Effects of dibutyl phthalate on reproductive function in pregnant and pseudopregnant rats

In our previous studies, dibutyl phthalate (DBP) was found to be embryoleth al and teratogenic in rats. In this study, the effects of DBP on reproducti ve function were investigated on pregnant and pseudopregnant rats. Rats wer e given DBP by gastric intubation at 0, 250, 500, 750, 1000, 1250 or 1500 m g/kg on Days 0 to 8 of pregnancy and the pregnancy outcome was determined o n Day 20 of pregnancy. The same doses of DBP were given to pseudopregnant r ats, with an induced decidual cell response, on Days 0 to 8 of pseudopregna ncy, and the uterine weight on Day 9 served as an index of the uterine deci dualization. DBP caused significant increases in the incidences of preimpla ntation loss in females successfully mated at 1250 and 1500 mg/kg and of po stimplantation loss in females having implantations at 750 mg/kg and above. The uterine decidualization in pseudopregnant rats was significantly decre ased at 750 mg/kg and above. These findings suggest that early embryonic lo ss due to DBP may be mediated, at least in part, via the suppression of ute rine decidualization, an impairment of uterine function. (C) 2000 Published by Elsevier Science Inc. All rights reserved.