慢传输型便秘肠神经系统一氧化氮合酶和P物质的分布意义

目的研究结肠一氧化氮（ＮＯ）和Ｐ物质（ＳＰ）在慢传输型便秘（ＳＴＣ）发病中的作用．方法应用一氧化氮合酶（ＮＯＳ）和ＳＰ的兔多克隆抗体，对手术切除的１５例ＳＴＣ患者（男２例，女１３例，年龄２６岁～６８岁）和１１例对照组患者乙状结肠标本进行免疫组化染色和半定量分析．结果ＳＴＣ患者乙状结肠肌间神经丛ＮＯＳ免疫反应性明显升高（χ２＝１５６３，Ｐ＜００１），而ＳＰ免疫反应性明显降低（χ２＝１３４４，Ｐ＜００１）；粘膜下神经丛ＮＯＳ及ＳＰ免疫反应性与对照组相差不显著．结论ＳＴＣ结肠神经系统ＮＯＳ和ＳＰ免疫反应性的异常变化，可能是其结肠传输减慢的神经病理基础     

Carbon monoxide regulates blood pressure cooperatively with nitric oxide in hypertensive rats

 Both carbon monoxide (CO), the product of heme oxygenase (HO), and nitric oxide (NO) elevate cyclic guanosine monophosphate levels in smooth muscle cells, leading to relaxation of the vessels. We examined the hypothesis that the effect of CO in regulating blood pressure could be augmented in hypertension where the function and/or production of NO is impaired. We used two hypertensive models, a spontaneously hypertensive rat (SHR), and a Wistar Kyoto rat (WKY) which was given the NO synthase (NOS) inhibitor N ^ω-nitro-l-arginine (L-NNA). In these hypertensive rats, we examined HO gene expression with Northern blot analysis, guanosine 3′,5′-monophosphate (cGMP) levels with enzyme-linked immunosorbent assay of each organ, and the response of blood pressure to treatment with an HO substrate (hemin, 23 μmol/kg body weight, i.p.) or HO inhibitor (zinc or tin protoporphyrin-IX; ZnPP or SnPP, 50 μmol/kg body weight i.p. or s.c.), for 4 or 8 consecutive days with plethysmography. Northern blot analysis showed that HO-1 and -2 mRNA levels in the left ventricle, aorta, kidney, and soleus muscle in the hypertensive rats were 2–5 times higher than those in control normotensive WKYrats. In contrast, both HO mRNA levels in the gastrocnemius muscle in the hypertensive rats were similar to those in control WKYrats. As to whether the HO/CO system contributes to the regulation of blood pressure, ZnPP or SnPP increased and hemin decreased systolic blood pressure (SBP), respectively, in the hypertensive rats (P < 0.01), but not in WKYrats, accompanied with changes in cGMP in each organ of the hypertensive rats. The effect of CO in the regulation of blood pressure is augmented, resulting in increased expression of HO gene when the function and/or production of NO is impaired. Received: May 31, 2001 / Accepted: February 16, 2002     

Plasticity in the enteric nervous system

Enteric ganglia can maintain integrated functions, such as the peristaltic reflex, in the absence of input from the central nervous system, which has a modulatory role. Several clinical and experimental observations suggest that homeostatic control of gut function in a changing environment may be achieved through adaptive changes occurring in the enteric ganglia. A distinctive feature of enteric ganglia, which may be crucial during the development of adaptive responses, is the vicinity of the final effector cells, which are an important source of mediators regulating cell growth. The aim of this review is to focus on the possible mechanisms underlying neuronal plasticity in the enteric nervous system and to consider approaches to the study of plasticity in this model. These include investigations of neuronal connectivity during development, adaptive mechanisms that maintain function after suppression of a specific neural input, and the possible occurrence of activity-dependent modifications of synaptic efficacy, which are thought to be important in storage of information in the brain. One of the applied aspects of the study of plasticity in the enteric nervous system is that knowledge of the underlying mechanisms may eventually enable us to develop strategies to correct neuronal alterations described in several diseases.     

