistochemical study

The possibility of a neuroendocrine differentiation in basal cell carcinomas (BCCs) has been a matter of debate for many years. In the present immunohistochemical study, applying the cytokeratins 8, 18 and 20 as the most established markers for Merkel cells (MCs), we did not find elevated numbers of MCs in any of 205 BCCs. This speaks against a neuroendocrine line of differentiation in BCCs. In contrast, we found various amounts of MCs in 15 of 36 trichoblastomas, which are the main benign differential diagnosis of BCC. In 4 trichoblastomas abundant MCs were spread over the whole epithelial tumor area. Additionally, the trichoblastomas' overlying epidermis exhibited significantly much higher numbers of MCs than the uninvolved adjacent skin or the epidermis overlying the BCCs. These findings might be an additional aid in the distinction between trichoblastomas and BCCs. Furthermore, concerning the recent discussion about the role of MC in growth and development of follicular germ, our observations are another sign of regulative influences of the MC, also in follicular germ under pathological conditions. Trichoblastomas with high numbers of MCs could be characterized as showing advanced differentiation toward the neuroendocrine component of the hair follicle, i.e., the MCs.

Neurochemical classification of myenteric neurons in the guinea-pig ileum

A strategy has been developed to identify and quantify the different neurochemical populations of myenteric neurons in the guinea-pig ileum using double-labelling fluorescence immunohistochemistry of whole-mount preparations. First, six histochemical markers were used to identify exclusive, non-overlapping populations of nerve cell bodies. They included immunoreactivity for the calcium binding proteins calbindin and calretinin, the neuropeptides vasoactive intestinal polypeptide, substance P and somatostatin, and the amine, 5-hydroxytryptamine. The sizes of these populations of neurons were established directly or indirectly in double-labelling experiments using a marker for all nerve cell bodies. Each of these exclusive populations was further subdivided into classes by other markers, including immunoreactivity for enkephalins and neurofilament protein triplet. The size of each class was then established directly or by calculation. These distinct, neurochemically-identified classes were related to other published work on the histochemistry, electrophysiology and retrograde labelling of enteric neurons and to the simple Dogiel morphological classification. A classification scheme, consistent with previous studies, is proposed. It includes 14 distinct classes of myenteric neurons and accounts for nearly all neurons in the myenteric plexus of the guinea-pig ileum.

Putative neuroendocrine cells in the Aplysia cerebral ganglion

We report on a special population of cells in the Aplysia cerebral ganglion that are characterized by several features compatible with neuroendocrine function. These cells can be recognized in living ganglia by their small size, white color and their typical distribution as a compact cluster in the central medial region of the dorsal ganglion surface. Upon intracellular recording, these cells generate action potentials of relatively long duration (about 25 ms), as compared with the faster action potentials of larger white cells or of non-white cells (about 4 ms). Intracellular injection of the small white cells with Lucifer yellow after recording revealed a dual projection area: single cells have one process which branches extensively into many varicose terminals as it courses through the neuropil, and then sends varicose terminals to the vascular sheath at the periphery of the ganglion. In cryostat sections, these cells were specifically characterized by their content of large granules, the staining characteristics of which distinguish them from lipochondria or lysosomes. Their ability to bind fluorochromes nonspecifically is of particular importance for the interpretation of histochemical localization studies based on immunofluorescence techniques.

