Many people experience allergic reactions to certain foods and drugs or other allergens. Anaphylaxis is a severe allergic reaction that affects the whole body and may be life-threatening. Symptoms include dizziness, rashes, trouble swallowing, and difficulty breathing. Research has shown that anaphylaxis occurs more frequently in adult women than in men, and until recently we had no idea why. However, scientists from the National Institute of Allergy and Infectious Diseases may have found the answer. In a recent study, they showed that estradiol, an estrogen, increases the amount of an enzyme that propagates allergic reactions.
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The researchers first induced anaphylaxis in male and female mice; they found that reactions were more severe and prolonged in female mice. By pre-treating some of the female mice with an ovariectomy or an estrogen antagonist, the discrepancy in levels of anaphylaxis among males and females decreased, implying that estrogen was responsible for the reaction’s severity. When the ovariectomized mice were given estradiol, they experienced a more severe anaphylaxis compared to the males.
Estradiol contributes to anaphylaxis by increasing expression of an enzyme called endothelial nitric oxide synthase (eNOS) that produces nitric oxide (NO), leading to the increased vascular permeability (leaky blood vessels) involved in an allergic reaction. The researchers blocked eNOS and again, this got rid of the increased anaphylaxis in female mice.
To sum it up, estrogen contributes to severe allergic reactions in mice, and since female mice have more estrogen than male mice, female mice have more severe anaphylaxis.
While the mechanism of anaphylaxis in humans is less clear, this study will help guide further research on the topic and is an example of how important it is to account for gender in studies.
Feature Image Source: Allergy by Fimb