Exhaled carbon monoxide and nitric oxide in COPD

STUDY OBJECTIVES: To investigate whether exhaled carbon monoxide (CO) and nitric oxide (NO) could be used as noninvasive in vivo biomarkers of oxidative stress in the lungs of patients with COPD. DESIGN: Single-center cross-sectional study. PATIENTS: Ten healthy nonsmokers, 12 smokers, 15 stable ex-smokers with COPD, and 15 stable current smokers with COPD. INTERVENTIONS: Subjects attended the outpatient clinic on one occasion for pulmonary function tests and exhaled CO and NO measurements. Measurements and results: Mean (+/- SEM) CO levels in ex-smokers with COPD were higher (7.4 +/- 1.9 ppm; p < 0.05) than in nonsmoking control subjects (3.0 +/- 0.3 ppm) but were lower than in current smokers with COPD (20.0 +/- 2.6 ppm; p < 0.001). There was no correlation between exhaled CO and NO. There was no correlation between CO and lung function tests in any group of patients. Exhaled NO was higher in ex-smokers with COPD (12.0 +/- 1.0 parts per billion [ppb]; p < 0.001) than in healthy nonsmokers (6.5 +/- 0.6 ppb) and in current smokers with COPD (7.6 +/- 1.1 ppb; p < 0.01) compared to healthy smokers (3.3 +/- 0.4 ppb). Ex-smokers with COPD had higher exhaled NO levels than did current smokers with COPD (p < 0.001) There was a negative correlation between exhaled NO and FEV(1) in both ex-smokers with COPD (r = -0.60; p < 0.02) and current smokers with COPD (r = -0.59; p < 0.02). CONCLUSION: The measurement of exhaled CO and NO may represent a new method for the noninvasive monitoring of airway inflammation and oxidant stress in COPD ex-smokers. Exhaled CO and NO are strongly affected by cigarette smoking, which limits their usefulness as biomarkers in current smokers.     

Understanding and controlling the enteric nervous system

The enteric nervous system or the 'Little Brain' of the gut controls gastrointestinal motility and secretion, and is involved in visceral sensation. In this chapter, new developments in understanding the function of the enteric nervous system are described. In particular, the interaction of this system with the interstitial cells of Cajal, the pacemaker cells of the gut, is highlighted. The importance of the interaction between the enteric nervous system and the immune system is discussed, especially in relation to functional bowel disorders and post-operative ileus. Evidence is also provided that neurones can change their function and phenotype, a phenomenon called neuronal plasticity, which contributes to the pathogenesis of visceral hypersensitivity. Finally, new developments in stem cell transplantation are described. All these new insights should lead to a better understanding of the enteric nervous system and hopefully to better ways of controlling it.     

Nitric oxide synthase and VIP distribution in enteric nervous system in idiopathic chronic constipation

Idiopathic chronic constipation has been correlated to neural abnormalities that consist of a reduced number of myenteric plexus neurons and a decreased concentration of VIP-positive nerve fibers within the circular muscle. Recent studies hypothesized the involvement of nitric oxide in motility disorders of the human gut. To date, no information is available on nitric oxide involvement in idiopathic chronic constipation. The density of VIP- and nitric oxide-producing neurons was evaluated by immunocytochemistry using anti-VIP and anti-nitric oxide synthase antibodies in five patients with idiopathic chronic constipation. A low total neuron density was found at the myenteric plexus. The density of VIP-positive neurons was low while that of nitric oxide synthase-positive neurons was high at both plexuses. Our data confirm that idiopathic slow-transit chronic constipation is due to abnormal neurogenic factors. The presence of numerous nitric oxide synthase-positive neurons, all along the colon and at both plexuses, supports the hypothesis that an excessive production of nitric oxide may cause the persistent inhibition of contractions.Supported by MURST University Funds.     

Inflammatory neuropathies of the enteric nervous system

Inflammatory neuropathy of the enteric nervous system is emerging as an important topic in the field of neurogastroenterology. Enteric ganglionitis can be either primary or secondary to a wide array of diseases (i.e., paraneoplastic, infectious, and neurological disorders) and is characterized by a dense infiltrate of inflammatory/immune cells mainly confined to the neural microenvironment. The clinical picture reflects the involved segment of the gastrointestinal tract (achalasia, gastroparesis, pseudo-obstruction, and megacolon). In these settings, symptoms may develop either acutely (frequently after a flulike episode in otherwise previously healthy individuals) or more slowly (e.g., in paraneoplastic syndromes). The inflammatory/immune response in enteric ganglionitis leads to neuronal dysfunction and degeneration over time and sometimes results in a complete loss of enteric neurons. The diagnosis of enteric ganglionitis is supported by detection of circulating antineuronal antibodies against select molecular targets, including Hu and Yo proteins, neurotransmitter receptors, and ion channels. Potential mechanisms involved in neuronal dysfunction include viral antigen expression in the enteric neural environment, molecular mimicry (onconeural antigens), and the role exerted by cellular and humoral autoimmunity. A short course of steroid or other immunosuppressive therapy has been shown to be helpful in the treatment of these conditions. This feature reinforces the concept of a cause/effect relationship of the immune-mediated insult damaging the enteric innervation. An increased awareness of the clinical features and the immunologic and neurodegenerative mechanisms of these forms of peripheral neuropathy is important to correctly diagnose this problem during the early stages of the disease process and to provide appropriate immunosuppressive therapies.     

