A new approach to the biological determination of the luteinizing hormone.

Abstract

ABSTRACT The response of the uterine weight of immature mice to FSH and LH preparations with low contamination by each other was studied. The new approach to the biological assay of LH, which could be designated the »uterine-augmentation« test, was based on injecting intact immature mice with a constant dose (4.44 IU) of a biologically pure FSH preparation plus increasing amounts of extracts containing LH. A dose as little as 0.068 IU of LH is capable to increase the uterine weight when injected together with 4.44 IU of biologically pure FSH. A significant uterine response can be obtained when animals are injected with 29.4 μg of 2nd IRP-HMG (equivalent to 0.128 IU-LH and 0.128 IU-FSH). When a constant dose of 4.44 IU of biologically pure FSH is added to each dose level of the 2nd IRP-HMG, a significant uterine response is obtained with 14.7 μg of this reference preparation. The end point was the mouse uterine weight. Some determinations of the LH activity in urinary extracts have been performed according to this new method and from the results it seems that the LH activities, as determined by the ovarian ascorbic acid depletion method, agree with those determined by the uterine-augmentation test. It also seems that the uterine weight response is proportional to the LH activity and not dependent on the FSH-LH ratio of the samples assayed.