Fatty acid synthesis in vivo and hepatic contribution to whole-body lipogenic rates in obese Zucker rats

Abstract

We have re-examined the claim by Godbole and York, based on the effect of surgical hepatectomy (Diabetologia 14:191, 1978), that liver contributed more than 90% of the newly synthesized FA found in adipose tissue of obese rats at the end of a 1-hr pulse of 3H2O. The amount of newly synthesized FA transported via plasma VLDL from liver to adipose tissue was estimated in lean and obese Zucker rats by determining the effects of Triton WR-1339, which blocks the uptake of VLDL-TGFA into tissues. Triton treatment was found not to cause any significant change in the amount of radioactive FA found in subcutaneous/perimetrial fat tissues, carcass or liver in either chow-fed or high-glucose, fed-refed lean or obese rats, although in the fed-refed dietary state the proportion found in the liver was increased over that in the chow-fed groups. Furthermore, the amounts of newly made FA which accumulated in the plasma of Triton-treated, chow-fed and glucose-fed refed animals during this period constituted only a few percentages of those found in the adipose tissue of these animals. Thus, in contrast to the claims of Godbole and York, no significant transfer of newly made FA from liver to adipose tissue occurs during a 1-hr experiment; it follows that the amount of these FA found in different tissues at the end of that period are valid measurements of their actual lipogenic activities in situ. It is suggested that the Godbole and York results are artifacts of their surgical hepatectomy procedure.