Abstract Title

Session S-08C: Occurrences and Impacts of Emerging Contaminants

Proposed Abstract Title

The pituitary gland as a target of endocrine disrupting compounds in coho salmon, Oncorhynchus kisutch

Keywords

Emerging Contaminants and Emergencies

Location

Room 606

Start Date

2-5-2014 8:30 AM

End Date

2-5-2014 10:00 AM

Description

There is growing evidence that chemicals in the aquatic environment may interfere with reproduction of fish. In vertebrates, the pituitary gland is a central regulator of reproduction, producing the gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which regulate gonadal development, sex steroid synthesis and gamete maturation. Despite the pituitary’s central role in regulating reproduction, there are limited data on impacts of contaminants of emerging concern (CECs) on the pituitary gland. Using high-throughput Illumina® sequencing and RNA-Seq we previously found that LH beta subunit (lhb) and FSH beta subunit (fshb) were among the most significantly up- and down-regulated transcripts, respectively, in immature coho salmon exposed to 17α-ethynylestradiol (EE2; synthetic estrogen in oral contraceptives) for up to 6 weeks. The aim of this study was to further our understanding of the potential impacts of CECs on gonadotropin synthesis. To this end, immature coho salmon were exposed to 0, 25 or 500 ng/L fluoxetine (FLX; antidepressant present in wastewater effluent) or 12 ng/L EE2 for up to 6 weeks in flow-through tanks. Total pituitary RNA was collected and gonadotropin subunit mRNA levels were analyzed by quantitative RT-PCR. As we previously found, 12 ng/L EE2 significantly up-regulated lhb mRNA levels at 1 and 6 weeks (450-fold and 1200-fold respectively) and down-regulated fshb at 6 weeks (-3-fold). Six weeks exposure to at least 25 ng/L fluoxetine also decreased fshb transcript levels (-2-fold) but had no effect on levels of lhb. In conclusion, we have shown that environmentally relevant levels of EE2 and FLX alter lhb and fshb mRNA levels in immature coho salmon. These results suggest that CECs may disrupt pituitary function and alter gonadotropin synthesis. Further research is needed to understand the effects of EE2 and FLX on FSH secretion and possible synergistic effects of EE2 and FLX with other chemicals in the environment. This project was supported in part by Washington SeaGrant project RB49 and EPA-Star project R835167.

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May 2nd, 8:30 AM May 2nd, 10:00 AM

The pituitary gland as a target of endocrine disrupting compounds in coho salmon, Oncorhynchus kisutch

Room 606

There is growing evidence that chemicals in the aquatic environment may interfere with reproduction of fish. In vertebrates, the pituitary gland is a central regulator of reproduction, producing the gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which regulate gonadal development, sex steroid synthesis and gamete maturation. Despite the pituitary’s central role in regulating reproduction, there are limited data on impacts of contaminants of emerging concern (CECs) on the pituitary gland. Using high-throughput Illumina® sequencing and RNA-Seq we previously found that LH beta subunit (lhb) and FSH beta subunit (fshb) were among the most significantly up- and down-regulated transcripts, respectively, in immature coho salmon exposed to 17α-ethynylestradiol (EE2; synthetic estrogen in oral contraceptives) for up to 6 weeks. The aim of this study was to further our understanding of the potential impacts of CECs on gonadotropin synthesis. To this end, immature coho salmon were exposed to 0, 25 or 500 ng/L fluoxetine (FLX; antidepressant present in wastewater effluent) or 12 ng/L EE2 for up to 6 weeks in flow-through tanks. Total pituitary RNA was collected and gonadotropin subunit mRNA levels were analyzed by quantitative RT-PCR. As we previously found, 12 ng/L EE2 significantly up-regulated lhb mRNA levels at 1 and 6 weeks (450-fold and 1200-fold respectively) and down-regulated fshb at 6 weeks (-3-fold). Six weeks exposure to at least 25 ng/L fluoxetine also decreased fshb transcript levels (-2-fold) but had no effect on levels of lhb. In conclusion, we have shown that environmentally relevant levels of EE2 and FLX alter lhb and fshb mRNA levels in immature coho salmon. These results suggest that CECs may disrupt pituitary function and alter gonadotropin synthesis. Further research is needed to understand the effects of EE2 and FLX on FSH secretion and possible synergistic effects of EE2 and FLX with other chemicals in the environment. This project was supported in part by Washington SeaGrant project RB49 and EPA-Star project R835167.