Action of Male Sex Hormone With and Without Estrin in the Female Rat. ∗

It has recently been reported that injection of male sex hormone simultaneously with estrin into normal female rats partially suppressed the characteristic histologic reaction of the anterior pituitary to estrin. 1 2 The degree of weight increase in the pituitary and the degree of degranulation of the chromophilic cells, together with a reduction in their relative percentages and an increase in that of the chromophobes, were more marked in the rats which received estrin alone than in those which received both estrin and male hormone. Previously, it had been demonstrated that injection of sufficient amounts of estrin into normal female rats resulted in the formation of large, active corpora lutea in the ovaries. 3-6 Estrin apparently induced such luteinization indirectly by stimulating the production or the release of a luteinizing factor by the anterior hypophysis. 5 Therefore, it was considered possible that in rats which received male hormone simultaneously with estrin there would be not only a suppressed histologic reaction of the anterior lobe to estrin but a reduction in the degree of luteinization in the ovary. In the experiments described below this assumption has been tested. The action of male hormone alone on the ovaries was also studied.

Series 1. Seventeen mature female rats received daily injections of both 500 gamma of male sex hormone† and 200 r.u. of estradiol-benzoate† for a period of 10 days while a second group of 42 females received daily injections of 200 r.u. of estrin alone for a like period. The mean pituitary weight of the rats receiving both male hormone and estrin was 11.7 mg.; that of rats receiving estrin alone was 20.4 mg. The mean ovary weight of rats receiving the combined injections was 54 mg.; the mean of those receiving estrin alone was 66 mg.