Age-, gender-, and tissue-dependent transcriptional responses of cyp19a1 and vtg in Murray rainbow fish Melanotaenia fluviatilis exposed to17β-estradiol

Aromatase (Cyp19a1), a key steroidogenic enzyme, which plays a key role in sex determination and differentiation. Vitellogenin (Vtg), a female specific eggprotein. However, gene is also present in juveniles and males, but normally silent; when they are exposed to estrogenic chemicals it will be activated. Current study investigated the effect of exogenous 17β-estradiol on the mRNA expression of cyp19a1 and vtg in juveniles and adult rainbow fish with exposure to either 100 or 400 ng/L E2 for 14 days. The cyp19a1 in the head and trunk region of juveniles, brain and gonads in both sexes of adult fish were studied using qPCR. Cyp19a1b was significantly elevated in the head and trunk region of juveniles at 400 ng/L E2 exposure but not at 100ng/L. Vtg showed concentration dependent increase in expression in the trunk regions of juveniles. In adults cyp19a1b significantly upregulated at 400 ng/L in brains of both sexes and in testes, but not in 100 ng/L E2. Cyp19a1a was not detected in tissues tested except for ovary and it decreased with increase in E2 concentration. In males, vtg was significantly upregulated in both concentrations of E2. Collectively, E2 at environmental concentrations can have a disruptive effect on the steroidogenic and reproductive pathways.