Fat mobilization and hyperlipemia from pituitary extracts in rabbits

Abstract

A crude pituitary extract, potent in inducing visible lipemia in male rabbits, caused a) an eightfold increase in free fatty acids of the serum 1–2 hours after injection, followed by a 2.5-fold increase of fatty acid output in vitro from adipose tissue, removed 4 hours after injection; b) a reduction in lipoprotein lipase activity of adipose tissue at the same time; c) an increase in liver fat which was already prominent at 4 hours and which preceded the ninefold increase of total lipids in the serum at 24 hours. The lipemia was prevented by large doses of heparin. A direct effect of the extract on adipose tissue in vitro was observed; this was partially inhibited by insulin and glucose. Pig growth hormone given in corresponding doses produced the same effect, but to a smaller degree. It was concluded that the hyperlipemia is due to a separate factor, and that the lipemia is a consequence of excessive lipolysis in association with diminished lipoprotein lipase activity.