Comparative changes between pancreas and pancreatic juice digestive enzyme contents during nutritional rehabilitation following severe protein malnutrition in the rat

Abstract

The relationship between digestive enzyme activities in the pancreas and pancreatic juice was studied in post-weaning rats fed on a low-protein diet (30 g cereal protein/kg) for 1 month and a refeeding balanced diet (235 g mixed protein/kg) for the following 3 months. A control group was fed on the balanced diet for 4 months. At the end of malnutrition and at various times of refeeding, activities of amylase (EC3.2.1.1), trypsin(EC3.4.21.4), chymotrypsin (EC3.4.21.1), lipase (EC3.1.1.3), phospholipase A2 (EC3.1.1.4) and cholesterolesterase (EC3.1.1.13) in pancreas and pancreatic juice were measured. Recovery of body and pancreas weights was obtained after 3 months of refeeding. Pancreas offered a higher resistance to the low-protein diet; a quicker recovery than that of the whole organism was observed during refeeding. Protein and RNA contents of pancreatic cells were depressed by protein depletion. At the end of refeeding, pancreatic and cell RNA contents were still depressed. In pancreas and pancreatic juice, protein depletion produced a decrease in enzyme activities, with the exception of phospholipase A2 and cholesterolesterase. During refeeding, activities were increased to various levels in pancreatic juice and pancreas. In pancreatic juice, a deficit in enzyme activities still prevailed at the end of refeeding. The retention thresholds (total activity in pancreas v. activity per h in pancreatic juice) of hydrolases were increased by malnutrition. They were all decreased by refeeding at various rates, but after 3 months of refeeding the thresholds were still markedly increased for all enzymes studied. After malnutrition and during refeeding, the dissociated enzyme activities in pancreas and pancreatic juice could be the expression of an alteration at different stages: synthesis, intracellular transport, storage mechanisms and secretion.