Abstract
Heretofore all the methods used for the assay of progesterone are based upon morphological changes in the uterine mucosa. Usually immature or mature rabbits have been employed. Suitable sensitization of the uterus has been obtained either by the injection of an oestrus-producing hormone (oestrone) or by using rabbits in spontaneous heat. The present communication, however, deals with preliminary experiments on a “physiological” method of assaying progesterone, i. e., by determining the dose necessary to cause contraction of the non-pregnant cat's uterus in response to sympathetic stimulation.
Ovulation and corpusluteum formation in the cat, as in the rabbit, take place after copulation but not spontaneously so that the ovaries of isolated non-pregnant adult cats do not contain corpora lutea. A further peculiarity of the cat's uterus is the change in its response to hypogastric stimulation or epinephrine as a result of pregnancy. Dale 1 and Cushny 2 independently showed that sympathetic stimulation in the non-pregnant cat causes inhibition of movements and relaxation whereas in the pregnant cat similar stimulation is followed by a uterine contraction, van Dyke and Gustavson 3 demonstrated that such a pregnancy-reversal in response could be elicited in normal or ovariectomized cats receiving both oestrin and corpus luteum extract but not after the injection of oestrin alone. All subsequent work indicated that the pregnancy-response of the cat's uterus can be obtained only if the cat's ovaries contain corpora lutea or if corpus luteum hormone has been injected.
It is not known what is the importance of sensitizing the uterus by first injecting oestrus-producing hormone. However, on the assumption that it is important in facilitating and possibly opposing the pregnancy-like reversal in response due to progesterone, I have tentatively adopted the procedure here outlined.
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