THE CORPUS LUTEUM-HYPOPHYSIS RELATIONSHIP.

Abstract

The effect of LH on the corpora lutea of adult hypophysectomized rats bearing autotransplanted hypophyses was studied. Treatment with LH or with control solutions was begun 2 weeks after operation, and continued for 10 or 24 days. The effect on luteal size was determined mainly from the weights of the corpora, while the effect on the maintenance of progesterone secretion was determined from the response of the vagina and uterus to 3 injections of estradiol benzoate (EB) of 50 [mu]g each. Ten days of LH treatment induced a significant reduction in the size of the corpora and the degree of progesterone secretion. FSH (follicle stimulating hormone) had the opposite effect; boiling LH destroyed the effect. The degree of luteolysis was directly related to the dose of LH. Luteolysis was not due to discontinuation of treatment, since it occurred to the same extent, regardless of whether the rats were observed 9 days after cessation of treatment, or were continuously treated for 24 days and autopsied on the day after the last treatment. The corpora of both control and LH-treated rats tested with EB were larger than those of equivalent rats not tested with EB. The specificity of the effect, and its possible mechanism and relationship to naturally occurring luteolysis were discussed.