U.S. Department of Health and Human Services

Sex-specific Differences in Pelvic Pain of Interstitial Cystitis/Painful Bladder Syndrome

Researchers studying interstitial cystitis/painful bladder syndrome (IC/PBS) in a rodent model have found evidence that females experience greater pelvic pain than males, but that this disparity does not correspond to estrogen levels or differences in bladder injury. The majority of IC/PBS patients are women, and some evidence has suggested a role for the hormone estrogen, the primary female sex hormone, in IC/PBS pain symptoms. Researchers investigated this hypothesis in a specific mouse model of IC/PBS. In this model, irritated nerves release a chemical that activates inflammatory cells in the bladder. These inflammatory cells, called mast cells, release histamine and other chemicals that inflame the bladder lining and cause pain. This “neurogenic cystitis” model recapitulates the pelvic pain seen in human patients and is also thought to be one possible pathway for how human IC/PBS develops. Using both female and male mice, the researchers induced nerve irritation with a viral infection and then compared female and male mice for potential sex-specific differences in pelvic pain, and also examined the effects of estrogen levels and genetic background. They found that while one genetic strain of mice experienced more pain than another, female mice from either strain experienced greater pelvic pain than male mice. However, when the scientists ablated estrogen production in some of the female mice prior to the viral infection, they found no significant differences in pelvic pain between those that had normal levels of estrogen and those that did not. Female and male mice with neurogenic cystitis also sustained similar levels of bladder inflammation and injury, making this a less likely explanation for differences in pelvic pain. These findings suggest that, in this rodent model of neurogenic cystitis, sex differences in pelvic pain exist but are not dictated by estrogen; genetic differences play a role in determining susceptibility to pelvic pain; and the two may be related. Further study of sex differences and the role of genetics in pelvic pain could have important implications for understanding IC/PBS pain in people.

Rudick CN, Pavlov VI, Chen MC, and Klumpp DJ. Gender specific pelvic pain severity in neurogenic cystitis. JUrol187: 715-724, 2012.​