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Anatomical markers for the subdivisions of the barn owl's inferior-collicular complex and adjacent peri- and subventricular structures.

The anatomy of the inferior-collicular complex of the barn owl, situated below the fourth ventricle in the tectal lobe, was studied by determining the distribution of antigens with antibodies directed against tyrosine hydroxylase, gamma-aminobutyric acid (GABA)(Abeta), dopamine- and cyclic AMP-regulated phosphoprotein (DARPP-32), calretinin, and calbindin. Additionally, the somata were stained with cresyl violet, and fibers were marked according to the Gallyas procedure. These markers were chosen to allow for an easy delineation of the boundaries between the subnuclei of the inferior colliculus. We could discriminate eight structures that belong to the three subnuclei of the inferior colliculus [the central nucleus (ICC), the superficial nucleus (ICS), the external nucleus (ICX)] and to the optic tectum. Periventricular tectal layers 15a and 15b stained well with all the antibodies used. The ICS, embedded in tectal layer 15a, may be divided into a dorsal and a ventral lamina. It does not have direct contact with the other nuclei of the inferior colliculus. The border between tectal layer 15a and ICX was well marked by all antibodies, but less so in Gallyas and cresyl violet stains. The ICC consists of a core and a medial and lateral shell. The core was clearly demarcated with antibodies against calretinin and calbindin. The border between the lateral shell and the ICX was marked less well than the borders between ICX and 15a, but the somata were much more darkly labeled with the DARPP-32 antibody in ICX than in the lateral shell of ICC. None of the markers delineated the border between the medial and lateral shell of ICC.

Animals↗

Local differences in vagal afferent innervation of the rat esophagus are reflected by neurochemical differences at the level of the sensory ganglia and by different brainstem projections.

The objective of the present study was to characterize further the vagal afferent fibers in the rat esophagus, particularly those in its uppermost part, their cell bodies in vagal sensory ganglia, and their central projections. We applied immunohistochemistry for calretinin, calbindin, and calcitonin gene-related peptide (CGRP); retrograde tracing with FluoroGold; and transganglionic tracing with wheat germ agglutinin-horseradish peroxidase in combination with neurectomies. Vagal terminal structures in the muscularis propria of the whole esophagus consisted of calretinin-immunoreactive intraganglionic laminar endings that were linked to cervical vagal and recurrent laryngeal nerve pathways. The mucosa of the uppermost esophagus was innervated by a very dense net of longitudinally arranged, calretinin-positive fibers that were depleted by section of the superior laryngeal nerve. Distal to this area, the mucosa was virtually devoid of calretinin-immunoreactive vagal afferents. Calretinin-positive mucosal fibers in the upper cervical esophagus were classified into four types. One type, the finger-like endings, was sometimes immunoreactive also for CGRP. About one-third of cell bodies in vagal sensory ganglia retrogradely labeled from the upper cervical esophagus expressed CGRP, whereas two-thirds coexpressed calretinin and calbindin but not CGRP. In addition to the central subnucleus of the nucleus of the solitary tract, vagal afferents from the upper cervical esophagus also projected heavily to the interstitial subnucleus. This additional projection was attributed to mucosal afferents traveling through the superior laryngeal nerve. The present study provides a possible morphological basis for bronchopulmonary and aversive reflexes elicited upon stimulation of the esophagus.

Animals↗

Development of neurons and fibers containing calcium binding proteins in the pallial amygdala of mouse, with special emphasis on those of the basolateral amygdalar complex.

