Host: The Japanese Society of Toxicology
Name : The 49th Annual Meeting of the Japanese Society of Toxicology
Date : June 30, 2022 - July 02, 2022
Loss of the biodiversity in wild birds is suspected to be due to adverse effects of chemicals including pesticides on reproduction. The avian reproduction test (OECD TG206) is usually performed, although the test using adult birds requires higher cost. Therefore, new avian tests are required to reduce the cost and animals for assessing reproductive chemical toxicity. In this study, we established the protocol for chemical expose to fertilized quail eggs and examined the effects of ethinyl estradiol (EE2) on the internal reproductive organs. At 2.5 days of incubation, fertilized eggs were cultured in surrogate eggshells and treated with EE2 with different doses. Twelve days after starting culture and EE2 treatment, embryos were autopsied to observe the internal genital organs. The expression of the genes for steroidogenic enzymes (P450scc, P45017α,lyase, 3β-HSD, 17β-HSD, P450arom) and sex steroid receptors (ERα, ERβ, AR) in the gonads and for sex steroid receptors in the Müllerian and Wollfian ducts were analyzed. EE2 induced residual Müllerian ducts and abnormal testis morphology in male embryos and abnormal Müllerian duct morphology in female embryos. Abnormalities of the ovaries and Wolffian ducts did not found. However, EE2 reduced the mRNA levels of P450scc and P45017α,lyase and increased the mRNA levels of sex steroid receptors in the ovaries. The morphology and sexual-differentiation-related gene expression of the reproductive organs in quail embryos may be useful and effective biomarkers to evaluate abnormal sexual differentiation in birds.
