EFFECT OF PROTEIN-ENERGY MALNUTRITION ON THE LIPID-COMPOSITION AND LEUCINE UPTAKE OF SMALL-INTESTINAL BRUSH-BORDER VESICLES OF GROWING RHESUS-MONKEYS

Mild to moderate protein energy malnutrition (PEM) was induced in youn g developing rhesus monkeys by giving them half of the casein-based sy nthetic diet which was given to control animals. After a body weight r eduction of 30-40%, the PEM animals were sacrificed. The small intesti ne was removed, flushed with ice-cold saline, everted and divided into equal proximal, middle and distal segments. Brush border membrane ves icles (BBMV) were prepared from all three segments and assayed for mar ker enzymes, e.g. sucrase and alkaline phosphatase, to assess their pu rity. Sucrase was found to be purified 23-fold and alkaline phosphatas e 12-fold compared to the respective homogenates in all three parts. I n PEM animals, uptake of [U-C-14]L-leucine into the BBMV was diminishe d in all three segments and cholesterol and phospholipid levels also d ecreased significantly. As a result there was an elevation in the mola r ratio of cholesterol to phospholipid, and the sphingomyelin: phospha tidylcholine molar ratio also increased. This signified a decrease in lipid fluidity and amino acid uptake in PEM in the small intestine. Hi stologically, a mild to moderate grade of partial villus atrophy was o bserved in the intestine. The diminished uptake and lipid fluidity of the membrane and the histological changes returned to their control va lues after nutritional rehabilitation.