Perfluorooctane sulfonate exposure alters sexual behaviors and transcriptions of genes in hypothalamic–pituitary–gonadal–liver axis of male zebrafish (Danio rerio)

Perfluorooctane sulfonate (PFOS) has been reported to be widely distributed in the environment and wildlife with persistence. PFOS has various biological toxicity, especially disturbing the endocrine system. However, few studies have systematically evaluated its effect on sexual behaviors alteration and reproduction-related genes. This study was performed to assess the effect of PFOS exposure on sexual behaviors and genes in hypothalamic–pituitary–gonadal–liver (HPGL) axis in adult zebrafish. Male adult zebrafish were exposed to PFOS (0, 2, 20, and 200 μg/L) and 5 μg/L estradiol (E2) continuously for 21 days. Sexual behaviors were analyzed by zebrafish behavior tracking system and the mRNA levels of HPGL-related genes was detected by RT-qPCR. Body weight of the fish was increased in 2, 200 μg/L PFOS and E2 groups, and body length was increased with exposure to 2 μg/L PFOS and E2. The hepatic-somatic index was decreased significantly after 2 and 20 μg/L PFOS treatments. Highest PFOS (200 μg/L) and E2 exposure impaired standard zebrafish sexual behaviors significantly such as chasing, nose-tail and tail-touching. In brains, the genes gonadotropin-releasing hormone (GnRH), gonadotropin-releasing hormone receptor (GnRHr) were down-regulated with exposure to PFOS with linear trend and E2 exposure, and follicle-stimulating hormone and luteinizing hormone were also down-regulated with exposure to 20 and 200 μg/L PFOS. In livers, the genes vitellogenin 1 and 3 were upregulated with some concentrations of PFOS and E2, but estrogenic receptor α, β2 were upregulated in any concentration of PFOS and E2. In testes, the expressions of follicle-stimulating hormone receptor, luteinizing hormone receptor, and androgen receptor genes were all significantly down-regulated with any exposure concentration of PFOS and E2. PFOS may alter the zebrafish reproductive system by disrupting endocrine activity and impairing sexual behaviors.