John Wiley & Sons, Ltd.

Effects of androstenedione exposure on fathead minnow (Pimephales promelas) reproduction and embryonic development

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High concentrations (300 ng/L) of androstenedione (A4) were identified in snowmelt runoff from fields fertilized with manure from livestock feeding operations in Wisconsin. In fishes, A4 is an active androgen and substrate for biosynthesis of functional androgens (e.g., testosterone and 11‐ketotestosterone) and estrogens (e.g., estradiol‐1713). Thus, A4 has the potential to be a powerful endocrine disruptor. This hypothesis was tested by exposing reproductively mature fathead minnows to 0.0, 4.5, 74, and 700ng/L A4 for 26 days in a flow through system. Various reproductive endpoints were measured including fecundity, fertilization success, secondary sexual characteristics, GSI, and hepatic vitellogenin mRNA expression. Additionally, fertilized embryos from the reproduction assay were used in an embryonic development assay to assess A4 effects on development and hatchability. In males, A4 significantly increased Vtg mRNA expression (estrogenic effect), significantly reduced GSI, and had no effect on tubercle expression (p=0.067). In females, A4 induced tubercle development (androgenic effect) with no effects on GSI. Fecundity was not significantly impacted. A4 exposure had no effect on fertilization, embryonic development, or hatchability. These data indicate exogenous A4, at environmentally relevant concentrations, can significantly modulate the reproductive physiology of the fathead minnows in a sex‐specific manner and should be monitored as an endocrine disruptor. This article is protected by copyright. All rights reserved

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