Site-specific formation of gastric ulcers by the electric stimulation of the left or right gastric branch of the vagus nerve in the rat

The present study was conducted to investigate the role of the parasympathetic nervous system innervating the stomach in gastric ulcer formation, with special reference to its neuroanatomic characteristics in rats. First, the effects of electric vagal stimulation on the gastric mucosa were examined. The electric stimulation of the left or right gastric branch of the vagus nerve caused gastric mucosal lesions to develop. Interestingly, however, gastric lesions were found on the anterior wall in the rats that had received electric stimulation to the left gastric branch of the vagus nerve and on the posterior wall in the rats that had received stimulation to the right gastric branch. Next, the cells of origin projecting to the left or right gastric branch of the vagus nerve were identified by means of a horseradish peroxidase retrograde tracer method. The left and right gastric branches were found to be innervated by the left and right dorsal motor nuclei of the vagus nerve in the medulla oblongata, respectively. It has been reported that the left and right dorsal motor nuclei of the vagus nerve separately innervate the anterior or posterior gastric wall. The present results, therefore, suggest that the long-lasting excitation of neurons in the dorsal motor nucleus facilitates the site-specific formation of gastric ulcers through the left or right gastric branch of the vagus nerve.     

Splenic nerve is required for cholinergic antiinflammatory pathway control of TNF in endotoxemia

The autonomic nervous system maintains homeostasis through its sympathetic and parasympathetic divisions. During infection, cells of the immune system release cytokines and other mediators that cause fever, hypotension, and tissue injury. Although the effect of cytokines on the nervous system has been known for decades, only recently has it become evident that the autonomic nervous system, in turn, regulates cytokine production through neural pathways. We have previously shown that efferent vagus nerve signals regulate cytokine production through the nicotinic acetylcholine receptor subunit α7, a mechanism termed “the cholinergic antiinflammatory pathway.” Here, we show that vagus nerve stimulation during endotoxemia specifically attenuates TNF production by spleen macrophages in the red pulp and the marginal zone. Administration of nicotine, a pharmacological agonist of α7, attenuated TNF immunoreactivity in these specific macrophage subpopulations. Synaptophysin-positive nerve endings were observed in close apposition to red pulp macrophages, but they do not express choline acetyltransferase or vesicular acetylcholine transporter. Surgical ablation of the splenic nerve and catecholamine depletion by reserpine indicate that these nerves are catecholaminergic and are required for functional inhibition of TNF production by vagus nerve stimulation. Thus, the cholinergic antiinflammatory pathway regulates TNF production in discrete macrophage populations via two serially connected neurons: one preganglionic, originating in the dorsal motor nucleus of the vagus nerve, and the second postganglionic, originating in the celiac-superior mesenteric plexus, and projecting in the splenic nerve.     

Use of horseradish peroxidase to identify hindbrain sites that influence gastric motility in the cat

To identify hindbrain sites that influence gastric motility, we administered multiple injections of horseradish peroxidase into the anterior surface of the antrum near the lesser curvature in 3 cats, and used light microscopy to identify horseradish peroxidase-positive neurons in the hindbrain. Retrogradely labeled neurons were found evenly distributed on both sides in the dorsal motor nucleus of the vagus. Labeling extended from 2.5 mm rostral to 2.0 mm caudal to the obex. Labeled neurons were not localized to a specific region of the dorsal motor nucleus of the vagus: no labeling was observed in the nucleus ambiguus or in the nuclei of the solitary tract. Electrical stimulation of the dorsal motor nucleus of the vagus in the area with the greatest number of labeled cell bodies was performed in 4 cats while monitoring antral motility, arterial pressure, and heart rate. Stimulation elicited pronounced antral contractions but no changes in arterial pressure or heart rate. These data demonstrate that the retrograde neuronal tracing technique permits localization of central nervous system sites that specifically influence gastric function.     

