Autoimmune autonomic ganglionopathy

Autoimmune autonomic ganglionopathy is an idiopathic acquired disorder of the autonomic nervous system associated with antibodies to the ganglionic nicotinic acetylcholine receptor found in sympathetic, parasympathetic and enteric ganglia. Symptoms and signs reflect diffuse impairment of autonomic functions. Prominent features are gastrointestinal dysmotility, orthostatic hypotension, and tonic pupils. Typical cases have a subacute onset (less than 3 months to maximum symptoms), are monophasic, and may show partial improvement over the course of several months. Other cases have a slowly progressive course which can resemble degenerative forms of autonomic failure. Treatment for milder cases is supportive care for symptom management. Anecdotally, plasma exchange, intravenous immunoglobulin, corticosteroids or immunosuppression have been used successfully to treat more severe cases. Autoimmune autonomic ganglionopathy represents one of a small group of autoimmune neuromuscular disorders that are caused by antibodies against ion channels.

Autonomic ganglia, acetylcholine receptor antibodies, and autoimmune ganglionopathy

Nicotinic acetylcholine receptors (AChR) are ligand-gated cation channels that are present throughout the nervous system. The ganglionic (alpha3-type) neuronal AChR mediates fast synaptic transmission in sympathetic, parasympathetic and enteric autonomic ganglia. Autonomic ganglia are an important site of neural integration and regulation of autonomic reflexes. Impaired cholinergic ganglionic synaptic transmission is one important cause of autonomic failure. Ganglionic AChR antibodies are found in many patients with autoimmune autonomic ganglionopathy (AAG). These antibodies recognize the alpha3 subunit of the ganglionic AChR, and thus do not bind non-specifically to other nicotinic AChR. Patients with high levels of ganglionic AChR antibodies typically present with rapid onset of severe autonomic failure, with orthostatic hypotension, gastrointestinal dysmotility, anhidrosis, bladder dysfunction and sicca symptoms. Impaired pupillary light reflex is often seen. Like myasthenia gravis, AAG is an antibody-mediated neurological disorder. Antibodies from patients with AAG inhibit ganglionic AChR currents and impair transmission in autonomic ganglia. An animal model of AAG in the rabbit recapitulates the important clinical features of the human disease and provides additional evidence that AAG is an antibody-mediated disorder caused by impairment of synaptic transmission in autonomic ganglia.

Chemical coding of submucosal type V neurons in porcine ileum

In this study, we attempted to determine the proportion of type V neurons relative to the putative whole neuron population in the two submucosal plexuses of pigs identified by their neurofilament immunoreactivity. The total neuron number was estimated in cuprolinic blue (CB)/anti-Hu protein (HU) costained wholemounts as the sum of the number of CB+/HU+, CB+/HU- and CB-/HU+ neurons. In the external submucosal plexus (ESP), HU labelled 98.6% and CB 97.3% of neurons. In the internal submucosal plexus, HU labelled 98.3%, whereas CB only marked 92.5% of neurons. Furthermore, we investigated the chemical coding of submucosal type V neurons and searched for submucosal, non-type V neurons displaying the same chemical coding as the myenteric type V neurons described earlier, i.e. the colocalization of calcitonin gene-related peptide (CGRP) and somatostatin (SOM). In order to facilitate immunohistochemical detection of neuroactive peptides, ileal segments were pretreated with colchicine prior to fixation. Type V neurons in the ESP occurred either as single cells displaying one or few prominent dendrite(s) or within aggregates displaying a dendritic tangle. In this plexus, type V neurons amounted to between 0.9 and 1.6% of all CB-stained neurons. ESP type V neurons displayed immunoreactivities for choline acetyl transferase (95.8%) and leucine-enkephalin (73.9%). All type V neurons were negative for neuronal nitric oxide synthase. Fifty-eight percent of ESP CGRP/SOM co-immunoreactive neurons displayed type V morphology, whereas 42% were non-type V neurons. Thus, the chemical coding of ESP type V neurons is in principal similar to that of the myenteric type V neurons described earlier. In the internal submucosal plexus, we found no type V neurons. In this plexus, 0.2% of all neurons counterstained with HU displayed CGRP/SOM coreactivity. As had been observed earlier concerning the myenteric type V neurons, ESP type V neurons were also closely apposed by conspicuous accumulations of boutons reactive for the same markers as the neurons themselves. Although we cannot exclude that axons of CGRP/SOM-reactive enteric, non-type V or extrinsic neurons end synaptically on type V neurons, we suggest that the main synaptic input to type V neurons originates from other type V neurons. This presents an argument for an interneuronal role of type V neurons.

Somatostatin immunoreactivity in quail pterygopalatine ganglion

In the ciliary ganglion of the chicken and quail, somatostatin (SOM) is an exclusive marker for parasympathetic postganglionic neurons innervating the choroid. A second parasympathetic pathway projecting to the choroid originates from the pterygopalatine ganglion. The aim of this study was to investigate SOM immunoreactivity in the pterygopalatine ganglion of the Japanese quail (Coturnix coturnix japonica) and on neurons within the choroid, the intrinsic choroidal neurons (ICN). We did so using immunohistochemistry and subsequent light, electron and confocal laser scanning microscopy. Pterygopalatine neurons were characterized by nNOS-immunohistochemistry or NADPH-diaphorase cytochemistry. SOM immunoreactivity was absent in the perikarya, but neurons were densely surrounded by SOM-positive nerve fibres. Electron microscopy revealed that these fibres formed contacts with and without membrane specializations on pterygopalatine neurons. In the choroid, neuronal nitric-oxide synthase (nNOS)-immunoreactive ICN were likewise closely apposed by SOM-immunoreactive nerve fibres, as revealed by confocal microscopy. There was no detectable co-localization of the markers. In the absence of tracing studies, it is open to speculation whether SOM immunoreactivity originates from preganglionic fibres of the superior salivatory nucleus, postganglionic fibres of the ciliary ganglion or fibres of the brainstem via as yet unknown pathways. SOM may regulate the production of NO in pterygopalatine neurons and ICN, respectively, and is therefore involved in neuronal circuits regulating ocular homeostasis.

Catecholamines and 5-hydroxytryptamine in tissues of the rabbit exocrine pancreas

OBJECTIVES

Norepinephrine (NE), dopamine (DA), epinephrine (Epi), and 5-hydroxytryptamine (5-HT) all modulate pancreatic exocrine secretion, yet their concentrations in specific tissues of the exocrine pancreas are unknown.

METHODS

Concentrations of catecholamines and 5-HT in rabbit pancreatic ganglia, acini, ducts and ampullae, and arteries and veins were measured using HPLC.

RESULTS

Concentrations of NE in ganglia from the head/neck region were significantly higher than those from the body (1620 +/- 220 vs. 778 +/- 179 pmol/mg protein). Acini contained little NE, DA, or 5-HT (9 +/- 2, 0.9 +/- 0.2, 13 +/- 5 pmol/mg protein). Ducts and ampullae contained NE (314 +/- 74 and 156 +/- 24 pmol/mg protein), DA (43 +/- 14 and 13 +/- 4 pmol/mg protein), Epi (63 +/- 29 and 39 +/- 6 pmol/mg protein), and 5-HT (696 +/- 151 and 3563 +/- 288 pmol/mg protein). Arteries and veins contained the highest concentrations of NE (1962 +/- 463 and 736 +/- 80 pmol/mg protein, respectively).

CONCLUSIONS

Pancreatic ganglia and blood vessels, rather than acini, are the main sites of noradrenergic sympathetic innervation of the rabbit exocrine pancreas. These nerves preferentially target ganglionic transmission in the head/neck versus the body. Serotonergic nerves provide little or no innervation of rabbit pancreatic ganglia or acini.

Neurochemical characterization of extrinsic innervation of the guinea pig rectum

The presence of markers for parasympathetic, sympathetic, and glutamatergic or peptidergic sensory innervation was investigated by using in vitro tracing with biotinamide, combined with immunohistochemistry, to characterise quantitatively extrinsic axons to myenteric ganglia of the guinea pig rectum. Of biotinamide-filled varicose axons, 3.6 +/- 1.3% were immunoreactive for tyrosine hydroxylase (TH) and 16.0 +/- 4.8% for vesicular acetylcholine transporter (VAChT). TH and vesicular monoamine transporter (VMAT1) showed high coexistence (83-100%), indicating that varicosities lacking TH immunoreactivity also lacked VMAT1. VAChT was detectable in 77% of choline acetyltransferase (ChAT)-immunoreactive varicosities. Calcitonin gene-related peptide (CGRP) was detected in 5.3 +/- 1.6% of biotinamide-labeled varicosities, the vesicular glutamate transporter (VGluT) 1 in 2.8 +/- 0.8%, and VGluT2 in 11.3 +/- 4.2% of varicosities of extrinsic origin. Varicosities from the same axon showed consistent immunoreactivity. A novel type of nerve ending was identified, with branching, flattened lamellar endings, similar to the intraganglionic laminar endings (IGLEs) of the proximal gut. Rectal IGLEs were frequently immunoreactive for VGluT1 and VGluT2. Thus most varicose axons of extrinsic origin, which innervate rectal myenteric ganglia, lack detectable levels of immunoreactivity for TH, VMAT1, VAChT, ChAT, VGluT1/2, or CGRP, under conditions in which these markers are readily detectable in other axons. Although some unlabeled varicosities may belong to afferent axons that lack detectable CGRP or VGluT1/2 in the periphery, this suggests that a large proportion of axons do not release any of the major autonomic or sensory transmitters. We speculate that this may vary under particular circumstances, for example, inflammation or obstruction of the gut.

