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Biomedical subjects

J B Furness

Publications and source records attributed to J B Furness.

At least 127 records · Page 7Linked to original sources
PubMed1994

Locations and chemistries of sympathetic nerve cells that project to the gastrointestinal tract and spleen.

Retrograde tracing was used to determine the locations of sympathetic nerve cells whose axons project to the stomach, small intestine, caecum, proximal colon, distal colon and spleen of the guinea-pig. Projections from prevertebral ganglia were organotopically arranged within and between ganglia. The cranially located coeliac ganglion provided the major input to proximal gut regions; the distal gut received more caudal input, from superior and inferior mesenteric and the hypogastric nerve ganglia. Nevertheless, minor proportions of the innervation of some target organs arose from other than the closest ganglion and the caecum had input from each of the coeliac, superior mesenteric and inferior mesenteric ganglia. Topography within a ganglion was best defined in the coeliac, in which nerve cells whose axons projected to the spleen, stomach and duodenum were preferentially laterally located, whereas most of those projecting to the proximal colon were medial. Fewer neurons projected from paravertebral--compared with prevertebral--ganglia to abdominal viscera. Projections to the stomach came from all thoracic chain ganglia, those to the duodenum and spleen from lower thoracic ganglia and those to the large intestine from lumbar chain ganglia. It is suggested that the previously reported chemical topography of nerve cells in sympathetic ganglia might be secondary to their organotopic organization.

Animals↗
PubMed1994

Locations of postganglionic nerve cells whose axons enter nerves originating from prevertebral ganglia.

Major nerve trunks that supply abdominal viscera contain axons of postganglionic neurons that originate in the coeliac ganglion, superior mesenteric ganglion, inferior mesenteric ganglia, hypogastric nerve ganglia and the sympathetic chain ganglia. Using the retrogradely transported neuronal marker Fast Blue, we mapped the distribution of labelled nerve cells after application of the dye to either the superior coeliac nerves, inferior coeliac nerves, superior mesenteric nerve, colonic nerves or hypogastric nerves. Distinctive patterns of nerve cell locations were associated with each nerve trunk. Within the coeliac ganglion, nerve cells that projected into the superior coeliac nerves were almost exclusively lateral, whilst neurons in the medial part of the coeliac ganglion and in the rostral pole of the superior mesenteric ganglion tended to project into the inferior coeliac nerves. Nerve cells located around the emerging superior mesenteric nerve in the superior mesenteric ganglion contributed the majority of axons to that nerve. Cells in both poles of the inferior mesenteric ganglia contributed the majority of postganglionic axons to the colonic nerves, but some cells in the caudal pole of the superior mesenteric ganglion also projected into the colonic nerves. Postganglionic axons in the hypogastric nerves originated from cells predominantly located in the caudal pole of the inferior mesenteric ganglion; however, cells in the rostral pole of the inferior mesenteric ganglia, the superior mesenteric, coeliac and hypogastric nerve ganglia also contributed some axons. Nerve cells of sympathetic chain ganglia projected into each of the nerve trunks; they were distributed rostro-caudally according to the nerve injected.

Animals↗
PubMed1994

Nitric oxide synthase in neurons of the gastrointestinal tract of an avian species, Coturnix coturnix.

The distribution of reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase staining and its colocalisation with nitric oxide synthase immunoreactivity was examined in neurons of the quail gastrointestinal tract. Immunoreactivity and enzyme activity were found in identical populations of neurons. Nitric oxide synthase activity was present in 30-40% of myenteric nerve cells in each region. Numerous reactive cells were also in the submucous plexus and many positive nerve fibres innervated the muscle. In the small intestine, some of the fibres innervating the circular muscle formed a deep muscular plexus and in the large intestine there was a submuscular plexus. Nerve fibres formed baskets around nerve cells of myenteric and submucous ganglia. Intramural arterioles were innervated, most prominently in the oesophagus and stomach. Very few fibres innervated the mucosa, except for some oesophageal glands and the core of villi in the cloaca. It is concluded that nitric oxide is probably involved in transmission to muscle of the avian intestine, as it is in mammals, and that it is probably also produced at neuroneuronal and neurovascular junctions.

