Effects of androstenedione on in utero development in rats

This study was conducted to characterize the effect of androstenedione on estrous cyclicity, mating behavior and fetal development. Thirty-day old rats received corn oil alone or androstenedione (in corn oil) at one of four concentrations (0, 1.0, 5.0, 10.0 or 30.0 mg/kg body weight) by gavage for two weeks prior to mating, during the mating period and throughout gestation. Dose related increases in serum androstenedione, estradiol and estrone were observed in all androstenedione treated animals at gestation day 20. A statistically significant increase in serum testosterone concentration was observed in the 30 mg/kg dose group. Feed and fluid consumption were not affected by androstenedione treatment during the pre-mating or gestational periods, however a statistically significant decrease in the number of females with regular estrous cycles was observed in the 10.0 and 30.0 mg/kg dose groups. Exposure to androstenedione did not affect mean body weight gain during pre-mating or gestation. Slight not statistically significant reductions in the number of implants, number of viable fetuses and number of viable male fetuses were observed in the 30.0 mg/kg androstenedione group. Reductions were not observed in the number of corpora lutea. Fetal growth in terms of fetal weight, crown-rump length, anogenital distance and the number of external abnormalities was not affected by androstenedione exposure. At the doses given, androstenedione had no specific effect on the development of individual bones, including sternebrae. Dose related effects of androstenedione were not observed on the development of soft tissues. A statistically significant increase in moderately enlarged ureter at the kidney was observed in both the 1.0 and 5.0 mg/kg dose groups. Organ weights (expressed per gram of body weight or per gram of brain weight) were not affected by androstenedione treatment.