Local commissural interneurons integrate information from intersegmental coordinating interneurons

The information that coordinates movements of swimmerets on different segments of the crayfish abdomen is conducted by interneurons that originate in each abdominal ganglion. These interneurons project axons to neighboring ganglia and beyond. To discover the anatomy of these axons in their target ganglia, we used Neurobiotin and dextran-Texas Red microelectrodes to fill them near their targets. Coordinating axons coursed through these target ganglia close to the midline and extended only a few short branches that did not approach the lateral neuropils. Two of the three types of coordinating axons made direct synaptic connections with a class of local commissural interneurons that relayed the information to targets in the swimmeret pattern-generating circuits. These commissural interneurons, named here ComInt 1 neurons, followed a particular route to cross the midline and reach their targets. ComInt 1 neurons were nonspiking; they received EPSPs from the coordinating axons near the midline and transmitted this information to their targets in the lateral neuropils using graded transmission. The output of each ComInt 1 was restricted to a single local circuit and had opposite effects on the power-stroke and return-stroke motor neurons driven by that circuit. ComInt 1 neurons were direct postsynaptic targets of both descending and ascending coordinating axons that originated in other anterior and posterior ganglia. Because of phase differences in the impulses in these different coordinating axons, their signals arrived simultaneously at each ComInt 1. We discuss these findings in the context of alternative models of the intersegmental coordinating circuit.

Synaptic dynamism measured over minutes to months: age-dependent decline in an autonomic ganglion

Naturally occurring rearrangements of synaptic terminals are common in the nervous systems of young mammals, but little is known about their incidence in adults. Using transgenic mice that express yellow fluorescent protein (YFP) in axons, we repeatedly imaged nerve terminals in the parasympathetic submandibular ganglion. We found that the pattern of synaptic branches underwent significant rearrangements over several weeks in young adult mice. In older mice, rearrangements were less common, and synaptic patterns on individual neurons were recognizable for many months to years. Axonal branches frequently retracted or extended on a time scale of minutes in young adult mice, but seldom in mature animals. These results provide direct evidence for a decrease in plasticity of interneuronal connections as animals make the transition from young adulthood to middle age. The long-term stability of synaptic patterns could provide a structural basis for the persistence of memory in the adult nervous system.

Immunohistochemical study of the otic ganglion in the pig

The presence of choline acetyltransferase (ChAT), vesicular acetylcholine transporter (VAChT), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), somatostatin (SOM), galanin (GAL), substance P (SP) and calcitonin gene-related peptide (CGRP) was studied in neurons and nerve fibers of the porcine otic ganglion. ChAT-positive neurons were very numerous while VAChT-positive nerve cells were moderate in number. The number of neurons containing NPY and VIP was lower and those containing SOM, GAL, SP or CGRP were observed as scarce, or single nerve cells. The above mentioned substances (except SOM) were present in nerve fibers of the ganglion. ChAT- and VAChT-positive nerve fibers were numerous, while the number of nerve terminals containing NPY, VIP and SP was lower. GAL- and CGRP-positive nerve fibers were scarce.

Functional organization of vasodilator neurons in pelvic ganglia of female guinea pigs: comparison with uterine motor neurons

Neurons producing vasodilation during reproductive activity constitute a large population of neurons in pelvic autonomic ganglia. We used intracellular recording, dye-filling and multiple-labeling immunohistochemistry to determine the morphology and electrophysiological properties of, and number of synaptic inputs to, vasodilator pelvic neurons in female guinea pigs. Vasodilator neurons, identified by their immunoreactivity for vasoactive intestinal peptide (VIP) and their location in paracervical ganglia, had simple dendritic arbors (1 primary dendrite) compared with nonvasodilator neurons (3 dendrites). Vasodilator neurons had more depolarized resting membrane potentials (-47 mV) than other paracervical neurons (-55 mV) and had smaller apparent cell capacitances (65 pF vs. 110 pF). Vasodilator and nonvasodilator neurons could not be distinguished on the basis of their action potential discharge characteristics or current voltage relationships. Most pelvic neurons ( approximately 70%) had tonic (slowly adapting) discharges. Fifty-five percent of vasodilator and 60% of nonvasodilator neurons showed inward rectification when hyperpolarized below -90 mV. Around 65% of neurons showed evidence of M-current. Both vasodilator and nonvasodilator neurons ( approximately 80%) expressed an A-like current. Vasodilator neurons and nonvasodilator neurons received 1-2 fast synaptic inputs following stimulation of pelvic or hypogastric nerve trunks. Most neurons received a least one strong synaptic input. These results indicate that vasodilator neurons and neighboring neurons projecting to other pelvic targets, primarily in the myometrium, express a similar range of ionic conductances and integrate few synaptic inputs. The similarities between these two populations of neurons may be related to their coactivation as part of spinal somato-pelvic reflexes. Vasodilation and uterine contraction during reproductive behavior in female guinea pigs are likely to involve input from preganglionic neurons at both lumbar and sacral spinal levels.

Leptin receptors, NPY, and tyrosine hydroxylase in autonomic neurons supplying fat depots in a pig

The goal of this study was to determine the immunohistochemical characteristics of peripheral adrenergic OBR-immunoreactive (OBR-IR) neurons innervating adipose tissue in a pig. The retrograde tracer, Fast Blue (FB), was injected into either the subcutaneous, perirenal, or mesentery fat tissue depots of three male and three female pigs each with approximately 50 kg body weight. Sections containing FB(+) neurons were stained for OBR, tyrosine hydroxylase (TH) or neuropeptide Y (NPY) using a double labeling immunofluorescence method. OBR, TH, and NPY immunoreactivities were present in the thoracic (T) and lumbar (L) ganglia of the sympathetic chain, as well as in the coeliac superior mesenteric ganglion (CSMG), inferior mesenteric ganglion (IMG), intermesenteric ganglia (adrenal-ADG, aorticorenal-ARG, and ovarian-OG or testicular-TG ganglion). These results indicate that, in addition to neuroendocrine functions, leptin may affect peripheral tissues by acting on receptors located in sympathetic ganglion neurons.

Chronic hypoxia upregulates connexin43 expression in rat carotid body and petrosal ganglion

Recent studies have demonstrated that oxygen-sensitive type I cells in the carotid body express the gap junction-forming protein connexin43 (Cx43). In the present study, we examined the hypothesis that chronic exposure to hypoxia increases Cx43 expression in type I cells as well as in chemoafferent neurons in the petrosal ganglion. Immunocytochemical studies in tissues from normal rats revealed diffuse and granular Cx43-like immunoreactivity in the cytoplasm of type I cells and dense punctate spots of immunoreactive product at the margins of type I cells and near the borders of chemosensory cell lobules. Cx43-like immunoreactivity was not detectable in petrosal ganglion neurons from normal animals. After a 2-wk exposure to hypobaric (380 Torr) hypoxia, Cx43 immunostaining was substantially enhanced in and around type I cells. Moreover, chronic hypoxia elicited the expression of Cx43-like immunoreactivity in the cytoplasm of afferent neurons throughout the petrosal ganglion. Quantitative RT-PCR studies indicate that chronic hypoxia evokes a substantial increase in Cx43 mRNA levels in the carotid body, along with a marked elevation of Cx43 expression in the petrosal ganglion. Increased Cx43 expression and gap junction formation in type I cells and sensory neurons may contribute to carotid body adaptation during sustained stimulation in extreme physiological conditions.