Exhaled nitric oxide and carbon monoxide in respiratory diseases

Breath tests have gained increasing interest in recent years mainly driven by the unmet clinical need to monitor airway diseases and to obtain information on unravelled aspects of respiratory disorders. A prototype of such measurement reaching clinical significance besides its use as a research tool is the measurement of exhaled nitric oxide (NO). It took hardly more than a decade after the discovery that exhaled breath contains NO for this measurement to be approved for clinical practice to monitor anti-inflammatory treatment in asthma. Recent studies demonstrate that using exhaled NO measurement to guide anti-inflammatory treatment in asthma may help clinical decision making. A similarly small molecule present in exhaled breath is carbon monoxide, which is not only a biomarker of cigarette smoking but has also been suggested to reflect ongoing oxidative stress/antioxidant defense. The scope of this review is the exciting field of exhaled monoxides. Since several other biomarkers have also been studied in the exhaled breath this review will provide a brief introduction to them.     

Central nervous system nitric oxide induces oropharyngeal swallowing and esophageal peristalsis in the cat

BACKGROUND & AIMS: The functional role of brainstem nitric oxide (NO) in swallowing and esophageal peristalsis remains unknown. We examined the effects of blockade of central nervous system (CNS) NO synthase (NOS) on swallowing and on primary and secondary peristalsis. METHODS: (1) The effect of intravenous (IV) NOS inhibitor N(G)-nitro-L-arginine (L-NNA) on swallowing and swallowing-induced peristalsis was examined. (2) An NOS inhibitor (N(G)-monomethyl-L-arginine [L-NMMA]) was administered into the fourth ventricle intracerebroventricularly (ICV), and its effects on swallowing and primary and secondary peristalsis were examined. RESULTS: (1) IV L-NNA significantly reduced the number of oropharyngeal swallows and the induction of primary peristalsis in the smooth muscle portion of the esophageal body; the change was not significant within the striated muscle portion. (2) L-NMMA given ICV significantly reduced the number of oropharyngeal swallows and the incidence of primary peristalsis in both smooth and striated muscle, but the reduction in amplitude was significant only for the smooth muscle contraction. There was a significant reduction in both the amplitude and incidence of secondary peristalsis, only in the smooth muscle portion. CONCLUSIONS: CNS NO is an important neurotransmitter in the induction of oropharyngeal swallowing and esophageal peristalsis. The neural substrates mediating striated and smooth muscle peristalsis may be both anatomically and neurochemically distinct.     

Catecholamine biosynthetic enzymes are expressed in replicating cells of the peripheral but not the central nervous system.

We sought to determine whether the precursors of catecholamine-containing neurons in the developing peripheral and central nervous systems of chickens and rats express the biosynthetic enzymes tyrosine hydroxylase [THase; tyrosine 3-monooxygenase; L-tyrosine, tetrahydropteridine: oxygen oxidoreductase (3-hydroxylating), EC 1.14.16.2] or dopamine beta-hydroxylase [DBHase; 3,4-dihydroxyphenylethylamine, ascorbate:oxygen oxidoreductase (beta-hydroxylating), EC 1.14.17.1], prior to the time they withdraw from the cell cycle. Chicken embryos (stages 26-27) were injected with [3H-thymidine and 4 hr later were prepared for the simultaneous demonstration of radioautographically labeled nuclei in immunoreactive THase cells. The brains and sympathetic chains of rat fetuses (days E12-E14), exposed for 2 hr to [3H]thymidine, were treated similarly except that peripheral tissues were stained with a specific antibody to DBHase as well as anti-THase. In the peripheral nervous system of both chicken and rat, nuclei of THase-containing cells were radioautographically labeled. DBHase-containing cells in the peripheral nervous system of rats were also labeled and thus are noradrenergic. THase was localized in cells of the brain of the same rat fetuses beginning on day E12 (no THase was detected on day E11 or E11.5) in the mantle layer of the ventral mesencephalic and rostrolateral rhombocephalic cellular groups; however. THase-containing cells in the central nervous system did not incorporate [3H]thymidine. We conclude that, during development, the adrenergic neuronal precursors of the peripheral nervous system but not of the central, have the capacity to synthesize catecholamines before they withdraw from the cell cycle. Differences in the maturation of peripheral and central neurons may be related to differences in their embryological origin.     

