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Query: UMLS:C0014848 (achalasia)
 2,804 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The esophageal primary motor disorders like achalasia, diffuse esophageal spasm or the nutcracker can involve the upper esophageal sphincter, the esophageal body, the lower esophageal sphincter or a combination of them. This article will focus on the esophageal body and abnormal peristalsis. A normal esophageal peristaltic contraction occurs after a latency period following a swallow and requires a minimum amplitude to be propulsive. Abnormal latencies may generate simultaneous contractions whereas low amplitude contractions may be inefficient i.e. GERD and high amplitude contractions my provoke chest pain or dysfagia i.e. diffuse spasm. The latency period between deglutition and contraction is due to a muscle inhibition immediately after the swallow. This inhibition is due to release of NO by an inhibitory neurone located in the myenteric plexus. At the end of the inhibition, the contraction occurs due to release of acetyl choline by an excitatory cholinergic neurone. The exact interplay between these two neurones will determine the <<timing>> or propagation velocity and the amplitude of esophageal contractions. Patients with achalasia have a predominant loss of inhibitory neurones (VIP and NOS) with a relative preservation of excitatory cholinergic neurones. The histophatologic and immunohistochemical status in patients with esophageal primary motor disorders other than achalasia is poorly characterised Examples of deglutitive inhibition in the esophagus can be observed during the relaxation of the lower esophageal sphincter or when a subject swallows very frequently. In order to quantify deglutitive inhibition we developed a method that induces an artificial high pressure zone in the mid esophageal body. During the latency period after a swallow, the high pressure zone relaxes (is inhibited). With this method, we could measure the magnitude and duration of the inhibitory phenomenon. There is a very good correlation between the degree of deglutitive inhibition and propagation velocity of esophageal contractions. The less inhibition, the faster the propagation velocity of contractions. Simultaneous contractions are the consequence of absent inhibition. Patients with esophageal primary motor disorders may have very fast propagating contractions and a small percentage of simultaneous contractions or up to 100% of simultaneous contractions. The correlation between the degree of inhibition and propagation velocity of contractions suggests that the different primary motor disorders are the expression of a progressive failure in esophageal inhibition.
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PMID:[Role of deglutitive inhibition in the pathophysiology of esophageal primary motor disorders]. 1060 60

It has been demonstrated that nitric oxide (NO) is a major inhibitory nonadrenergic, noncholinergic (NANC) neurotransmitter in the gastrointestinal (GI) tract. NO released in response to nerve stimulation of the myenteric plexus causes relaxation of the smooth muscle. NO is synthesized by the activation of neuronal NO synthase (nNOS) in the myenteric plexus. Released NO plays an important physiological role in various parts of the GI tract. NO regulates the muscle tone of the sphincter in the lower esophagus, pylorus, sphincter of Oddi, and anus. NO also regulates the accommodation reflex of the fundus and the peristaltic reflex of the intestine. Previous studies have shown that NOS inhibitors delay gastric emptying and colonic transit. The reduction of nNOS expression, associated with impaired local production of NO, may be responsible for motility disorders in the GI tract. There is accumulated evidence that dysfunction of NO neurons in the myenteric plexus may cause various GI diseases. These reports are reviewed and possible mechanisms of altered nNOS expression are discussed in this article. In particular, impaired nNOS synthesis of the myenteric plexus seems to be an important contributing factor to the pathogenesis of achalasia, diabetic gastroparesis, infantile hypertrophic pyloric stenosis, Hirschsprung's disease, and Chagas' disease. Reduced NO release and/or nNOS expression are suspicious in a subset of patients with functional dyspepsia. Although the etiology of intestinal pseudo-obstruction remains unknown, it is conceivable that extrinsic denervation may upregulate nNOS expression, resulting in enhanced muscular relaxation and disturbed peristalsis. An animal model of colitis showed impaired nNOS expression in the colonic myenteric plexus. Antecedent infection may be associated with the impaired NO pathways observed in functional dyspepsia, colitis, and Chagas' disease.
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PMID:Pathophysiological significance of neuronal nitric oxide synthase in the gastrointestinal tract. 1276 83

Nitric oxide (NO), produced by the neural nitric oxide synthase enzyme (nNOS) is a transmitter of inhibitory neurons supplying the muscle of the gastrointestinal tract. Transmission from these neurons is necessary for sphincter relaxation that allows the passage of gut contents, and also for relaxation of muscle during propulsive activity in the colon. There are deficiencies of transmission from NOS neurons to the lower esophageal sphincter in esophageal achalasia, to the pyloric sphincter in hypertrophic pyloric stenosis and to the internal anal sphincter in colonic achalasia. Deficits in NOS neurons are observed in two disorders in which colonic propulsion fails, Hirschsprung's disease and Chagas' disease. In addition, damage to NOS neurons occurs when there is stress to cells, in diabetes, resulting in gastroparesis, and following ischemia and reperfusion. A number of factors may contribute to the propensity of NOS neurons to be involved in enteric neuropathies. One of these is the failure of the neurons to maintain Ca(2+) homeostasis. In neurons in general, stress can increase cytoplasmic Ca(2+), causing a Ca(2+) toxicity. NOS neurons face the additional problem that NOS is activated by Ca(2+). This is hypothesized to produce an excess of NO, whose free radical properties can cause cell damage, which is exacerbated by peroxynitrite formed when NO reacts with oxygen free radicals.
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PMID:The involvement of nitric oxide synthase neurons in enteric neuropathies. 2189 78

The etiology of achalasia is believed to be the neuropathy associated with chronic inflammation of the nerve plexus, but the cause of plexus inflammation is unknown. The purpose of this study was to evaluate the pathophysiology of achalasia by examining the muscularis externa of the esophagus. We used the muscularis externa of the esophagus of 62 patients with achalasia (median 44 years, male : female 32:30) who underwent surgical treatment (achalasia group) and of 10 patients (median 65.5 years, male : female 9:1) who underwent esophagectomy for thoracic esophageal cancer (control group) to perform immunohistochemical staining with S-100, CD43, c-kit (CD117), n-NOS, vasoactive intestinal polypeptide (VIP), and ubiquitin. The cell counts that were positive for S-100, n-NOS, VIP, and ubiquitin were significantly lower in the achalasia group compared with the control group (P < 0.001, P= 0.001, P < 0.001, and P= 0.001, respectively). There were no statistically significant differences with respect to CD43 and c-kit staining (P= 0.586 and P= 0.209, respectively). In conclusion, the pathophysiology of achalasia is therefore considered to be an impaired production of NO and VIP, which both affect interstitial cell of Cajal and smooth muscles, and this impairment is therefore considered to play a role in the pathophysiology of achalasia.
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PMID:Immunohistochemical study of the muscularis externa of the esophagus in achalasia patients. 2230 23