Cellular localization of the diazepam binding inhibitor in glial cells with special reference to its coexistence with brain-type fatty acid binding protein

The diazepam binding inhibitor (DBI) was originally isolated from the brain as an intrinsic ligand of the benzodiazepine binding site on the type-A gamma-aminobutyric acid receptor (GABA(A) receptor). Its wide-spread distribution in non-neural tissues outside the brain suggests that DBI has various functions other than GABA-mediated neurotransmission. Since DBI is identical with the acyl-CoA binding protein, which has the ability to bind long chain acyl-CoA esters, the major function of DBI may possibly be related to lipid metabolism. This idea was supported by our previous study showing the consistent coexpression of DBI and fatty acid binding proteins (FABPs) in epithelia throughout the gastrointestinal tract. The present histochemical study focused on the distribution of DBI in neural tissues, and revealed a definite existence of DBI in non-neuronal supporting cells in both the central and peripheral nervous systems. In the brain, intense immunoreactivity for DBI was detected in the cerebellar Bergmann glia, olfactory ensheathing glia, subgranular layer of the dentate gyrus, and retinal Muller cells. In the peripheral nervous system, satellite cells in sensory/autonomic ganglia, Schwann cells, and sustentacular cells in the adrenal medulla were immunoreactive to a DBI antibody. Moreover, the colocalization of DPI and brain-type FABP (B-FABP) was observed in most of the non-neuronal supporting cells mentioned above, indicating that DBI and B-FABP are cooperatively involved in the energy metabolism of astrocytes and related cells, which are thought to support neuronal development and functions.

L-arginine immunoreactive enteric glial cells in the enteric nervous system of rat ileum

L-arginine is a precursor of nitric oxide (NO) that may be involved in neuronal activity in the gastrointestinal tract. It is known that NO is formed from L-arginine by NO synthase which is localized in neurons in the enteric nervous system. The present study demonstrated that significant L-arginine immunoreactivity was present in the enteric ganglia. Ultrastructural examination showed that L-arginine immunoreactivity was present in the ganglionic glial cells but not in neurons. These findings suggest that enteric glial cells may represent the main reservoir of L-arginine, which may possibly be transferred to neurons when used.

Co-localization of androgen receptor with estrogen receptor beta in the lower urinary tract of the male rat

PURPOSE

Androgens and estrogens influence voiding. In this study their target sites in the lower urinary tract of the male rat were identified.

MATERIALS AND METHODS

Cryosections of the bladder body, bladder neck, prostatic urethra, mid proximal urethra and prostatic autonomic ganglia of adult male rats were immunostained with specific estrogen receptor alpha, estrogen receptor beta (ERbeta) or androgen receptor (AR) antibodies. The sections were then examined under conventional, fluorescence or confocal fluorescence microscopy.

RESULTS

Co-expression of AR and ERbeta in the urothelium, bladder smooth muscle cells, proximal urethra striated muscle cells and neurons in the autonomic ganglia of the prostatic plexus suggests that estrogen and androgen have direct effects in the lower urinary tract.

CONCLUSIONS

The local interaction of AR and ERbeta in the hormonal control of voiding is an intriguing possibility.

Nerve cells associated with the endocrine pancreas in young mice: an ultrastructural analysis of the neuroinsular complex type I

The neuroinsular complex type 1 is composed of pancreatic endocrine islet cells and nerve cell bodies intrinsic to the islet. The details of the relation between nerve cells and between endocrine cells and nerve cells in the complex are unknown. Pancreata from newborn and 18-day-old mice were analysed by electron microscopy to establish the ultrastructural morphology of the neuroinsular complex. Immunohistochemical staining for protein gene-product 9.5 was also performed. The study showed that nerve cell bodies were closely associated to each other in the periphery of the islets with no connective tissue separating the cells. The nerve cells were closely associated to both beta-cells and alpha-cells. Direct intercellular contacts were observed between nerve cells and endocrine cells and between Schwann cells and endocrine cells. Varicose nerve endings were frequently observed in the neuroinsular complex. In the peripheral parts the varicosities were mostly being associated to the nerve cell bodies. The varicosities contained small clear or small clear and larger dense cored vesicles, suggesting cholinergic and peptidergic contents. The varicosities made specialized synaptic connections with adjacently located nerve cells. The study shows that the neuronal part of the neuroinsular complex is closely associated to the endocrine islet cells and that it is richly innervated, indicating an important regulatory function of the nerve cell component in the neuroinsular complex.

Differential regulation of trkA and p75 in noradrenergic pelvic autonomic ganglion cells after deafferentation of their cholinergic neighbours

In rats, following lesion of lumbar or sacral preganglionic axons, many pelvic ganglion cells undergo axogenesis to form baskets of terminals around select populations of nearby ganglion cells. The aim of the current study was to address mechanisms underlying initiation of this sprouting, focusing on a possible role for nerve growth factor (NGF). Immunohistochemical localization of NGF receptors (trkA and p75) showed that virtually all noradrenergic and a minority of cholinergic pelvic neurons expressed both receptors. Terminals immunoreactive for each substance were found in pelvic viscera. In pelvic ganglia, many glial cells expressed p75 but not trkA, and very few lumbar or sacral preganglionic neurons expressed either receptor. Lumbar and/or sacral preganglionic inputs were removed from ganglion cells by cutting the hypogastric, pelvic or both nerves, and tissues analysed 8 days later. Levels of receptor expression in noradrenergic pelvic ganglion cells were estimated by calculating the proportion that were receptor-immunopositive, and quantifying the intensity of trkA or p75 immunofluorescence. No lesion had a significant effect on trkA expression, however, a marked decrease in p75 occurred after cutting pelvic nerves, i.e. after deafferentation of neighbouring cholinergic neurons. These injuries appeared to cause little overall change in glial p75 expression. This study shows that manipulations that trigger sprouting from noradrenergic pelvic neurons cause downregulation of p75 but not trkA. Interestingly, this is occurring while some of their target organs are synthesizing high levels of NGF. This contrasts with other NGF-sensitive cells, in which one or both receptor types are upregulated by increased exposure to the ligand. The current study is also the first to show a change in p75 expression in neurons that are neither deafferented nor axotomized.

Calbindin-D28k in cerebrovascular extrinsic innervation system of the rat

Calbindin-D28k, one of the calcium-binding proteins, belongs to the EF hand family and is commonly found in neurons. It serves as a representative neuronal marker for neuroanatomical investigations. The authors' knowledge of its precise function, however, is yet very limited. In this study, we examined the existence of nerve fibers with calbindin-D28k immunoreactivity in the cerebral blood vessels and ganglia that innervate the cerebral blood vessels in the rat. Numerous nerve fibers with calbindin-D28k immunoreactivity were observed on the walls of the major extracerebral arteries forming the circle of Willis and its branches. Calbindin-D28k immunoreactivity was seen in many neurons of the trigeminal, dorsal root and jugular ganglia. A small number of neurons showed calbindin-D28k immunoreactivity in the otic and superior cervical ganglia. Calbindin-D28k immunoreactivity was not detected in the sphenopalatine or internal carotid ganglia. Pericellular basket-like formations of nerve terminals with calbindin-D28k immunoreactivity were observed in the sphenopalatine, otic, internal carotid and superior cervical ganglia. The present study demonstrated calbindin-D28k immunoreactivity in the cerebrovascular nerve fibers as well as in their origins--the cranial ganglia. These findings are significant in understanding the calcium-mediated mechanism of the neural control of the cerebral blood vessels.

An immunocytochemical study of intrapancreatic ganglia, nerve fibres and neuroglandular junctions in Brockmann bodies of the tompot blenny (Blennius gattoruggine), a marine teleost

The innervation of the Brockmann bodies in the teleost fish, Blennius gattoruggine, was studied using immunocytochemical techniques at both the light and electron microscopy levels. Islet innervation consisted of intrapancreatic ganglia, generally localized inside the rim of the exocrine tissue of the Brockmann bodies, in proximity to the islet, nerve fibres and nerve terminals with synaptic complexes. The intrapancreatic ganglia were of variable size, with different numbers of ganglionic cells, that appeared unipolar in section. The cell bodies showed immunoreactivity to galanin, oxytocin, peptide tyrosine tyrosine and glucagon. The extrinsic and intrinsic nerve fibres passed through the exocrine parenchyma and crossed the connectival septa and islet connectival sheath, penetrating into the islets, where they became increasingly thinner. They terminated on the endocrine cells with dilated nerve terminals. At least three types of terminals were detected, depending on the different vesicle content: peptidergic, cholinergic or adrenergic. They presented specialized synaptic structures, the neuroglandular junctions, some of which contained neurosecretory granules immunogold labelled by galanin antiserum. This new finding confirms the role of galanin as a neurotransmitter. This rich supply of innervation may be important in the regulation and integration of islet secretion.

