THE EFFECT OF ICSH-β AND ITS COMBINATION WITH PROLACTIN ON THE MAINTENANCE OF PREGNANCY IN THE RAT

Abstract

ABSTRACT In the rat hypophysectomized on day 5 of pregnancy, replacement hormonal treatment daily with 100 μg ICSH or 2 mg prolactin alone was not effective for maintenance of pregnancy, whereas the combination of 50–200 μg ICSH and 2 mg prolactin gave live embryos in 40–90% of treated animals. In the animal hypophysectomized at more advanced stage of pregnancy, ICSH alone was able to maintain pregnancy. When 400 μg ICSH-β was used instead of 100 μg ICSH in conjunction with 2 mg prolactin, this treatment was also effective for maintenance of pregnancy in the animal hypophysectomized on day 5. If hypophysectomized on day 8, either reconstituted ICHS or ICHS-β alone could maintain pregnancy. ICSH-α was ineffective in the animal hypophysectomized on either day 5 or day 8 of pregnancy. Thus it appears that ICSH-β is the biologically active subunit in the ICSH molecule for maintenance of pregnancy in the rat.