Effects of Estrogens on Astrocytes Exposed to Stressors

Hormone replacement therapy (HRT), used by many women to alleviate menopausal symptoms such as hot flashes and mood swings, is often a combination ofhormones such as estrogens, progesterone, and conjugated equine estrogens (CEE), extracted from the urine of pregnant mares. Previous studies have found positive correlations between estradiol and cellular protection, but recent research has concluded CEE provide less protective mechanisms as compared to endogenous hormones. This research sought to compare the effects of estrogen treatments (single and combined estrogen) on viability when astrocytes were induced with stressors (epinephrine, cortisol, and low oxygen concentration). Cultured human astrocytes were treated with 17p-estradiol and equilenin, either alone or in combination. Following estrogen treatments, astrocytes were induced with stressors, and an MTT assay was used to measure cell viability. Estradiol was expected to provide the most protection as a single hormone treatment for all three stressors. Higher concentrations of equilenin either alone or in combination with estradiol yielded significantly lower cell viability following epinephrine and cortisol stressors. There was no viability difference found in astrocytes stressed with low oxygen concentration. The analysis of this research helped to elucidate the relative protective effects of two forms of estrogens. Future research on estrogen binding using primary human astrocytes and neurons would help further understand the neurological effects of estrogens neurologically. The implications of this study suggest HRT could be detrimental to neurological cells, and these negative effects are dose dependent