Neuronal and extraneuronal expression and regulation of the human alpha5 nicotinic receptor subunit gene

The mRNA encoding the human alpha5 nicotinic subunit was detected in several structures of the nervous system but appeared to be mainly expressed in cerebellum, thalamus, and the autonomic ganglia. For the first time, the alpha5 transcript was also detected in several non-neuronal tissues, with maximal expressions being found throughout the gastrointestinal tract, thymus, and testis. Many other extraneuronal sites expressed alpha5, but there were also nonexpressing organs, such as the liver, spleen, and kidney. To understand the transcriptional mechanisms controlling such a diversified expression of alpha5 in neuronal and nonneuronal cells, we isolated the 5'-regulatory region of the human gene and characterized its properties. Here we identify the alpha5 core promoter and demonstrate that the DNA regions surrounding it contain elements (with positive or negative activities) that work in a tissue-specific fashion. In particular, the segment specifying the 5'-untranslated region in neuronal cells has most of the properties of an enhancer because it activates a heterologous promoter in a position- and orientation-independent fashion. We therefore conclude that the expression of alpha5 relies on a highly complex promoter that uses distinct regulatory elements to comply with the different functional and developmental requirements of the various tissues and organs.

Functional vagal input to chemically identified neurons in pancreatic ganglia as revealed by Fos expression

The importance of neural elements in the control of both endocrine and exocrine pancreatic secretory functions and their coordination with gastrointestinal, hepatic, and general homeostatic functions is increasingly recognized. To better characterize the vagal efferent input to the pancreas, the capacity of electrical vagal stimulation to induce expression of c-Fos in neurochemically identified neurons of intrapancreatic ganglia was investigated. At optimal stimulation parameters, unilateral stimulation of either the left or right cervical vagus induced Fos expression in approximately 30% of neurons in the head and 10-20% of neurons in the body and tail of the pancreas. There was no Fos expression if no stimulation or stimulation with a distally cut vagus was applied. Large proportions of neurons contained nitric oxide synthase as assessed with NADPH diaphorase histochemistry (88%) and choline acetyltransferase. The proportion of nitrergic and nonnitrergic neurons receiving vagal input was not different. It is concluded that a significant proportion of pancreatic neurons receives excitatory synaptic input from vagal preganglionic axons and that many of these vagal postganglionic neurons can produce nitric oxide and acetylcholine.

Myasthenia gravis, thymoma, intestinal pseudo-obstruction, and neuronal nicotinic acetylcholine receptor antibody

Intestinal pseudo-obstruction occurs rarely in patients with myasthenia gravis (MG) and thymoma. The etiology of the intestinal pseudo-obstruction remains to be elucidated, although an autoimmune mechanism is postulated. We present the first report of neuronal nicotinic acetylcholine receptor (AChR)-specific antibody in a patient with seropositive MG, malignant thymoma, and intestinal pseudo-obstruction. This finding provides evidence that intestinal pseudo-obstruction associated with thymoma and possibly other neoplasms may be related to antibodies against the neuronal nicotinic receptors at autonomic ganglia.

Neurokinin-1 receptor localisation in guinea pig autonomic ganglia

We have used multiple-labelling immunohistochemistry and confocal microscopy to determine the distribution of immunoreactivity to the tachykinin neurokinin-1 (NK(1)) receptors in guinea pig sympathetic ganglia. Although nerve fibres containing immunoreactivity to substance P were common in all ganglia except the superior cervical ganglia, most neurons expressing NK(1) receptor immunoreactivity were not closely surrounded by pericellular baskets of substance P-immunoreactive boutons. Conversely, many neurons surrounded by baskets of substance P-immunoreactive boutons lacked NK(1) immunoreactivity. In the coeliac and inferior mesenteric ganglia, NK(1) receptor expression was restricted almost entirely to noradrenergic neurons that contained somatostatin immunoreactivity and projected to the enteric plexuses. In the lumbar chain and paracervical ganglia, NK(1) immunoreactivity was expressed by nonnoradrenergic vasodilator neurons containing immunoreactivity to vasoactive intestinal peptide. Taken together, our results show that sympathetic neurons in different functional pathways express NK(1) receptor immunoreactivity. However, the neurons that could respond to endogenously released substance P through NK(1) receptors may be distant from presynaptic release sites. These observations suggest that, in sympathetic ganglia, substance P may modulate ganglionic transmission through heterosynaptic actions on NK(1) receptors.

Monoamine- and histamine-synthesizing enzymes and neurotransmitters within neurons of adult human cardiac ganglia

BACKGROUND

Cardiac ganglia were originally thought to contain only cholinergic neurons relaying parasympathetic information from preganglionic brain stem neurons to the heart. Accumulating evidence, however, suggests that cardiac ganglia contain a heterogeneous population of neurons that synthesize or respond to several different neurotransmitters and neuropeptides. Reports regarding monoamine and histamine synthesis and neurotransmission within cardiac ganglia, however, present conflicting information or are limited in number. Furthermore, very few studies have examined the neurochemistry of adult human cardiac ganglia. The purpose of this study was, therefore, to determine whether monoamine- and histamine-synthesizing enzymes and neurotransmitters exist within neurons of adult human cardiac ganglia.

METHODS AND RESULTS

Human heart tissue containing cardiac ganglia was obtained during autopsies of patients without cardiovascular pathology. Avidin-biotin complex immunohistochemistry was used to demonstrate tyrosine hydroxylase, L-dopa decarboxylase, dopamine beta-hydroxylase, phenylethanolamine-N-methyltransferase, tryptophan hydroxylase, and histidine decarboxylase immunoreactivity within neurons of cardiac ganglia. Dopamine, norepinephrine, serotonin, and histamine immunoreactivity was also found in ganglionic neurons. Omission or preadsorption of primary antibodies from the antisera and subsequent incubation with cardiac ganglia abolished specific staining in all cases examined.

CONCLUSIONS

Our results suggest that neurons within cardiac ganglia contain enzymes involved in the synthesis of monoamines and histamine and that they contain dopamine, norepinephrine, serotonin, and histamine immunoreactivity. Our findings suggest a putative role for monoamine and histamine neurotransmission within adult human cardiac ganglia. Additional, functional evidence will be necessary to evaluate what the physiological role of monoamines and histamine may be in neural control of the adult human heart.

Lack of induction of substance P gene expression by hypoxia and absence of neurokinin 1-receptor mRNAs in the rat carotid body

Peripheral chemoreceptors are commonly thought to respond to hypoxia by releasing neurotransmitters from the type 1 cells of the carotid body; these molecules then bind to post-synaptic receptors on the carotid sinus nerve. The tachykinin substance P (SP) may act as an important neurotransmitter/neuromodulator in hypoxic chemotransmission in peripheral arterial chemoreceptors. In order to elucidate the role of SP in modulating hypoxic chemotransmission, we have used quantitative in situ hybridization histochemistry, to determine the effect of hypoxia on SP gene induction, and the localization of neurokinin 1 (NK-1) receptor mRNA in the carotid body and petrosal ganglia complex in rats at 21 days post-natal age. For comparison, we also determined: (1) the effect of hypoxia on tyrosine hydroxylase (TH) gene induction and (2) the localization of the mRNA encoding the D2-dopamine receptor. SP mRNA was not detected in the rat carotid body during normoxia and its expression was not induced after a 1 h of exposure to hypoxia (10% O2/90% N2), a stimulus that was sufficient to cause a significant increase (P < 0.01) in TH mRNA levels in the carotid body. Both SP and TH mRNAs were abundantly expressed in multiple cells in the petrosal and the jugular ganglia. However, these mRNAs were not co-localized and SP and TH mRNA levels were not affected by hypoxia in these ganglia. Although D2-dopamine receptor mRNA was abundantly expressed in the rat carotid body, we found no evidence of NK-1 receptor mRNA in the carotid body. In contrast, both NK-1 receptor mRNA and D2-dopamine receptor mRNA were present in petrosal ganglion cells. In the rat, SP does not appear to modulate hypoxic chemotransmission by being made in and released from type 1 cells in the carotid body, and neither does SP modulate the activity of type 1 cells by binding to NK-1 receptors on these cells.

Characterisation of the adventitial rectal ganglia in the male rat by their immunohistochemical features and projections

In recent years, considerable progress has been made in characterising the neural circuitry of the pelvic plexus, particularly in the male rat. However, the small ganglia on the adventitial surface of the rectum remain largely unstudied. We have used immunohistochemistry and retrograde tracing techniques to determine the content and projections of these neurons. The adventitial ganglia contain 600-1,000 neurons. All of these are immunoreactive for choline acetyltransferase, 44% are immunoreactive for calbindin, and 35% are immunoreactive for vasoactive intestinal peptide. Very few (1-5%) adventitial neurons contain tyrosine hydroxylase or neuropeptide Y. In contrast, most adventitial neurons are surrounded by varicose axons that do contain tyrosine hydroxylase or neuropeptide Y. Retrograde tracing studies showed that the primary targets of adventitial neurons within the bowel are the internal anal sphincter and the circular muscle directly adjacent to the sphincter. However, more adventitial neurons project out of the gut wall than to targets within the bowel. These are most likely to be viscerofugal and rectospinal neurons. Combining the immunohistochemical and tracing observations, these studies suggest that the rat adventitial ganglia do not represent an additional source of pelvic (autonomic postganglionic) neurons but, instead, that they are comprised primarily of viscerofugal and rectospinal neurons. This is very different from the adventitial rectal ganglia of the cat, which represent merely an extension of the pelvic plexus.

