A Role for Intraluteal Estrogen in the Mediation of Luteinizing Hormone Action on the Rat Corpus Luteum during Pregnancy*

Abstract

The ability of rat corpora lutea to accumulate estradiol via aromatization of testosterone suggests that estradiol might have a direct role in the regulation of luteal function. Rats were treated with LH antiserum on day 10 of pregnancy or with LH antiserum plus testosterone which was administered by a testosterone- filled Silastic capsule implanted sc on day 9 and left in place until the end of the experiment on day 14. In rats treated with LH antiserum alone, serum progesterone, luteal estradiol content, and luteal cell nuclear content of estradiol receptor had decreased sharply within 24 h, whereas luteal LH receptor remained elevated. Treatment with LH antiserum plus a large testosterone implant prevented the decline in serum progesterone and nuclear estradiol receptor and caused a dramatic elevation in luteal estradiol content. By day 14, rats treated with antiserum alone had aborted, LH receptor content was reduced 92%, serum progesterone was 7 ± 1 ng/ml, luteal estradiol concentration 5 ± 7 pg/mg t...