Reproductive toxicity and estrogen activity in Japanese medaka (Oryzias latipes) exposed to environmentally relevant concentrations of octocrylene

The growing use of octocrylene (OC) in sunscreens has posed a great threat to aquatic organisms. In the present study, to assess its reproductive toxicity and mechanism, paired Japanese medaka (Oryzias latipes) (F0) were exposed to OC at nominal concentrations of 5, 50, and 500 mu g/L for 28 d. Significant increases were observed in the gonadosomatic index (GSI) and hepatosomatic index (HSI) of F0 medaka at 500 mu g/L OC (p < 0.05) without significant differences in fecundity. The fertility was significantly decreased at all treatments (p < 0.05). Significant increases in the percent of mature oocytes were observed at 5 and 500 mu g/L OC, in which contrary to the percent of spermatozoa (p < 0.05). The plasma sex hormones and vitellogenin levels significantly increased in males at all treatments and in females at 50 and 500 mu g/L OC (p < 0.05). In addition, the levels of fsh beta and lh beta in the brains and the levels of fshr, lhr and cyp17 alpha in the gonads were significantly upregulated in males at all treatments (p < 0.05), in line with those of ar, er alpha, er beta and cyp19 beta in the brains of male and female. The upregulation of vtg in male and female livers was observed only at 500 mu g/L OC and upregulation of star and hsd3 beta was observed in testis at all treatments (p < 0.05). Continued exposure to OC significantly induced increases in the time to hatching, morphological abnormality rates, and cumulative death rates of F1 embryos, inconsistent with body length of F1 larvae (p < 0.05). Therefore, the responses of the exposed fish at the biochemical and molecular levels indicated reproductive toxicity and estrogenic activity of OC, providing insights into the mechanism of OC. (C) 2020 Elsevier Ltd. All rights reserved.