Adenylyl cyclase co-distribution with the CaBPs, calbindin-D28 and calretinin, varies with cell type: assessment with the fluorescent dye, BODIPY forskolin, in enteric ganglia

The aims of the present study were: (1) to evaluate BODIPY forskolin as a suitable fluorescent marker for membrane adenylyl cyclase (AC) in living enteric neurons of the guinea-pig ileum; (2) to test the hypothesis that AC is distributed in several subpopulations of enteric neurons; (3) to test the hypothesis that the distribution of AC in the myenteric plexus is not unique to AH/Type 2 neurons. BODIPY forskolin was used to assess the co-distribution of AC in ganglion cells expressing the specific calcium-binding proteins (CaBPs), calretinin, calbindin-D28, and s-100. Cultured cells or tissues were incubated with 10 microM BODIPY forskolin for 30 min and fluorescent labeling was monitored by using laser scanning confocal microscopy. BODIPY forskolin stained the cell soma, neurites, and nerve varicosities of Dogiel Type I or II neurons. About 99% of myenteric and 27% of submucous ganglia contained labeled neurons. About 14% of myenteric and 3% of submucous glia with immunoreactivity for s-100 protein displayed BODIPY forskolin fluorescence. BODIPY forskolin differentially labeled myenteric neurons immunoreactive for calbindin-D28 (80%) and calretinin (17%). The majority (63%) of BODIPY forskolin-labeled myenteric neurons displayed no immunoreactivity for either CaBP. In submucous ganglia, the dye labeled 44.6% of calretinin-immunoreactive neurons, representing 21% of all labeled neurons; it also labeled varicose nerve fibers running along blood vessels. AC thus exists in myenteric Dogiel type II/AH neurons, enteric cholinergic S/Type 1 neurons, and other unidentified non-cholinergic S/Type 1 neurons. Our data also support the hypothesis that AC is expressed in distinct functional subpopulations of AH and S neurons in enteric ganglia, and show that BODIPY forskolin is a suitable marker for AC in immunofluorescence co-distribution studies involving living cells or tissues.

Neuronal subpopulations in autonomic ganglia associated with the chicken ureter: an immunohistochemical study

The neurochemical coding of neurones located in ganglia of the nerve trunk accompanying the chicken ureter was analysed and quantified using NADPH-diaphorase reactivity and immunohistochemistry against tyrosine hydroxylase (TH), nitric oxide synthase (NOS), calbindin (CAL), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), somatostatin (SOM), substance P (SP) and calcitonin gene-related peptide (CGRP) in untreated or colchicine-treated preparation. Almost all neurones were either positive for TH (38%) or for SOM (60%). Only 4% of the neurones were both TH- and SOM-positive and 3% of the neurones exhibited neither TH nor SOM immunoreactivity. The relative numbers of NPY-, NOS-, CAL- and VIP-positive neurones were 57%, 28%, 14% and 7%, respectively. No SP- or CGRP-positive neurones were observed. All NADPH-diaphorase-positive neurones expressed NOS immunoreactivity. Only in some TH-positive neurones was NPY and/or NOS found. Four major subpopulations were found in the ureteric ganglia. The SOM-positive neurones were subdivided into SOM/NPY/NOS- (28% of all neurones), SOM/NPY- (18%) and SOM/CAL/NPY-positive neurones (14%). A subpopulation of these peptid- ergic neurones also contained VIP. About 35% of the neurones contained TH only. Neurones of all subpopulations (72% of the neurones), except most of the CAL-positive neurones, were encircled by dense plexus of varicose SP/CGRP-positive, presumably sensory nerve fibres. Dense plexus of VIP-positive fibres were observed around 89% of the neurones. The chemical coding of the neuronal subpopulations identified in the ganglia accompanying the chicken ureter resembled that observed in the ganglia of Remak's nerve but was remarkably different from that of the autonomic neurones described in mammalian species.

Nitrergic innervation of the cat liver

The aim of this work was to study the nitrergic innervation in the liver of the cat using immunocytochemical procedures. At the hepatic hilus, a rich plexus of neuronal nitric oxide synthase immunoreactive (nNOS-IR) nerve fibers and ganglia was detected around the interlobular branch of the bile duct. nNOS-IR nerve fibers were observed running with the components of the intralobular portal triads located close to the hepatic hilus, as well as with a few vessels and ducts of the deeper parenchyma. These latter fibers, beside others located in Glisson's capsule, occasionally showed short ramifications entering the parenchyma itself. The present results suggest that, in the cat liver, nNOS is involved in the autonomic control of hepatic blood flow, with a limited role in the regulation of hepatobiliary excretory activity and hepatocellular metabolic function.

Selective disruption of neurotransmission by acetylcholinesterase antibodies in sympathetic ganglia examined with intracellular microelectrodes

Antibodies to acetylcholinesterase (AChE) induce adrenergic dysfunction in rats by selective, complement-mediated destruction of preganglionic sympathetic nerve terminals. To analyze this phenomenon at the neuronal level, monoclonal antibodies to AChE (1.6 mg) were injected via the tail vein, and superior cervical ganglia (SCG) or inferior mesenteric ganglia (IMG) were studied in vitro. In control SCG, all impaled neurons generated action potentials during direct injection of depolarizing current or indirect stimulation through the preganglionic nerve. Current injection remained effective in ganglia from treated rats, but preganglionic stimulation was greatly impaired: at 12 h and 3 d, less than 10% of the neurons responded, even to a maximal stimulus (150 V); at 9 d, only 25% responded. By contrast, in IMG, synaptic transmission was much less affected by antibody exposure: 60% or more of examined neurons responded to preganglionic stimulation. Differences in antibody access did not explain differing sensitivities of SCG and IMG since immunohistochemistry showed rapid accumulation of IgG deposits in both ganglia. These results are believed to reflect widespread but subtotal preganglionic sympathectomy by AChE antibodies. Current information indicates that paravertebral ganglia are all antibody-sensitive, but some prevertebral ganglia are resistant, suggesting immunochemical differences between them.

Nitric oxide synthase, choline acetyltransferase, catecholamine enzymes and neuropeptides and their colocalization in the anterior pelvic ganglion, the inferior mesenteric ganglion and the hypogastric nerve of the male guinea pig

By the indirect immunofluorescence method, the distribution of nitric oxide synthase (NOS)-like immunoreactivity (LI) and its possible colocalization with neuropeptide immunoreactivities, with two enzymes for the catecholamine synthesis pathway, tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH), as well as the enzyme for the acetylcholine synthesis pathway, choline acetyltransferase (ChAT) were studied in the anterior pelvic ganglion (APG), the inferior mesenteric ganglion (IMG) and the hypogastric nerve in the male guinea pig. The analyses were performed on tissues from intact animals, as well as after compression/ligation or cut of the hypogastric nerve. In some cases the colonic nerves were also cut. Analysis of the APG showed two main neuronal cell populations, one group containing NOS localized in the caudal part of the APG and one TH-positive group lacking NOS in its cranial part. The majority of the NOS-positive neurons contained ChAT-LI. Some NOS-positive cells did not contain detectable ChAT, but all ChAT-positive cells contained NOS. NOS neurons often contained peptides, including vasoactive intestinal peptide (VIP), neuropeptide tyrosine (NPY), somatostatin (SOM) and/or calcitonin gene-related peptide (CGRP). Some NOS cells expressed DBH, but never TH. The second cell group, characterized by absence of NOS, contained TH, mostly DBH and NPY and occasionally SOM and CGRP. Some TH-positive neurons lacked DBH. In the IMG, the NOS-LI was principally in nerve fibers, which were of two types, one consisting of strongly immunoreactive, coarse, varicose fibers with a patchy distribution, the other one forming fine, varicose, weakly immunoreactive fibers with a more general distribution. In the coarse networks, NOS-LI coexisted with VIP- and DYN-LI and the fibers surrounded mainly the SOM-containing noradrenergic principal ganglion cells. A network of ChAT-positive, often NOS-containing nerve fibers, surrounded the principal neurons. Occasional neuronal cell bodies in the IMG contained both NOS- and ChAT-LI. Accumulation of NOS was observed, both caudal and cranial, to a crush of the hypogastric nerve. VIP accumulated mainly on the caudal side and often coexisted with NOS. NPY accumulated on both sides of the crush, but mainly on the cranial side, and ENK was exclusively on the cranial side. Neither peptide coexisted with NOS. Both substance P (SP) and CGRP showed the strongest accumulation on the cranial side, possibly partly colocalized with NOS. It is concluded that the APG in the male guinea-pig consists of two major complementary neuron populations, the cholinergic neurons always containing NOS and the noradrenergic neurons containing TH and DBH. Some NOS neurons lacked ChAT and could represent truly non-adrenergic, non-cholinergic neurons. In addition, there may be a small dopaminergic neuron population, that is containing TH but lacking DBH. The cholinergic NOS neurons contain varying combinations of peptides. The noradrenergic population often contained NPY and occasionally SOM and CGRP. It is suggested that NO may interact with a number of other messenger molecules to play a role both within the APG and IMG and also in the projection areas of the APG.

