Estrogen increases the pain sensitivity of the female intestine and makes you more sensitive to certain foods. The discovery suggests new treatments.
Abdominal cramps, bloating, diarrhea, urgency to go to the bathroom… are some of the symptoms of irritable bowel syndrome (Irritable Bowel Syndrome, IBS), a chronic inflammation of the intestine, a disorder that affects women much more frequently. A study published in Science explains why this debilitating condition has a clear female prevalence: estrogen, the main sexual hormones in women, has something to do with it.
Pain amplifiers
A group of scientists from the University of California in San Francisco observed that these hormones alter the pain sensitivity of the intestine by acting on cellular pathways that have remained unknown until now, and increase the inflammation developed by the intestine in response to certain foods. Confirming the role of estrogen is the fact that when male mice were given the same levels of hormones as females, their sensitivity to pain in the intestine increased to that observed in their mice.
Working with mice, the scientists first tried to understand where estrogen receptors were located in the female intestine, finding them mainly in L cells, located in the lower part of the colon, the terminal tract of the digestive system. When estrogen binds to these cells, they cause them to release a hormone (peptide YY or PYY) which stimulates nearby endothelial cells, those that line the internal surface of blood vessels, to release serotonin. This neurotransmitter activates nerve fibers that sense pain. When estrogen is blocked in female mice, pain in the intestine is dramatically reduced.
The discovery also explains why the PYY hormone, long believed to be an appetite suppressant and also used in some weight loss drugs, caused significant intestinal disorders: as it emerged, it plays a role in the pain signaling pathways of the intestine.
A anti-inflammatory diet
Estrogens also increase the sensitivity of L cells to short-chain fatty acids, substances resulting from the digestion of certain foods (such as some carbohydrates that intestinal bacteria ferment, releasing short-chain fatty acids as final products). This explains why the Low-FODMAP diet, a diet low in fermentable carbohydrates often recommended to those suffering from irritable bowel syndrome, can be useful for reducing intestinal discomfort.
New therapeutic strategies
In men these same biological processes are active, but little amplified due to low estrogen levels. The important fact is that the molecular pain perception pathways found could be targeted by drugs, to limit discomfort in women with IBS.
Furthermore, knowing that hormones play such an important role in these processes will help us understand what happens in phases such as pregnancy, breastfeeding or at different times of the menstrual cycle.
