Diet Composition and Insulin Effect on Amylase to Lipase Ratio in Pancreas of Diabetic Rats

Abstract

In man and in rat, the diabetic state is associated with diseases of exocrine pancreatic function. In this work, streptozotocin diabetes was shown to lead to a 95% decrease in the amylase to lipase ratio in rats. Diabetes was reversed by either pancreas transplantation or insulin treatment. Transplantation of neonatal pancreases was successful in reversing the diabetic-induced alterations of exocrine pancreatic function. To assess whether insulin acts directly on the exocrine pancreas, or through the enhancement of glucose utilization, animals were fed either a low-fat diet or a high-fat diet during insulin treatment; this latter diet is well known to impair insulin’s effect on glucose metabolism. When diabetic rats were fed a low-fat diet, insulin treatment was able to correct the hyperketonemia and to reverse the amylase to lipase ratio to the prediabetes level. In contrast, the insulin treatment failed to restore the amylase to lipase ratio when the diabetic rats were fed the high-fat diet. Despite insulin treatment, the hyperketonemia worsened implying that glucose utilization remained low as would be expected on a high-fat diet. The dependence of the insulin effect upon diet composition demonstrates that the rate of glucose metabolism is the primary factor in the regulation of amylase to lipase ratio.

Immunocytochemical studies of pancreatic acinar cells in normal and streptozotocin-induced diabetic rats

“…Similar observations were made on normally fed and on overnight fasted animals, indicating that the intake of food by diabetic animals did not stimulate amylase secretion. These results are supported by our biochemical analysis, and are in agreement with previous reports demonstrating a depletion of pancreatic amylase under diabetic conditions [15,16,18,19,28,29]. According to the results obtained, these alterations do not seem to correspond to a direct influence of streptozotocin, since pancreatic tissue of animals having received the drug but not having developed an hyperglycaemic state shows no major modification in amylase secretion.…”

“…However, it is difficult to establish in a definite way if the alterations observed are directly related to the insulin deficiency or are the result of the hyperglycaemic state. Indeed, regulation of amylase secretion by circulating blood glucose levels has also been suggested [2,3,29]. Nevertheless, the lack of amylase under diabetic conditions may well represent an adaptation process through which the animal reduces glucose absorption.…”

Exocrine Pancreatic Secretion in Suckling Goats. Adaptative Effects of Maternal Milk and a Milk Substitute

“…Values obtained under resting conditions seem to indicate an adaptation of pancreatic enzymes to the amount of fat in the diet similar to that described in the rat, because kids fed with milk (i.e., with a higher intake of fat), presented higher lipase and lower amylase activities than animals fed with the milk replacer (Bazin & Lavan, 1979). Furthermore, as in the rat, changes in amylase were inverse to those in lipase: amylase activity declined as the amount of dietary fat and lipase activity increased (Deschodt-Lanckman et al, 1971;Sabb et al, 1986;Wicker & Puigserver, 1987).…”

Regulation of Pancreatic Lipase by Dietary Medium Chain Triglycerides in the Weanling Rat

“…The released medium-chain fatty acids (MCFA) may exert less allosteric inhibition on PL, and medium-chain 2-monoglycerides may isomerize more rapidly than those of long-chain length, thereby facilitating rapid hydrolysis (33). Such rapid hydrolysis might affect the regulation of PL through effects on either the release of secretin or gastric inhibitory polypeptide, proposed mediators of the dietary regulation of PL (36,37), or the generation of ketones, another proposed mediator (38). MCT are known to be oxidized more readily than LCT and may generate greater amounts of ketone at lower levels.…”