Biomedical subjects

W L Neuhuber

Publications and source records attributed to W L Neuhuber.

At least 55 records · Page 3Linked to original sources

PubMed1994

Vagal innervation of the rat pylorus: an anterograde tracing study using carbocyanine dyes and laser scanning confocal microscopy.

In an attempt to identify the distribution and structure of vagal fibers and terminals in the gastroduodenal junction, vagal efferents were labeled in vivo by multiple injections of the fluorescent carbocyanine dye DiA into the dorsal motor nucleus (dmnX), and vagal afferents were anterogradely labeled by injections of DiI into the nodose ganglia of the same or separate rats. Thick frontal cryostat sections were analysed either with conventional or laser scanning confocal microscopy, using appropriate filter combinations and/or different wavelength laser excitation to distinguish the fluorescent tracers. Vagal efferent terminal-like structures were present in small ganglia within the circular sphincter muscle, which, in the absence of a well-developed, true myenteric plexus at this level, represent the myenteric ganglia. Furthermore, vagal efferent terminals were also present in submucosal ganglia, but were absent from mucosa, Brunner's glands and circular muscle fibers. Vagal afferent fibers and terminal-like structures were more abundant than efferents. The most prominent afferent terminals were profusely branching, large net-like aggregates of varicose fibers running within the connective tissue matrix predominantly parallel to the circular sphincter muscle bundles. Profusely arborizing, highly varicose endings were also present in large myenteric ganglia of the antrum and duodenum, in the modified intramuscular ganglia, and in submucosal ganglia. Additionally, afferent fibers and terminals were present throughout the mucosal lining of the gastroduodenal junction. The branching patterns of some vagal afferents suggested that individual axons produced multiple collaterals in different compartments. NADPH-diaphorase positive, possibly nitroxergic neurons were present in myenteric ganglia of the immediately adjacent antrum and duodenum, and fine varicose fibers entered the sphincter muscle from both sides, delineating the potential vagal inhibitory postganglionic innervation. These morphological results support the view of a rich and differentiated extrinsic neural control of this important gut region as suggested by functional studies.

Animals↗

PubMed1994

NADPH-diaphorase-positive nerve fibers associated with motor endplates in the rat esophagus: new evidence for co-innervation of striated muscle by enteric neurons.

NADPH-diaphorase histochemistry was combined with demonstration of acetylcholinesterase and immunocytochemistry for calcitonin gene-related peptide to study esophageal innervation in the rat. Most of the myenteric neurons stained positively for NADPH-diaphorase, as did numerous varicose nerve fibers in the myenteric plexus, among striated muscle fibers, around arterial blood vessels, and in the muscularis mucosae. A majority of motor endplates (as demonstrated by acetylcholinesterase histochemistry or calcitonin gene-related peptide immunocytochemistry) were associated with fine varicose NADPH-diaphorase-positive nerve fibers. Analysis of brainstem nuclei, sensory vagal, spinal, and sympathetic ganglia in normal and neonatally capsaicin-treated rats, and comparison with anterogradely labeled vagal branchiomotor, preganglionic and sensory fibers led to the conclusion that NADPH-diaphorase-positive fibers on motor endplates originate in esophageal myenteric neurons. No association of NADPH-diaphorase-positive nerve fibers with motor endplates was found in other organs containing striated muscle. These results suggest extensive, presumably nitrergic, co-innervation of esophageal striated muscle fibers by enteric neurons. Thus, control of peristalsis in the esophagus of the rat may be more complex than hitherto assumed.

Acetylcholinesterase↗

PubMed1994

Nitrergic innervation of the rat esophagus: focus on motor endplates.

Nitric oxide synthase immunocytochemistry and correlated NADPH-diaphorase histochemistry were utilized to investigate nitrergic innervation of the rat esophagus. Almost all neuronal cell bodies and fibers around blood vessels, and in submucosa and mucosa which were immunoreactive for NOS, also co-stained for NADPH-diaphorase. A combined demonstration of motor endplates with tetramethylrhodamine alpha-bungarotoxin or calcitonin gene-related peptide immunocytochemistry demonstrated a nitrergic co-innervation of striated muscle fibers in all portions of the esophagus. The proportion of endplates co-stained increased from 35% to 78% from the cervical to the abdominal portion of the esophagus. These data indicate a role for NO in neuromuscular transmission in striated muscle of the esophagus.