Androgens modulate nitric oxide synthase messenger ribonucleic acid expression in neurons of the major pelvic ganglion in the rat

Expression and androgen regulation of the gene for neuronal nitric oxide synthase (NOS I) were examined in neurons of the major pelvic ganglia in male rats. Some of these postganglionic neurons innervate the penis and produce nitric oxide, which is believed to play a major role in penile erection. Rats were either castrated or sham operated and implanted with SILASTIC brand capsules filled with powdered testosterone (T) or 5alpha-dihydrotestosterone (5alphaDHT) or left empty. After 4 days, the number of neurons intensely stained for NADPH-diaphorase as well as those giving a NOS I signal in in situ hybridization experiments increased in castrated rats treated with testosterone by 31% and 42%, respectively, relative to those in untreated castrated rats. This suggests that the increase in NADPH-diaphorase activity resulted from enzyme synthesis and was due to a modification of NOS I messenger RNA (mRNA) accumulation. After 7 days, Northern blot analysis showed that castration produced a decrease in the amount of NOS I mRNA relative to that of ribosomal RNA. This decrease was almost prevented by T treatment. No significant differences were observed by reverse transcriptase-PCR between 7-day and 28-day treatments. However, in 7-day castrated rats treated with 5alphaDHT, NOS I signals relative to those of hypoxanthine phosphoribosyltransferase, taken as reference, were significantly higher than those in castrated rats and resembled those in sham-castrated rats, suggesting that 5alphaDHT was probably more potent than testosterone in preventing the decrease in NOS I mRNA levels elicited by castration. These results show that NOS I can be positively regulated by androgens and are consistent with the suggestion that these steroids play a role in the physiological processes of penile erection.

Cloning of a new chicken trkC extracellular isoform and its mRNA expression in E9 sensory and autonomic ganglia

Neuronal development and maintenance are regulated by trophic interactions with the target tissues and the innervating nerve. The neurotrophin family of polypeptide growth factors, consisting of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and neurotrophin-4/5 (NT-4/5), are produced in limited amounts in target areas. They bind to tyrosine receptor kinases of the trk family, including trkA, trkB and trkC, which mediate intracellular signalling in the responding neurons. There are reports of different isoforms of trkA, trkB and trkC having different signalling capacities. This study reports a novel deletion of the first cysteine-rich domain in the extracellular part of chicken trkC. We describe the mRNA expression of this isoform compared to non-deleted forms in E9 peripheral ganglia studied by reversetranscriptase-polymerase chain reaction (RT-PCR) and in situ hybridization. We also compare the mRNA expression pattern of two existing signal peptide sequences and the distribution of trkC mRNA detected by the use of a kinase specific probe. The results show that the novel isoform is expressed in peripheral sensory and autonomic ganglia. Moreover both signal peptide forms are detected in these ganglia by RT-PCR. In addition, in situ hybridization results showed a weak mRNA expression of the novel isoform in the E9 dorsal root ganglion (DRG) but not in Remak's ganglion. The two existing signal peptides are equally expressed in the DRG and Remak's ganglion, at labelling densities comparable to those for the full-length catalytic form of trkC.

Neurons in the chicken ureter are innervated by substance P- and calcitonin gene-related peptide-containing nerve fibres: immunohistochemical and electrophysiological evidence

Numerous ganglia or single neurones immunoreactive to protein gene-product 9.5 (PGP) were demonstrated in the chicken ureter. Ganglia were observed in the main nerve trunks accompanying the ureter (400-2,000 cells), in the adventitia (1-45 cells; density; 79 +/- 12 ganglia/cm2; mean +/- S.E.M.), in the circular muscle (1-9 cells; 76 +/- 10 ganglia/cm2) and in the longitudinal muscle (1-8 cells; 232 +/- 41 ganglia/cm2). Most of the PGP-positive neurones in the nerve trunk ganglia (approximately 66%) and in the smooth muscle layers (85%) were encircled by a dense plexus of varicose nerve fibres containing both substance P (SP) and calcitonin gene-related peptide (CGRP). SP-positive somata were rarely observed. Immunogold electron microscopy revealed that SP- and CGRP-immunoreactivity were colocalised in the same dense core vesicles. A strong reduction of SP-positive nerve fibres was observed in organ cultures of the ureter, indicating their extrinsic origin. The fibres might originate from the dorsal root ganglia, where SP and CGRP were colocalised in 20-30% of the neurones. The sensitivity of ureteric neurones to SP and CGRP was investigated in recordings obtained from mechanosensitive nerve fibres with cell bodies located in or adjacent to the ureter (U-G units). The majority (71%) of the U-G units was excited by local application of SP in a dose-dependent manner. The SP-sensitive U-G neurones had higher mechanical thresholds (29 +/- 5 mmHg) as opposed to the SP-insensitive ones (10 +/- 3 mmHg). Repeated applications of high doses of SP to the U-G units resulted in desensitisation and reduced the response to mechanical stimuli. None of the U-G units responded to local application of CGRP, but all U-G units were excited by acetylcholine. The data support the hypothesis that SP-containing primary afferents are involved in the modulation of the activity of ureteric neurons in the chicken.

Colocalization of acetylcholinesterase and vasoactive intestinal peptide (VIP) in nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) positive neurons in the intralingual ganglia and perivascular nerve fibers around lingual arteries in the porcine, monkey and canine tongue

Distribution of nitric oxide synthase in the intrinsic ganglia in the porcine, monkey and canine tongue was histologically investigated using the reduced nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) method, acetylcholinesterase histochemistry and vasoactive intestinal peptide (VIP) immunohistochemistry. The majority of intralingual ganglionic cells showed intense NADPH-d reactivity with positive acetylcholinesterase reaction or positive VIP immunohistochemistry. The NADPH-d positive, acetylcholinesterase-rich and the NADPH-d positive, VIP immunoreactive nerve fibers are particularly conspicuous around intralingual blood vessels. These fibers around the arteries in the tongue may be partly derived from the intralingual ganglion cells, because some bundles associated with these nerve cells were easily traced on the wall of blood vessels. The present study suggests the view that the three markers coexist in the axons and nerve terminals of these intralingual neurons.

Cathepsin D in intestinal ganglion cells. A potential aid to diagnosis in suspected Hirschsprung's disease

There is still a need for a better method of detecting immature ganglion cells in paraffin sections of colorectal luminal biopsies in cases suspected of Hirschsprung's disease. The lysosomal aspartic proteinase cathepsin D has been immunolocalized to various cell types, including ganglion cells. We investigated its expression in intestinal ganglion cells to determine whether it could be used as an aid in the detection of immature ganglion cells in rectal biopsies from children suspected of having Hirschsprung's disease. Routinely processed tissues of eight adult intestines resected for gunshot wounds and six ganglioneuromas (for mature ganglion cells), of six colons resected for neonatal necrotizing enterocolitis (for immature ganglion cells), and of 11 cases of suspected and three cases of known Hirschsprung's disease were immunostained with a polyclonal antibody to cathepsin D using the avidin-biotin-peroxidase method. In all cases, all ganglion cell bodies present showed intense granular cytoplasmic reactivity for cathepsin D. The granules crowded the cytoplasm and formed a collarette around the nucleus. In the submucosa, the only other immunoreactive cells were histiocytes, but they could be distinguished from ganglion cells by their characteristic nuclear features and their occurrence singly and unassociated with nerves. The three resection specimens with Hirschsprung's disease showed a clear transition between the ganglionic and the aganglionic segments. We conclude that cathepsin D is a promising marker of immature ganglion cells in cases suspected of Hirschsprung's disease.

