Gender Differences in Stress Response May Explain Preponderance of IC in Women
Mohammadi E, Prusator DK, Healing E, Hurst R, Towner RA, Wisniewski AB, Greenwood-Van Meerveld B. Sexually dimorphic effects of early life stress in rat pups on urinary bladder detrusor muscle contractility in adulthood. Biol Sex Differ. 2016 Jan 27;7:8. doi: 10.1186/s13293-016-0062-1. eCollection 2016.
It remains unknown why women are more commonly affected with interstitial cystitis/painful bladder syndrome (IC/BPS). However, since IC/BPS is often reported in women with a history of adversity early in life, some researchers believe that early life stress in women may be causing abnormalities in urinary bladder muscle. To test this theory, researchers exposed young male and female rats to a stressor (“odor shock” with a strong smell given at predictable or unpredictable intervals); after the rats reached adulthood, researchers then assessed bladder function and other parameters. They found that in adulthood, the female rats exposed to unpredictable odor shocks had a significant decrease in muscle contractile responses, as well as an increase in voiding volume, compared to the female rats who received predictable odor shocks or no shocks at all. By comparison, the male rats who had been exposed to unpredictable odor shocks exhibited no difference in contractility or voiding volume. While studies in rats are not as convincing as studies in humans, researchers say there is at least now some evidence that early life stress could indeed lead to abnormalities that precipitate IC/BPS. Moreover, since the abnormalities were only evident in female rats, the researchers suggested that this is a gender specific effect that could account (at least in part) for the predominance of IC/BPS among women.