Relationship between adipose polyamine concentrations and triacylglycerol synthetic enzymes in lean and obese Zucker rats.

Previous studies from our laboratory demonstrate that polyamines, namely spermine and spermidine, stimulate adipose triacylglycerol formation from the sn-glycerol-3-phosphate pathway by activation of several enzymes from this pathway, including sn-glycerol-3-phosphate acyltransferase, Mg(2+)-dependent phosphatidate phosphohydrolase and diacylglycerol acyltransferase. Since obesity in Zucker rats was associated with increased accumulation of adipocyte triacylglycerols, we have examined the relationship between changes in the activities of various triacylglycerol 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 showed a 4-fold rise in the concentration of spermine and spermidine which was accompanied by 4- to 14-fold increases in the activities of various triacylglycerol synthetic enzymes, including Mg(2+)-dependent phosphatidate phosphohydrolase. These studies suggest that obesity in Zucker rats is associated with the activation of various adipose triacylglycerol synthetic enzymes resulting from increased concentrations of endogenous spermine and spermidine.