Effects of prenatal exposure to low doses of diethylstilbestrol, o,p ' DDT, and methoxychlor on postnatal growth and neurobehavioral development in male and female mice

We examined effects of a wide range of doses of three man-made estrogenic c hemicals during fetal life on neurobehavioral changes during early postnata l life in mice. Pregnant mice were fed a 4-log range of o,p'DDT, methoxychl or (MXC), and the drug diethystilbestrol (DES) from gestation days 11 to 17 . Offspring were examined for changes in postnatal growth and the developme nt of neuromuscular reflexes. Fetal exposure to the estrogenic chemicals al tered the number of live pups per litter, the sex ratio of the litters, the anogenital distance of male and female offspring at birth (a bioassay for fetal androgen action), and the body weight of offspring at birth and durin g the first 5 days of postnatal life. In most cases, however, the dose-resp onse relationships were complex (non-monotonic), with effects at the highes t dose examined being opposite to effects seen at lower doses. The two mark ers of neurobehavioral development, righting and cliff avoidance reflexes, were not sensitive indicators of prenatal estrogen exposure. Only maternal exposure to the lowest MXC dose produced an increase in reactivity in right ing and cliff avoidance tests in offspring. (C) 2001 Academic Press.