Amino Acid Oxidoreductases↗
PubMed1993

The distribution of nitric oxide synthase-containing autonomic preganglionic terminals in the rat.

Nitric oxide synthase (NOS)-immunoreactivity was co-localised with NADPH diaphorase activity in preganglionic sympathetic neurons and in their terminals in pre- and paravertebral sympathetic ganglia. The density of NOS-containing terminals varied between ganglia. Reactive terminals were densest in the superior cervical, stellate and inferior mesenteric ganglia, where the majority of the neurons were surrounded by reactive fibres, and the coeliac and superior mesenteric ganglia, where about half the postganglionic somata were surrounded by reactive terminals. Fibres were least abundant in the pelvic ganglia and thoracic and lumbar sympathetic chain ganglia. NOS reactivity did not coincide with the distribution of calcitonin gene related peptide immunoreactivity, a marker for the terminals of NOS-containing sensory neurons in the rat. The distribution of nerve cells and terminals suggests that NOS is present in more than one functional subpopulation of sympathetic preganglionic neurons.

Amino Acid Oxidoreductases↗
PubMed1993

Structure of the tertiary component of the myenteric plexus in the guinea-pig small intestine.

The tertiary component of the myenteric plexus consists of interlacing fine nerve fibre bundles that run between its principal ganglia and connecting nerve strands. It was revealed by zinc iodide-osmium impregnation and substance P immunohistochemistry at the light-microscope level. The plexus was situated against the inner face of the longitudinal muscle and was present along the length of the small intestine at a density that did not vary markedly from proximal to distal. Nerve bundles did not appear to be present in the longitudinal muscle as judged by light microscopy, although numerous fibre bundles were encountered within the circular muscle layer. At the ultrastructural level, nerve fibre bundles of the tertiary plexus were found in grooves formed by the innermost layer of longitudinal smooth muscle cells. In the distal parts of the small intestine, some of these nerve fibre bundles occasionally penetrated the longitudinal muscle coat. Vesiculated profiles in nerve fibre bundles of the tertiary plexus contained variable proportions of small clear and large granular vesicles; they often approached to within 50-200 nm of the longitudinal smooth muscle cells. Fibroblast-like cells lay between strands of the tertiary plexus and the circular muscle but were never intercalated between nerve fibre varicosities and the longitudinal muscle. These anatomical relationships are consistent with the tertiary plexus being the major site of neurotransmission to the longitudinal muscle of the guinea-pig small intestine.

Animals↗
PubMed1993

Distribution of enteric nerve cells projecting to the superior and inferior mesenteric ganglia of the guinea-pig.

Retrograde tracing, using Fast Blue dye, was employed to determine the distribution of enteric nerve cells that project to the superior mesenteric and inferior mesenteric ganglia of the guinea-pig. Retrogradely labelled neurons were found in the myenteric but not submucous ganglia. When the superior mesenteric ganglion was injected, labelled neurons were found in low frequencies (less than 5 nerve cell bodies/cm2) in the duodenum, jejunum, ileum, caecum and proximal colon. The distal colon was analysed in five segments of equal length (1-5; oral to anal). Segment 1 had about 4 labelled nerve cells/cm2, whereas segments 2 to 5 displayed an average of about 25 nerve cells/cm2. The rectum contained about 36 labelled neurons/cm2. After injection of the inferior mesenteric ganglia with Fast Blue, no labelled neurons were found in the duodenum, jejunum, ileum or caecum. No labelled cells were observed in the gallbladder. A small number of labelled cells occurred in the proximal colon and in segment 1 of the distal colon. The frequency of labelled cells increased markedly in the more anal regions of the distal colon, and reached a peak in the rectum (138 cells/cm2). Both nerve lesions and immersion of the cut nerve in Fast Blue solution showed that the superior mesenteric nerve carries the axons of neurons located in the middle distal colon to the superior mesenteric ganglion. Almost half of the neurons in the rectum that project to the inferior mesenteric ganglia do so via the hypogastric nerves.(ABSTRACT TRUNCATED AT 250 WORDS)

Amidines↗
PubMed1993

Total numbers of neurons in myenteric ganglia of the guinea-pig small intestine.