Amino Acid Oxidoreductases↗

PubMed1994

Visualization of human choroidal ganglion cells with the supravital fluorescent dye 4-(4-diethylaminostyryl)-N-methylpyridium iodide.

The distribution and morphology of ganglion cell bodies and nerve fibers in supravital human choroidea is studied by staining with the fluorescent dye 4-(4-diethylaminostyryl)-N-methylpyridium iodide (4-Di-2-ASP). We have used the choroids from human donor eyes donated for cornea transplantation. The isolated tissues were rinsed in ringer solution and processed within up to 24 h after death with 3 microM of 4-Di-2-ASP in Ringer for 5-60 min at different temperatures (4-37 degrees C). After incubation, choroid whole flat mounts were observed in a fluorescence microscope. A delicate network of nerve fibers could be distinguished as soon as 5 min after immersion in 4-Di-2-ASP. In addition, labelled ganglion cell perikarya could be seen after longer incubation periods. They occurred individually or grouped in small ganglia of up to 8 cells and were linked together by various processes, which could also be traced to blood vessels. The fluorescent dye 4-Di-2-ASP provides a quick and simple method to visualize the innervation of the human choroid, including local ganglion cells. This nontoxic fluorescent technique will permit further manipulation and electrophysiological investigation of choroidal innervation.

Adolescent↗

PubMed1994

[Specifics of innervation of the cranio-cervical transition].

Innervation at the craniocervical transition differs from other regions of the body in certain respects. In particular, thick-calibre neck muscle afferents project directly to the external cuneate nucleus and to the vestibular nuclear complex. This projection is most prominent in segments C2 and 3 and is sparse or absent in more caudal segments. Thus, proprioceptive neck muscle afferents gain direct access to vestibulospinal, vestibulooculomotor and other secondary or even higher-order vestibular neurons. There is extensive convergence of proprioceptive neck and labyrinthine afferents on these neurons, which plays an important role in the control of balance, posture and movements. It can be assumed that dysfunction of this cervicovestibular network results in a variety of clinical problems, in particular, so-called cervical balance disorders.

Afferent Pathways↗

PubMed1993

Tyrosine-hydroxylase-containing vagal afferent neurons in the rat nodose ganglion are independent from neuropeptide-Y-containing populations and project to esophagus and stomach.

Immunoreactivity to the rate limiting enzyme of catecholamine synthesis, tyrosine hydroxylase, has been described in the inferior sensory (= nodose) ganglion of the vagal nerve in the rat. The aim of the present study was to characterize further this neuronal population. The neurons do not represent displaced autonomic efferent neurons, since they do not receive synaptic input, as indicated by the absence of synaptophysin-immunoreactive terminals. In addition to the immunoreactivity to tyrosine hydroxylase, a tyrosine hydroxylase cRNA probe hybridizes with nodose ganglion neurons as demonstrated by in situ hybridization and Northern blotting. Many but not all of the tyrosine hydroxylase-immunoreactive neurons are also immunoreactive to the dopamine synthesizing enzyme, aromatic-L-amino-acid-decarboxylase, but lack the noradrenaline-synthesizing enzyme, dopamine-beta-hydroxylase, thus favoring synthesis of dopamine. Neuropeptide Y, which is often colocalized with catecholamines, is also present in a subset of nodose ganglion neurons, as indicated by immunohistochemistry, in situ hybridization and Northern blotting. However, double-labeling immunofluorescence has revealed that these two antigens are localized in different cell populations. Retrograde neuronal tracing utilizing fluorescent dyes (Fast blue, Fluoro-gold) combined with tyrosine hydroxylase immunohistochemistry has demonstrated that the esophagus and stomach are peripheral targets of tyrosine-hydroxylase-containing vagal viscero-afferent neurons.

Animals↗

PubMed1993

Rectospinal neurons: cell bodies, pathways, immunocytochemistry and ultrastructure.

