EFFECT OF SMALL DOSES OF OESTRADIOL BENZOATE ON PITUITARY PRODUCTION AND RELEASE OF I. C. S. H. IN GONADECTOMIZED MALE AND FEMALE RATS

Abstract

ABSTRACT The influence on the I. C. S. H.-content of the pituitary gland and the blood serum of long-term treatment of gonadectomized male and female rats with several low doses of oestradiol benzoate was investigated. It was found that only in females treatment with 0.1 and 0.2 μg of oestradiol benzoate daily results in an increase of the pituitary I. C. S. H.-content, whereas in the serum content a (non-significant) decrease was observed. In male rats the pituitary I. C. S. H.-content was not influenced by treatment with these doses, but the serum content decreased. Higher doses of oestradiol (0.5 and 2.0 μg daily) caused, both in males and in females, a decrease of the I. C. S. H.-content in the hypophysis as well as in the serum. It is assumed that oestrogen, if chronically administered, exerts two different actions on pituitary I. C. S. H.: it depresses the production of I. C. S. H. and inhibits the release. In females, these two effects have different threshold levels, that for the release being the lower one. In males the threshold for the inhibition of production has to be lower.