Effect of Phenol on Ovarian Secretion of 17β-Estradiol in Common Carp Cyprinus carpio

Abstract

Phenol is a common substance present in many industrial wastewaters and in nonspecific pesticides. Due to its solubility and volatility phenol is often found in marine and freshwater environment. It is lipophilic compound and has a high potential for accumulating along the trophic chain. Phenol thus is not only a threat to natural environment but also to human health. The effects of phenol on the secretion of 17β-estradiol were examined in female common carp Cyprinus carpio. Vitellogenic stage fish were exposed to physiological safe dose of phenol for 0, 24, 48 and 96h. In the in vitro experiments, vitellogenic follicles were incubated with phenol and dose- and time-course effects on leuteinising hormone (LH) induced steroid production were examined. Exposure of fish with phenol gradually attenuated serum and ovarian 17β-estradiol levels with increasing time and maximum inhibition was noticed after 96h. Administration of phenol significantly inhibited LH-induced secretion of 17β-estradiol by the ovarian follicles in vitro. To clarify the mechanism of attenuated production of 17β-estradiol in phenol-treated follicles, stimulated by LH, in vitro effect phenol and LH on aromatase activity (conversion of testosterone to 17β-estradiol) and cytochrome P450arom gene expression in carp ovarian follicles were investigated. Physiological safe dose of phenol significantly inhibited LH-stimulated aromatase activity and P450arom gene expression in ovarian follicles. The present study further demonstrated that LH-induced activation of ovarian steroidogenic factor-1 (SF-1) is strongly inhibited by phenol treatment. These results suggest that physiological safe dose of phenol as endocrine disruption (ED) potential and the effect can be mediated via several cellular pathways including the inhibition of SF-1 activity, aromatase activity and P450arom gene expression.