Denervation-induced changes in perineuronal plexuses in the major pelvic ganglion of the rat: immunohistochemistry for vasoactive intestinal polypeptide and tyrosine hydroxylase and histochemistry for NADPH-diaphorase

To characterize further the injury response of autonomic ganglia, we have examined the effect of chronic denervation on perineuronal plexuses that are immunoreactive for vasoactive intestinal polypeptide (VIP) and tyrosine hydroxylase (TH) or that stain for nicotinamide adenine dinucleotide phosphate (NADPH) in the rat major pelvic ganglion, and their relationship to an identified sub-population of neurons in the ganglion (the penile neurons). Penile neurons contain VIP and NADPH diaphorase (NADPH-D) but lack TH. VIP-immunoreactive (VIP-IR) and TH-IR perineuronal plexuses (baskets) are rare in the rat major pelvic ganglion and those present are not associated with penile neurons. A small increase in VIP-IR baskets occurs 2 weeks after proximal interruption of the pelvic nerve, but TH-IR baskets increase five-fold. The emergent VIP-IR and TH-IR baskets enclose TH-negative neurons, none of which are penile ganglion cells. These changes remain up to 4 weeks after denervation. Interrupting the pelvic nerve nearer the margin of the major pelvic ganglion results in a rapid, more dramatic increase in VIP-IR, in cell bodies and beaded fibers, than that seen with the more proximal lesion. About 27% of neurons in the ventral pole of the ganglion are enveloped by NADPH-D perineuronal baskets. The incidence of NADPH-D baskets falls to less than 1% after acute interruption of the pelvic and hypogastric nerves, but their frequency returns to control levels in chronically denervated ganglia. The rapid, vigorous changes in peptide (VIP) fibers after the pelvic nerve is cut close to the major pelvic ganglion may be attributable to the interruption of axons of postganglionic neurons and to preganglionic nerve fibers, whereas the slowly developing changes in VIP-IR and TH-IR fibers after more proximal lesions may represent the more modest effects of true decentralization. The source and significance of the VIP-IR, TH-IR, and NADPH-D baskets that appear in chronically denervated ganglia remain unclear.

Expression of dopamine D2-receptor mRNA isoforms at the peripheral chemoreflex afferent pathway in developing rabbits

The two isoforms of dopamine D2 receptor, D2 short (D2s) and D2 long, are generated by alternative splicing of premessenger RNA and differ in the length of their third cytoplasmic loop. Expression of these two isoforms has not yet been studied at the level of the peripheral arterial chemoreflex pathway. Using reverse transcriptase-polymerase chain reaction, we evaluated the relative abundance of dopamine D2 receptor mRNA by amplifying a common segment between both D2 receptor mRNA isoforms which reflects the total D2-receptor mRNA and the two isoforms in the carotid bodies, the petrosal ganglia, and the superior cervical ganglia of 1-, 10-, and 25-day-old and adult rabbits, GH4C1 cell line, which does not express D2 receptors, was used as negative control, whereas GH4C1 19 cell line, which expresses only the D2s mRNA and the striatum of each age, were used as positive controls. Both D2-receptor mRNA isoforms were found to be expressed in all organs studied of newborn and adult rabbits. The expression of total D2 receptor mRNA in 10- and 25-day-old and adult rabbits was found to be 3-, 5-, and 1.5-fold more, respectively, compared with 1-day-old rabbits for all organs studied. Our data suggest that the expression of D2-receptor mRNA is modulated with age at the level of the peripheral arterial chemoreflex pathway.

Colocalisation of NADPH-diaphorase with neuropeptides in the ureterovesical ganglia of humans

Neurones in the ureterovesical ganglion complex provide autonomic innervation to the pelvic ureter, the ureterovesical junction and the bladder trigone. We examined the distribution and peptide co-expression pattern of nitric oxide synthase (NOS) in the human ureterovesical ganglia by combining NADPH-diaphorase histochemistry with immunoreactivity for vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), and calcitonin gene-related peptide (CGRP). Less than 20% of nerve cells in the large ganglia of the ureterovesical complex were stained for NOS activity. In elderly individuals, ganglion cells regularly exhibited conspicuous morphological alterations suggestive of degenerative changes. Most of the NOS-positive cell bodies costained for VIP-immunoreactivity. A minority of NOS-expressing cells also reacted for NPY-immunoreactivity. CGRP-immunoreactivity was present in varicose terminal-like nerve fibres which were found to encircle NOS-containing perikarya. Occasionally, NOS-positive somata were surrounded by plexiform axon terminals which immunostained for VIP or NPY. We conclude that the passage of urine across the ureterovesical junction is under relaxatory control of a local nitric oxide/VIP(NPY) pathway which may be modulated by preganglionic efferent and/or primary afferent input.

Endogenous opioid peptides in parasympathetic, sympathetic and sensory nerves in the guinea-pig heart

Research has suggested that exogenous opioid substances can have direct effects on cardiac muscle or influence neurotransmitter release via presynaptic modulation of neuronal inputs to the heart. In the present study, multiple-labelling immunohistochemistry was employed to determine the distribution of endogenous opioid peptides within the guinea-pig heart. Approximately 40% of cardiac ganglion cells contained immunoreactivity for dynorphin A (1-8), dynorphin A (1-17) and dynorphin B whilst 20% displayed leu-enkephalin immunoreactivity. Different populations of opioid-containing ganglion cells were identified according to the co-existence of opioid immunoreactivity with immunoreactivity for somatostatin and neuropeptide Y. Immunoreactivity for prodynorphin-derived peptides was observed in many sympathetic axons in the heart and was also observed, though to a lesser extent, in sensory axons. Leu-enkephalin immunoreactivity was observed in occasional sympathetic and sensory axons. No immunoreactivity was observed for met-enkephalin-arg-gly-leu or for beta-endorphin. These results demonstrate that prodynorphin-derived peptides are present in parasympathetic, sympathetic and sensory nerves within the heart, but suggest that only the prodynorphin gene is expressed in guinea-pig cardiac nerves. This study has shown that endogenous opioid peptides are well placed to regulate cardiac function via both autonomic and sensory pathways.

Met-enkephalin Arg-Phe-immunoreactive neurons in the central nervous system of the pond snail Lymnaea stagnalis

The distribution of an opioid peptide related to YGGFMRF was determined in the CNS and other organs of the pond snail, Lymnaea stagnalis, by RIA and immunocytochemistry. RIA revealed the highest levels in the CNS (1 pmol/organ) and penis (400 fmol/organ). There were also significant levels in the haemolymph, most of which was not associated with haemocytes (580 fmol/ml). Both serial section and whole-mount immunocytochemistry of the CNS revealed immunoreactive cells in every ganglion with the majority in the cerebral and pedal ganglia. In the pedal ganglia some of the immunoreactive cells were close to the cells of the A-cluster, which are known to respond to opioids, and could innervate them. In the cerebral ganglia the immunoreactive cells included a group of neurosecretory cells, the caudo dorsal cells (CDCs) and the terminals of these cells in the cerebral commissure were also stained. The CDCs secrete peptides into the haemolymph and so could be the source of the YGGFMRF immunoreactivity. Immunoreactivity (including the CDCs) was observed in locations that correspond to those reported for other fragments of proenkephalin, such as Met- and Leu-enkephalin, suggesting that they may share a common precursor, a Lymnaea proenkephalin. A map of the 358 YGGFMRF-immunoreactive cells in the CNS is presented, many of which have not been previously identified.

Chemical coding of neurons that project from different regions of intestine to the coeliac ganglion of the guinea pig

The chemical codings of neurons that project from the small intestine, caecum, proximal colon, distal colon and rectum to the coeliac ganglion of the guinea pig were investigated. The coeliac ganglion was injected with the retrogradely transported dye Fast Blue, and each of the regions was examined 6 days later in wholemounts that had been prepared for immunohistochemical localisation of pairs of antigens. In both the small and large intestines, all intestinofugal neurons were immunoreactive (IR) for choline acetyltransferase (ChAT). In each region of the large intestine, the largest population, representing 50-60% of retrogradely labelled neurons in each region, was immunoreactive for ChAT, bombesin (BN), calbindin (Calb) and nitric oxide synthase (NOS). Most intestinofugal neurons in the small intestine contain bombesin and VIP-IR along with ChAT-IR but none contain either Calb or NOS. Thus, nerve endings of enteric origin in the coeliac ganglion that contain NOS-IR or Calb-IR come from the large intestine and those with bombesin-IR but not NOS-IR are from the small intestine. The gastric wall was injected with Fast Blue in order to label noradrenergic (NA) neurons in the coeliac ganglion and to determine, by localisation of NOS and bombesin-IR, whether they receive inputs from the small and large intestine. Some NA neurons received inputs from the large intestine (and perhaps also from the small intestine) and some received inputs exclusively from the small intestine. Most NA neurons that received intestinofugal inputs had the chemical code NA/-; some were immunoreactive for somatostatin (NA/SOM neurons), but those with IR for neuropeptide Y (NA/NPY) rarely received intestinofugal inputs.