Adrenal Medullary Nodules in Beckwith-Wiedemann Syndrome Resemble Extra-Adrenal Paraganglia

Clues to mechanisms regulating development and tumorigenesis may be provided by studies of unusual diseases. Beckwit-Wiedemann syndrome (BWS) is a rare congenital disorder apparently related to abnormal regulation of insulin-like growth factor-2 (IGF-2) production. IGF2 mRNA has been previously localized to the chief cells of extra-adrenal paraganglia and to adult, but not fetal, adrenal medulla. Expression of IGF-2 by neuroblastomas has been hypothesized to reflect extra-adrenal paraganglionic differentiation. In the adrenals of a fetus with 8W5, we have observed both increased numbers of chromaffin cells and organoid nodules resembling extra-adrenal paraganglia. Immunoreactive IGF-2 was observed in both cell types, but was also observed in chromaffin cells in the normal fetal adrenal. The findings suggest autocrine or paracrine influences of IGF-2 in regulating the number and phenotype of cells derived from sympathoadrenal precursors in the developing adrenal medulla as well as in extra-adrenal paraganglia. These results have implications for the interpretation of data from neuroblastoma studies.

Distribution of hippocampal cholinergic neurostimulating peptide (HCNP)-like immunoreactivity in organs and tissues of young Wistar rats

This report concerns the distribution of the hippocampal cholinergic neurostimulating peptide (HCNP) in tissues and organs of 11-day-old Wistar rats. HCNP, originally isolated and purified from the hippocampus of young rats, is an undecapeptide (acetyl-Ala-Ala-Asp-Ile-Ser-Gln-Trp-Ala-Gly-Pro-Leu). HCNP distribution was investigated by using immunohistochemical techniques, employing an affinity-purified rabbit antibody that specifically recognizes HCNP and its 21-kDa precursor protein. Positively stained cells were detected in a variety of tissues and organs, including salivary gland, small intestine, colon, pancreas, bronchiole, adrenal gland, testis, as well as several others. The nerve fibres around blood vessels of almost all organs expressed HCNP. Our results suggest that HCNP or its precursor, or both, may have a specific function not only in the central nervous system, but also in the peripheral nervous system, and possibly in certain specialized duct and gland cells as well.

Renin-like immunoreactivity in human placenta and fetal membranes

Five antibodies that stained renin in the kidney were used to investigate the presence of renin in human placenta and fetal membranes. Despite a large number of experimental approaches to enhance penetration of the immunoglobulins, only two of them showed immunostaining in placenta and fetal membranes. Staining was found in placental syncytiotrophoblast, the amnionic epithelium overlying the placenta, and in glandular epithelial cells present in the decidua adhering to the fetal membranes. It was most consistent, however, in a small infiltrating cell type dispersed through the fetoplacental layers. The two antibodies that revealed immunostaining in all preparations showed high affinity cross-reactivity with cathepsin D. Among other, less plausible, explanations, this raises the possibility that the bulk of 'renin' found in placenta and fetal membranes is not identical to renal renin, but may be cathepsin D or a substance related to both cathepsin D and renin.

Localization of heparin-binding epidermal growth factor-like growth factor in human gastric mucosa

BACKGROUND & AIMS

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) has been recently identified as a member of the EGF family. EGF receptors to which HB-EGF can bind have been detected in some types of gastric epithelial cells. The aim of this study was to investigate whether HB-EGF is produced in gastric epithelial cells to maintain normal gastric mucosa.

METHODS

Gene expression and production of HB-EGF protein were investigated using Northern hybridization and immunohistochemistry, and the types of cells producing this protein were determined in human gastric mucosa.

RESULTS

HB-EGF messenger RNA was detected in the body and antrum. Immunohistochemical staining showed that HB-EGF was localized mainly in parietal cells of fundic glands and in gastrin cells of pyloric glands. Also, the immunoreactivity of EGF receptors was observed in parietal cells and gastrin cells and faintly in surface epithelial cells and mucous neck cells of the proliferative zone.

CONCLUSIONS

The results suggest that HB-EGF is synthesized mainly in parietal cells and gastrin cells and may act in an autocrine and/or paracrine manner in the regulation of proliferation and differentiation of the gastric mucosal cells through their surface EGF receptors.