Role of nitric oxide in defense of the central nervous system against Mycobacterium tuberculosis

Murine models of tuberculous meningitis (TBM) have not reflected the severity of disease in humans. Based on reports that activated murine microglial cells, but not human microglial cells, express inducible nitric oxide synthase (iNOS), the objective of this study was to determine whether iNOS-knockout (iNOS(-/-)) mice would provide such a model. iNOS(-/-) mice infected with M. tuberculosis developed serious clinical manifestations and granulomatous lesions containing tubercle bacilli throughout the meninges, all of which were absent in wild-type mice. This study underscores the importance of nitric oxide in defense against TBM and suggests that iNOS(-/-) mice are an appropriate model for human TBM.     

Local nitric oxide production in viral and autoimmune diseases of the central nervous system.

Because of the short half-life of NO, previous studies implicating NO in central nervous system pathology during infection had to rely on the demonstration of elevated levels of NO synthase mRNA or enzyme expression or NO metabolites such as nitrate and nitrite in the infected brain. To more definitively investigate the potential causative role of NO in lesions of the central nervous system in animals infected with neurotropic viruses or suffering from experimental allergic encephalitis, we have determined directly the levels of NO present in the central nervous system of such animals. Using spin trapping of NO and electron paramagnetic resonance spectroscopy, we confirm here that copious amounts of NO (up to 30-fold more than control) are elaborated in the brains of rats infected with rabies virus or borna disease virus, as well as in the spinal cords of rats that had received myelin basic protein-specific T cells.     

Insulin, nitric oxide and the sympathetic nervous system: at the crossroads of metabolic and cardiovascular regulation

Epidemiological studies demonstrate an association between insulin resistance, hypertension and cardiovascular morbidity. Over the past decade, evidence has accumulated indicating that short-term insulin administration, in addition to its metabolic effects, also has important cardiovascular actions. The sympathetic nervous system and the L-arginine-nitric oxide pathway have emerged as central players in the mediation of insulin's cardiovascular actions. The underlying mechanisms and the factors that may govern the interaction between insulin and these two major cardiovascular regulatory systems have been studied extensively in healthy people and insulin-resistant subjects. Here we summarize the current understanding and gaps in knowledge on insulin's cardiovascular actions in humans, and discuss possible pathophysiological consequences of their alteration. Based on recent new insight, we propose that a genetic and/or acquired defect of nitric oxide synthesis could represent a central defect triggering many of the metabolic, vascular and sympathetic abnormalities characteristic of insulin-resistant states, all of which may predispose to cardiovascular disease.     

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。     

食管肠神经系统调控的研究进展

食管受到各级神经系统及体液的调控,而完成蠕动与收缩功能.食管的活动有赖于肠神经系统(enteric nervous system,ENS)的调控协调作用.食管存在着兴奋性神经元和抑制性神经元两种,他们通过多种神经递质相互作用而决定食管的紧张度、蠕动与收缩.对食管神经机制的理解及研发新型药物治疗食管功能紊乱和胃食管反流有重要意义.本文综述近十年来食管脑神经系统的研究进展.     

Exhaled monoxides as a pulmonary function test: use of exhaled nitric oxide and carbon monoxide.

Although there has been tremendous improvement in the technologic ability to measure exhaled gases and monitor biologic processes in the lung, it has not yet found a clinical role outside the research laboratory. Common themes seem to be significant overlap in the amount of exhaled gases in clinically distinct populations, confounding variables such as infection, smoking, and environmental exposure, and lack of consistent change with disease management. If these tests are ever to be used by the general pulmonologist, consistent links between the measurements and the response to disease modification will need to be demonstrated at the very least and, ideally, the clinician would like to see improved outcomes when these noninvasive tests are employed regularly.