A novel class of enteric neurons projecting directly from the rectal wall to the spinal cord, "rectospinal neurons", was investigated in rats by combined retrograde neuronal tracing, immunocytochemistry and electron microscopy. Rectospinal neurons were almost confined to myenteric ganglia of the distal rectum below the pelvic diaphragm and were labeled preferentially by injections into spinal cord segments L6/S1. Injections into more rostral spinal cord segments resulted in hardly any labeled enteric neurons. Dorsal and ventral rhizotomy experiments indicated an almost exclusive projection of rectospinal neurons through dorsal roots L6/S1 to the respective spinal cord segments. Among various peptides immunostained, vasoactive intestinal polypeptide and calcitonin gene-related peptide were selectively found in rectospinal neurons, which were also shown to contain calbindin, neurofilament protein- and peripherin-immunoreactivity. Vasoactive intestinal polypeptide- and calbindin-immunostaining were frequently co-localized in the same perikarya, while calcitonin gene-related peptide-immunoreactive rectospinal neurons probably represented a separate population. Neonatal capsaicin treatment did not significantly reduce the number of rectospinal neurons. Electron microscopy revealed synaptic contacts on the surface of rectospinal neurons. Taken together, these results establish rectospinal neurons as an anatomically and neurochemically distinct class of enteric neurons. Synaptic contacts on rectospinal neurons suggest that these neurons may function as a direct link from the enteric to the central nervous system, thus indicating that connections between these two networks are reciprocal.

Afferent Pathways↗

PubMed1992

An anterograde tracing study of the vagal innervation of rat liver, portal vein and biliary system.

In order to investigate the distribution and structure of the vagal liver innervation, abdominal vagal afferents and efferents were selectively labeled by injecting WGA-HRP or Dil into the nodose ganglia, and DiA into the dorsal motor nucleus, respectively. Vagal afferent fibers produced characteristic terminal-like structures at three locations in the liver hilus: 1. Fine varicose endings preferentially surrounding, but not entering, the numerous peribiliary glands in the larger intra and extrahepatic bile ducts 2. Large, cup-shaped terminals in almost all paraganglia 3. Fine varicose endings in the portal vein adventitia. No fibers and terminals were found in the hepatic parenchyma. While about two thirds of the vagal afferent fibers that originate in the left nodose ganglion, and are contained in the hepatic branch, bypass the liver hilus area on their way to the gastroduodenal artery, a significant number (approx. 10% of the total) of vagal afferents that do innervate the area, originates from the right nodose ganglion, and projects to the periarterial plexus of the common hepatic artery and liver pedicle most likely through the dorsal celiac branch. Varicose vagal efferent fibers were present within the fascicles of the vagal hepatic branch and fine terminal-like structures in a small fraction of the paraganglia. No efferents were found to terminate in the hepatic parenchyma or on the few neurons embedded in nerves or paraganglia. In contrast to the paucity of vagal terminals in the hepatic parenchyma, an abundance of vagal efferent and afferent fibers and terminals with distinctive distribution patterns and structural characteristics was present in esophagus and gastrointestinal tract.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗

PubMed1992

A direct projection from the medial vestibular nucleus to the cervical spinal dorsal horn of the rat, as demonstrated by anterograde and retrograde tracing.

Phaseolus vulgaris leucoagglutinin and wheat germ agglutinin-horseradish peroxidase were iontophoretically injected into different parts of the vestibular nuclear complex (VNC) of the rat. Injections centered into the caudal part of the medial vestibular nucleus revealed a vestibulospinal projection predominantly to the dorsal horn of the cervical spinal cord, besides the expected projection to the intermediate zone (IZ) and ventral horn (VH). While most of the anterogradely labelled fibres could be localized in laminae III to V, some scattered fibres were also seen in laminae I and VI. Lamina II remained free of labelling. The dorsal horn (DH) area with detectable anterograde labelling showed a rostrocaudal extension from C1-C6. Injections into other parts of the VNC labelled fibres and terminals in the IZ and VH while the DH remained almost free of labelling. Additionally, fluorogold and wheat germ agglutinin-horseradish peroxidase were pressure- or iontophoretically injected at different levels into the spinal cord to confirm the projection to the dorsal horn by means of retrograde tracing. Labelled neurons in the area of the medial vestibular nucleus (MVN), from which anterograde labelling in the DH was obtained, were only detectable after fluorogold and wheat germ agglutinin-horseradish peroxidase injections into the cervical spinal cord, in particular its DH. This projection from the caudal medial vestibular nucleus to the dorsal horn of the cervical spinal cord probably enables the VNC to influence sensory processing in the DH, in addition to its well-established influence on posture and locomotion via projections to the intermediate zone and ventral horn.