We studied the development of neurons and fibers containing calbindin, calretinin, and parvalbumin in the mouse pallial amygdala, with special emphasis on those of the basolateral amygdalar complex. Numerous calbindin-immunoreactive (CB+) cells were observed in the incipient basolateral amygdalar complex and cortical amygdalar area from E13.5. At E16.5, CB+ cells became more abundant in the lateral and basolateral nuclei than in the basomedial nucleus, showing a pattern very similar to that of gamma-aminobutyric acid (GABA)ergic neurons. Many CB+ cells observed in the pallial amygdala appeared to originate in the anterior entopeduncular area/ganglionic eminences of the subpallium. The density of CB+ cells gradually increased in the pallial amygdala until the first postnatal week and appeared to decrease later, coinciding with the postnatal appearance of parvalbumin cells and raising the possibility of a partial phenotypic shift. Calretinin (CR) immunoreactivity could be observed in a few cells and fibers in the pallial amygdala at E14.5, and by E16.5 it became a good marker of the different nuclei of the basolateral amygdalar complex. Numerous CB+ and CR+ varicosities, part of which have an intrinsic origin, were observed in the basolateral amygdalar complex from E16.5, and some surrounded unstained perikarya and/or processes before birth, indicating an early formation of inhibitory networks. Each calcium binding protein showed a distinct spatiotemporal expression pattern of development in the mouse pallial amygdala. Any alteration in the development of neurons and fibers containing calcium binding proteins of the pallial amygdala may result in important disorders of emotional and social behavior.

Amygdala↗

Co-occurrence of calcium-binding proteins and calcium-permeable glutamate receptors in the primary gustatory nucleus of goldfish.

Primary vagal gustatory afferents utilize glutamate as a neurotransmitter acting on AMPA/kainate receptors of second-order neurons. Some forms of ionotropic glutamate receptors permit passage of Ca++ ions upon activation by appropriate ligands. Calcium-binding proteins (CaBPs) play a buffering role for regulating the concentration of intracellular calcium. In the present study, we used immunohistochemistry to examine the distribution and morphology of neurons with CaBPs, including calretinin, calbindin, and parvalbumin, and to compare this distribution with neurons exhibiting Ca++-permeable glutamate receptors as determined by kainate-stimulated uptake of Co++ in the vagal lobe of goldfish. Calretinin- and calbindin-positive neurons occurred throughout the sensory zone including round unipolar, horizontal; and perpendicular bipolar or multipolar somata. Parvalbumin neurons were mainly round monopolar neurons, especially common in the superficial layers of the sensory zone. In the motor zone, while parvalbumin labeled nearly all motoneurons, calretinin labeled only external motoneurons. In double labeling with calretinin and parvalbumin, few neurons in the sensory layer labeled with both antisera. Immunocytochemistry following kainate-stimulate uptake of Co++ showed that most calretinin, but few parvalbumin immunopositive neurons also were labeled by cobalt in the central and deep layers of the sensory zone. All motoneurons were labeled by Co++, including those immunoreactive for calretinin or parvalbumin. These results indicate that calretinin expression is strongly correlated with calcium-permeable ionotropic glutamate receptors in the neurons of the sensory zone of the goldfish vagal lobe, but even within this limited region, not all Ca++-permeable neurons possess any of the CaBPs examined.

Animals↗

Reelin-expressing neurons in the postnatal and adult human hippocampal formation.

Reelin plays a major role in the development of laminated brain structures. In the developing neocortex and hippocampus, Reelin is secreted by Cajal-Retzius cells in the marginal zone. In the present report, we characterize Reelin-immunoreactive neurons in the perinatal and adult human hippocampal formation. Two main populations of cells are described: Cajal-Retzius cells and interneurons. Cajal-Retzius cells are defined as neurons that coexpress Reelin and p73, a nuclear protein of the p53 family. Colocalization experiments of p73 with calcium-binding proteins indicate that most Cajal-Retzius cells express calretinin, but not calbindin. Cajal-Retzius cell density decreases dramatically during the postnatal period, although a few Reelin/p73-positive neurons are still found in the adult. At birth, Reelin-positive, p73-negative neurons are present in all layers of the hippocampal formation. Their morphology and localization indicate that they belong to a heterogeneous population of interneurons. They are numerous in the strata lacunosum-moleculare and radiatum of CA1-CA3, in the hilus, and in the molecular layer of the dentate gyrus, but less common in stratum oriens and alveus, and rare in the principal cell layers. Subpopulations of Reelin-positive interneurons express calretinin or calbindin. The packing density of Reelin-positive cells decreases postnatally, which may be related to the disappearance of Cajal-Retzius cells and to the growth of the hippocampal formation. The presence of Reelin-immunoreactive cells in the adult hippocampal formation indicates that Reelin is not restricted to development but that it may have additional functions in adult life.

