Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0022104 (irritable bowel syndrome)
 8,033 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Over the last decade, the role of visceral sensitivity has been largely recognized in the pathophysiology of functional digestive disorders, particularly in the irritable bowel syndrome. These studies have highlighted the role of afferent pathways arising from the gut as a possible target for new treatments intended to relieve pain or modify altered reflexes present in such patients. These pharmacological targets have been identified mainly by studies on animal models of visceral hyperalgesia of various origins including local inflammation. Locally, several mediators are of paramount importance for sensitization of nerve endings: 5-hydroxytryptamine, bradykinin, tachykinins, calcitonin gene-related peptide, and neurotrophins. Selective antagonists to various subtypes of their receptors are currently available and have been shown to be active in these animal models. Other substances, such as somatostatin, opiold peptides, cholecystokinin, oxytocin, and adenosine, modulate the transmission of nociceptive inputs from the gut to the brain and are of clinical interest. This article reviews the current understanding of these mediators. Although these agents seem to be promising tools for the treatment of visceral hyperalgesia and its consequences (abdominal pain and disturbed reflexes), their clinical efficacy remains to be shown. A better understanding of the nature and the location of the defect in the sensory pathways may permit the selection of subgroups of patients for treatment according to the pharmacological properties of these new therapeutic agents.
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PMID:Mediators and pharmacology of visceral sensitivity: from basic to clinical investigations. 913 53

Over the past decade, attention has been paid to the role of visceral sensitivity in the pathophysiology of functional bowel disorders, especially irritable bowel syndrome, and visceral hypersensitivity is the most widely accepted mechanism responsible for both motor alterations and abdominal pain. Inflammatory mediators sensitize primary afferents, especially C-fibre polymodal nociceptors, favouring the recruitment of silent nociceptors that give rise to secondary spinal sensitization. After local tissue injury, the release of chemical mediators such as potassium ions, ATP, bradykinin and prostaglandin E2 directly activate nerve endings and indirectly trigger the release of algesic mediators such as histamine, 5-hydroxytryptamine and nerve growth factor from other cells, which, in turn, stimulate proximal afferent nerve endings and silent nociceptors. Among the intermediary structures activated by inflammatory mediators and susceptible to the release of proalgesic substances, mast cells and platelets play a crucial role; however, immunocytes such as macrophages and neutrophils or sympathetic nerve terminals are also candidates. Moreover, events likely to activate synthesis of mediators by mast cells, such as stress and septic shock, also trigger colonic hypersensitivity. Prolonged visceral hyperalgesia may also depend on spinal sensitization. A number of substances are candidates to play a role at the spinal cord level in mediating painful and nonpainful sensations. Among them, substance P, dynorphins and glutamate play a pivotal role in postsynaptic sensitization, particularly during and after gut inflammation. Finally, despite the complexity of the relationship between inflammatory mediators and gut hypersensitivity, numerous results strongly suggest that alteration neuroimmune communications at the gut level may trigger a series of events that give rise to chronic changes in visceral sensitivity.
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PMID:Effects of inflammatory mediators on gut sensitivity. 1020 8

A complex relationship links biliary symptoms with the mechanisms of gallbladder emptying and the presence of gallstones. This relationship has been investigated by clinical studies of symptoms associated with gallstones, by investigation of gallbladder emptying and cholecystokinin (CCK) release in patients with gallstones, and after cholecystectomy, or truncal vagotomy, and in the irritable bowel syndrome (IBS). Laboratory studies examined receptor density on bovine gallbladder, and contractility of human gallbladder in response to a variety of stimuli was studied in vitro. A set of six symptoms associated with the presence of gallstones was identified; IBS appeared to be present in two-fifths of patients before cholecystectomy but only one-third of these patients had persistent IBS symptoms one year after operation. Gallbladder emptying studies confirmed the poor contraction of stone-bearing gallbladders; abnormal patterns of emptying were also found in patients with IBS. Gallbladder emptying and filling appear to be largely neurally regulated. CCK receptor density was very low in gallbladder tissue, suggesting that receptors on nerve cells might mediate the action of CCK. Relaxation of gallbladder muscle was mediated by adrenergic and nitrergic nerves. The inflammatory mediator bradykinin, however, had a strong direct action on muscle cells to cause gallbladder contraction. The work reported here gives an overview of the symptoms and mechanisms of disease associated with the presence of stones in the gallbladder.
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PMID:Arris & Gale lecture. Regulation and responses of gallbladder muscle activity in health and disease. 1459 32

