Effects of endocrine disruptor mixtures on functions of cultured porcine ovarian follicular cells.

Abstract

Objective. Involvement of various endocrine disruptors (EDs) in pathophysiology of reproductive system disorders has been suggested previously. The studies have shown adverse effects of the individual substances, however, in the real-life situation, numerous chemicals enter the organism on a daily basis. This points to the importance of examination of the combined effects of exogenous chemicals on biological systems, including reproductive system. The ovaries are a target of different EDs, which may impact the processes within the ovarian follicles. The aim of the present study was to examine the effects of binary or ternary mixtures combining selected nonpersistent disruptors: bisphenol A (BPA), BPA-dimethacrylate (BPADM), benzyl butyl phthalate (BBP), 4-chloro-3-methylphenol (CMP), or alkylphenols (4-octylphenol, OP; 4-nonylphenol, NP; and tert-octylphenol, TOP) on ovarian follicular cell functions. Methods. Porcine oocyte-cumulus complexes (OCCs) and granulosa cells (GCs) were treated with the tested ED mixtures (BPA+BBP, CMP+BBP, BPA+BPADM, BPA+BBP+CMP, and OP+NP+TOP) in a wide concentration range from 10-10 to 10-4 M. Follicle-stimulating hormone (FSH)-induced cumulus expansion was assessed after 24 h of culture according to a subjective scoring system. After 44-h treatment, oocyte nuclear maturation was evaluated. Basal and FSHstimulated progesterone production by OCCs and GCs was measured by commercial radioimmunoassay after 44 h and 72 h of the culture, respectively. One-way ANOVA and Bonferroni post-test were used for statistical analysis of data. Results. The results obtained showed that the lower concentrations of ED mixtures (10^-10- 10^-6 M) did not exert significant changes, while the highest concentration (10-4 M) significantly inhibited cumulus expansion, oocyte meiotic maturation, and progesterone production by OCCs and GCs. Moreover, the inhibitory effects of ED mixtures seem to be more profound than the effects caused by the individual substances. Conclusion. The experimental approach of testing mixtures should provide a more comprehensive view on the effects of the ubiquitous EDs on various cell types of the reproductive organs.