Toxoplasma gondii: Decreased resistance to infection in mice due to estrogen

Abstract

Exposure to pharmacological concentrations of potent estrogenic compounds, including 17β-estradiol, diethylstilbestrol, and α-dienestrol, increased the susceptibility of mice to Toxoplasma gondii as measured by brain cyst formation. Compounds with weak estrogenic activity or other hormonal activity, including 5α-dihydrotestosterone, progesterone, and zearalanol, did not alter host resistance to infection. The ability of estrogens to alter susceptibility was inhibited by the estrogen antagonist, tamoxifen. The restoration of ovariectomized mice with normal physiological concentrations of estrogen had no effect on subsequent infection with T. gondii. These results indicate that pharmacological, but not physiological, levels of estrogen selectively alter host resistance to T. gondii, possibly through hormonal events.