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EFFECTS OF THE HORMONAL GROWTH SUPPLEMENT TRENBOLONE ON REPRODUCTIVE ENDOCRINOLOGY OF THE FATHEAD MINNOW
Citation:
Ankley, G T., K M. Jensen, M D. Kahl, E A. Makynen, M. W. Hornung, J J. Korte, AND L. E. Gray Jr. EFFECTS OF THE HORMONAL GROWTH SUPPLEMENT TRENBOLONE ON REPRODUCTIVE ENDOCRINOLOGY OF THE FATHEAD MINNOW. Presented at Society of Toxicology Annual Meeting, Nashville, TN, March 17-21, 2002.
Description:
As part of an ongoing effort to develop and validate a fathead minnow (Pimephales promelas) assay to detect chemicals that affect processes controlled by estrogens and androgens, we determined the effects of trenbolone on reproductive endocrinology of the fish. Trenbolone is a synthetic androgen receptor agonist commonly used as a growth supplement in beef cattle. Reproductively-active animals were exposed for 21 days via the water to nominal trenbolone concentrations of 0, 5, 50, 500, 5000 and 50,000 ng/L. During this time, reproductive performance of the fish was monitored daily. At conclusion of the assay, a number of parameters related to endocrine function were assessed in the animals. Reductions in fecundity of the fish, and masculinization of the females were observed in concentrations of 50 ng trenbolone/L and greater. Masculinization was expressed as induction of nuptial tubercles, structures normally observed only on the heads of reproductively-active males. While these data demonstrate that trenbolone is a potent androgen in fish under laboratory conditions, an assessment under relavant field conditions would be required to evaluate whether or not the observed responses would occur in wild populations of fish. This abstract does not necessarily reflect EPA policy.