RAT PLASMA VLDL COMPOSITION AND CONCENTRATION AND HEPATIC LIPASE AND LIPOPROTEIN-LIPASE ACTIVITIES ARE IMPAIRED DURING 2 TYPES OF PROTEIN-MALNUTRITION AND UNAFFECTED BY BALANCED REFEEDING

The relationships between VLDL concentrations and composition and chan ges in hepatic lipase and lipoprotein lipase activities were determine d in rats, during the consumption of two low protein diets (2% casein or 5% gluten) (protein malnutrition) for 28 d, followed by the refeedi ng of a balanced diet for 14 d (15% casein) (refeeding). A control gro up was fed 15% casein for 42 d. In the control group, total lipolytic activity increased with age (r = 0.83, P < 0.001), whereas in both dep leted groups, this activity remained low and stable throughout the per iod of protein malnutrition. At d 28 of protein malnutrition, plasma t otal lipolytic activities were significantly reduced in both depleted groups, (P < 0.05); hepatic lipase values represented 23% of the contr ol value and lipoprotein lipase activity was about 11% of the control value. Moreover, lipid supply was even more dramatically diminished by the strong reduction in plasma VLDL concentration in both depleted gr oups. At d 14 of refeeding, lipoprotein lipase activities remained low in both depleted groups. Hepatic lipase activity was similar in the c ontrol and casein groups, but significantly higher in the gluten group . The VLDL composition varied significantly with each type of protein malnutrition and could be attributable to the different low levels of plasma VLDL-apolipoprotein C of rats fed both depleted protein diets, which involve an inhibiting or activating effect on lipoprotein lipase activity. Therefore, our results indicated that both protein-deficien t diets investigated may diminish fatty acid supply in the various tis sues involved.