Abstract
[Objective] The aim of this study was to clarify whether the route of administration is critical factor for evaluating the effects of environmental estrogens in birds. [Methods] Immature 3-week-old male quail were treated with a single intraperitoneal (i.p.) injection of estrogenic chemicals dissolved in corn oil, and mRNA levels of ZP1, VTG-II, and apoVLDL were measured in the liver on 1, 2, 3, and 4 days after injection. Mature female quail were received i.p. injection of estrogenic chemicals daily for ten consecutive days. Fertile eggs were collected and incubated for 8, 10, 12, 14, and 16 days. Total RNA was reverse-transcribed with oligo (dT) primers, and cDNA was subjected to real-time PCR. [Results] Transcription of ZP1, VTG-II, and apoVLDL genes were highly specific for mature females, and no significant expression was observed in liver of untreated males. The mRNA levels of ZP1, VTG-II, and apoVLDL increased one day after injection of ethinyl estradiol (EE) or diethylstilbestrol (DES), but not of nonylphenol, bisphenol A, genistein, or coumestrol. ApoVLDL was the most sensitive gene for evaluating the estrogenic effects in the liver of Japanese quail. Expressions of estrogen-sensitive genes were enhanced in the liver of male embryos after maternal exposure to EE, but not to DES. These results provided an additional insight into the relationship between the route of administration and the effects of estrogenic compounds in birds.
