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The effects of progesterone and synthetic derivatives on Fathead Minnow ( Pimphales promelas ) embryos. JA Stine and DB Huggett, Ph.D. Department of Biological Sciences Ronald E. McNair Post Baccalaureate Achievement Program University of North Texas Denton, Texas. Introduction: . - PowerPoint PPT Presentation
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The effects of progesterone and synthetic derivatives on Fathead Minnow (Pimphales promelas) embryos.
JA Stine and DB Huggett, Ph.D.Department of Biological Sciences
Ronald E. McNair Post Baccalaureate Achievement ProgramUniversity of North Texas
Denton, Texas
Introduction:
• Pharmaceuticals and personal care products are being routinely detected in surface waters throughout the United States.
• Little information is available on their fate and potential effects in aquatic systems.
• This project attempts to quantify the effect of progesterone and its synthetic derivatives on aquatic organisms.
Progesterone Background• Progesterone and its synthetic forms are
commonly used for the purpose of oral contraception and hormone replacement therapy in humans.
• In fish, progestins (e.g. 17α,20β-dihydroxy-4-pregnen-3-one) are extremely important for many physiological processes, including oocyte maturation and embryo morphogenesis.
• Given the importance of progestins in mammals and fish, it is essential to determine the developmental consequences of progesterone and synthetic derivatives in the environment.
Fathead Minnow
• The organism used in this study is the fathead minnow (Pimephales promelas).
• Vast amount of data available concerning all aspects of growth, life cycle, and development.• Known “sentinel species” for aquatic toxicity.• Widely available and easily cultured.
Objectives of Study:
• To determine the developmental toxicity of progesterone, norethindrone, and medroxyprogesterone to the fathead minnow.
• This objective will be achieved by:1.Exposing fathead minnow embryos for 96 hr to each
of the test chemicals2.microscopically staging and investigating
developmental abnormalities3.assessing survival after the 96 hr exposure.
Materials and Methods:
• P. promelas were cultured and held in standard systems in the Aquatic Toxicology Lab at the University of North Texas.
• < 24 hr old eggs collected and sorted prior to exposure.
• P. promelas eggs were placed in exposure jars with differing concentrations of progesterone or synthetic derivatives.
• 10 eggs were placed in each of three replicate jars for a total of 30 eggs exposed per concentration.
Materials and Methods, Cont’d.• The eggs were staged and observed every 24
hr until the exposure was terminated (96 hr). • Abnormalities or death of embryos were
noted and recorded.• Exposure solutions were renewed every 24 hr
(static renewal).• Images of abnormal embryos were taken on
the last day of the study using a Ziess dissecting scope, digital camera, and Axiovision software.
Figure 1. Lethality of Compounds
Progesterone Medroxyprogesterone Norethindrone0
5
10
15
20
25
30
35
Lethality of Progesterone Compunds 96 Hr. post Exposure
ControlSolvent Control0.625 mg/L1.25 mg/L2.50 mg/L5.0 mg/L
Exposure Compound
Num
ber S
urvi
ving
Figure 2: Number Of Abnormalities
Progesterone Medroxyprogesterone Norethindrone0
5
10
15
20
25
30
Number of Abnormalities 96 hr. Post Exposure
.078 mg/L
.15625 mg/L
.3125 mg/L0.625 mg/L21.25 mg/L22.50 mg/L25.0 mg/L2
Exposure Compound
Num
ber o
f Def
orm
ities
Figure 3: Bradycardia per Concentration
Control Solvent Control
0.78 mg/L .15625 mg/L
.3125 mg/L 0.625 mg/L 1.25 mg/L 2.50 mg/L 5.00 mg/L0
20
40
60
80
100
120
140
160
Bradycardia Per Exposure Concentration
ProgesteroneMedroxyprogesterone
Concentration of Exposure Compound
Hear
trat
e in
Bea
ts P
er M
inut
e (b
pm)
Discussion of Findings:
• The rank order potency in this experiment was: progesterone > medroxyprogesterone > norethindrone
• Progesterone significantly reduced survival at concentrations ≥ 1.25 mg/L.
• All compounds tested produced cardiovascular abnormalities.
Discussion of Findings, Cont’d.
• An increased prevalence of cardiac edema, ventricular enlargement and elongation were observed at 0.625 mg/L.
• Bradycardia was observed beginning at the lowest dose concentration, 0.078 mg/L, and increased proportionally per exposure concentration.
• Mammalian data demonstrate that progesterone does alter normal cardiovascular physiology.
• In the 2.5 and 5 mg/L medroxyprogesterone exposed fish, blood accumulated in the heads of the fish.
Figure 4. Representative Embryos following 96 Hr. Exposure to Progesterone
Directions for Future Research:
• Further study is needed to determine the mechanism(s) of malformations in the fathead minnow embryos following progestin exposure.
• Are amphibian embryos affected in the same way as piscine embryos?
• What are the Lowest Observable Effect Level (LOEL) for progesterone and synthetics or both fish and amphibians?
• What is the LC50 for progesterone and synthetics?
• Is the Nip3a pathway affected by presence of exogenous progesterone?
• Perform field studies to investigate the impacts of progesterone on fish and amphibians
• Cattle dominated watersheds
Acknowledgements:
UNT McNair Scholars ProgramDr. David HalaDr. Lene PetersenMr. David Baxter UNT Department of Biological Sciences
Literature Cited:
Brammer, JD; Puyear, R; et al; Prehatching development of the Fathead Minnow, Pimephales promelas Rafinesque.; July 1996. EPA 600-R-96-079. Office of Research and Development, U.S. Environmental Protection Agency. 49 pages