SUPEROVULATION IN THE IMMATURE RAT AS A POSSIBLE ASSAY FOR LH AND HCG1

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Abstract
It has been demonstrated that superovulation can be used as a quantitative assay for luteinizing hormone (LH) and human chorionic gonadotropin (HCG). The use of pregnant mare serum gonadotropin (PMS) to induce maximal growth and number of Graafian follicles results in an increase in the magnitude of the response. Treatment with a single dose of PMS failed to induce ovulation; however, injection of high dosages of PMS (10 to 20 I.U.) in immature rats pre- treated with PMS caused 20 to 60% of the animals to ovulate. The intravenous injection of both HCG and LH increased the sensitivity of the assay by a factor of 10, as compared to the subcutaneous route of administration. A minimal response was obtained with 0.025 I.U. of HCG and 0.1 [mu]g of the Armour''s standard LH given (i.v.). In the latter instance this test appeared to be 150-fold more sensitive than the test involving increase in weight of the prostate. A statistical analysis of the assay is given indicating a high precision for the average response. The [lambda].m for HCG and LH was 0.21 when given subcutaneously and 0.07 when given i.v. Preliminary tests with urine from normal males and females revealed the presence of an ovulation factor although consistent results were not obtained.