Animals↗

PubMed1990

A cervical primary afferent input to vestibular nuclei as demonstrated by retrograde transport of wheat germ agglutinin-horseradish peroxidase in the rat.

Wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) was microiontophoretically injected into the vestibular nuclear complex of the rat. Retrogradely labeled neurons were found in ipsilateral spinal ganglia C2-C3 only if the injection site was in the caudal part of the medial vestibular nucleus (MVN). Injections into rostral parts of the MVN, the superior, lateral and descending vestibular nuclei (SVN, LVN, DVN), the nucleus of the solitary tract (STN) and the reticular formation did not result in spinal ganglion labeling. Thus, the caudal part of the MVN appears to be the main vestibular termination site for rostral cervical primary afferents.

Animals↗

PubMed1989

Vagal afferent fibers almost exclusively innervate islets in the rat pancreas as demonstrated by anterograde tracing.

Anterograde tracing from the nodose ganglion with wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) was utilized to investigate vagal afferent innervation of the rat pancreas. Labelled afferent fibers were consistently detected in islets in all animals. Only about 10% of islets were labelled even in best cases. In only 5 out of 16 rats, acini and excretory ducts received afferent innervation. Injections into the right nodose ganglion resulted in labelling preferentially within the splenic lobe, whereas injections into the left ganglion labelled fibers predominantly in the duodenal lobe. These results point to a non-random distribution of vagal afferent fibers within the pancreas, and suggest a role for these afferents in the regulation of endocrine pancreatic function.

Afferent Pathways↗

PubMed1989

Central distribution of cervical primary afferents in the rat, with emphasis on proprioceptive projections to vestibular, perihypoglossal, and upper thoracic spinal nuclei.

The projections of primary afferents from rostral cervical segments to the brainstem and the spinal cord of the rat were investigated by using anterograde and transganglionic transport techniques. Projections from whole spinal ganglia were compared with those from single nerves carrying only exteroceptive or proprioceptive fibers. Injections of horseradish peroxidase (HRP) or wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) were performed into dorsal root ganglia C2, C3, and C4. Free HRP was applied to the cut dorsal rami C2 and C3, greater occipital nerve, sternomastoid nerve, and to the C1/2 anastomosis, which contains afferents from suboccipital muscles and the atlanto-occipital joint. WGA-HRP injections into ganglia C7 and L5 were performed for comparative purposes. Injections of WGA-HRP or free HRP into rostral cervical dorsal root ganglia and HRP application to C2 and C3 dorsal rami produced labeling in dorsal and ventral horns at the level of entrance, the central cervical nucleus, and in external and main cuneate nuclei. From axons ascending to pontine and descending to upper thoracic spinal levels, medial collaterals were distributed to medial and descending vestibular, perihypoglossal and solitary nuclei, and the intermediate zone and Clarke's nucleus dorsalis in the spinal cord. Lateral collaterals projected mainly to the trigeminal subnucleus interpolaris and to lateral spinal laminae IV and V. Results from HRP application to single peripheral nerves indicated that medial collaterals were almost exclusively proprioceptive, whereas lateral collaterals were largely exteroceptive with a contribution from suboccipital proprioceptive fibers. WGA-HRP injections into dorsal root ganglia C7 and L5 failed to produce significant labeling within vestibular and periphypoglossal nuclei, although they demonstrated classical projection sites within the brainstem and spinal cord. The consistent collateralisation pattern of rostral cervical afferents along their whole rostrocaudal course enables them to contact a variety of precerebellar, vestibulospinal, and preoculomotor neurons. These connections reflect the well-known significance of proprioceptive neck afferents for the control of posture, head position, and eye movements.

Afferent Pathways↗

PubMed1989

Vagal paraganglia of the rat.

