FURTHER OBSERVATIONS ON THE EFFECT OF PITUITARY GLAND EXTRACTS UPON THE SERUM LIPIDS OF THE RABBIT1

Abstract

The effects of crude pituitary extract upon the serum and liver lipids of the rabbit were studied. A single injection of crude pituitary extract in the fed rabbit causes a rapid elevation of serum free fatty acid (FFA) concentration. Serum FFA level attains a maximum 2 hours after the injection and remains elevated for more than 18 hours after the injection. Liver fat concentration increases progressively during the entire 18 hour period after the injection. The concentrations of serum total lipid and triglyceride do not change until 8 to 12 hours after the injection, when a marked increase occurs. The increment of serum lipid 18 hours after the injection has the following composition: 85% triglyceride, 10% phospholipid, 5% cholesterol. A single hog anterior pituitary lobe has 5.4 times more lipemia-producing activity than a single hog posterior pituitary lobe. Lyophilized pituitary glands contain considerably more lipemia-producing activity than acetonedried pituitary glands. Lipemia-producing activity is not present in 9 other animal organs which were tested. The lipemia-producing activity is more readily extracted from the gland by alkaline than by acid solvents.