Strange-male-induced pregnancy disruption in mice: reduction of vulnerability by 17 beta-estradiol antibodies.

It is well-established that novel males can disrupt early pregnancy in house mice. Inseminated female C57BL mice were either left undisturbed or each exposed indirectly to a novel HS male through a wire-mesh grid during days 1-6 of pregnancy. Varied dosages of antibodies to 17 beta-estradiol were administered to females exposed to males. Vehicle-treated females exposed to novel males showed fewer litters than did nonexposed controls. Male-exposed females given 1 ml daily of the antibody showed rates of pregnancy comparable to those observed in controls. These data suggest that estrogen levels might play a role in strange-male-induced pregnancy disruptions, converging with evidence implicating estrogens in stress-induced pregnancy blocks.