Neuropeptide immunoreactivity and co-existence in cardiovascular nerves and autonomic ganglia of the estuarine crocodile, Crocodylus porosus, and cardiovascular effects of neuropeptides

The two aortas of the crocodile are in open connection at two sites, the foramen of Panizzae immediately outside the ventricles, and the arterial anastomosis at the level of the gut. The present study was performed to elucidate the innervation of the cardiovascular structures of the crocodile, in part to provide a further basis for the assumption that the apertures of the foramen and the anastomosis may be altered, possibly leading to changes in the flow profiles of the central vessels. The presence of smooth muscle arranged at the circumference of the foramen and in the walls of the anastomosis was demonstrated. The cardiovascular structures were innervated by nerves containing co-existing tyrosine hydroxylase, NPY and somatostatin immunoreactivities, which also occurred in neurons of the sympathetic ganglia. CGRP and substance P immunoreactive material co-existed in cardiovascular nerves, and in the nodose ganglion. In addition, bombesin, VIP and galanin immunoreactive nerves were found. Effects of neuropeptides on blood flows and blood pressures were studied in vivo. Substance P increased all blood flows measured, NPY increased the flow through the arterial anastomosis while neurotensin caused an initial decrease in the flow through the arterial anastomosis. In conclusion, there is a rich innervation of the heart and major vessels of the estuarine crocodile, including the foramen of Panizza and the arterial anastomosis. These nerves possibly regulate the distribution of blood in the cardiovascular system, which is further suggested by the results of the injection of neuropeptides.

Mitogenic and antimitogenic effects of pituitary adenylate cyclase-activating polypeptide (PACAP) in adult rat chromaffin cell cultures

The neurotransmitter, pituitary adenylate cyclase-activating polypeptide (PACAP), is present in the rat adrenal medulla and is a potent stimulus for catecholamine secretion. Previous studies have suggested that neurally derived signals stimulate proliferation of chromaffin cells in adult rats. To determine whether PACAP might be involved in mitogenic signalling, its effects on bromodeoxyuridine incorporation were studied in adrenal medullary cell cultures from adult female rats. Both PACAP 27 and PACAP 38 are able to stimulate proliferation of adult rat chromaffin cells in vitro, either alone or in conjunction with PMA, an activator of protein kinase C. BrdU-labelled nuclei are observed in both epinephrine and norepinephrine cells, and proliferation of both cell types is stimulated by the same concentrations of PACAP that elicit secretion of catecholamines. The mitogenic effects of PACAP are potentiated by indolidan, a phosphodiesterase inhibitor known to cause pheochromocytomas in rats, and are inhibited by H-89, an inhibitor of protein kinase A. Mitogenic concentrations of PACAP inhibit mitogenic effects of nerve growth factor. These findings support the hypothesis that neurally derived signals regulate chromaffin cell proliferation in adult rats. Indolidan and a variety of nongenotoxic agents that cause pheochromocytomas in rats may do so indirectly by increasing neurally mediated chromaffin cell turnover. The antagonism between PACAP and NGF suggests that neurotransmitters may supersede growth factors in regulating chromaffin cell proliferation during development by suppressing or co-opting portions of growth factor signaling pathways.

The neurite growth promoting protease nexin 1 in glial cells of the olfactory bulb of the gerbil: an ultrastructural study

The glia-derived serine protease inhibitor and neurite outgrowth promoter protease nexin-1 (PN-1) is expressed in Schwann cell precursors and astroblasts during embryogenesis. In the adult nervous system, PN-1 persists in the Schwann cells and olfactory glia only. Light-microscopic immunohistochemistry has revealed the presence of PN-1 in the olfactory mucosa and in the nerve fiber layer of the olfactory bulb. The present electron-microscopic study of the gerbil olfactory bulb confirms the occurrence of PN-1 in ensheathing cells of the olfactory nerve fiber layer, a special type of glia which envelopes olfactory axons. In addition, PN-1 is contained in typical astrocytes of the nerve fiber layer and of the glomerular layer. It is inferred that synthesis of PN-1 in the olfactory bulbs is maintained throughout adulthood because its neurite outgrowth promoting action is required for the continuous renewal of olfactory receptor neurons.