Oligoneuronal Hypoganglionosis in Patients with Idiopathic Slow-Transit Constipation

PURPOSE: Several alterations of the enteric nervous system have been described as an underlying neuropathologic correlate in patients with idiopathic slow-transit constipation. To obtain comprehensive data on the structural components of the intramural nerve plexus, the colonic enteric nervous system was investigated in patients with slow-transit constipation and compared with controls by means of a quantitative morphometric analysis. METHODS: Resected specimens were obtained from ten patients with slow-transit constipation and ten controls (nonobstructive neoplasias) and processed for immunohistochemistry with the neuronal marker Protein Gene Product 9.5. The morphometric analysis was performed separately for the myenteric plexus and submucous plexus compartments and included the quantification of ganglia, neurons, glial cells, and nerve fibers. RESULTS: In patients with slow-transit constipation, the total ganglionic area and neuronal number per intestinal length as well as the mean neuron count per ganglion were significantly decreased within the myenteric plexus and external submucous plexus. The ratio of glial cells to neurons was significantly increased in myenteric ganglia but not in submucous ganglia. On statistical analysis, the histopathologic criteria (submucous giant ganglia and hypertrophic nerve fibers) of intestinal neuronal dysplasia previously described in patients with slow-transit constipation were not completely fulfilled. CONCLUSION: The colonic motor dysfunction in slow-transit constipation is associated with quantitative alterations of the enteric nervous system. The underlying defect is characterized morphologically by oligoneuronal hypoganglionosis. Because the neuropathologic alterations primarily affect the myenteric plexus and external submucous plexus, superficial submucous biopsies are not suitable to detect these innervational disorders.     

A model of lytic, latent, and reactivating varicella-zoster virus infections in isolated enteric neurons

Because human primary afferent neurons are not readily obtained, we sought to develop a model in which the lytic, latent, and reactivating phases of varicella-zoster virus (VZV) infection were recapitulated in neurons from an animal source. Enteric neurons were obtained from the small intestine of adult guinea pigs and from the bowel of fetal mice. Latency was established when these neurons were infected by cell-free VZV in the absence of fibroblasts or other cells of mesodermal origin. In contrast, lytic infection ensued when fibroblasts were present or when the enteric neurons were infected by cell-associated VZV. Latency was associated with the expression of a limited subset of viral genes, the products of which were restricted to the cytoplasm. Lysis was associated with the expression of viral glycoproteins, nuclear translocation of latency-associated gene products, and rapid cell death. Reactivation was accomplished by expressing VZV open reading frame (ORF) 61p or herpes simplex virus ICP0 in latently infected neurons. Isolated enteric neurons from guinea pigs and mice recapitulate latent gene expression in human cranial nerve and dorsal root ganglia. Expression of latency-associated VZV gene products was detected in 88% of samples of adult human intestine, suggesting that VZV not only infects enteric neurons but also is latent in the human enteric nervous system. This in vitro model should facilitate further understanding of latency and reactivation of VZV.     

Reovirus nonstructural protein σ1s is required for establishment of viremia and systemic dissemination

Serotype-specific patterns of reovirus disease in the CNS of newborn mice segregate with the viral S1 gene segment, which encodes attachment protein σ1 and nonstructural protein σ1s. The importance of receptor recognition in target cell selection by reovirus implicates the σ1 protein as the primary effector of disease outcome. However, the contribution of σ1s to reovirus disease is unknown. To define the function of σ1s in reovirus pathogenesis, we generated a σ1s-deficient virus by altering a single nucleotide to disrupt the σ1s translational start site. Viruses were recovered that contain nine gene segments from strain type 3 Dearing and either the wild-type or σ1s-null S1 gene segment from strain type 1 Lang. Following peroral inoculation of newborn mice, both viruses replicated in the intestine, although the wild-type virus achieved higher yields than the σ1s-null virus. However, unlike the wild-type virus, the σ1s-deficient virus failed to disseminate to sites of secondary viral replication, including the brain, heart, and liver. Within the small intestine, both viruses were detected in Peyer''s patches, but only the wild-type virus reached the mesenteric lymph node. Concordantly, wild-type virus, but not σ1s-deficient virus, was detected in the blood of infected animals. Wild-type and σ1s-null viruses produced equivalent titers following intracranial inoculation, indicating that σ1s is dispensable for viral growth in the murine CNS. These results suggest a key role for σ1s in virus spread from intestinal lymphatics to the bloodstream, thereby allowing the establishment of viremia and dissemination to sites of secondary replication within the infected host.     

