RELATIONSHIP BETWEEN ADIPOSE POLYAMINE CONCENTRATIONS AND TRIACYLGLYCEROL SYNTHETIC ENZYMES IN LEAN AND OBESE ZUCKER RATS

Previous studies from our laboratory demonstrate that polyamines, name ly spermine and spermidine, stimulate adipose triacylglycerol formatio n from the sn-glycerol-3-phosphate pathway by activation of several en zymes from this pathway, including sn-glycerol-3-phosphate acyltransfe rase. Mg2+-dependent phosphatidate phosphohydrolase and diacylglycerol acyltransferase. Since obesity in Zucker rats was associated with inc reased accumulation of adipocyte triacylglycerols, we have examined th e relationship between changes in the activities of various triacylgly cerol synthetic enzymes and the endogenous concentrations of spermine and spermidine in the adipose tissues from lean and obese animals. As compared with lean rats, the adipocytes from obese rats skewed a 4-fol d rise in the concentration of spermine and spermidine which was accom panied by 4- to 14-fold increases in the activities of various triacyl glycerol synthetic enzymes, including Mg2+-dependent phosphatidate pho sphohydrolase. These studies suggest that obesity in Zucker rats is as sociated with the activation of various adipose triacylglycerol synthe tic enzymes resulting from increased concentrations of endogenous sper mine and spermidine.