Paraganglia are associated with every branch of the rat vagus nerve except the pharyngeal branch. Some of the paraganglia closely resemble the glomus caroticum, whereas others appear like small, intensely fluorescent (SIF) cells of autonomic ganglia. The paraganglionic cells of SIF cell-like bodies (SLB) store catecholamines (the most abundant is probably noradrenaline) and in some cases neurotensin. The innervation pattern of SLB is variable and their physiological role remains unclear. Paraganglionic cells of glomus-like bodies (GLB) predominantly store dopamine and probably also to a lesser extent noradrenaline. These putative chemoreceptor organs receive sensory innervation from nodose ganglion neurons as revealed by degeneration experiments and by anterograde neuronal tracing. Substance P- and calcitonin gene-related peptide-immunoreactive fibres seen in the region of vascular entry into the GLB may account for some of these sensory fibres, but the peptide/classical transmitter stored in sensory terminals synapsing on paraganglionic cells is unknown. Ultrastructural immunocytochemistry revealed vasoactive intestinal polypeptide (VIP)-immunoreactive fibres lying in the interstitial space between paraganglionic cells and large capillaries. These fibres may originate from VIP-immunoreactive neurons, being frequently attached to GLB. The major difference between GLB and the glomus caroticum concerns their blood supply and related innervation: Arteries and arterioles do not penetrate into GLB and, accordingly, noradrenaline- and neuropeptide Y-containing nerve fibres are lacking within GLB. This peculiar arrangement of paraganglionic parenchyma and arterial blood supply may be one of the reasons for the different physiological properties of vagal and carotid arterial chemoreceptors.

Amines↗

PubMed1988

Rectospinal neurons: evidence for a direct projection from the enteric to the central nervous system in the rat.

Wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP), horseradish peroxidase (HRP), and Fluorogold injections were made into the spinal cord segments L4-S2, and HRP was applied to cut L6 and S1 dorsal roots in the rat. These procedures resulted in retrograde labeling of neuronal cell bodies in the rectal wall. Labeled neurons were found both inside and outside myenteric ganglia. Their occurrence was restricted to 5 mm proximal of the external anal sphincter. These cell bodies might represent an additional type of afferent neuron, furnishing a direct information pathway from the rectal wall to the spinal cord.

Afferent Pathways↗

PubMed1987

Sensory vagal innervation of the rat esophagus and cardia: a light and electron microscopic anterograde tracing study.

Wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) was injected into nodose ganglia of rats. In the esophagus and cardia, dense networks of anterogradely labeled fibers and beaded terminal-like arborisations were observed around myenteric ganglia after combined histochemistry for HRP and acetylcholinesterase. The muscularis externa and interna proper were free of label except for a few traversing fibers. Submucosal and mucosal labeling was rather sparse except for the most oral part of the esophagus, where a dense mucosal innervation was found. Control experiments including WGA-HRP injections into the cervical vagus nerve, nodose ganglion injections after supranodose vagotomy, and anterograde [3H]leucine tracing from the nodose ganglion indicated that all labeled fibers in the esophagus and cardia originated from sensory neurons in the nodose ganglion. Electron microscopy revealed that labeled vagal sensory terminals related to myenteric ganglia were mostly large, mitochondria-rich profiles located predominantly on the surface of the ganglia. Specialized membrane contacts connected sensory terminals with other unlabeled profiles possibly derived from intrinsic neurons. The polarity of these contacts suggested the vagal sensory terminals to be presynaptic to intrinsic neurons of the myenteric ganglia. A hypothesis is formulated postulating a mechanoreceptive role for 'myenteric' vagal sensory terminals, providing both the brainstem (via the vagus nerve) and, by synaptic action upon intrinsic neurons, the myenteric plexus with information on tension and motility of the esophagus and cardia.

Animals↗

PubMed1986

Vagal primary afferent terminals in the dorsal motor nucleus of the rat: are they making monosynaptic contacts on preganglionic efferent neurons?

After horseradish peroxidase (HRP) application to the cut cervical vagus nerve in rats, labelled primary afferent terminals could be demonstrated in the dorsal motor nucleus at the ultrastructural level by a combined glucose oxidase-silver-gold intensification technique. Some labelled boutons contacted labelled dendrites of preganglionic neurons. Thus, the occurrence of a few monosynaptic primary afferent-preganglionic efferent contacts in the dorsal motor nucleus could be demonstrated.

