- Abstract: The aim of this study was to analyze the effects of synthetic para-nonylphenol isomers administered chronically throughout pregnancy and lactation on the reproductive system of mouse pups. The two synthetic isomers used in this study showed higher (3E22NP) or lower (44NP) estrogen receptor (ER) binding activity on in vitro yeast assay than a commercial NP (NPmix). Female mice were implanted with a tube filled with one of three NPs and estradiol-17 β (E2) before mating. The tube was kept in... Show More
Publications citing this author (4)
[Show abstract] [Hide abstract] ABSTRACT: Nonylphenol (NP) has been proven to be one of the most investigated xenohormones interacting with the estrogen receptor. Technical nonylphenol (t-NP) contains at least 20 para-substituted isomers. It has been shown that NP isomers vary in their estrogenic potency. So the use of mixtures or impure substances can lead to misinterpretations and unsatisfying conclusions. In the present study, experiments were performed to examine effects of NP isomers on steroidogenesis of rat Leydig cells. Primary cultured Leydig cells were exposed to NP isomers (p33-NP, p262-NP, p353-NP, p363-NP) at the optimized inhibitory concentration 5μmol/L for 6h. NP isomers showed various degrees of inhibition of testosterone biosynthesis, with p363-NP leading to the most significant decrease and others sharing the similar efficacy. The expression of 3b-HSD, Cyp11a1, Star and the apoptosis of Leydig cells were further measured to investigate the underlying mechanisms. We demonstrated that NP isomers can affect the steroidogenesis of rat Leydig cells, at least in part, through their influence on gene expression and cell apoptosis, but varied in their individual degree. However, the final results were not completely coincident with their estrogenic potency tested in vitro, which implies that effects of NP isomers on steroidogenesis appear to be mediated through some other underlying mechanisms besides their various estrogenic potency.
- In a research performed by Sato et al. (2009) , 3E22NP and 44NP were chosen since 3E22NP has 9.2 times higher activity than 44NP (Katase et al., 2008). To their surprise, there were similar differences to the control for both isomers in vivo, in spite of the large difference in the estrogenic potency in vitro (Katase et al., 2008; Sato et al., 2009 ). These unexpected results have presented an essential question whether the effects of NP isomers on steroidogenesis are related to their estrogenic potency to bind to ER, but at the moment there is no definite explanation for this discrepancy.