Stimulation of Lipogenesis in Thyroid Tissue in vitro by Free Fatty Acids

Abstract

RECENTLY, it has been demonstrated that some of the in vitro actions of certain pituitary hormones on adipose tissue can be reproduced by simple supplementation of the suspending medium with albumin-complexed free fatty acids¹. This has prompted a more generalized analysis of the effects of free fatty acids on the metabolism of surviving preparations of target endocrine glands. We have incubated slices of sheep and human thyroid tissue at 38° C. and pH 7.4 in modified Krebs–Ringer tris-phosphate or Krebs–Ringer bicarbonate² containing 2 mgm./ml. of uniformly labelled glucose (glucose-U-¹⁴C), 10 mgm./ml. of fat-free bovine albumin³, and varying quantities of sodium oleate. Direct chemical analysis⁴ disclosed that such exogenous supplementation with oleate augmented the thyroidal pool of free fatty acids. The associated striking increases in lipogenesis from glucose-U-¹⁴C form the basis of the present report.