Effects Of Protein Restriction Research Articles

The Effect of Protein Restriction on the Progression of Renal Insufficiency

Dietary protein intake may be an important determinant of the rate of decline in renal function in patients with chronic renal insufficiency. We conducted a prospective, randomized study of the efficacy of protein restriction in slowing the rate of progression of renal impairment. The study lasted 18 months and included 64 patients with serum creatinine concentrations ranging from 350 to 1000 micromol per liter. The patients were randomly assigned to follow either a regular diet or an isocaloric protein-restricted diet (0.4 g of protein per kilogram of the body weight per day). Blood-pressure levels and the balance between calcium and phosphate were similar in the two groups. End-stage renal failure developed in 9 of the 33 patients (27 percent) who followed the regular diet during the study, as compared with 2 of the 31 patients (6 percent) who followed the protein-restricted diet (P less than 0.05). The mean (+/- SE) glomerular filtration rate, as measured by the clearance of 51Cr bound to EDTA, fell from 0.25 +/- 0.03 to 0.10 +/- 0.05 ml per second (P less than 0.01) in the group on the regular diet, whereas it fell from 0.23 +/- 0.04 to 0.20 +/- 0.05 ml per second (P not significant) in the group on the protein-restricted diet. We conclude that dietary protein restriction is effective in slowing the rate of progression of chronic renal failure.

Dietary Protein Restriction Decreases Insulin-Like Growth Factor I Independent of Insulin and Liver Growth Hormone Binding*

To determine the role of hypoinsulinemia and liver somatogenic (GH) receptors in growth retardation and decreased serum insulin-like growth factor I (IGF-I) levels during protein restriction, we have used a rat model where the effects of a low protein intake on body weight (BW), serum IGF-I concentration, and liver GH binding could be evaluated in the presence of low or high insulin concentrations. Two days after being made diabetic with streptozotocin (60 mg/kg BW), 6-week-old female rats (nine per group) were begun on a low (5%) or normal (15%) protein diet, without or with insulin supplementation (3 U lente daily). Nondiabetic rats fed both diets were used as controls (nine per group). In the nondiabetic animals, 7 days of protein restriction reduced BW gain by 50% (P less than 0.001), serum insulin by 44% (P less than 0.025), and serum IGF-I concentrations by 28% (P less than 0.001) without significantly changing liver GH binding. By day 9, BW was decreased in the diabetic animals by 12%, serum insulin by 80%, serum IGF-I by 55%, and liver GH binding by 62%; these effects were similar in the 5% and 15% protein-fed rats (P less than 0.001 vs. the corresponding controls). In the diabetes fed the normal diet, insulin treatment restored BW gain, serum IGF-I, and liver GH binding to normal values. In contrast, in the diabetics fed a protein-restricted diet and treated with insulin, BW gain and serum IGF-I concentrations remained low, similar to those in the malnourished controls. This diet-induced growth attenuation was observed despite high circulating insulin (2-3 times normal values), appropriate glucose control (63 +/- 9 mg/dl), and near restoration of liver GH binding. We conclude that while both protein restriction and diabetes attenuate growth and reduce IGF-I concentrations, the effects of protein restriction are independent of the effects of insulin and probably act by alteration of postreceptor mechanisms.

糖尿病性腎症の進展防止に対する早期蛋白制限食導入効果について 長期Prospective Follow Up Study

糖尿病性腎症の進展防止に対する早期蛋白制限食導入効果について 長期Prospective Follow Up Study

Can the Effects of Protein Restriction on the Progression of Renal Failure Also Be Achieved by Pharmacological Means?

A review is given of recent data on the role of cyclo-oxygenase products in mediating glomerular hyperfiltration in renal disease and on the role of prostaglandins in protein-induced glomerular hyperfiltration. The possible beneficial effects of cyclo-oxygenase inhibitors and thromboxane synthetase inhibitors are discussed.

Effect of Protein Restriction on the Development of Diabetic Nephropathy

Effect of Protein Restriction on the Development of Diabetic Nephropathy

Effects of protein restriction, melatonin administration, and short daylength on brain benzodiazepine receptors in prepubertal male rats.

