Environmental polycyclic aromatic hydrocarbons mixture, in human blood levels, decreased oestradiol secretion by granulosa cells via ESR1 and GPER1 but not ESR2 receptor.

Tissue-dependent oestrogenic and anti-oestrogenic activity of polycyclic aromatic hydrocarbons (PAHs) has been suggested. In this study, the effect of two PAH mixtures, M1 composed of all 16 priority pollutants and M2 composed of five (noted in the highest levels) compounds, on follicle-stimulating hormone receptor (FSHR) expression, basal or FSH-induced oestradiol (E2) secretion and aromatase cytochrome P450 (P450arom) protein expression, by non-luteinised human granulosa cell line (HGrC1) was determined. In addition, the consequences of gene silencing of oestrogen receptor alfa (siESR1), oestrogen receptor beta (siESR2) and a G protein-coupled receptor (siGPER1) on the above parameters were described. Neither PAH mixture had an effect on basal FSHR protein expression; however, both mixtures increased FSH-induced FSHR expression. Decreased E2 secretion and P450arom expression was also demonstrated. In both basal and FSH treated cells, siESR1 and siGPER1 reversed the inhibitory effect of the mixtures on E2 secretion; however, in siESR2 cells, the inhibitory effect was still observed. This study showed that both classic ESR1 and GPER1 were involved in the inhibitory effect of both PAH mixtures on E2 secretion and confirmed that expression of P450arom could be downregulated through the aryl hydrocarbon receptor and additionally through the ESR2.