Immunogold study of non-collagenous matrix components in normal and exfoliative iris

The present investigation was undertaken to determine if some of the components of exfoliation material in iris tissue were unique to exfoliation or were part of normal iris architecture. Eleven normal iris specimens and 10 exfoliative iris specimens were processed for cryoultramicrotomy and London resin white embedding. Immunogold electron microscopy was used to investigate the fine structural distribution of amyloid P component, elastin, entactin, fibronectin, gp115, and vitronectin in normal iris and their association with exfoliation material. Exfoliation material was positive for amyloid P component and possibly gp115, neither of which were present in normal iris tissue. Elastin and fibronectin were present in the normal iris stroma but were not associated with exfoliation material. The distribution of amyloid P component in the vessel lumen and wall led to the conclusion that amyloid P is a serum contaminant. The presence of gp115 in exfoliation material represents the synthesis of a component novel to the iris vascular cell synthetic repertoire.

Patterns of neuronal colocalisation of tyrosine hydroxylase, neuropeptide Y, vasoactive intestinal polypeptide, calcitonin gene-related peptide and substance P in human ureter

The patterns of colocalisation of neuropeptides, tyrosine hydroxylase (TH), and protein gene product 9.5 (PGP), were studied in nerve fibres supplying the upper and lower human ureter using a double labelling immunofluorescence technique. The majority (85%-95%) of nerve fibres within the ureter contained neuropeptide Y-like immunoreactivity (NPY-LIR), in combination with other peptides. Approximately 52%-63% of the total ureteral innervation was made up of NPY-LIR fibres also expressing TH-LIR, while 21%-42% of fibres contained NPY-LIR in combination with vasoactive intestinal polypeptide (VIP)-LIR. These two immunochemically defined classes did not overlap, since TH- and VIP-LIR were never present within the same nerve fibre. Other minor populations of neurones included those containing calcitonin gene-related peptide (CGRP)-LIR in combination with substance P (SP)-LIR (4%-17%) and those without SP (5%). Rare coexistences were also noted between CGRP- and VIP-LIR (1%-2%), CGRP- and NPY-LIR (< or = 1%), and CGRP- and TH-LIR (< 1%). Regional differences in innervation were found. There were fewer of each class of nerve fibres in the upper ureter compared to the lower ureter. In addition, the proportion of VIP/NPY-LIR fibres of the total innervation was less in the upper ureter, where they were very sparse. Differences in the distribution to various tissue targets were also observed. In the lower ureter, TH/NPY-LIR fibres were localised predominantly to the outer muscle fascicles and adventitia, while VIP/NPY immunoreactive nerves supplied the submucosa and inner smooth muscle fascicles. Both of these populations were also found around blood vessels. A population of presumptive sensory fibres expressing CGRP/SP-LIR were typically present immediately beneath the urinary epithelium and around blood vessels, and only very rarely within muscle fascicles. The finding that TH/NPY- and VIP/NPY-LIR fibres innervate different layers of the ureter raises the possibility that the muscle layers of the ureter may be independently controlled.

Collagens in the aged human macula

Immunogold cytochemistry was used to investigate the fine structural distribution of collagen types I-VI in Bruch's membrane and choroid of the aged human macula. Macular tissue was obtained from ten eyes, and processed for cryoultramicrotomy and London Resin white embedding. Striated collagen fibrils within the inner and outer collagenous layers were found to contain collagen types I, III and V. In addition, type V collagen was also present in the basement membrane of the choriocapillaris. Gross thickening of the choriocapillaris basement membrane was attributed to the deposition of type IV collagen. However, type IV collagen appeared to be absent from the basement membrane of the retinal pigment epithelium. The interesting location of type VI collagen on the choroidal side of the choriocapillaris suggested that its function is to anchor the choriocapillaris onto the choroid. The collagens studied were absent from fibrous banded material, long-spacing collagen, the elastic layer and amorphous granular material. It was concluded that, of the collagen types studied, only the deposition of type IV collagen contributes to the age-related thickening of Bruch's membrane.