The possibility that there are changes in brain benzodiazepine binding sites controlled by photoperiod was investigated in two strains of male rats. The hypothesis was tested by 3H-diazepam binding studies in various brain regions of prepubertal rats maintained in 14 or 10 h of light or treated with late-afternoon injections of melatonin (50 micrograms/day). Protein restriction was applied during the experiment to sensitise the animals to the treatments. Under the conditions employed, rats kept in short daylength throughout or kept on long photoperiod and given late-afternoon melatonin injections showed evidence of delayed puberty (seminal vesicle, ventral prostate, and testis weight decreased by 45%, 55%, and 60% respectively, compared to control rats). Binding measurements were made 1 h before and 2 and 5 h after the onset of darkness in the pubertal (42-day-old) or experimentally prepubertal rats. In the rats of the Porton strain (for which protein restriction was obligatory for the gonadal response) there was no consistent treatment or time effects on specific binding of 3H-diazepam to washed membranes of the hypothalamus, midbrain, or striatum. Similarly, there were no differences in the stimulation of 3H-diazepam binding by 100 microM GABA or the inhibition of binding by 50 microM N-acetyl 5 methoxy kynurenamine. By contrast, in Wistar rats, specific binding to midbrain membranes was reduced 5 h after dark compared to 2 h (37% saline; 20% melatonin) and the extent of stimulation by GABA in the hypothalamus was increased 5 h after darkness (35.6% to 46.7% saline; 37.4% to 50% melatonin). Melatonin treatment resulted in significantly higher specific binding in the hypothalamus 2 h after dark (10%, control fed; 20%, protein restricted) but reduced the GABA induced stimulation of binding in the midbrain (35.5% to 25%, control fed; 33.7% to 23.5%, protein restricted). The Bmax of benzodiazepine binding to unwashed cortical P2 synaptosomal membranes has been reported to increase twofold in adult Wistar rats at mid-dark. By contrast the Bmax of juvenile Wistar rats in this study increased only 17% (116 +/- 2.4 fmol/mg protein to 140 +/- 3 fmol/mg protein) between 2 and 5 h after darkness. In melatonin-treated animals the increase in Bmax of 3H-diazepam binding was blocked (124 +/- 5 fmol/mg protein at 2 h; 127 +/- 3 fmol/mg protein at 5 h) and the Kd reduced (4.5 +/- 0.5 to 4.0 +/- 0.2 nM).(ABSTRACT TRUNCATED AT 400 WORDS)

Protein turnover in tissues of the fetal rat after prolonged maternal malnutrition.

Protein turnover in fetal diaphragm, heart, liver, and brain was determined at 21 days gestation in fetal rats whose mothers had received a protein-restricted diet (6% protein) throughout gestation. This diet resulted in severe combined protein-calorie malnutrition. Fetal body weight was significantly decreased at days 19-22 gestation versus controls (27% protein diet) when pregnant animals were protein-restricted (e.g. 40% decrease in body weight at day 22 gestation versus controls). Protein synthesis was determined by intravenous injection of "massive" amounts of [3H]phenylalanine to pregnant animals and measuring free and protein-bound specific radioactivities in fetal tissues. Rate constants for protein degradation were calculated by subtracting fractional growth rate from protein synthesis. Fractional protein synthesis was reduced in diaphragm (0.26 versus 0.41 days-1), heart (0.41 versus 0.52 days-1), and liver (0.35 versus 0.89 days-1) in fetuses from malnourished mothers relative to controls. Similarly, fractional protein degradation was decreased in these fetal tissues-diaphragm (0.03 versus 0.06 days-1), heart (0.14 versus 0.18 days-1), and liver (0.25 versus 0.80 days-1). Reduced protein accretion during maternal malnutrition in these fetal tissues is secondary to decreased protein synthesis out of proportion to the concurrent reduction in protein degradation. Protein synthesis and degradation in fetal brain from malnourished mothers were not altered versus controls. These effects of malnutrition on protein turnover in fetal tissues throughout pregnancy in the rat correspond closely with the effect of protein restriction in young adult rats and the effect of protein-calorie malnutrition on whole body protein turnover in human infants.

