Serum lipids and apolipoproteins in the rat refed after starving: influence of the molecular form of nitrogen (protein, peptides, or free amino acids).

Efficient treatment of deep denutrition should promote the restoration of normal intestinal villous structure and the return to a positive nitrogen balance. To determine whether the plasma measurement of lipoproteins could serve as sensitive indexes of villous architecture and/or nitrogen balance, these parameters were compared in rats starved for three days and refed three types of diets containing either whey proteins (WP), whey protein hydrolysate (WPH), or amino acids, known to differ in their capacity to promote restoration of normal villous architecture. Starvation lowered the concentration of triglycerides and phospholipids but not cholesterol. Apolipoprotein AI and AIV concentrations were also significantly lowered (30% and 40%, respectively), but ApoE was significantly increased by 40%. Upon refeeding with all three diets, plasma lipids progressively returned to control values except for triglycerides, which were significantly elevated by the protein and peptide diets. Apoprotein AI continued to decrease for 24 hours on the peptide and amino acid diets. Control levels were restored in all groups after 48 hours. ApoAIV increased progressively in parallel with the restoration of the intestinal mucosa; after 48 hours of refeeding, plasma concentrations of apo AIV were significantly correlated with jejunal villous height and protein content (P less than .01). ApoE was depressed below control levels in the WP and WPH groups at 24 and 48 hours and restored only after 96 hours. Because ApoE was affected, both in the fed state and during refeeding by the form of dietary nitrogen, it may prove to reflect nitrogen balance and/or insulin: glucagon balance.(ABSTRACT TRUNCATED AT 250 WORDS)