Neuropeptide Y in submucosal ganglia: regional differences in the innervation of guinea-pig large intestine

Since information about possible regional differences in the innervation of the guinea-pig large intestine is incomplete, a comparative study was made of the occurrence of neurones and nerve fibres of the submucosa showing immunoreactivity (IR) to neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP). In addition, a quantitative analysis was made of submucosal neurones in regions of guinea-pig large intestine selected for probable differences in their function. There were two principal findings: First, the density of NPY-IR neurone somata was high in the ascending colon (mean +/- SEM 3148 +/- 464 neurones/cm2; n = 5 animals) and progressively declined in an anal direction, the descending colon having 348 +/- 125 neurones/cm2 (in the same 5 animals); immunoreactive cell bodies were rare in the rectum. The reduced density was also reflected in a fall in the number of NPY-IR neurones/ganglion from 3.0 +/- 0.3 in the ascending colon to 0.5 +/- 0.2 in the descending colon. Second, varicose NPY-IR intraganglionic fibres were a conspicuous feature of the duodenum, caecum, transverse colon, descending colon and rectum, but not of the ileum, ascending colon or distal spiral. Moreover, in the descending colon and rectum the fibres were arranged in a loose 'cobweb' structure around non-NPY-IR neurone somata; in the caecum, there was an apparent paucity of NPY-IR somata but the exceptionally dense intraganglionic varicose fibre network may have obscured NPY-IR somata. In all regions, fibre baskets were rare. In the ascending colon, only 25 +/- 5% of ganglia (compared to 92 +/- 2% of ganglia in the descending colon) showed any intraganglionic nerve fibres; furthermore, when they occurred, these were not of the 'cobweb' type but, rather, they gave the ganglia a speckled appearance. In very immature fetuses at a stage of development when no neuropeptide somata could be found in either the myenteric or submucosal plexuses, many NPY-IR nerve fibres were present in the submucosa with a distribution similar to that of adult guinea pigs. With respect to the density of VIP-IR neurones in the large intestine, there was only a 40% reduction in the number of neurones/cm2 from proximal to distal colon, in contrast to the corresponding 90% reduction in the density of NPY-IR neurones. The number of VIP-IR neurones/ganglion (6.4) and the proportion of ganglia with VIP-IR fibres (> 90%) were constant. It is concluded that the striking regional dissimilarities in (i) the occurrence of NPY-IR neurone somata and (ii) in the disposition of intraganglionic NPY-IR nerve fibres indicate potentially important regional differences in the functions of neuropeptide Y as an antisecretory peptide in the local regulation of chloride transport in the mucosa and as a modulator of ganglionic transmission, respectively.

Distribution of pituitary adenylyl cyclase activating peptide (PACAP) immunoreactivity in neurons of the guinea-pig digestive tract and their projections in the ileum and colon

Pituitary adenylyl cyclase activating peptide (PACAP) is a novel hypothalamic peptide that is widely distributed in neurons, including those of the gastrointestinal tract. In this study, a polyclonal antiserum directed against PACAP-27 was used to investigate the localisation of PACAP throughout the gut and to determine the projections of PACAP-immunoreactive (IR) neurons in the guinea-pig small and large intestines. PACAP-IR fibres were seen in the myenteric and submucous plexuses, in the longitudinal and circular muscle layers and around blood vessels of the submucosa throughout the gut. In both the small and large intestine, PACAP-IR cell bodies, most with Dogiel type-I morphology, were seen in the myenteric ganglia following colchicine treatment. Lesion studies (myotomy and myectomy operations) revealed that PACAP-IR interneurons projected anally in the ileum and colon. Myectomy operations resulted in a loss of PACAP-IR fibres in the circular muscle under the operation, whereas PACAP-IR fibres remained in the submucosa and around blood vessels. Following extrinsic denervation of the ileum, the number of PACAP-IR fibres in the submucosal ganglia and around blood vessels decreased. This suggests that a portion of PACAP-IR fibres supplying the submucosal ganglia and blood vessels have an extrinsic source. To investigate this, immunohistochemical studies were performed on sympathetic and dorsal root ganglia. Numerous reactive cells were seen in the dorsal root ganglia, but none was seen in sympathetic pre- or paravertebral ganglia.

Selective association of nerve fibres immunoreactive for substance P or bombesin with putative cholinergic neurons of the male rat major pelvic ganglion

The male rat major pelvic ganglion contains both sympathetic and parasympathetic neurons that supply the lower urinary and digestive tracts, and the reproductive organs. The aim of this study was to describe the distribution and identify potential targets of sensory and intestinofugal axons in this ganglion. Two putative markers of these projections were chosen, substance P for primary sensory axons and bombesin for myenteric intestinofugal projections. Varicose substance P-immunoreactive axons were associated only with non-noradrenergic (putative cholinergic) somata, and most commonly with those that contained vasoactive intestinal peptide. Immunoreactivity for substance P was also present in a small group of non-noradrenergic somata, many of which were immunoreactive for enkephalins, neuropeptide Y or vasoactive intestinal peptide. Bombesin immunoreactivity was found only in preterminal and terminal (varicose) axons, the latter of which were exclusively associated with non-noradrenergic somata that contain neuropeptide Y-immunoreactivity. Some varicose axons containing either substance P- or bombesin-immunoreactivity were intermingled with clumps of small, intensely fluorescent cells. These studies indicate that substance P- and bombesin-immunoreactive axons are likely to connect with numerically small, but discrete, populations of pelvic neurons.

Co-localization of nitric oxide synthase and vasoactive intestinal peptide immunoreactivity in neurons of the major pelvic ganglion projecting to the rat rectum and penis

Nitric oxide synthase (NOS)- and vasoactive intestinal peptide (VIP)-immunoreactive neurons projecting to the upper rectum or penis were examined using retrograde tracing combined with immunohistochemistry in the major pelvic ganglion of male rats. Five days after injection of Fluoro-Gold (FG) into the upper rectum or penis, the major pelvic ganglion was treated with colchicine. FG injected into the upper rectum labelled many ganglion neurons in the major pelvic ganglion. Immunohistochemistry showed that 37% of FG-labelled neurons were immunoreactive for NOS and 33% for VIP. After injection of FG into the penis, 41% of FG-labelled neurons were immunoreactive for NOS and 25% for VIP. Serial cryostat sections stained for NOS and VIP, respectively, showed the co-localization of NOS and VIP in the ganglion cells projecting to the rectum and penis. In the major pelvic ganglion of the colchicine-treated animals, about 17% of the ganglion cells were immunoreactive for NOS and 32% were immunoreactive for VIP. These neurons were small in diameter (less than 30 microns). A histogram showing cell sizes in cross-sectional areas of NOS-immunoreactive neurons coincided with that of VIP-immunoreactive neurons. Most of the NOS- and VIP-immunoreactive neurons were less than 600 microns. These results indicate that small neurons containing both NOS and VIP in the major pelvic ganglion project to the rectum and penis. In the penile erectile tissues and enteric ganglia, NO and VIP may be released from the same axons and may act concomitantly on the target tissue.

Evidence for coexistence of ATP and nitric oxide in non-adrenergic, non-cholinergic (NANC) inhibitory neurones in the rat ileum, colon and anococcygeus muscle

The possible coexistence of the two non-adrenergic, non-cholinergic (NANC) inhibitory neurotransmitters, adenosine 5'-triphosphate and nitric oxide in the myenteric plexus was investigated using whole-mount preparations of rat ileum, proximal colon and anococcygeus muscle. The presence of adenosine 5'-triphosphate in neurones was examined using the quinacrine fluorescence technique. After localizing and taking photographs of quinacrine-fluorescent neurones and nerve fibres, the same tissues were then fixed and processed for NADPH-diaphorase activity, a marker for nitric oxide-containing neurones. We have demonstrated for the first time that almost all quinacrine-fluorescent myenteric neurones in the proximal colon are also NADPH-diaphorase reactive, while only a subpopulation of quinacrine-fluorescent neurones in ileum and anococcygeus muscle were also NADPH-diaphorase reactive.

Immunohistochemical and morphometrical development of the dorsal root ganglion as a neural crest derivative: comparison with the fetal CNS

The developmental difference between the dorsal root ganglion (DRG), paravertebral ganglion (PVG) and the central nervous system (CNS) in embryos and fetuses was investigated using immunohistochemical (neuron-specific enolase (NSE) and human natural killer-1 (HNK-1)) and morphometrical methods. NSE positive cells developed from 7 weeks of gestation in the DRG as early as the anterior horn cells of the spinal cord, while the pyramidal cells of the cerebral cortex matured after 20 weeks of gestation. HNK-1 positive granules were present until 14 weeks gestation in the spinal cord and until 26-27 weeks in the DRG and PVG. This early development of DRG cells may be closely related to the peripheral organ maturation during the embryonic or early fetal period.