Effects of Transplacental 17‐α‐Ethynyl Estradiol or Bisphenol A on the Developmental Profile of Steroidogenic Acute Regulatory Protein in the Rat Testis

Abstract

Previous research from our laboratory has determined the transcript profiles for developing fetal rat female and male reproductive tracts following transplacental exposure to estrogens. Prenatal exposure to bisphenol A (BPA) or 17-α-ethynyl estradiol (EE) significantly affects steroidogenic acute regulatory (StAR) protein transcript levels in the developing male rat reproductive tract. The purpose of this study was to establish the intratesticular distribution and temporal expression pattern of StAR, a key gene involved in steroidogenesis. Beginning on gestation day (GD) 11, pregnant Sprague-Dawley rats were exposed daily to 10μg/kg/day EE and fetal testes were harvested at GD16, 18, or 20. Quantitative reverse transcriptase PCR (QRT-PCR) demonstrated no significant difference in StAR transcript levels present at GD16. However, at GD18, StAR transcripts were significantly decreased following exposure. Immunohistochemistry demonstrated similar StAR protein levels in interstitial region of GD16 testes and an obvious decrease in StAR protein levels in the interstitial region of GD18 testes. Moreover, starting at GD11 additional dams were dosed with 0.001 or 0.1 μg/kg/day EE or 0.02, 0.5, 400 mg/kg/day BPA via subcutaneous injections. QRT-PCR validated previous microarray dose-related decreases in StAR transcripts at GD20, whereas immunohistochemistry results demonstrated decreases in StAR protein levels in the interstitial region at the highest EE and BPA doses only. Neither EE nor BPA exposure caused morphological changes in the developing seminiferous cords, Sertoli cells, gonocytes, or the interstitial region or Leydig cells at GD16-20. High levels of estrogens decrease StAR expression in the fetal rat testis during late gestation.