# underlying mechanism?



## Guest (Aug 29, 2001)

DGReview Potential Underlying Mechanism Identified for Irritable Bowel SyndromeAmerican Journal of Gastroenterology08/23/2001By Elda HauschildtVisceral afferent hypersensitivity could be the underlying mechanism in irritable bowel syndrome (IBS).Indian researchers identified the mechanism after objectively determining the hypersensitivity of gut afferents through the recording of cerebral evoked potential after rectal stimulation.They report that perception thresholds to rectal electrical stimuli are lower in IBS patients."Rectal stimulation led to recognisable and reproducible cerebral evoked potentials," say investigators from the Institute of Post Graduate Medical Education and Research in Calcutta, India.They observed: "P1, N1 and P2 latencies were shorter in IBS patients than in controls. P1/N1 amplitude was greater in IBS patients."Shorter latency and increased amplitude of cerebral evoked potential after rectal stimulation in patients with IBS compared to controls provide objective evidence supporting visceral afferent hypersensitivity as the underlying mechanism in IBS," the researchers concluded.They recorded cerebral evoked potential after rectal stimulation in 13 IBS patients and nine healthy controls.Investigators measured rectal perception thresholds to electrical stimulation. They then recorded cerebral evoked potentials from 2 centimetres behind vertex at intensity 50 percent above perception threshold and with filter settings.They note that gut hypersensitivity had already been shown to be present in IBS. American Journal of Gastroenterology, 2001; 96: 2150-2157. tom


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## Mike NoLomotil (Jun 6, 2000)

This, in combination with investigations from other investigators who have found the markers, simply corresponds well to the findings of neuroactive, neurotoxic, vasocative, and musculoactive mediators involvement in patients with IBS symptom sets. Hypersensitivity does not occur spontaneously. There are vast storehouses of chemicals which have this effect both within the bowel and within the bloodstream. The effect of specific mediators released in the gut from the humoral immune system and within the microvasuclature from the cellular immune system can and does provide the specific chemicals which upregulate the sensory and motor nerves, and lower the stimulus-response threshold of gut smooth muscle. Blocking the release of mediators by avoiding precipitating events and/or specific immunomodulaor adminsitration reduces their release thus reduces their effects and the symptoms. So thes findings are another puzzle piece which fits this puzzle well. And ths primary site of insult is the small bowel not the large bowel, so it is very difficult to study and eludes detection unless specicif markers are sought after.I just wish the investigators quantifying the chemical mediators present would get together with the investigators studying their effects and do both things at the same damn time. It would be alot easier to discuss. This has not been done concommittantly yet with a wide array of mediators and multiple-compaertments....only one here and one there in one compartment here or there (ie: PGE2 in stool, CD1 specific cells in lamina propria; ECP in jejunal washings, etc......). An effort will be mounted to do the definitive investigation of this type, but the cost is going to be high. Getting the money is going to be a challenge as no drug is going to come from it, but a better understanding of prophylaxis. So here we go again to the private sector.







MNL_______________ www.leapallergy.com


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## wanderingstar (Dec 1, 1999)

Sounds about right to me. They've known this for a while now though haven't they, it brings to mind something about filling the bowel with air and measuring pain perception... ? Or am I just making things up again?







Hypersensitivity to pain: we IBSers feel pain in response to normal goings on in our GI tract, where others would only feel a slight twinge, pressure, or nothing at all.Hypersensitivity to food: foods which can easily prompt immune responses are more likely to bother IBS people than GI-healthy people. Hypersensitivity to anxiety and stress: others feel 'butterflies' in their tummies, some IBSers get cramps and diarrhoea - it's the fight or flight response amplified. But is this article talking about pain *perception* or level of pain? Maybe it doesn't matter as the result is the same?Again, I always want to know WHY does this happen. Just like WHY do people have allergies, asthma, autoimmune diseases etc etc. ------------------susanIBS D/C type & M.E/CFS


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