Persistence of neuroadapted mumps virus in brains of newborn hamsters after intraperitoneal inoculation.

Neuroadapted mumps virus produces systemic infection in newborn hamsters after intraperitoneal inoculation. Virus is disseminated via a low-level viremia and appears to enter the central nervous system by passage through the choroid plexus. At such sites, choroidal and ependymal epithelial cells are productively infected and become a source for further viral spread throughout the brain parenchyma. The development of neutralizing and hemagglutination-inhibiting antibodies in serum correlates with the clearance of virus from most systemic sites. However, peristence of virus in both brain and kidney is demonstrated late in this infection.     

Intestinale Innervationsstörungen: Anatomische Grundlagen und Diagnostik

Histopathological insights into intestinal innervation disorders require the knowledge of the anatomical topography and structure of the enteric nervous system (ENS). The ENS of the human colon is composed of intramural nerve meshes located in different layers of the intestinal wall (plexus musculares, plexus myentericus, plexus submucosi, plexus mucosi). A differentiated visualization of the components of the ENS is achieved-by enzyme- and immunohistochemical methods. In comparison to cross-sections, wholemount preparations of the intestinal wall allow a two dimensional demonstration of the network-character of the nerve plexus and preserve the anatomical in-situ conditions. A complete histopathological diagnosis of the ENS requires full-thickness biopsies or resected specimens, as an assessment of the entire plexus layers is achieved only by this procedure. The establishment of reference values by means of morphometrical studies of ENS contributes to an objective and standardized histopathological diagnosis. Aganglionosis, hypoganglionosis, intestinal neuronal dysplasia and heterotopias are considered to be the most acknowledged forms of intestinal innervation disorders. In addition, degenerative changes of enteric nerve plexus, visceral neuropathies and a disturbed homeostasis of enteric neurotransmitters are described. Recently, a pathogenetical significance for functional intestinal motility disorders has been attributed to interstitial cells of Cajal (ICC). The ENS and ICC play a major role in mediating and coordinating gastrointestinal motility and therefore shoud be taken into account in clinical disorders of the intestinal motor function.     

钙敏感受体在肠神经系统中的表达

目的观察与探讨G-蛋白耦联受体(CASR)在豚鼠肠神经系统中的表达。方法以豚鼠为试验对象,先进行RT-PCR设计,然后采用Western blotting来检测豚鼠肠神经系统中CASR蛋白,并且应用间接法双重免疫荧光标记对肠神经系统整体、肠神经系统中的肌间神经丛黏膜下神经丛中的CASR分布及数量等进行测定,荧光标记物采用FITC和Cy3。结果无论是肠神经系统中的肌间神经丛还是黏膜下神经丛,不同的肠神经细胞中含有不同的神经元标记物,即均存在CASR。结论豚鼠肠神经系统存在钙敏感受体的表达,因此,关于CASR在肠神经系统中的相关研究具有重要的临床意义,可能为将来研究CASR在肠道神经系统中的功能及肠炎症中的作用奠定基础。     

Development of interstitial cells of Cajal in a full-term infant without an enteric nervous system

The relationship between the development of the enteric nervous system and interstitial cells of Cajal (ICC) in the human small intestine was investigated in a full-term infant who presented with intestinal pseudo-obstruction. Immunohistochemistry revealed absence of enteric nerves and ganglia but abundant c-Kit immunoreactivity associated with Auerbach's plexus (ICC-AP). However, c-Kit immunoreactivity associated with the deep muscular plexus (ICC-DMP) and intermuscular ICC was absent. Electron microscopy showed ICC-AP with a normal ultrastructure; ICC-DMP were seen but were severely injured, suggesting degeneration. In vitro recording of intestinal muscle showed slow wave activity as well as response to cholinergic stimulation. Fluoroscopic examination of the small bowel showed a variety of motor patterns, including rhythmic, propagating contractions. In conclusion, total absence of enteric nerves was associated with absence of normal ICC-DMP. However, a normal musculature, including a network of ICC-AP, allowed for generation of rhythmic, propagating contractile activity, suggesting the presence of functional motor activity.     

