Effects of nonylphenol on the production of progesterone on the rats granulosa cells

We investigated the effects of nonylphenol (NP) on release of progesterone (PG) by granulosa cells (GCs) of rats in vitro and in vivo. First, GCs were treated with different doses of NP for 2-24h alone or with human chorionic gonadotropin (hCG). Maximal PG secretion at 8h noted, GCs were treated for 2h with hCG, 8-bromo-adenosine 3′:5′-cyclic monophosphate (8-Br-cAMP), forskolin, A23187, nifedipine, and pregnelonone to evaluate the NP effects on PG steroidogenesis. Results indicated that all of chemicals except nifedipine stimulated the PG release compared to vehicle, but the stimulatory effects could not be enhanced by different doses of NP. Second, GCs were isolated to react with hCG, 8-Br-cAMP and PD98059 after the immature female rats gavaged with different doses of NP (ONP) for 7 days. PG released significantly when rats treated with oral NP 100 compared to 0μg/kg/day. Third, GCs collected from the female offspring of mother rats which gavaged with NP 100μg/kg/day for 21 days during pregnancy (MONP) reacted with different doses of chemicals. The results showed that PG release in the presence of chemicals was significantly higher in ONP and MONP groups; however, this stimulation was not noted by dose-dependent. The plasma concentration of PG was higher in ONP (100μg/kg/day) and the offspring of MONP groups. The steroidogenic acute regulatory (StAR) protein expressed higher in all three groups by Western blotting. This study results indicated that low dose of NP stimulated PG release in rat GCs by activation of StAR protein.