The turnover of phosphate in the pineal body compared with that in other parts of the brain

Abstract

The phosphate metabolism in 19 different parts of the brain of rats has been measured with radioactive P. The pineal body, with the highest specific activity, is 3-4 times higher than that of the pituitary gland and choroid plexus. The remaining parts of the brain have a low activity. The high specific activity of the pineal body has also been found in a number of other animals. All parts of the brain have a higher specific activity 40 min. after injn. with radioactive P than 145 min. and 24 hr. after. The high phosphate turnover is due to the pineal body and not to the blood in the organ. The radioactive phosphate in the pineal changes principally in 2 ways: (a) a rapid turnover in which P32 enters chiefly into the carbohydrate phosphate esters; (b) a slow one during which P32 enters the phospholipids and nucleic acids. After extirpation of the eyes, a marked increase takes place in the phosphate turnover of the medulla oblongata.