The uptake of hydrocortisone in mouse brain and ependymoblastoma

✓ At 2, 10, and 60 min after intravenous injection of tritiated hydrocortisone into tumor-bearing mice, samples of brain and tumor were taken for autoradiography. Within 2 min of injection, large amounts of the steroid had left the bloodstream and had penetrated normal brain. By 60 min virtually all the drug had left the brain. The most radioactive structure was the choroid plexus. Within the normal and edematous brain, hydrocortisone was not found in cells alone but was spread randomly throughout the tissue. Edematous brain adjacent to implanted tumor contained much more steroid than normal brain. This difference was maximal at 10 min after injection. Edematous white matter adjacent to tumor was usually as radioactive as tumor. In the ependymoblastoma at 2 min after injection, neoplastic cells and interstitial tissue adjacent to blood vessels contained much hydrocortisone. At 10 min the drug was uniformly spread through the tumor tissue and by 60 min was largely gone. The uptake of the drug by the edematous brain suggests a direct local action. The high choroid plexus concentration may indicate a direct action there, perhaps to reduce cerebrospinal fluid production.