Effects of PCB-77 in adult zebrafish after exposure during early life stages

Abstract

Polychlorinated biphenyls (PCBs) are a class of industrial chemicals that cause endocrine changes, since they are able to bind to estrogen receptors and interfere with estrogen-regulated processes, such as fish vitellogenesis. Therefore, the present work aimed to assess potential endocrine effects of PCB-77 exposure during zebrafish (Danio rerio) gonadal differentiation. To achieve that, zebrafish juveniles were exposed to increasing concentrations of PCB-77 for 14 days during a critical window of gonad differentiation (30–44 days post-fertilization). Vitellogenin (Vtg) levels and several endpoints such as survival, growth, gonadosomatic index (GSI) and hepatosomatic index were recorded at the end of exposure and/or after 3 months in clean medium. The results obtained showed a reduction of Vtg-like proteins in juveniles, just after exposure to PCB-77 accompanied, after 3 months, by a decrease in gonadal Vtg levels and GSI of females. These results suggest that exposure to PCB-77 during the critical window of gonadal differentiation decreased vitellogenesis in juvenile zebrafish which lasted until adulthood affecting the normal development of female gonad, which might have further implications in reproduction success.

Keywords:

• Danio rerio
• endocrine disruption
• fish
• ovaries
• persistent organic pollutants
• vitellogenin

Acknowledgments

Thanks are due for the financial support to CESAM (UID/AMB/50017/2019), to FCT/MEC through national funds, and the co-fundingby the FEDER, within the PT2020 Partnership Agreement and Compete 2020. The work of MSM and CQ is funded by national funds (OE), through FCT – Fundação para a Ciência e a Tecnologia , I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19.

Additional information

Funding

The Portuguese Foundation for Science and Technology (FCT) and POCH/UE (Programa Operacional Capital Humano/União Europeia) supported the post-doctoral fellowships of CQ (SFRH/BPD/89951/2012) and MSM (SFRH/BPD/100448/2014). We acknowledge the financial support of CESAM (UID/AMB/50017/2013), through the FCT/MEC national funds, and the co-funding by the FEDER (POCI-01-0145-FEDER-00763), within the PT2020 Partnership Agreement and Compete 2020.