Protein-energy malnutrition in infant non-human primates (Macaca nemestrina). I. Correlation of biochemical changes with fine structural alterations in the liver.

Male infant pigtail monkeys (Macaca nemestrina) aged 6-9 months and born in captivity were fed restricted amount of either an adequate protein diet (20% casein) or a protein-deficient diet (2% casein). After 3-5 months of receiving the low protein containing diet, ultrastructural evaluation of hepatic parenchymal cells revealed extensive fatty metamorphosis, marked fragmentation and vesiculation of the rough endoplasmic reticulum, some evidence of distension of the nuclear membrane, variable degree of mitochondrial polymorphism and gigantism, increased intracytoplasmic accumulation of glycogen particles and enhanced prominence of collagen fibres in the intercellular and perisinusoidal spaces. Biochemical studies indicated severe distortion in the plasma profile of free amino acids by Week 10 of malnutrition, with a prominent decrease in valine/glycine ratio (9% in the malnourished animals compared to a ratio of 55-63% in the control group). While plasma concentration of glycine was elevated above baseline value throughout the period of malnutrition, the level of alanine showed an initial rise followed by a significant drop (-58% at Week 20). Although showing wide individual variation, plasma level of corticosteroid in general tended to increase with duration of protein malnutrition, an observation consistent with the accumulation of glycogen and enlargement of mitochondria in the hepatic cells.