Effects of age, and protein malnutrition followed by a balanced diet on the non-parallel change in digestive enzymes in the pancreas and their secretion in the rat.
1. Ninety male Wistar rats were divided into two groups. A control group (C) was fed on a balanced diet, containing 200 g protein/kg for 51 d. An experimental group (E) was fed on a low-protein diet containing 50 g protein/kg for 28 d (PM), and then on a balanced diet for 23 d (BR). At different days of PM and BR, the pancreas and the pancreatic juice were collected 40 min after injection of 0.1 mCi [3H]leucine. The amounts of amylase (EC 3.2.1.1), trypsinogen 2 (EC 3.4.21.4), chymotrypsinogen 1 (EC 3.4.21.1) and lipase (EC 3.1.1.3) were determined after separation by the isoelectric focussing technique. Incorporation of [3H]leucine into the four hydrolases of pancreatic juice and pancreas was also determined. 2. In control rats a progressive increase in the concentration of digestive enzymes and the amounts secreted were observed with age. Maturation was reached when the rats were 9 weeks old. In rats E, PM inhibited maturation of the pancreas. However, individual enzymes were not affected to the same extent and at the same time. As soon as re-feeding was initiated, pancreas maturation took place and a significant increase in these variables was observed. The increases varied according to the hydrolase and did not appear at the same time. 3. In control rats, a preferential secretion of newly synthesized enzymes was observed in young rats, whereas with age, the proportion of newly synthesized enzymes excreted decreased slowly. In group E rats, at the beginning of PM, the proportion of newly synthesized enzymes secreted was very low and increased with time. 4. In rats C and E, our results indicated a non-parallelism between pancreatic enzyme levels and amounts secreted. This non-parallelism was different in both groups, it was changed with age and pancreas maturation in group C, and according to nutritional state in group E.
Prost
J
J
Université de Bourgogne, Laboratoire de Physiologie de la Nutrition, Faculté des Sciences Mirande, Dijon, France.
Belleville
J
J
Valantin-Rollet
C
C
D000375:Aging / Q000502:physiology*; D000681:Amylases / Q000032:analysis; D000818:Animals; D002919:Chymotrypsinogen / Q000032:analysis; D004044:Dietary Proteins / Q000008:administration & dosage; D006867:Hydrolases / Q000378:metabolism*; D007525:Isoelectric Focusing; D008049:Lipase / Q000032:analysis; D008297:Male; D010179:Pancreas / Q000201:enzymology*; D011502:Protein-Energy Malnutrition / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains; D014362:Trypsinogen / Q000032:analysis
D004044:Dietary Proteins; D014362:Trypsinogen; D002919:Chymotrypsinogen; D006867:Hydrolases; D008049:Lipase; D000681:Amylases