[Changes in hydrolytic lysosomal enzymes of liver associated with protein and protein-calorie malnutrition]

The effect of a low protein (1%) diet (protein-deficient diet) and a low protein-calorie diet (restricted diet) on the activity of the hydrolytic enzymes acid ribonuclease, acid deoxiribonuclease, acid and alkaline phosphatases and beta-glucuronidase has been studied in the liver of Wistar rts. Experimentation was carried out over 30 days and then comparisons were made against well-nourished (10% protein, controls), and one another. Body weight of deficient animals decreased in deficient animals, especially in protein-deficient rats. Liver weight also dropped significantly in malnourished rats. In terms of organ weight relative to body weight, there was a clear increase of protein-deficient rats, compared with controls. Enzyme activities expressed per total organ fell significantly in deficient rats compared with controls, but alkaline phosphatase activity increased. A large increase in hydrolytic activity expressed per mg of protein in beta-glucuronidase and alkaline phosphatase values was registered in protein-deficient and restricted rats. Also, acid ribonuclease activity increased in deficient-protein animals, but it fell in protein-calorie deficient animals compared with controls. However, acid deoxiribunuclease and acid phosphatase activities were not modified. We therefore concluded that protein-deficient and restricted diets increase catabolism in liver through a modulation of lysosomal hydrolase activities.