Adolescent↗

The avian as an animal model for the study of the vitamin D endocrine system.

This paper presents a summary of experimental studies which utilized the White Leghorn cockerel, Gallus domesticus, as a suitable avian model for a detailed analysis of the mode of action of the seco-steroid vitamin D. It is now apparent that there exists a complex endocrine system which coordinates the metabolism of the parent vitamin D into a family of over 30 metabolites; the principal metabolites are 1,25(OH)2D3 and 24R,25(OH)2D3, which together orchestrate the spectrum of biological responses attributable to vitamin D. Key advances in elucidation of the scope of vitamin D endocrine system include the tissue distribution of both its steroid receptor and its gene-induced product, a 28,000 dalton calcium binding protein, termed calbindin-D28k. To date no less than 23 tissues have been found to have specific 1,25(OH)2D3 receptors; of these at least 10 were identified in avian studies. Similarly, nine avian tissues have been found to express the vitamin D-induced calcium binding protein, calbindin-D28k. These observations collectively demonstrate both the broad scope of the vitamin D endocrine system and the appropriateness of using avians as valid models for vitamin D endocrine research which has applicability and validity for mammals, including man.

Animals↗

Molecular analysis of the vagal motoneuronal degeneration after right vagotomy.

The aim of this study was to investigate the vagal motoneuronal degeneration after right vagotomy using in situ hybridization, RT-PCR, and immunohistochemistry methods. The morphology of the vagal motoneurons in dorsal motor nucleus of the vagus nerve (DMV) and nucleus of ambiguus (NA) after right vagotomy was examined by using Nissl staing and TUNEL. The expression of inducible nitric oxide synthase (iNOS), bcl-2, bax, and caspase-3 in DMV and NA of rats after right vagotomy was studied. Additionally, the involvement of the N-methyl-D-aspartate (NMDA) receptor-calcium-neuronal nitric oxide synthase (nNOS) pathway in the vagal motoneuronal degeneration was addressed by double-immunolabeling analysis of nNOS with NMDAR1 and calbindin D28K in right-vagotomized rats. The neurons in right DMV and NA displayed a darkly stained, shrunken morphology at 1 day and 5 days following right vagotomy as shown by Nissl staining. Quantitative analysis revealed that, at 1 day and 5 days following right vagotomy, the number of neurons in right DMV, but not NA, was significantly reduced in comparison with that of control rats. Occasional TUNEL-positive neurons were detected in right DMV of rat at 1 day after right vagotomy. The expression of iNOS protein and mRNA was absent in DMV and NA of control rats. However, the iNOS mRNA expression was induced bilaterally in DMV and NA at 1 day postoperation and continued to be up-regulated until 5 days after vagotomy as shown by in situ hybridization. Immunohistochemistry analysis also showed the increased expression of iNOS in bilateral DMV and NA of vagotomized rats. RT-PCR analysis revealed the enhanced bcl-2 and reduced bax mRNA levels and subsequent up-regulation of both bcl-2 and bax mRNA in right sides of the vagotomized brainstems at 1 day and 5 days postoperation, respectively. In situ hybridization analysis confirmed the up-regulation of bcl-2 and bax mRNA in right DMV and NA of the rats at 5 days following operation. Immunohistochemistry analysis showed up-regulated Bcl-2 immunoreactivity and undetectable changes in Bax immunoreactivity in DMV and NA of rats at 1 day after vagotomy, whereas enhancement of both Bcl-2 and Bax immunoreactivity was observed at 5 days postoperation. In addition, the caspase-3 mRNA level was elevated ipsilaterally in DMV and NA at 1 day and 5 days following right vagotomy. Double-immunofluorescence analysis showed complete colocalization of nNOS with NMDAR1 and with calbindin in ipsilateral DMV and NA at 10 days following right vagotomy. This study suggests that the signal pathway for NMDAR1-calcium-nNOS and the up-regulation of iNOS in DMV and NA may be involved in the vagal motor neurodgeneration after right vagotomy. Furthermore, our results imply that the apoptosis pathway mediated by Bcl-2, Bax, and caspase-3 may be activated in vagal motoneurons after right vagotomy.

