17β-estradiol and xenoestrogens reveal synergistic effect on mitochondria of human sperm.

Objectives: The aim of the study was to investigate the influence of 17β-estradiol (main endogenous estrogen) and selected xenoestrogens (genistein, bisphenol-A), individually and in combination, on the mitochondrial function of human sper-matozoa. In natural environment, human beings are exposed to multiple xenoestrogens, so their impact is combined with endogenous steroids.
Material and Methods: The effects of ligands on human spermatozoa were assessed regarding the following phenomena: spermatozoa vitality (propidium iodide staining), phosphatidylserine membrane translocation (staining with annexin V marked with fluorescein), mitochondrial membrane potential (using JC-1 fluorochrome), and production of superoxide anion in mitochondria (using MitoSOX RED dye).
Results: Two-hour incubation of spermatozoa with 17β-estradiol, genistein, and bisphenol-A neither altered cell vitality nor stimulated phosphatidylserine membrane translocation. Incubation of spermatozoa with 17β-estradiol or bisphenol-A sepa-rately, as well as incubation with the three ligands simultaneously, resulted in altered mitochondrial membrane potential. Spermatozoa incubation with the three ligands significantly increased the mitochondrial superoxide anion level.
Conclusions: It seems safe to conclude that human spermatozoa mitochondria are target cell structures for both, 17β-estradiol and xenoestrogens. The reaction to the 17β-estradiol and xenoestrogens mixture suggests a synergistic mechanism of action. Xenoestrogens may increase the sensitivity of spermatozoa to 17β-estradiol.