Effects of sex hormones and of pregnancy on the selenium metabolism.

In order to obtain information about the hormonal regulation of the selenium metabolism, the element level in the blood serum of rats was determined by means of neutron activation analysis after administration of sex hormones and during pregnancy. While the decreases in the mean selenium concentrations found after the treatment with progesterone and progesterone + estrone were too low to enable us to establish response patterns, marked changes were observed in the serum of gravid rats. Here the selenium level dropped significantly (P less than 0.001) by 25% between the 10th and 15th day of gestation.