The influence of prolactin on the assay of human menopausal gonadotrophin (HMG) and human chorionic gonadotrophin (HCG) has been studied. Various bioassay methods were used and the experiments were conducted in two independent laboratories.
In hypophysectomized immature male rats the response of the ventral lobe of the prostate to HMG was not affected by simultaneous administration of prolactin. It was concluded that, in the case of urinary extracts, prolactin did not interfere with the specificity of this test for interstitial cell stimulating hormone activity.
Valid assays of HMG by the rat uterus and mouse uterus tests could be obtained in the presence of relatively large quantities of prolactin.
When HCG was assayed by the rat uterus test and by tests depending on the enlargement of the accessory reproductive organs in male rats, simultaneous administration of prolactin did not affect the results obtained.
In immature male rats prolactin did not prevent the regression of the accessory organs which occurs after castration.