The pituitary gland as a target of endocrine disrupting compounds in coho salmon, Oncorhynchus kisutch
Presentation Abstract
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.
Session Title
Session S-08C: Occurrences and Impacts of Emerging Contaminants
Conference Track
Emerging Contaminants and Emergencies
Conference Name
Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)
Document Type
Event
Start Date
2-5-2014 8:30 AM
End Date
2-5-2014 10:00 AM
Location
Room 606
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Coho salmon--Salish Sea (B.C. and Wash.)--Endocrinology; Endocrine disrupting chemicals in water--Research--Salish Sea (B.C. and Wash.)
Geographic Coverage
Salish Sea (B.C. and Wash.)
Rights
This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.
Type
Text
Language
English
Format
application/pdf
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.
