scholarly journals Stimulation of amino acid transport into liver cells from rats adapted to a high-protein diet

1982 ◽  
Vol 206 (1) ◽  
pp. 13-18 ◽  
Author(s):  
P Fafournoux ◽  
C Rémésy ◽  
C Demigné
Keyword(s):  
Amino Acids ◽  
Decisive Role ◽  
High Protein Diet ◽  
Isolated Hepatocytes ◽  
Hepatic Uptake ◽  
High Protein ◽  
Protein Diet ◽  
High Protein Diets ◽  
Protein Diets

After adaptation of rats to a 90%-casein diet, hepatic uptake of alanine is strikingly increased in vivo, with concomitant appearance of a concentration of favourable for uptake. With a high-protein diet, uptake of 2-aminoisobutyrate by isolated hepatocytes in the presence of various concentrations of substrates suggested induction of the A system (high-affinity system), whose emergence has been reported during starvation or after glucagon treatment. The other system (ASC, L) were characterized: induction processes only affected the A system. Dibutyryl cyclic AMP addition resulted in an increase in 2-aminoisobutyrate transport at low substrate concentration, the response being greater after adaptation to a high-protein diet. Evidence is presented suggesting that the increased uptake of amino acids by the liver of rats fed on high-protein diets is obtained by developing favourable gradients and enhancing transport capacities. These adaptations allow sufficient amounts of amino acids to enter the liver, where accelerated metabolism plays a decisive role.

scholarly journals High protein diet: benefits and risks

2021 ◽  
Vol 17 (4) ◽  
pp. 393-400
Author(s):  
M. V. Altashina ◽  
E. V. Ivannikova ◽  
E. A. Troshina
Keyword(s):  
Cardiovascular Diseases ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Eating Patterns ◽  
Nonalcoholic Fatty Liver ◽  
High Protein Diets ◽  
Protein Diets ◽  
Mineral Bone Density

The nature of human nutrition has become increasingly important as an effective element in the prevention and treatment of many pathologies, especially obesity, type 2 diabetes and cardiovascular diseases. High protein diets are some of the most popular eating patterns and the Dukan diet has taken the lead in popularity among the diets of this type. An increase of protein in the diet is effective in reducing body weight, primarily due to the loss of adipose tissue, without a significant effect on muscle mass. Another advantage of a high-protein diet is earlier and longer satiety compared to other diets, which makes it comfortable for use. Besides obesity, high protein diets are presumably effective for treating such diseases as nonalcoholic fatty liver disease, diabetes mellitus and cardiovascular diseases However, despite the important advantages, this nutritional model is not universal and is contraindicated in patients with diseases of liver, kidneys and osteoporosis. Besides, the prolonged use of a high protein diet may increase the risks of urolithiasis and reduced mineral bone density even for healthy individuals. Thus, the increase in the proportion of protein in the diet should take place exclusively under the supervision of a physician.

Effect of adrenalectomy and hypophysectomy on responses of rat liver enzymes to high-protein diets

1968 ◽  
Vol 46 (10) ◽  
pp. 1253-1260 ◽  
Author(s):  
R. A. Freedland
Keyword(s):  
Enzyme Activity ◽  
Rat Liver ◽  
Liver Enzymes ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Metabolic Function ◽  
Simple Pattern ◽  
High Protein Diets ◽  
Protein Diets

Although many enzymes are increased by either a high-protein diet or cortisol adminstration, there was no evidence of a glucocorticoid requirement for the high-protein mediated increases. This was particularly noticeable for enzymes markedly increased by feeding a high-protein diet. Neither adrenalectomy nor hypophysectomy prevented the diet-mediated increases, although in certain instances the responses were decreased. Many enzymes which were unaffected or decreased in the intact rat by feeding a high-protein diet had markedly different responses after endocrine removal. There did not appear to be a general or simple pattern of these altered responses. Therefore predictions on possible activity changes could not be made, except for those enzymes normally increased by a high-protein diet on the basis of metabolic function or hormonal effects. Possible hormonal controls of these changes in enzyme activity are discussed.

Splanchnic sequestration of amino acids in aged rats: in vivo and ex vivo experiments using a model of isolated perfused liver

2008 ◽  
Vol 294 (3) ◽  
pp. R748-R755 ◽  
Author(s):  
M. Jourdan ◽  
L. Cynober ◽  
C. Moinard ◽  
M. C. Blanc ◽  
N. Neveux ◽  
...  
Keyword(s):  
Amino Acids ◽  
Ex Vivo ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Aged Rats ◽  
Sprague Dawley ◽  
Adult Rats ◽  
Urea Production

