Bisphenol A modulates expression of gonadotropin subunit genes in the hermaphroditic fish, Kryptolebias marmoratus

Abstract

Pituitary gonadotropins (GTHs), follicle stimulating hormone β (FSH-β), and luteinizing hormone β (LH-β) are the key hormones in the hypothalamus–pituitary–gonad (HPG) axis, and form the heterodimers between a common α subunit (gonadotropin-α) and FSH-β and/or LH-β. To obtain a better understanding on the modulation of gonadotropin subunit genes expression upon bisphenol A (BPA) exposure in hermaphroditic fish, we studied differential regulation of gonadotropin subunit genes from Kryptolebias marmoratus after the exposure of several EDCs. Expression profiles of these three genes when using quantitative real-time RT-PCR revealed that brain/pituitary tissues were highly expressed in these genes compared to other tissues. At different developmental stages, expression of those genes dramatically increased over the course of development but showed a decrease in expression at the secondary male (showing atresia) stage. When adult fish were exposed to BPA (600 μg/L for 96 h), a significant upregulation of these three genes was observed in the brain/pituitary. A time course study also revealed the increased expression of gonadotropin subunit genes over 12 h with a more pronounced effect on the expression of FSH-β and LH-β genes, indicating that both genes were associated with the BPA exposure on the transcriptional regulation. This is the first report of gonadotropin subunit genes from K. marmoratus, with particular emphasis on the modulation of their expressions by EDCs. In addition, these findings suggest that EDCs modulate the expression of gonadotropin subunit genes and would act as potential biomarkers upon EDCs exposure.