Two techniques that are thought to stain all of the neurons in the myenteric ganglia of the intestine are NADH diaphorase histochemistry and immunohistochemistry using a "nerve cell body" antiserum. However, this assumption has never been directly verified. In the present study myenteric ganglia of the guinea-pig ileum were prepared as whole-mounts and stained with either of these techniques. All nerve cells that could be identified in the whole-mounts were counted. The whole-mounts were then embedded flat in resin and serially sectioned at 1 micron. Nerve cells were identified and counted from the serial sections, and the data compared to those obtained from the whole-mounts. NADH diaphorase histochemistry did not reveal all the neurons at incubation times that gave selective staining. In contrast, "nerve cell body" antiserum stained the entire neuronal population. To determine the total number of nerve cell bodies/ganglion and the proportion of nerve cell bodies with calbindin immunoreactivity, whole-mounts that had been processed for calbindin immunohistochemistry were serially sectioned and reconstructed. The total number of neurons per myenteric ganglion was 105 +/- 10 (SE). Calbindin-immunoreactive neurons comprised about 20% of the myenteric neurons, which is considerably less than previous estimates, because previously the total population has been underestimated. The spatial density of myenteric neurons in the undistended ileum of the guinea-pig is 17,300 nerve cells/cm2.

Animals↗
PubMed1993

Origins of synaptic inputs to calretinin immunoreactive neurons in the guinea-pig small intestine.

Calretinin immunoreactivity is almost completely confined to two classes of neuron in the myenteric plexus of the guinea-pig small intestine, longitudinal muscle motor neurons and ascending interneurons. Nerve cell bodies of the two classes can be readily identified by their sizes and positions in ganglia. The motor neurons, which are small Dogiel type I neurons, are about 20% and the interneurons, which are medium-sized Dogiel type I neurons, are about 5% of myenteric neurons. In the present work, we have also discovered a minor population (0.1%) of small filamentous neurons. In unoperated regions of intestine, at the light microscopic level, numerous calretinin immunoreactive nerve fibres were found in the tertiary plexus that innervates the longitudinal muscle and a medium density of varicose fibres formed pericellular endings in the myenteric ganglia. After double myotomy operations, in areas of plexus 0.5 to 1.5 mm wide which were isolated from ascending and descending inputs, calretinin-immunoreactive fibres of the tertiary plexus were unchanged, but the pericellular endings in the ganglia disappeared. Both the ascending interneurons and the longitudinal muscle motor neurons received ultrastructurally identified synapses and close axonal contacts that were calretinin-immunoreactive. These were counted in semi-serial sections from normal intestine and from regions between myotomy operations. In unoperated intestine, the proportions of calretinin-immunoreactive synapses on small, calretinin-immunoreactive, Dogiel type I nerve cells and small filamentous nerve cells were 30% and 0.1% respectively and on medium-sized Dogiel type I cells the proportion was 28%. Electron microscopy revealed an almost complete loss of immunoreactive inputs to the small Dogiel type I cells between double myotomies, but the number of unreactive inputs was the same as in normal intestine. This work demonstrates that the ascending calretinin-immunoreactive interneurons connect with one another to form ascending chains in the myenteric plexus and that they also provide about 1/3 of the inputs received by calretinin-immunoreactive longitudinal muscle motor neurons. Many of the remaining inputs to these motor neurons are local; we have deduced that these are mainly from primary sensory neurons.

Animals↗
PubMed1993

Projections of nitric oxide synthesizing neurons in the guinea-pig colon.

