EDCs-induced glucocorticoid receptor related genes expression of the river pufferfish,Takifugu obscurus

Endocrine disrupting chemicals (EDCs) are of substantial concern when contaminating waters. We studied gene expression of larvae from river pufferfish, Takifugu obscurus exposed to EDCs. We cloned the full- or partial-length cDNA sequence of genes related to the cortisol pathway, such as the glucocorticoid receptor (GR), mineralocorticoid receptor (MR), heat shock protein (HSP) 70 and 90, phosphoenolpyruvate carboxykinase (PEPCK) and the FK506-binding protein 4 (FKBP52). The tissue and time-dependent expression of mRNA was studied by real-time PCR in T. obscurus exposed to two representative EDCs (bisphenol-A and 4-tert-octylphenol). HSP70, HSP90, MR and FKBP52 mRNA expression level was much higher than GR and PEPCK expression. GR mRNA expression level was significantly upregulated after 48 h in both EDC-treated fish groups compared with the control. Both groups also showed down-regulation patterns after 48 h. The initial expression of PEPCK in both groups was down-regulated after 24 h. In the bisphenol-A treated group, the expression of FKBP52 showed substantially high up-regulation from 6 to 48 h after exposure, and then strikingly reduced its expression level at 72 h. Our results provide insights into the EDCs metabolizing system of T. obscurus and offers baseline information for further research related to the possible use as a bio-indicator of this commercially important aquaculture fish species.