Physiology of esophageal motor function

The esophagus is a region with three functional zones: (1) the upper esophageal sphincter; (2) the esophageal body; and (3) the lower esophageal sphincter. Control mechanisms within the central nervous system and peripherally serve to integrate these functional zones in a region where voluntary and involuntary control mechanisms and the activity of two different types of muscle are intimately coordinated. The distal 50 to 60 per cent of the esophagus in humans is entirely smooth muscle. Extrinsic control for esophageal motor function resides in a brainstem swallowing center with an afferent reception system, an efferent system of motor neurones, and a complex organizing or internuncial system of neurones. Sensory information from the esophagus is carried in the vagus nerves, but sensory pathways are also present in sympathetics entering the spinal cord. The vagus nerve receiving fibers both from the nucleus ambiguus and the dorsal motor nucleus innervates the striated and smooth muscle esophagus, respectively, including the sphincters. There is a myenteric nerve plexus in both the striated and smooth muscle segments. In the smooth muscle esophagus, there are two important effector neurones, an excitatory cholinergic neurone, and a nonadrenergic, noncholinergic (NANC) inhibitory neurone. The striated muscle contraction is directed and coordinated by sequential excitation through vagal fibers programmed by the central control mechanism. There are at least four potential control mechanisms for peristalsis in the smooth muscle esophagus: efferent motor fibers programmed by the swallowing center fire sequentially during peristalsis; the intramural neural mechanism can be excited to produce peristalsis near the onset of stimulation or with a delay after termination of stimulation; there is evidence for myogenic propagation of a peristaltic contraction. In humans, swallow-induced peristalsis is cholinergic and appears to result primarily from sequencing and activation of the intramural excitatory cholinergic neurones. Both central and peripheral levels of control are highly integrated to focus on the excitatory cholinergic neurones. It is likely that under normal circumstances, the central control mechanism exerts the dominant influence on these neurones for initiation and coordination of peristalsis in the smooth muscle esophagus. In humans, resting tone in the lower esophageal sphincter is predominantly cholinergic, but this tone is regulated by a balance between many excitatory and inhibitory influences. The relaxation on swallowing is caused by active inhibition of the muscle through NANC inhibitory neurones and cessation of tonic neural excitation to the     

Neuropathy in the brain-in-the-gut

* The enteric nervous system has sensory neurons, interneurons and motor neurons and functions as a brain-in-the-gut. * Smooth muscles of the digestive tract are autogenic in the absence of neural control. * Enteric inhibitory motor neurons control excitability of the autogenic musculature. * The neuropathic form of chronic intestinal pseudo-obstruction is a form of disinhibitory motor disease linked with neuropathic degeneration in the enteric nervous system. * Patients with inflammatory degenerative neuropathy may progress from irritable bowel syndrome (IBS)-like symptoms to chronic pseudo-obstruction. * Detection of anti-enteric neuronal antibodies may be a useful diagnostic test for early stages of inflammatory degenerative neuropathy in patients with symptoms of a functional gastrointestinal disorder. Awareness is increasing that autoimmune attack targeted to neuronal elements of the enteric nervous system may underlie irritable bowel-like symptoms that progress to chronic pseudo-obstruction. The inflammatory neuropathy disrupts the integrative functions of the brain-in-the-gut, including reduction in the population of inhibitory motor neurons to the musculature. Extreme loss of inhibitory motor neurons is manifest as disinhibitory motor disease characterized by achalasia in smooth muscle sphincters and hyperactive, disorganized contractile behaviour of intestinal circular muscle which results in pseudo-obstruction. Detection of anti-enteric neuronal antibodies in the serum of patients with early symptoms of a functional gastrointestinal motility disorder may prove to be a useful diagnostic test for inflammatory enteric neuropathy.     