The neuronal form of the enzyme nitric oxide synthase, which is an obligatory constituent of neurons that utilise nitric oxide as a transmitter, was revealed histochemically in this study by its ability to transfer a proton from reduced nicotinamide adenine dinucleotide phosphate to nitro-blue tetrazolium. In the guinea-pig colon, nitric oxide synthase was located in numerous irregularly-shaped myenteric neurons with single axons. In the submucosa, a small number of neurons had strong enzyme activity, whereas many were weakly stained. Nerve fibres were found in the longitudinal muscle, circular muscle, muscularis mucosae and ganglia of the two plexuses. No nerve fibres were found in the lamina propria of the mucosa. The same distribution of nerve cells and fibres was revealed using immunohistochemistry for nitric oxide synthase. Lesion studies showed that the axons of myenteric neurons all projected anally. Myenteric cells were the source of nerve fibres in the circular muscle and in more anally located myenteric ganglia. The sparse innervation of submucous ganglia was intrinsic to the submucous plexus. It is suggested that nitric oxide synthase is one of the transmitters of inhibitory neurons to the muscle and is also utilized by descending interneurons of the myenteric plexus.

Amino Acid Oxidoreductases↗
PubMed1993

Projections of nerve cells from the duodenum to the sphincter of Oddi and gallbladder of the Australian possum.

BACKGROUND: This study investigated the existence of direct neural connections between the duodenum and the biliary tract in the Australian possum. METHODS: Retrogradely transported neuronal dyes, Fast Blue and Dil, were injected into the wall of the gallbladder and the sphincter of Oddi. The duodenum, biliary tract, and sympathetic and sensory ganglia were examined for the presence of labeled cell bodies. RESULTS: Two to 3 weeks after gallbladder injection, labeled nerve cell bodies were found in the myenteric plexus of the proximal duodenum but were rare in the duodenum distal to the sphincter of Oddi. No neurons were found in the submucous plexus. Labeled nerve cells were also found in the sphincter of Oddi. After injection of the sphincter, labeled neurons were in both the submucous and myenteric plexuses of the duodenum, on either side. Approximately one third of labeled myenteric neurons were immunoreactive for enkephalin. Labeled cell bodies were also in the coeliaco-mesenteric, nodose, and dorsal root ganglia after both gallbladder and sphincter injection. After a myotomy on the proximal duodenum, no neurons were labeled on the pyloric side of the lesion by subsequent sphincter injection of dye. CONCLUSIONS: Direct neural pathways connect the duodenum with the gallbladder and the sphincter of Oddi, and the sphincter with the gallbladder; this implies that enteric nerve circuits participate in coordinating duodenal and biliary functions.

Animals↗
PubMed1993

Simultaneous intracellular recordings from enteric neurons reveal that myenteric AH neurons transmit via slow excitatory postsynaptic potentials.

Simultaneous intracellular electrical recordings were made from pairs of neurons separated circumferentially by 100-200 microns of the myenteric plexus of the guinea-pig ileum in vitro. The recording electrodes were filled with the dye neurobiotin which was injected into impaled nerve cells, and later revealed histochemically. Intracellular current pulses were used to evoke action potentials via the recording electrode in one type of myenteric neuron, in most cases an AH neuron, while a second electrode was used to record from a simultaneously impaled S neuron or AH neuron. AH neurons are thought to be primary sensory neurons, whereas S neurons are interneurons and motor neurons. Ninety pairs of neurons were adequately tested for interaction. From these, 17 S neurons and three AH neurons that responded to AH neuron stimulation were detected. In each case, the response was a slow depolarization that was seen only in response to a train of stimuli at 10 Hz. The slow depolarizations were enhanced by passing depolarizing current and diminished by hyperpolarization. Responses were also diminished by lowering external Ca.2+ and elevating Mg2+. In all cases in which intracellular recording indicated communication between neurons, morphological evidence of connection was seen. In no case was there communication without connection, but in four instances, morphological connections appeared to exist, although no physiological evidence of communication was obtained.

Action Potentials↗
PubMed1993

Nitric oxide targets in the guinea-pig intestine identified by induction of cyclic GMP immunoreactivity.

