COMPARATIVE STUDIES ON THE METABOLISM OF OESTRADIOL IN THE BRAIN, THE PITUITARY AND THE LIVER OF THE RAT

: Radioactive oestradiol was incubated with homogenates of hypothalamus, pituitary and liver and slices of cortex, hippocampus, hypothalamus, pituitary and liver of ovariectomized rats. 2- and 4-substituted oestrogens were the main metabolites in the brain and were found in the same proportions. In the liver only the 2-substituted oestrogens were the main metabolites, while the 4-substituted ones were of minor quantitative importance. On the basis of wet weight the 2-hydroxylating capacity of the liver was approximately 50 fold greater than that of the brain and the 4-hydroxylating capacity about the same as that of the brain. Only slight differences in the 2- and 4-hydroxylating capacity of various brain areas were observed, although apparently the hypothalamus and the pituitary were more active in the formation of catecholestrogens than the cortex and the hippocampus.