THE DECIDUOMA ASSAY: A METHOD FOR MEASURING PROLACTIN

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Abstract
SUMMARY: Mice 3 months of age were hypophysectomized on the 1st day of dioestrus and treated with prolactin for 5 consecutive days commencing immediately after hypophysectomy. One uterine horn was traumatized on the 3rd day of the experiment and autopsy was performed on the 6th day. Prolactin maintained the function of the corpus luteum and induced the formation of deciduomata in the injured uterine horn. The increase in weight of the damaged uterine horn compared with the control horn was used as the end point. Since mechanical injury alone caused an increase of up to 10·4 mg., a positive response was taken as an increase of 11 mg. or more. The response was treated as quantal and the percentage of positive responses was transferred to probits. Parallel line assays were used with three or two dose levels of the standard and the unknown. The design permitted a simultaneous study of the effects of a preparation on both the damaged and the undamaged horns of the uterus. Prolactin caused an increase in weight of the damaged horn and gonadotrophin an increase in weight of both horns, but when prolactin was contaminated with gonadotrophin it could still be assayed by the difference in weight between the two. Three different preparations of ovine prolactin (Armour) were assayed against the 2nd International Prolactin Standard and the results compared favourably with the maker's estimate of potency. Two preparations were also assayed by the pigeon crop gland and by the dioestrus methods and the results were similar. The index of discrimination was about unity.