Effect of Protein Restriction on Macrophage Phagocytic Capacity in Young Mice

C57BL/6J male mice were fed ad libitum either a 6% (low) or 25% (control) protein diet for 2 to 6 weeks. At periods of 2, 3, 5 or 6 weeks following initiation of the feeding protocol thioglycollate-elicited peritoneal macrophages were assayed for Fc receptor-mediated phagocytic capability with IgG-coated sheep red blood cells (SRBC). Binding via this receptor (as monitored at 2°C) was not affected by the protein restriction throughout the study. Ingestion of prebound IgG-SRBC was initially suppressed (2 weeks on diet) in macrophages from animals fed low protein but rose to a level significantly higher than similarly treated control animals after 5 weeks on the diet. At 3 and 6 weeks macrophages from control and low protein-fed animals exhibited no differences in ingestion capability. Overall phagocytosis (no prebinding of IgG-SRBC) was similar in trend to the data observed for ingestion. The data indicate both an altered response to phagocytosis with the low protein diet and the importance of quantitating the relationship between the duration of the nutritional insult and the parameter being measured.

Role of the Biliary slgA in the Gastointestinal Tract and the Effect of Malnutrition on the Biliary slgA in the Rat

AbstractThe secretory IgA (slgA) was purified from rat bile, and the role of slgA in the intestine and the effect of protein restriction on biliary slgA were investigated in the rat. The purified biliary slgA contained s‐chain and L‐chain and secretory component (SC), and was about 400,000 of molecular weight, about 11.7S. Biliary slgA itself was not digested by trypsin and intestinal fluid, though monomeric IgA (mlgA) was digested. By the challenge of DNP‐BSA, specific antibody against DNP‐BSA was secreted into bile and excreted into feces. Only DNP‐BSA alone was hydrolyzed by trypsin in the presence of biliary slgA containing specific DNP‐BSA antibody. When rats were raised on a diet restricted in protein the concentration of IgA, particularly slgA, in bile and the biliary immune response decreased markedly. These results suggest that biliary slgA involves an important function in the defense of intestinal absorption of foreign antigens such as organisms of infectious diseases and macromolecules in foods, and that the production or the secretion of biliary slgA is sensitively affected by the nutritional situation.

The effect of protein nutrition on host and tumor metabolism

Since the introduction of intravenous hyperalimentation (IVH) as a nutritional adjunct in multimodal cancer therapy (X), the risk of providing nutrient substrates for more rapid tumor growth has been a concern of those who use IVH to rehabilitate malnourished cancer patients nutritionally. Because of the technical difficulties in studying glucose and amino acid utilization in cancer patients, an experimental model was designed to simulate the nutritional problems encountered in cachectic cancer patients. Tumor-bearing rats were protein depleted with a protein-free diet, and then randomized into three groups which either continued on the protein-free diet, resumed a regular protein diet, or received intravenous hyperalimentation. By manipulating the dietary protein intake, the effects of protein restriction and repletion on host and tumor metabolism could be compared and related to the clinical situation in which hyperalimentation is used to replete malnourished cancer patients nutritionally. Host and tumor metabolism were evaluated by measuring the activity of three important enzymes that control glucose production and specific amino acid degradation. Fructose 1,6-diphosphatase (FDPase, EC 3.1.3.11) is considered one of the rate-limiting enzymes in the gluconeogenic pathway because of its slow kinetics and irreversible catalytic action (25). Glutamate -pyruvate transaminate (GPT, L-alanine:Z

The performance of laying hens fed various dietary protein levels in the growing period and first laying year

Two experiments examined the effects of protein restriction in the growing period on the production of egg type pullets. The protein levels of diets fed in the growing period were 15, 13, and 11 per cent. The treatments were incorporated in factorial designs with nutritional treatments in the laying period involving diet protein levels of 17, 15, and 13 per cent and, for one of the experiments, with housing densities of either 4 sq. ft. or 2 sq. ft. per bird. Restriction of protein during the growing period retarded growth and delayed sexual maturity, but neither of the levels of restriction examined increased subsequent laying performance. Eggs lost due to delays in the onset of production were not compensated for by increases in subsequent production and egg weight was generally depressed by protein restriction. The pattern of egg production was altered by restriction. A 13 per cent protein layer diet introduced at point of lay also reduced bodyweight gain and delayed age at sexual maturity. Interactions between nutritional and housing treatments in the growing and laying periods were apparent in egg production and egg weight.