Animals↗

Gene transfer of glial cell-derived neurotrophic factor and cardiotrophin-1 protects PC12 cells from injury: involvement of the phosphatidylinositol 3-kinase and mitogen-activated protein kinase kinase pathways.

Gene therapy for neurodegenerative diseases may utilize the expression of neurotrophic factors because of their potential to promote survival and regeneration of injured neuronal cells. Increasing numbers of these factors are being considered for gene transfer, but their specificity and efficacy in neuroprotection are greatly variable. The major aims of this study were to carry out gene transfer of various neurotrophic factors and investigate their mechanisms of action as well as their protective effects on the viability of rat pheochromocytoma (PC12) cells. We used glutamate, S-nitroso-N-acetyl-DL-penicillamine (SNAP), and staurosporine to induce excitatory damage, oxidative stress, and apoptosis, respectively, because these mechanisms are thought to participate in various disease processes leading to degeneration of cells. We utilized adenovirus vectors for efficient gene transfer of trophic factors (glial-cell derived neurotrophic factor [GDNF] and cardiotrophin-1 [CT-1]) or calbindin-D28k. We found that GDNF and CT-1 gene transfers were equally effective in saving PC12 cells from injury, but calbindin expression did not show any beneficial effects. GDNF gene transfer was much more efficient in protecting PC12 cells from damage than direct GDNF administration. The protection by GDNF expression against staurosporine was mediated through both phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase kinase (MAPK kinase; MEK) pathways, but only the MEK pathway was involved in the protection against SNAP. In contrast, the protective effect of GDNF against glutamate toxicity was independent of these RET-dependent signal transduction pathways.

Analysis of Variance↗

Organization and expression of the mouse spot35/calbindin-D28k gene: identification of the vitamin D-responsive promoter region.

Spot35/calbindin-D28k is transcriptionally induced by 1,25-dihydroxyvitamin D3 in the intestine and kidney but not the brain. The structural organization of the mouse calbindin-D28k gene has now been determined and its transcriptional activation examined. Two direct repeat motifs homologous to other vitamin D-responsive elements were identified at positions -2295 to -2281 and -1160 to -1146. Undirectional deletion analyses of the 5' flanking region indicated that the sequence between -1339 and -1038 conferred vitamin D sensitivity on a reporter construct. Furthermore, the proximal (AGGTGAtgaAAGTCA), but not the distal (AGGTGAacaGGTTCA), direct repeat enhanced 1,25(OH)2D3-stimulated transcription in an orientation-dependent manner when placed upstream of the heterologous SV40 promoter. In conclusion, the proximal direct repeat plays a critical role in mediating the vitamin D-induced expression of calbindin-D28k in the kidney.

Animals↗

Huntingtin immunoreactivity in the rat neostriatum: differential accumulation in projection and interneurons.

