ESTROGEN ANTIBODIES REDUCE VULNERABILITY TO STRESS-INDUCED FAILURE OFINTRAUTERINE IMPLANTATION IN INSEMINATED MICE

In Experiment 1, inseminated mice were randomly assigned to either an undisturbed control condition or four conditions involving exposure to restraint stress on days 1 through 5 of pregnancy. Restrained animals received one of three doses of estrogen antibodies or just vehicle in jections on each day of restraint. Restrained animals receiving vehicl e only showed significantly fewer uterine implantation sites than did unrestrained controls, while restrained animals given estrogen antibod ies showed more implantation sites than did vehicle-treated restrained animals. In Experiment 2, varied dosages of refined estrogen antibodi es were administered to inseminated females concurrent to restraint-st ress on days 1 through 5 of pregnancy. More females receiving the high er dosages of antibodies produced litters than did restrained females with just vehicle injections, and at the highest dose the number of li tters was similar to that produced by undisturbed control females. The se results converge with other evidence to suggest that stress-induced pregnancy blocks are mediated by estrogens.