Animals↗

PubMed1986

The central projections of primary afferent neurons of greater splanchnic and intercostal nerves in the rat. A horseradish peroxidase study.

The central projections of primary afferent fibers of the greater splanchnic nerve of the rat were investigated using the transganglionic horseradish peroxidase transport technique. In addition, the corresponding spinal ganglion cells and the preganglionic sympathetic neurons were demonstrated. For comparing visceral and somatic afferents, intercostal nerve afferents were labelled by the same technique. Splanchnic afferent dorsal root ganglion cells were found at segments T3 to T13 ipsilaterally, with the greatest density at T8 to T12. Labelled cells represented about 10%-15% of all neurons in the ganglia at maximal projection levels. They were randomly distributed within individual ganglia. The great majority were medium to small sized and round to slightly oval in shape. In the spinal cord, labelled visceral afferent axons were found maximally at T8 to T11, but could be detected in decreasing density up to T1 and down to L1. They were distributed over Lissauer's tract and the dorsal funiculus to a medial and lateral collateral pathway (MCP and LCP, respectively). The MCP, somewhat more prominent than the LCP, was destined primarily to clustered presumptive terminal fields in medial lamina I and outermost lamina IIa. Only a few axons continued further to laminae V and X. Splanchnic afferent axons, most likely derived from the MCP, formed a longitudinal bundle ventral to the central canal. The LCP consisted of more or less well-defined axon bundles emanating from the lateral Lissauer's tract and curving round the lateral edge of the dorsal horn and through the dorsolateral funiculus. Presumptive terminal sites of LCP axons are the lateral laminae I and IIa, the nucleus of the dorsolateral funiculus and the dorsal part of lamina V. A few LCP axons were seen in the vicinity of lateral dendrites of preganglionic sympathetic axons. Visceroafferent terminals were absent from laminae IIb-IV and VII. The possible consequences of the MCP/LCP duality for the central connections of splanchnic afferents are discussed. Some splanchnic afferents ascended to the gracile and cuneate nuclei, and rarely to the spinal trigeminal nucleus. These results fit into the general concept of visceroafferent terminal organization that has emerged during the last few years. Differences to other reports in the detailed arrangement of fibers and terminals are discussed. Somatoafferent cell bodies represented the vast majority of neurons in the respective spinal ganglia. Cell sizes encompassed the whole range from very small to very large without a clear predominance of one particular size class.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMedDate not supplied

Neuropeptide content of peripheral nerve in relation to nerve function in neuropathy.

OBJECTIVE: In this study an APAAP (alcalic-phophatase-anti-alcalic-phosphatase) technique was used to distinguish afferent (calcitonin-gene-related-peptide (CGRP) or substance-P-(SP) positive) and autonomic (tyrosin-hydroxylase (TH), neuropeptide Y (NPY) or vasoactive-intestinal-polypeptide- (VIP) positive) nerve fibers in sural nerve biopsy material from patients with moderate sensory neuropathy. A panneuronal marker against protein-gene-product 9.5 (PGP 9.5) was used for detection of the total amount of nerve fibers. Second aim was to analyze possible correlations between the impairment in tests for the function of unmyelinated fibers (i.e. thermal threshold testings, sensitivity to painful mechanical stimulation, axon reflex-mediated flare reaction and sudomotor activity) and nerve pathology. RESULTS: A high correlation between CGRP and SP (p < 0.00003) and between TH and NPY, respectively, (p < 0.004) was found, but not between afferent and autonomic markers or between specific markers and PGP 9.5. While no correlations between sensory neuropeptides (CGRP and SP) and specific testings of afferent fiber function or between neuropeptide content and clinical data could be demonstrated, there was a significant correlation between the TH content of the sural nerve and the sweat output, stimulated by acetylcholine iontophoresis at the level of the foot (p = 0.019) and upper leg (p = 0.011). CONCLUSION: This study demonstrates the possibility of visualizing subgroups of unmyelinated nerve fibers in sural nerve biopsies selectively with this technique. The density of TH-positive sympathetic nerve fibers, but not the density of afferent c-fibers, is correlated with corresponding results in specific tests of c-fiber function.

Adult↗