Huntington's disease is caused by a mutation of the gene encoding the protein huntingtin. Features of the human disease, characterized by selective loss of neurons from the neostriatum, can be replicated in rodents by administration of excitotoxins. In both affected individuals and the rodent model, there is massive loss of striatal projection neurons with selective sparing of interneurons. Furthermore, in the human disease the earliest evidence of striatal injury is found in striosomal regions of the striatum. The mRNA encoding huntingtin is known to be expressed by neurons throughout the brain, a distribution which does not account for the selective patterns of neuronal death which are observed. Using fluorescence immunocytochemistry and confocal microscopy with an antibody to huntingtin, we have observed that in rats a subset of striatal projection neurons contains dense accumulations of huntingtin immunoreactivity (HT-ir), while most neurons in the striatum contain much smaller amounts. The intensely stained neurons are concentrated within the striatal striosomes, as defined by calbindin-D28K staining. In the matrix regions, relatively few neurons contain dense accumulations of HT-ir, and these cells always lack perikaryal staining for calbindin-D28K. Striatal interneurons, identified by the presence of immunoreactivity for choline acetyltransferase, parvalbumin, calretinin, or neuronal nitric oxide synthase, exhibit little or no HT-ir. The paucity of HT-ir in striatal interneurons, as well as the prominence of staining in a subset of striosomal neurons, mirrors the selective vulnerability of these different types of cells in early stages of human Huntington's disease and in rodent excitotoxic models of the disorder. Our observations suggest that mechanisms which modulate the accumulation of huntingtin may play a central role in the neuronal degeneration of Huntington's disease.

Animals↗

Laminar distribution of Fos/calcium-binding protein and Fos/neurofilament protein-labeled neurons in rat motor and sensory cortex after picrotoxin-induced seizures.

Cerebrocortical Fos induction after picrotoxin-induced seizure occurs in spiny neurons and, to a lesser extent, in neurons defined by calcium-binding protein immunoreactivity. In motor and sensory cortex of rats we have defined the laminar distribution of Fos expression in these neurons. Initially we defined the laminar distributions of parvalbumin-, calbindin-D 28K-, and calretinin-immunoreactive aspiny neurons; these were unique for each class and similar across cortical regions. Spiny cells defined by SMI32 immunoreactivity were distributed with two peaks and there were differences between cortical regions. Parvalbumin-immunoreactive neurons exhibited peak numbers where numbers of SMI32-immunoreactive neurons were low. The distribution of Fos induction across laminae matched that of its class for calbindin-D 28K and calretinin neurons; however, Fos induction was less in infragranular compared with supragranular for parvalbumin in motor cortex and SMI32 containing neurons in both cortices. In both these latter cell classes Fos induction was inversely correlated with neuronal size. It is suggested that cell size within some cell classes is one factor that determines the extent of Fos induction within that class following seizures.

Animals↗

The IGF-I amino-terminal tripeptide glycine-proline-glutamate (GPE) is neuroprotective to striatum in the quinolinic acid lesion animal model of Huntington's disease.

Huntington's disease is an incurable genetic neurological disorder characterized by the relatively selective degeneration of the striatum. Lesioning of the striatum in rodents using the excitatory amino acid agonist, quinolinic acid (QA), effectively mimics the human neuropathology seen in Huntington's disease. Using this animal model of Huntington's disease, we investigated the ability of the insulin-like growth factor-I (IGF-I) amino-terminal tripeptide glycine-proline-glutamate (GPE) to protect striatal neurons from degeneration. Adult rats received a single unilateral intrastriatal injection of QA (100 nmol) and then daily injection of either vehicle or GPE (0.3 microgram/microliter/day) into the striatum for 7 days. QA at this dose resulted in a partial lesioning of the striatum after 7 days to approximately 50% of cells of unlesioned levels in vehicle-treated animals. The major striatal neuronal phenotype, GABAergic projection neurons, were identified by immunocytochemical labeling of either glutamate decarboxylase 67 (GAD(67)) or the calcium binding protein calbindin in alternate sections. Treatment with GPE for 7 days reversed the loss in projection neurons when assessed by counts of calbindin-stained cells; however, these rescued cells did not regain immunologically detectable levels of GAD(67). GPE also significantly reversed the phenotypic degeneration of cholinergic interneurons identified by immunolabeling for choline acetyltransferase (ChAT) and NADPH diaphorase interneurons identified histochemically. GPE treatment failed to rescue the calcium binding protein interneuron populations of parvalbumin and calretinin neurons. These findings reveal that exogenous administration of GPE selectively prevents excitotoxin induced phenotypic degeneration of striatal projection neurons and cholinergic and NADPH diaphorase interneurons in an animal model of Huntington's disease.

Animals↗

Immunolocalization of peptide 19 and other calcium-binding proteins in the guinea pig cochlea.

