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Effects of Norethindrone and Levonorgestrel on Reproductive Parameters in a Marine Fish
Citation:
Johnston, T., L. Mills, Saro Jayaraman, G. Zaroogian, D. Borsay Horowitz, AND S. Laws. Effects of Norethindrone and Levonorgestrel on Reproductive Parameters in a Marine Fish. Midwest Society of Environmental Toxicology and Chemistry (SETAC) 26th Annual Meeting, Chicago, Illinois, April 10, 2018.
Impact/Purpose:
Progestins, pharmaceuticals found in birth control pills and hormone therapies, make their way into aquatic environments through discharge from wastewater treatment plants. The impact of unintended exposure to the progestins levonorgestrel and norethindrone on reproductive endpoints in the marine fish Tautogolabrus adspersus (cunner) was investigated in laboratory experiments. Effects on egg production, egg fertility and egg viability of spawning adults was measured daily. Changes in the estrogen synthesizing enzyme aromatase in brains and gonads of exposed fish was determined. Results suggest that unintended exposure of fish to progestins in the aquatic environment may have reproductive consequences.
Description:
Progestins and other hormones are continuously added to surface and ground waters through waste water treatment plant (WWTP) effluent in concentrations of low to hundreds of ng/L (Orlando and Ellestad 2014). The exposure effects of pharmaceutical progestins from oral contraceptives and hormone replacement therapy on aquatic wildlife have been minimally understood and are now just emerging as important studies (Orlando and Ellestad 2014, Fent 2015). In surface waters, the progestin levonorgestrel (LNG) has been found in concentrations of 5.3-7 ng/L and NOR at 2.8 ng/L (Vulliet et al. 2008). Most research on the effects of progestins in teleost fish has been conducted using fresh water species (Orlando and Ellestad 2014). We present here the effects of NOR and LNG upon reproductive endpoints in cunner (Tautogolabrus adspersus), a marine reef fish. Our goal was to compare egg production, egg fertility, and egg viability over the course of the study period for the LNG and NOR studies. We were also interested in changes in aromatase activity in brains and gonads of cunner exposed to NOR and LNG, as well as any changes in gonadosomatic index (GSI). To test the effects of LNG and NOR, we divided actively spawning cunner among 18 experimental tanks for each test chemical. Each tank received one male and two female cunner. We randomly assigned each tank to one of three gavage treatments for both the LNG and NOR studies. We assessed egg production, fertility, and viability daily. We isolated microsomes from cunner brains and gonads that had been collected at the end of the reproductive experiments and analyzed them for aromatase activity. In our studies, LNG caused a significant decrease in cumulative egg production over time (F=9.47, p=0.0001), as well as decreases in fertility (F=31.23, p<0.0001) and viability (F=37.42, p<0.0001). Compared to controls, LNG treatment decreased aromatase activity in the brains of male fish at the high dose (p=0.019) and increased aromatase activity in ovaries in both the low dose (p=0.014) and high dose (p=0.0026). NOR caused a significant decrease in the cumulative number of eggs/g female produced (p=0.0039). NOR also caused a significant decrease in both female GSI (p=0.0089, F=6.017) and male GSI (p=0.0233, F=4.973) in the high treatment. Compared to controls, NOR increased aromatase activity in the male brain at the high (p=0.023) dose. The aromatase activities in cunner ovaries were significantly higher due to NOR treatment (p=0.00047) at the low dose. Analysis of plasma from NOR-treated fish showed NOR is metabolized to ethynylestradiol in cunner. This research suggests that marine fish may suffer reproductive impairment when exposed to progestins.