Re-expression of glia-derived nexin/protease nexin 1 depends on mode of lesion-induction or terminal degeneration: observations after excitotoxin or 6-hydroxydopamine lesions of rat substantia nigra

The serine protease inhibitor and neurite outgrowth promoter glia derived nexin (GDN) is expressed in the rat CNS during embryogenesis and persists in the olfactory system of the adult where receptor neurons are replaced throughout life. We investigated whether GDN-immunoreactivity also appears in the adult at sites of synaptic rearrangement following nerve cell death and anterograde terminal degeneration in experimental models for Parkinson's disease. Rat substantia nigra was unilaterally lesioned by stereotaxic application of different toxins: 6-hydroxydopamine, which selectively destroys dopaminergic neurons, the excitotoxic glutamate analog ibotenic acid, or the glutamate receptor agonists N-methyl-D-aspartate and quisqualate, which cause circumscript lesions of the whole substantia nigra. Nerve cell death and astroglial reactivity were monitored by parallel cresyl staining and immunocytochemistry for glial fibrillary acidic protein, at survival times ranging from 2 to 100 days. Sustained de novo synthesis of GDN occurred in the dopamine depleted caudate putamen following excitotoxin or 6-hydroxydopamine induced degeneration of the substantia nigra and of the nigrostriatal pathway provided that the lesions were nearly complete. This is consistent with compensatory changes occurring in deafferented caudate putamen and suggests a permissive role of GDN in neuronal plasticity. In the substantia nigra astroglia exhibited GDN-immunoreactivity following excitotoxin injection but not after application of 6-hydroxydopamine. Thus differences in action mechanisms of neurotoxins may have distinct consequences on the astrocyte mediated response of the same affected brain region.

Mast cell immunohistochemistry: non-immunological immunostaining mediated by non-specific F(ab')2-mast cell secretory granule interaction

During investigations of murine and human mast cell immunoreactivity with potential anti-interleukin-4 antibodies, non-specific, non-immunological labelling of mouse and human mast cells became apparent. Non-specific, non-immunological labelling was identified by (i) immunolabelling of mast cells when using control isotype primary antibodies, (ii) ability of conjugated secondary antibodies to label mast cells without prior mast cell exposure to a primary antibody, (iii) extinction of the non-specific labelling and retention of specific labelling when the pH of the diluting and washing buffers is shifted from pH 7.2 to pH 6.0, and (iv) reduction/extinction of the labelling when the antibodies are pre-incubated with soluble heparin prior to immunostaining. The site of the reactivity on the electron microscope level was shown to be confined to the mast cell secretory granules. The results of this study support the hypothesis that non-specific labelling of mast cells results from an ionic interaction between the F(ab')2 segments of antibodies and the heparin constituent of the mast cell secretory granules. This study points out the necessity of stringent controls when using immunohistochemistry to determine mast cell reactivity to various antibodies.

Collagens in the aged human macular sclera

Scleral tissue from the region of the human macula was studied by the immunogold labeling technique (cryoultramicrotomy and LR white resin embedding) in an attempt to identify the fine structural distribution of collagen types I-VI. Labeling of the striated collagen fibrils suggested colocalisation of collagen types I, III and V with type V occurring at the fibril surface. Both types V and VI collagen were localised to filamentous strands in the interfibrillar matrix. Collagen types II and IV were absent from the scleral stroma.

