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This study aimed to determine the effects of Androstenodione (AED) on the transcriptional expression of genes involved in the hypothalamic-pituitary-gonadal (HPG) and the hypothalamic-pituitary-adrenal (HPA) axes in the zebrafish embryos/larvae. Zebrafish embryos were exposed to 0, 4.0, 45.0, 487.0, and 980.0 ng/L of AED from the day of fertilization to 144 h post fertilization (hpf), during which the transcriptional profiles of key genes related to the HPG and HPA axes were examined daily using quantitative real-time PCR. The AED exposure significantly up-regulated several receptor signaling pathways and the key genes involved in various steps of the steroidogenic pathways were also affected. In addition, the AED exposure could significantly modulate the transcriptional profiles of the other target genes related to hypothalamic and pituitary hormones. The findings of this study suggest that AED, at environmentally relevant concentrations, affects the adrenal endocrine systems and the reproduction of zebrafish by interrupting the HPG and HPA axes., (Copyright © 2018. Published by Elsevier Inc.)

Androstenedione (AED) is a naturally occurring steroid hormone. It is metabolized to potent androgens, which may induce androgenic effects in fish. However, little is known whether and how the androgens interfere with the fish gonadal development and reproduction. This study aimed at demonstrating the effects of long-term AED exposure on reproduction and development in mosquitofish (Gambusia affinis). The growth, development and several morphological endpoints, including the segment number and length of anal fin, histological changes of gonads and liver, were evaluated in mosquitofish during development from fertilized embryo to adulthood (180 days) after exposure of AED at environmentally relevant concentrations. We found that the growth (length, body weight and condition factor) of fish was negatively correlated with AED concentration in females, but not in males. The significant elongation of the ray and increment of segment numbers in the anal fin, were detected in all mosquitofish after exposure. Moreover, AED exposure (0.4gµ/L) caused damages in gonads and reduced the number of pregnant females. These findings indicate that AED has adverse effects on the growth and development of the western mosquitofish after long-term exposure (180d). Long-term exposure (180d) to AED, including environmentally relevant concentration (0.4µg/L and 4µg/L), induced masculinization in female mosquitofish under the experimental conditions., (Copyright © 2017 Elsevier Inc. All rights reserved.)