Calcium ions are known to play critical roles in a variety of cochlear functions. The distributions of a number of calcium binding proteins that regulate calcium ion levels within the cochlea have previously been described. In this report we extend and refine previous reports of the distribution of immunostaining for calmodulin, calbindin, and calretinin and show for the first time the distribution for peptide 19. There were longitudinal and radial gradients of immunostaining for peptide 19 within outer hair cells that appeared to match previously described gradients of efferent innervation of these cells. Gradients of immunostaining for calbindin within outer hair cells were in the opposite directions, which suggests that levels of this protein are correlated with afferent innervation density and perhaps the abundance of subsurface cisternae. No gradients were seen in the distributions of cells stained for calmodulin and calretinin, which included sensory cells and supporting cells respectively. All ganglion cells were stained for calmodulin but the other proteins appeared to be present in limited ganglion cell subpopulations. In addition to staining of sensorineural elements, antisera to all compounds but peptide 19 showed immunostaining of cells within the lateral wall and the spiral limbus. The results suggest that the proteins under study are involved in a wide variety of calcium-regulated functions within the cochlea. Knowledge of the unique distribution of each of the compounds should facilitate further studies of their roles in cochlear function.

Animals↗

Cajal-Retzius cells, inhibitory interneuronal populations and neuropeptide Y expression in focal cortical dysplasia and microdysgenesis.

Focal cortical dysplasia (FCD) and microdysgenesis (MD) are likely to represent abnormalities of radial neuronal migration during cortical development. We investigated the distribution of reelin-positive Cajal-Retzius cells, known to be important in the later stages of radial neuronal migration and cortical organization, in 12 surgical cases of both MD and FCD. Quantitation revealed significantly higher numbers of these cells in MD cases compared to controls. As the majority of cortical interneurones arise via tangential rather than radial migration, we studied the distribution and morphology of inhibitory interneuronal subsets immunolabelled for calbindin, parvalbumin and calretinin within these malformations. Frequent findings were a reduction of inhibitory interneurones in the region of FCD and abnormally localised hypertrophic or multipolar calbindin-positive interneurones in both FCD and MD. Neuropeptide Y immunostaining showed a striking increase in the density of the superficial plexus of fibres in both MD and FCD cases in addition to labelling of dysplastic neurones, which may represent an adaptive anti-convulsant mechanism to dampen down seizure propagation.

Adolescent↗

Purkinje cell neuroaxonal dystrophy similar to nervous mutant mice phenotype in two sibling kittens.

Three 4-month-old kittens from the same litter were presented, two of which were exhibiting cerebellar signs. Euthanasia was requested. No cerebellum atrophy was disclosed on necropsy. General cerebellar anatomy was normal, including the thickness of the cortical layers, myelination, and neurons of the deep cerebellar nuclei. In the ataxic cat vermis, Purkinje cells were lacking along broad parasagittal bands symmetrically disposed relative to the midline. Many Purkinje cells were also lacking in the hemispheres. The nodulus and the flocculus were normal. Surviving Purkinje cells had frequent main dendrite swellings visible with anti-calbindin and anti-microtubule associated protein. In affected regions, calbindin and phosphorylated neurofilaments immunesera stained numerous axonal torpedoes located in the granular layer and the folial white matter. They were also present in processes of the deep cerebellar nuclei and lateral vestibular nucleus. Loss of synaptic endings onto the neurons of these nuclei was evident. Hypertrophied Purkinje cell recurrent axons and enhanced retrograde synaptic endings were present in the granular layer. Bergmann glia was strongly labeled by anti-GFAP, but no abnormal supplementary fibers were seen. None of these alterations were present in the normal sister. However, abnormal vacuolation of the Purkinje cell main dendrites was evident in all three cats, but not in six unrelated control cats that were 3-6 months old. The inferior olive and pontine nuclei were also normal. The two ataxic cats had a primary Purkinje cell degeneration that shared many common features with the abnormal Purkinje cells of the nervous mutant mouse.

