High-protein diet: effect on insulin secretion patterns from streptozotocin-diabetic rats and mice

In the present study we have investigated the effect of a high-protein feeding on glucose induced-insulin secretion patterns from high dose streptozotocin (SZ) injected rats and mice, and from mice given multiple low doses of SZ. For this purpose male rats and mice were fed either a high-protein, carbohydrate-free diet, or control diets, before and after i.p. injections of SZ, or citrate buffer only. Our results show that when SZ was given as a single diabetogenic dose, rats and mice kept on the high-protein diet presented lower serum glucose levels, normal basal insulin values, and higher first and second phases of stimulated insulin release, when compared with diabetic animals on control diets. Furthermore, when rats prolonged their high-protein feeding from 4 to 11 days after SZ injection, there was an additional increment in insulin secretory capacity with a further diminution in serum glucose levels. We also show that high-protein feeding in mice given multiple low doses of SZ (a model of autoimmune diabetes), produced a diminution in serum glucose values, and an improvement in both phases of stimulated insulin release. Thus, in the two models of experimental diabetes used here, high-protein feeding exerts beneficial effects in beta cell responsiveness to glucose.

Efecto de una dieta libre de proteínas sobre la secreción de insulina y somatostatina en ratas / [The effect of a protein-free diet on insulin and somatostatin secretion in rats]

We have used a model of experimental protein-energy malnutrition induced in weaned rats by administration of a protein free diet during 2 weeks. Some malnourished rats were then refed with a control diet for 4, 9 or 30 days. Control rats were fed for the same periods with the balanced control diet. Malnourished rats showed a loss in body weight of approximately 25

. After 30 days of refeeding, the animals gained weight reaching values higher than that of control rats. Insulin secreted by perifused pancreatic slices from malnourished rats, was impaired in first and second glucose-induced secretory phases. Basal secretion was also diminished in incubation of pancreatic slices. When malnourished rats were refed for 4 days, basal insulin secretion reached control values. Stimulated insulin secretion was normalized at 9 and 30 days of refeeding. Our result on somatostatin (SRIF) secretion in malnourished rats showed basal hypersecretion and diminished first and second glucose-induced secretory phases. During refeeding basal SRIF secretion was normalized from day 4. On the contrary stimulated secretion was significantly increased at 4 and 9 days of refeeding, and on day 30 values did not differ from controls. In protein energy malnutrition, the disturbed hormonal state can represent adaptative mechanisms to the protein depletion and hormonal changes have also an essential role in refeeding.

High-protein diet: effect on insulin secretion patterns from streptozotocin-diabetic rats and mice

In the present study we have investigated the effect of a high-protein feeding on glucose induced-insulin secretion patterns from high dose streptozotocin (SZ) injected rats and mice, and from mice given multiple low doses of SZ. For this purpose male rats and mice were fed either a high-protein, carbohydrate-free diet, or control diets, before and after i.p. injections of SZ, or citrate buffer only. Our results show that when SZ was given as a single diabetogenic dose, rats and mice kept on the high-protein diet presented lower serum glucose levels, normal basal insulin values, and higher first and second phases of stimulated insulin release, when compared with diabetic animals on control diets. Furthermore, when rats prolonged their high-protein feeding from 4 to 11 days after SZ injection, there was an additional increment in insulin secretory capacity with a further diminution in serum glucose levels. We also show that high-protein feeding in mice given multiple low doses of SZ (a model of autoimmune diabetes), produced a diminution in serum glucose values, and an improvement in both phases of stimulated insulin release. Thus, in the two models of experimental diabetes used here, high-protein feeding exerts beneficial effects in beta cell responsiveness to glucose.

Efecto de una dieta libre de proteínas sobre la secreción de insulina y somatostatina en ratas / [The effect of a protein-free diet on insulin and somatostatin secretion in rats]

We have used a model of experimental protein-energy malnutrition induced in weaned rats by administration of a protein free diet during 2 weeks. Some malnourished rats were then refed with a control diet for 4, 9 or 30 days. Control rats were fed for the same periods with the balanced control diet. Malnourished rats showed a loss in body weight of approximately 25

. After 30 days of refeeding, the animals gained weight reaching values higher than that of control rats. Insulin secreted by perifused pancreatic slices from malnourished rats, was impaired in first and second glucose-induced secretory phases. Basal secretion was also diminished in incubation of pancreatic slices. When malnourished rats were refed for 4 days, basal insulin secretion reached control values. Stimulated insulin secretion was normalized at 9 and 30 days of refeeding. Our result on somatostatin (SRIF) secretion in malnourished rats showed basal hypersecretion and diminished first and second glucose-induced secretory phases. During refeeding basal SRIF secretion was normalized from day 4. On the contrary stimulated secretion was significantly increased at 4 and 9 days of refeeding, and on day 30 values did not differ from controls. In protein energy malnutrition, the disturbed hormonal state can represent adaptative mechanisms to the protein depletion and hormonal changes have also an essential role in refeeding.