Abstract
Summary
Pregnant rats were hypophysectomized and pituitary autografted on day 2, the day after sperm were observed in the vaginal lavage. Estradiol-17β (E-17-β) was injected (0.1 μg/day) on days 8 through 16 to induce implantation and maintain pregnancy. This protocol resulted in a 4 day delay of implantation, and day 8 becomes equivalent to day 4 of normal pregnancy. A single dose of LHAS (equivalent to 1.4 times the dose necessary to cause abortion on day 8 in the normal pregnant rat) failed to prevent implantation when administered on day 7 or cause fetal resorption when administered on days 11, 12, 13, 14 or 15 (equivalent to days 4, and 7 through 11). LHAS given on the two successive days 13 and 14 (days 9 and 10 equivalent) was also without effect. These results suggest that LHAS causes abortion in the rat by acting on pituitary LH-like material and not on the ovary, developing fetus or placenta.
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