Vagal activities are involved in antigen-specific immune inflammation in the intestine

Background and Aims: The mechanism of intestinal immune inflammation, such as food allergy, remains to be further understood. The present study aims to investigate the role of the vagal nerve in the pathogenesis of skewed T‐helper 2 (Th2) responses in the intestine. Methods: The expression of the immunoglobulin E (IgE) receptor on the vagus nerve in the mouse intestine was observed by immunohistochemistry. Vagus ganglion neurons (VGN) were isolated from mice and cultured in vitro. The IgE receptor/IgE complex on vagus neurons was examined by immune precipitation assay. A food allergy mouse model was developed; the effect of the partial removal of the vagal nerve (PRVn) via surgery or administration with anticholinergic agents on the suppression of Th2 inflammation was evaluated. Results: The high‐affinity IgE receptor was detected on the intestinal vagus nerve. An increase in the expression of the IgE receptor on the vagus nerve was observed in the intestines of mice with intestinal immune inflammation. Isolated mouse VGN express IgE receptor I, which could form complexes with IgE. Re‐exposure to specific antigens activated the sensitized VGN, manifesting the release of transmitter glutamate that could activate dendritic cells by increasing the expression of CD80 and major compatibility complex class II and suppressing interleukin‐12. The PRVn suppressed Th2 inflammation in the intestine. Conclusions: The intestinal vagus nerve in mice expresses a high‐affinity IgE receptor. An antigen‐specific immune response can activate the vagus nerve in the intestine and induces the release of transmitters to modulate dendritic cell phenotypes that facilitate the development of skewed Th2 polarization in the intestine.     

Orexins, orexigenic hypothalamic peptides, interact with autonomic, neuroendocrine and neuroregulatory systems

We determined the immunohistochemical distributions of orexin-A and orexin-B, hypothalamic peptides that function in the regulation of feeding behavior and energy homeostasis. Orexin-A and -B neurons were restricted to the lateral and posterior hypothalamus, whereas both orexin-A and -B nerve fibers projected widely into the olfactory bulb, cerebral cortex, thalamus, hypothalamus, and brainstem. Dense populations of orexin-containing fibers were present in the paraventricular thalamic nucleus, central gray, raphe nuclei, and locus coeruleus. Moderate numbers of these fibers were found in the olfactory bulb, insular, infralimbic and prelimbic cortex, amygdala, ventral, and dorsolateral parts of the suprachiasmatic nucleus, paraventricular nucleus except the lateral magnocellular division, arcuate nucleus, supramammillary nucleus, nucleus of the solitary tract, and dorsal motor nucleus of the vagus. Small numbers of orexin fibers were present in the perirhinal, motor and sensory cortex, hippocampus, and supraoptic nucleus, and a very small number in the lateral magnocellular division of the paraventricular nucleus. Intracerebroventricular injections of orexins induced c-fos expression in the paraventricular thalamic nucleus, locus coeruleus, arcuate nucleus, central gray, raphe nuclei, nucleus of the solitary tract, dorsal motor nucleus of the vagus, suprachiasmatic nucleus, supraoptic nucleus, and paraventricular nucleus except the lateral magnocellular division. The unique neuronal distribution of orexins and their functional activation of neural circuits suggest specific complex roles of the peptides in autonomic and neuroendocrine control.     

Medullary parasympathetic projections innervate specific sites in the feline stomach

The purpose of our study was to determine the site of origin of vagal neurons that innervate specific parts of the stomach (the fundus, corpus, and antrum/pylorus). This was done by injecting the retrograde fluorescent tracer Fast Blue into these parts of the cat stomach and examining the hindbrain for cells labeled with retrograde tracer. We found that vagal preganglionic innervation to the stomach originates from two medullary nuclei, namely, the dorsal motor nucleus of the vagus (bilateral) and the nucleus retroambiguus (left). All parts of the stomach receive innervation from the dorsal motor nucleus of the vagus (primarily from the area ranging from 0.5 to 1.8 mm rostral to the obex), but only the fundus and corpus receive innervation from the nucleus retroambiguus. Injection of tracer into the fundus labeled cells within the lateral half of the dorsal motor nucleus of the vagus and injection of tracer into the antrum/pylorus labeled cells within the medial portion. Finally, injection of tracer into the corpus labeled cells throughout the mediolateral axis of the dorsal motor nucleus of the vagus. The finding of a columnar organization of the dorsal motor nucleus of the vagus implies some type of functional organization of gastrointestinal control. The fact that vagal inputs to the stomach arise from the dorsal motor nucleus of the vagus and nucleus retroambiguus suggests a separation of vagal pathways controlling different gastric functions (e.g., pacemaker activity, motility, and secretion).     