Animals↗

Immunoreactivity for calcium-binding proteins in the claustrum of the monkey.

The claustrum is topographically and reciprocally connected with many different cortical areas, and anatomical and physiological data suggest it is composed of functionally distinct subdivisions. We asked if the distribution of cells immunoreactive for three calcium-binding proteins, parvalbumin, calbindin D-28k and calretinin would delineate functional subdivisions in the claustrum. We also asked if, as in cortex, different cell types were immunoreactive for the different proteins. We found that cells with parvalbumin-ir were large, multipolar cells. Cells immunoreactive for calretinin were bipolar cells with elongated cell bodies and beaded dendrites. There were three different types of cells immunoreactive for calbindin. The most numerous were small cells with round or oval cell bodies and numerous fine, winding processes. A second type were large multipolar, cells that resembled the parvalbumin-ir cells. The third class were bipolar cells with large, elongated cell bodies. Each type of cell resembles a cell type described in earlier Golgi studies, and each has a morphological cortical counterpart. While the different cell types varied in density, each was seen over the anterior-posterior and dorsal-ventral extent of the claustrum.

Animals↗

The distribution of P2X5 purinergic receptors in the enteric nervous system of mouse.

The distribution of the P2X(5) purinoceptor in the enteric nervous system of the mouse was studied by immunohistochemistry. P2X(5) receptor immunoreactivity was widely distributed in myenteric and submucosal plexuses throughout the gastrointestinal tract. In myenteric plexuses, immunoreactivity for the P2X(5) receptor was observed in nerve fibres that enveloped ganglion cell bodies, and possibly on glial cell processes. P2X(5) receptor immunoreactivity was colocalised with vasoactive intestinal peptide and surrounded ganglion cells that contained calretinin, calbindin or nitric oxide synthase. In the submucous plexus, P2X(5) receptor immunoreactivity occurred throughout the cytoplasm and on the surface membranes of the nerve cells. Double-labelling studies showed that 22%, 9%, 6% and 68% of P2X(5) receptor-immunoreactive neurones were also immunoreactive for calretinin, calbindin, nitric oxide synthase and vasoactive intestinal peptide, respectively. Thus, the P2X(5) receptor subunit is expressed in specific functional groups of neurones. P2X(2) and P2X(3) receptors were also present in the mouse enteric plexuses but no immunoreactivity for P2X(1), P2X(4) or P2X(6) receptors was found.

Animals↗

Localisation of neurokinin 3 (NK3) receptor immunoreactivity in the rat gastrointestinal tract.

The localisation of the neurokinin 3 receptor (NK3r) in the rat gastrointestinal tract has been studied by using a polyclonal antiserum against the C-terminal portion (amino acids 388-452) of the rat NK3r. In the oesophagus, immunoreactivity for the NK3r was found on smooth muscle cells of the muscularis mucosae. NK3r immunoreactivity was not present on muscle cells of other regions. Nerve cell bodies immunoreactive for NK3r were seen in the myenteric and submucous plexuses of the small and large intestine, but not in the stomach or oesophagus. Immunoreactivity was largely confined to nerve cell surfaces. The reaction product was on the cell soma and initial parts of axons. Reactivity was not seen on nerve terminals. Immunoreactive nerve cells had Dogiel Type II morphology. Patterns of co-localisation of NK3r and immunoreactivity for other markers were examined in the ileum, to provide a basis from which to deduce the functional identity of NK3r-immunoreactive nerve cells. Most of the NK3r-immunoreactive nerve cells were also immunoreactive for the calcium-binding proteins, calretinin and calbindin, and all were immunoreactive for the NK1 receptor (NK1r). Nerve cells that were immunoreactive for nitric oxide synthase were not immunoreactive for either NK3r or NK1r. The projections of the calbindin and calretinin neurons were determined by nerve lesion studies. Their morphology, projections to the mucosa and other ganglia and immunoreactivity for the calcium-binding proteins suggest that the NK3r-immunoreactive neurons are intrinsic sensory neurons.

Animals↗