Colon plays major role in interstitial cystitis flare-ups

In a surprising new finding, researchers from Northwestern University's Feinberg School of Medicine in Chicago have shown that the colon is irritated by spicy food, which can cause a flare-up of symptoms in patients with interstitial cystitis.

The findings, which were published in Nature Clinical Practice Urology (2008; 5:494-500), provide an explanation for how the body actually “hears” pelvic pain and opens up new treatment possibilities, researchers say.

The researchers discovered that the colon's central role in the pain is caused by the wiring of pelvic organ nerves. When the colon is irritated by food, colon nerves also send a pain signal to the spinal cord, and this new signal is the tipping point.

“It was known that there was cross talk between organs, but until now, no one had applied the idea to how pain signals affect this real-world disease, how the convergence of these two information streams could make these bladder symptoms worse," said principal investigator David Klumpp, PhD.

The findings suggest the bladder pain can be treated rectally with an anesthetic in a suppository or applied topically to pelvic skin, Dr. Klumpp said.
In the study, Dr. Klumpp and colleagues created a model of a mouse that mimicked an inflamed bladder with pelvic pain. They injected lidocaine into the bladder, and the pain vanished. Next, they injected lidocaine into the uterus, and there was no diminishment of the pain. Lastly, they tried lidocaine in the colon.

"In the colon, it knocked down pain just as effectively as if we put it in the bladder. We thought if the colon can suppress bladder-associated pain, maybe it can make it worse in the way that foods irritate bladder symptoms," Dr. Klumpp explained.

To test this, researchers injected a small dose of red pepper into the colon of a normal mouse. The injection didn't provoke any pain, but when a similar injection was made into a mouse with pelvic pain, the pelvic pain worsened.

"We likened it to what happens to humans," Dr. Klumpp said. "Pepperoni pizza does nothing to most people other than heartburn, but when you give it to a person with an inflamed bladder, that will cause their symptoms to flare because the nerves from the bladder and bowel are converging on the same part of the spinal cord."

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