Synaptophysin--a common constituent of presumptive secretory microvesicles in the mammalian pinealocyte: a study of rat and gerbil pineal glands

Recent studies have established that pinealocytes of the mammalian pineal gland contain marker molecules of neuroendocrine cells or paraneurons like the synaptic vesicle-associated protein synaptophysin (p38). The objective of this study was to identify the subcellular synaptophysin-positive compartment and to characterize in detail the intracellular distribution of this protein in rat and gerbil pinealocytes. An analysis of serial semithin sections of plastic-embedded pineals immunostained for synaptophysin, including computer-assisted optical density measurements of synaptophysin immunoreactivities, demonstrated unequivocally that synaptophysin was highly concentrated in dilated process terminals of the pinealocytes. More than 75% of these process terminals were found to border or lie within the pericapillary space. At the ultrastructural level, they contained accumulations of small clear vesicles of variable size that turned out to be the site of synaptophysin immunoreactivity when immunogold staining was performed. In addition, microvesicles surrounding synaptic ribbons were also immunolabeled. Hence, the pinealocyte is the first neuroendocrine cell type that has now been shown to concentrate synaptophysin-positive microvesicles in perivascular process endings. This observation lends strong support to the hypothesis that small clear vesicles in neuroendocrine cells in general, and in pinealocytes in particular, serve secretory functions. The quantitative analysis of completely sectioned process endings revealed that the microvesicles outnumber by far the amount of dense core vesicles and therefore cannot arise by endocytosis of dense core vesicle membranes. Thus, small synaptic-like vesicles probably constitute an independent secretory pathway of the paraneuronal pinealocytes. In the present study, we could also establish the absence of immunoreactivity for synapsin I (belonging to a family of neuron-specific nerve terminal phosphoproteins) from pinealocytes. Synapsin I immunoreactivity was only detectable in intrapineal nerve terminals and varicosities. Taken together, the immunostaining patterns of the pineal gland obtained with antibodies directed against synaptic vesicle-associated proteins render the mammalian pinealocyte a very special type of neuroendocrine cell or paraneuron rather than a "classic" neuron.

Neuropeptide F: primary structure from the tubellarian, Artioposthia triangulata

1. A neuropeptide exhibiting vertebrate pancreatic polypeptide immunoreactivity has been isolated and sequenced from extracts of the terrestrial turbellarian, Artioposthia triangulata. 2. This neuropeptide, designated neuropeptide F, consists of 36 amino acid residues terminating in a phenylalaninamide. 3. The full primary structure was established as: KVVHLRPRSSFSSEDEYQIYLRNVSKYIQLYGRPRF.NH2. The molecular mass, deduced from this sequence, was 4433 Da. 4. This neuropeptide exhibits C-terminal homology with neuropeptide F (Moniezia expansa) and with the vertebrate neuropeptide Y/pancreatic polypeptide superfamily of which it may represent a phylogenetic precursor.

Projections and pathways of submucous neurons to the mucosa of the guinea-pig small intestine

Double-labelling immunohistochemistry and retrograde transport of the carbocyanine dye, DiI, were used to establish the pathways of submucous neurons to the mucosa of the guinea-pig small intestine. Following the application of DiI to a villus, DiI-labelled nerve cell bodies were found in the submucous plexus up to 8.3 mm circumferentially and 3.8 mm longitudinally. The size of each of the four characterised classes of submucous neurons was determined and their distributions and projections mapped. Cells characterised by vasoactive intestinal polypeptide immunoreactivity accounted for 52% of DiI-labelled cells and had the longest projections. Cells characterised by neuropeptide Y (19%) or by calretinin immunoreactivity (13% of all DiI-labelled neurons) had relatively short projections and cells with substance P immunoreactivity (20%) had intermediate lengths of projection. When DiI was applied directly to the submucous plexus, filled neurons of all classes had significantly shorter projections, indicating that they must run for considerable distances in other pathways to the mucosa, probably via the non-ganglionated plexus. On average, each villus is innervated by at least 70 submucous neurons. From quantitative estimates there are 9 submucous neurons per villus. Thus, each submucous neuron is likely to supply about 8 villi. This demonstrates a high degree of convergence and divergence in the innervation of the mucosa.