In this study, anaphylaxis was induced in both female and male mice by using histamine, as well as Immunoglobulin E (IgE) and Immunoglobulin G (IgG) receptor aggregation. Anaphylaxis was assessed by monitoring body temperature, release of mast cell mediators, and lung weight.
Researchers were able to observe that female mice experienced anaphylaxis that was more severe and lasted longer compared to their male counterparts. This enhanced severity was eliminated after pretreatment with an estrogen receptor antagonist or ovariectomy. They found that estrogen influenced blood vessels and enhanced the levels and activity of endothelial nitric oxide synthase (eNOS), an enzyme that drives anaphylaxis. When eNOS activity was blocked, the gender difference disappeared. When they blocked estrogen in female mice, this decreased the severity of their allergic responses.
This study demonstrates a link between estrogen and eNOS in severe allergic reactions in female mice. The results may shed light on why women have more severe allergic reactions than men, however, further research is needed to determine whether there is a similar effect in humans.
Estrogen increases the severity of anaphylaxis in female mice through enhanced endothelial nitric oxide synthase expression and nitric oxide production, Valerie Hox, et.al.,The Journal of Allergy and Clinical Immunology, doi:https://dx.doi.org/10.1016/j.jaci.2014.11.003, published 29 December 2014.