The influence of dietary fat and meal frequency on lipoprotein lipase and hormone-sensitive lipase in rat adipose tissue.

Activities of NaCl-inactivated lipoprotein lipase (LPL) and protamine-resistant hormone-sensitive lipase (HSL) in adipose tissue, accumulation of carcass fat, and serum triglycerides (TG) were determined in meal-fed (MF) and ad libitum-fed (AD) rats. At each feeding frequency, diets provided total fat as 15 or 30% of calories and polyunsaturated fatty acids (PUFA) as 2.5 or 11% of calories. The average energy intake of MF rats was 67% that of AD rats. Total weight gained by MF rats was only 60% that of the AD rats. Significantly greater activities of LPL, HSL, and LPL:HSL in adipose of MF rats suggested a greater capacity for fat accumulation which was not realized at the limited energy intake. In AD rats, the percentage of body fat was significantly correlated with LPL:HSL and with serum TG, suggesting that the relative enzyme activities and fat deposition may be influenced by the concentration of circulating TG. Mean body fat of rats receiving the 30% fat diet was significantly greater than that of rats fed 15% fat. Both serum TG and adipose LPL activity were significantly reduced when the diet contained high levels of PUFA.