The immunohistochemical localization of cyclic GMP was used to determine potential physiological sites of action of nitric oxide in the guinea-pig small intestine and colon. In control tissue, cyclic GMP-immunoreactivity was observed only in macrophages, whose identity was confirmed by double-label experiments using either F4/80, a macrophage-specific antibody, or fluorescein isothiocyanate-labelled dextran injected intravenously. Following exposure to the nitric oxide donor, sodium nitroprusside, cyclic GMP-immunoreactivity was induced in subpopulations of neurons in the myenteric and submucosal plexuses of the ileum and colon. In the colon, cyclic GMP-immunoreactivity was induced in 5-10% of myenteric neurons. The cyclic GMP-immunoreactive neurons did not contain nitric oxide synthase. In the ileum, cyclic GMP-immunoreactive neurons comprised about 2% of myenteric neurons and 40% of submucosal neurons; these cyclic GMP-immunoreactive neurons were also immunoreactive for vasoactive intestinal peptide, but they did not contain nitric oxide synthase. Interstitial cells between the mesothelium and the longitudinal muscle layer, vascular smooth muscle and vascular pericytes also showed sodium nitroprusside-induced cyclic GMP-immunoreactivity. The interstitial cells of Cajal at the inner surface of the circular muscle layer and the smooth muscle cells of the circular and longitudinal muscle layers showed increases in cyclic GMP-immunoreactivity that varied in extent from animal to animal. The results suggest that nitric oxide could act at several sites in the intestine through the stimulation of guanylyl cyclase.

1-Methyl-3-isobutylxanthine↗
PubMed1993

Structure and innervation of the extrahepatic biliary system in the Australian possum, Trichosurus vulpecula.

The morphology, microanatomy and innervation of the biliary tree of the Australian possum, Trichosurus vulpecula, was examined. The gross morphology of the gallbladder, hepatic and cystic ducts, and the course of the common bile duct, conforms to those of other species. The sphincter of Oddi has an extraduodenal segment that extends 15mm from the duodenal wall; within this segment the pancreatic and common bile ducts are ensheathed together by sphincter muscle. Their lumens unite to form a common channel within the terminal intraduodenal segment. Nerve cell bodies of the gallbladder were found in an inter-connecting network of ganglia that were located in the serosa, muscularis and mucosa. Nerve fibres innervated the muscle, arterioles and the mucosa. Few ganglia were found along the supra sphincteric portion of the common bile duct. Nerve trunks followed the duct and a dense nerve fibre plexus was found in the mucosa. In the sphincter most ganglia were located in two plexuses, the first between the layers of the external sphincter muscle, which was continuous with the external muscle of the duodenum, and the second was associated with the internal sphincter muscle. Nerve fibres were numerous in the sphincter muscle, and were also found in the subepithelial and periglandular plexuses of both the pancreatic and common bile ducts.

Animals↗
PubMed1993

Nitric oxide synthase in the enteric nervous system of the rainbow trout, Salmo gairdneri.

The distribution of nitric oxide synthase (NOS) was determined in the gastrointestinal tract of the rainbow trout, Salmo gairdneri. NOS immunoreactivity and the NADPH diaphorase histochemical reaction were co-localized in nerve cells in the myenteric ganglia. However, only about 60% of NADPH diaphorase-stained nerve cells in the vagus nerve trunks were immunoreactive for NOS. Reactive myenteric nerve cells were found throughout the gastrointestinal tract, comprising about 10-15% of all nerve cells. Reactive nerve cells and fibres appeared in the myenteric ganglia and nerve trunks. The circular muscle was innervated by reactive nerve fibres throughout the gastrointestinal tract. Some NOS-containing cell bodies were also in this layer. The submucous plexus contained reactive nerve fibres in each region of the gut; in the large intestine a few reactive nerve cell bodies were also seen in this plexus. The muscle in the mucosal folds of the large intestine was densely innervated. The observations suggest that nitric oxide is an enteric transmitter in teleost fish, as it is in mammals.

