Pharmacologic modification of the time course of ovum transport in guinea pigs

Various agents were examined for their effects on ovum transport in the guinea pig. Estrogen significantly accelerated ovum transport in this species. The experiments further demonstrated that estrogen did not act by inducing prostaglandin synthesis, nor by altering plasma progesterone levels. The estrogen-induced acceleration was significantly antagonized by tamoxifen, an antiestrogen that acts by interfering with estrogen receptor synthesis. Cycloheximide also antagonized the effects of estrogen on ovum transport. These data suggest that the modification of ovum transport by estrogen is due to the entrance of estrogen into the nuclei of target cells, and subsequent protein synthesis. Although we assume that this action occurs at the level of the oviduct, our experiments do not prove this assumption.