There is mounting evidence that the vanilloid (capsaicin) receptor; transient receptor potential channel, vanilloid subfamily member 1 (TRPV1), is subjected to multiple interacting levels of control. The first level is by reversible phosphorylation catalyzed by intrinsic kinases (e.g. protein kinase A and C) and phosphatases (e.g. calcineurin), which plays a pivotal role in receptor sensitization vs. tachyphylaxis. In addition, this mechanism links TRPV1 to intracellular signaling by various important endogenous as well as exogenous substances such as bradykinin, ethanol, nicotin and insulin. It is not clear, however, whether phosphorylation per se is sufficient to liberate TRPV1 under the inhibitory control of phosphatydylinositol-4,5-bisphosphate. The second level of control is by forming TRPV1 heteromers and their association with putative regulatory proteins. The next level of regulation is by subcellular compartmentalization. The membrane form of TRPV1 functions as a nonselective cation channel. On the endoplasmic reticulum, TRPV1 is present in two differentially regulated forms, one of which is inositol triphosphate-dependent whereas the other is not. These three TRPV1 compartments provide a versatile regulation of intracellular Ca(2+) levels. Last, there is a complex and poorly understood regulation of TRPV1 activity via control of gene expression. Factors that downregulate TRPV1 expression include vanilloid treatment and growth factor (notably, nerve growth factor) deprivation. By contrast, TRPV1 appears to be upregulated during inflammatory conditions. Interestingly, following experimental nerve injury and in animal models of diabetic neuropathy TRPV1 is present on neurons that do not normally express TRPV1. Combined, these findings imply an important role for aberrant TRPV1 expression in the development of neuropathic pain and hyperalgesia. In humans, disease-related changes in TRPV1 expression have already been described (e.g. inflammatory bowel disease and irritable bowel syndrome). The mechanisms that regulate TRPV1 gene expression under pathological conditions are unknown but a better understanding of these pathways has obvious implications for rational drug development.
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PMID:Biochemical pharmacology of the vanilloid receptor TRPV1. An update. 1512 91

The plasma kallikrein-kinin system (KKS) participates in the pathogenesis of inflammatory reactions involved in cellular injury, coagulation, fibrinolysis, kinin formation, complement activation, cytokine secretion and release of proteases. It has been shown that KKS activation in the systemic inflammatory response syndrome results in decrease of its component plasma proteins. Similar changes have been documented in diabetes, sepsis, children with vasculitis, allograft rejection, disseminated intravascular coagulation, patients with recurrent pregnancy losses, hereditary angioedema, adult respiratory distress syndrome and coronary artery disease. Direct involvement of the KKS in the pathogenesis of experimental acute arthritis and acute and chronic enterocolitis has been documented by previous studies from our laboratory using experimental animal models. It has been found that in HK deficient Lewis rats, experimental IBD was much less severe. We showed a genetic difference in kininogen structure between resistant Buffalo and susceptible Lewis rats, which results in accelerated cleavage of HK and it is responsible for the susceptibility to the inflammatory process in the Lewis rats. It has been demostrated that therapy with a specific plasma kallikrein inhibitor (P8720) modulated the experimental enterocolitis, arthritis and systemic inflammation. Furthermore, it has been shown that a bradykinin 2 receptor (B2R) antagonist attenuates the inflammatory changes in the same animal model. We have showed that a monoclonal antibody targeting HK decreases angiogenesis and arrests tumor growth in a syngeneic animal model. In summary, these results indicate that the plasma KKS plays a central role in the pathogenesis of chronic intestinal inflammation, arthritis and angiogenesis.
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PMID:[High molecular weight kininogen in inflammation and angiogenesis: a review of its properties and therapeutic applications]. 1670 6