Amino Acid Oxidoreductases↗
PubMed1992

Projections and chemical coding of neurons with immunoreactivity for nitric oxide synthase in the guinea-pig small intestine.

The distribution of nitric oxide synthase (NOS) immunoreactivity was investigated in the guinea-pig small intestine. There were many immunoreactive nerve cell bodies in the myenteric plexus but very few in submucous ganglia. NOS immunoreactivity was not found in non-neuronal cells except for rare mucosal endocrine cells. Abundant immunoreactive nerve fibres in both myenteric and submucous ganglia, and in the circular muscle, arose from myenteric nerve cells whose axons projected anally along the intestine. NOS immunoreactivity coexisted with VIP-immunoreactivity, but not with substance P immunoreactivity. We conclude that nitric oxide synthase is located in a sub-population of enteric neurons, amongst which are inhibitory motor neurons that supply the circular muscle layer.

Amino Acid Oxidoreductases↗
PubMed1992

Calcitonin gene-related peptide neurons innervating the canine digestive system.

The pattern of nerve cells and fibers containing calcitonin gene-related peptide immunoreactivity (CGRP-IR) was investigated in the canine digestive tract by means of immunohistochemistry. CGRP-IR nerve fibers innervate all the layers of the gut, including the vasculature, with different densities depending on the region. CGRP-IR processes are sparse in the esophagus and stomach, where they are mostly confined to the enteric plexuses and vasculature. CGRP-IR fibers are quite abundant in the small and large intestine, where they form dense arborizations in the mucosa, and are numerous in the muscularis mucosae, deep muscular plexus and circular muscle. The myenteric and submucous plexuses of the intestine contain dense networks of CGRP-IR fibers and numerous CGRP-IR ganglion cells. On the other hand, in the enteric ganglia of the esophagus and stomach, in the intrapancreatic ganglia and in the ganglionated plexus of the gallbladder, CGRP-IR is restricted to non-varicose processes. A moderate density of CGRP-IR fibers supplies the endocrine and exocrine pancreas, and the fibromuscular layer and lamina propria of the gallbladder. The density of CGRP innervation in different regions can be summarized as follows: intestine >> pancreas and gallbladder > or = antrum > cardia > gastric corpus and distal esophagus. CGRP- and tachykinin (TK)-IRs are colocalized in a substantial population of fibers, particularly those distributed to the mucosa, muscularis mucosae and vasculature, whereas there was no evidence of colocalization in intrinsic ganglion cells. The present results suggest that (1) the CGRP innervation of the dog digestive system includes an intrinsic and an extrinsic component, and (2) CGRP- and TK-IRs are co-expressed in extrinsic nerve fibers. These findings extend previous observations in rats and guinea pigs and provide insights into the sites of action of CGRP in the digestive system of the dog, which has served as a model for CGRP functional studies.

Animals↗
PubMed1992

Co-localization of nitric oxide synthase immunoreactivity and NADPH diaphorase staining in neurons of the guinea-pig intestine.

Neuronal nitric oxide synthase (NOS), an enzyme capable of synthesizing nitric oxide, appears to be identical to neuronal NADPH diaphorase. The correlation was examined between NOS immunoreactivity and NADPH diaphorase staining in neurons of the ileum and colon of the guinea-pig. There was a one-to-one correlation between NOS immunoreactivity and NADPH diaphorase staining in all neurons examined; even the relative staining intensities obtained were similar with each technique. To determine whether pharmacological methods could be employed to demonstrate that NADPH diaphorase staining was due to the presence of NOS, tissue was pre-treated with NG-nitro-L-arginine, a NOS inhibitor, or L-arginine, a natural substrate of NOS. In these experiments on unfixed tissue, it was necessary to use dimethyl thiazolyl tetrazolium instead of nitroblue tetrazolium as the substrate for the NADPH diaphorase histochemical reaction. Neither treatment caused a significant decrease in the level of NADPH diaphorase staining, implying that arginine and NADPH interact at different sites on the enzyme.

Amino Acid Oxidoreductases↗