A STUDY OF ADRENAL RADIOACTIVITY SUBSEQUENT TO PARENTERAL Co60-LABELED VITAMIN B12

Abstract

Data, gathered during a study on tissue distribution of parenterally administered radioactive vitamin B12, shows that the adrenal concentrates a relatively large amount of this radioactivity and that its ability to do so is markedly influenced by parenteral testosterone propionate. 30 days old littermate albino rats, consisting of testosterone-treated and control animals, received a single subcutaneous injection of 0.25 [mu]g. Co60-labelled vitamin B12. With the exception of 6 animals, the rats received a subcutaneous daily injection of 16.6[mu]g- unlabelled vitamin B12 from their 34th to 40th day of age; all rats were sacrificed on the 40tn day. The radioactivity of the ashed kidney, liver, adrenal, and thyroid tissues was measured. The adrenal was found to assume a place among two of the tissues, the kidney and liver, which show the highest radioactivity concentration in the body; the thyroid contained a relatively insignificant amount of radioactivity. In addition it was observed that although the adrenal gland decreased in size following parenteral testosterone propionate, the absolute amount of radioactivity in the gland increased by more than 4 fold. From these observations it is inferred that the radioactivity present in the adrenal gland, following the administration of labelled vitamin B12, is intimately concerned with the activity of the gland.