Origins of peptide and norepinephrine nerves in the mucosa of the guinea pig small intestine

Norepinephrine, acetylcholine, and certain peptides are contained in mucosal nerves and have potent effects on transepithelial water and electrolyte fluxes. It is difficult to ascribe roles for these nerves as their sources are unknown. The present studies were undertaken to determine the origins of nerve fibers that are found in the mucosa of the guinea pig small intestine and which contain one of the following substances: vasoactive intestinal peptide, substance P, somatostatin, neuropeptide Y, cholecystokinin, or norepinephrine. Nerve fiber origins were ascertained by making lesions to sever pathways through which the nerves could reach the mucosa. The lesioning operations were homotopic autotransplants of short (2 cm) segments of intestine; myectomies, in which a 5-10-mm length of intestine was stripped of longitudinal muscle and myenteric plexus; and extrinsic denervation, in which nerves reaching the intestine through the mesentery were severed. The results of these studies, considered along with previously published work, led to the upcoming conclusions. Nerve fibers in the mucosa showing immunoreactivity for vasoactive intestinal peptide, somatostatin, cholecystokinin, and neuropeptide Y arise from cell bodies in the overlying submucous plexus. Substance P fibers arise in part from the overlying submucous plexus and in part from the overlying myenteric plexus. Mucosal norepinephrine fibers arise from extrinsic sympathetic ganglia. Enkephalin, gastrin-releasing peptide, and 5-hydroxytryptamine, which are in some enteric nerves, are not found in submucous nerve cells and few, if any, fibers containing these substances supply the mucosa. Thus, the mucosa receives a dense nerve supply, much of which arises locally from submucous ganglia.     

用免疫组织化学法证实人脑神经根、脊髓后根神经节的狂犬病毒抗原

应用免疫组织化学法（ＳＰ）法检查５例死于狂犬病的人脑神经根、脊髓后根神经节,结果显示在嗅束（４／４）、视交叉（３／３）、动眼神经根（１／１）、迷走神经根（１／３）的神经细胞胞浆内和每个节段的脊髓后根神经节的神经节细胞胞浆内有狂犬病毒抗原,而神经纤维阴性。结果表明狂犬病毒可以通过神经系统的脊髓后根和脑神经根传播。     

Rapid inhibition of neurons in the dorsal motor nucleus of the vagus by leptin

The peptide leptin conveys the availability of adipose energy stores to the brain. Increasing evidence implicates a significant role for extrahypothalamic sites of leptin action, including the dorsal vagal complex, a region critical for regulating visceral parasympathetic function. The hypothesis that leptin suppresses cellular activity in the dorsal motor nucleus of the vagus nerve (DMV) was tested using whole-cell patch-clamp recordings in brainstem slices. Leptin caused a rapid membrane hyperpolarization in 50% of rat DMV neurons. Leptin also hyperpolarized a subset of gastric-related neurons (62%), identified after gastric inoculation with a transneuronal retrograde viral tracer. The hyperpolarization was associated with a decrease in input resistance and cellular responsiveness and displayed characteristics consistent with an increased K+ conductance. Perfusion of tolbutamide (200 microM) reversed the leptin-induced hyperpolarization, and tolbutamide or wortmannin (10-100 nM) prevented the hyperpolarization, indicating that leptin activated an ATP-sensitive K+ channel via a phosphoinositide-3-kinase-dependent mechanism. Leptin reduced the frequency of spontaneous and miniature excitatory postsynaptic currents (EPSCs), whereas inhibitory postsynaptic currents (IPSCs) were largely unaffected. Electrical stimulation of the nucleus tractus solitarii (NTS) resulted in constant-latency EPSCs, which were decreased in amplitude by leptin. The paired-pulse ratio was increased, suggesting leptin effects involved activation of receptors presynaptic to the recorded neuron. A leptin-induced suppression of EPSCs, but not IPSCs, evoked by focal photolytic uncaging of glutamate within the NTS was also observed, supportive of leptin effects on the glutamatergic NTS projection to the DMV. Therefore, leptin directly hyperpolarized and indirectly suppressed excitatory synaptic activity to DMV neurons involved in visceral regulation, including gastric-related neurons.