Splanchnic sequestration of amino acids (SSAA) is a process observed during aging that leads to decreased peripheral amino acid (AA) availability. The mechanisms underlying SSAA remain unknown. The aim of the present study was to determine whether a high-protein diet could increase nitrogen retention in aged rats by saturating SSAA and whether SSAA could be explained by dysregulation of hepatic nitrogen metabolism. Adult and aged male Sprague-Dawley rats were housed in individual metabolic cages and fed a normal-protein (17% protein) or high-protein diet (27%) for 2 wk. Nitrogen balance (NB) was calculated daily. On day 14, livers were isolated and perfused for 90 min to study AA and urea fluxes. NB was lower in aged rats fed a normal-protein diet than in adults, but a high-protein diet restored NB to adult levels. Isolated perfused livers from aged rats showed decreased urea production and arginine uptake, together with a release of alanine (vs. uptake in adult rats) and a hepatic accumulation of alanine. The in vivo data suggest that SSAA is a saturable process that responds to an increase in dietary protein content. The hepatic metabolism of AA in aged rats is greatly modified, and urea production decreases. This result refutes the hypothesis that SSAA is associated with an increase in AA disposal via urea production.

scholarly journals High-Protein Diets for Treatment of Type 2 Diabetes Mellitus: A Systematic Review

2019 ◽  
Vol 10 (4) ◽  
pp. 621-633 ◽  
Author(s):  
Samar Malaeb ◽  
Caitlin Bakker ◽  
Lisa S Chow ◽  
Anne E Bantle
Keyword(s):  
Diabetes Mellitus ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Controlled Trials ◽  
Randomized Controlled ◽  
Glycemic Outcomes ◽  
High Protein Diets ◽  
Protein Diets

ABSTRACT Diet has the potential to be a powerful and cost-effective tool for treatment of type 2 diabetes mellitus (T2D). High-protein diets have shown promise for this purpose. The objective of this systematic review was to evaluate whether high-protein diets improve glycemic outcomes in people with T2D. We conducted a systematic search of literature published prior to 1 February 2018 to find clinical studies of high-protein diet patterns for treatment of T2D in human participants. A high-protein diet was defined as a diet with protein content greater than that of a typical diet in the United States (>16% of total energy as protein). Studies were excluded if weight loss >5% occurred or if no glycemic outcomes were measured. A total of 21 independent articles met our criteria and were included. Most tested diets had a protein content of around 30% of total energy. Many studies supported the use of high-protein diets for patients with T2D, but were limited by small size (n = 8–32) and short duration (1–24 wk). Randomized controlled trials tended to be larger (n = 12–419) and longer (6 wk–2 y), and had mixed results, with many trials showing no difference between a high-protein diet and control. Many randomized controlled trials were limited by low compliance and high dropout rates >15%. There were no consistent beneficial or detrimental effects of high-protein diets on renal or cardiovascular outcomes. Evidence was insufficient to recommend 1 type of protein (plant or animal) over the other. Our review suggests that interventions to improve compliance with diet change over the long term may be equally important as specific macronutrient recommendations for treatment of T2D.

scholarly journals Monoclonal antibodies used in immunocytochemical localization by electron microscopy of carbamoyl phosphate synthetase I in liver from rats fed high-protein diets.

1987 ◽  
Vol 35 (8) ◽  
pp. 897-907 ◽  
Author(s):  
A Martinez-Ramon ◽  
E Knecht ◽  
S Grisolía
Keyword(s):  
Electron Microscopy ◽  
Monoclonal Antibodies ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Cross Sectional ◽  
High Protein Diets ◽  
Protein Diets

Carbamoyl phosphate synthetase I (CPS-I) is the most abundant protein of rat liver mitochondria. Biochemical measurements in liver homogenates have shown that the liver from rats fed a high-protein diet contains more CPS-I per gram tissue protein than controls. However, there is no information on changes in the intact tissue at the cellular and mitochondrial level. Therefore, monoclonal antibodies to beef liver CPS-I were produced by the hybridoma technique. Four clones, C-241/1A, B, C, and D secreted immunogammaglobulin (IgG) IgG1. Using C-241/C, we measured by electron microscopy immunogold procedures the labeling of CPS-I in mitochondria from liver of rats fed high protein (casein, 50 and 80% of total food intake) diets. CPS-I (expressed as gold particles/micron2 of mitochondrial cross-sectional area) was greater than in mitochondria from control rats (20% casein diet), whether the rats were fed for 1, 6, or 14 months on the high-protein diets. The immunocytochemical measurements shown here demonstrate that the increase in the level of CPS-I in high-protein diets is a reflection of both the larger number of CPS-I molecules per mitochondrial area and the larger proportion of the total hepatocyte volume occupied by mitochondria. Similar measurements were carried out with glutamate dehydrogenase (GDH) using previously characterized monoclonal antibodies. No differences in GDH labeling were found with high-protein diets. Interestingly, when mitochondria from hepatocytes of rats fed a high-protein diet were divided into two subpopulations on the basis of mitochondrial cross-sectional size (i.e., greater or less than 0.7 micron2), the large mitochondria had 1.2 times more CPS-I and 0.8 times less GDH than the small mitochondria nearby.

Fluxes and membrane transport of amino acids in rat liver under different protein diets

1990 ◽  
Vol 259 (5) ◽  
pp. E614-E625 ◽  
Author(s):  
P. Fafournoux ◽  
C. Remesy ◽  
C. Demigne
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aromatic Amino Acids ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Transport Systems ◽  
Low Concentrations ◽  
Significant Uptake

The aim of the present work was to evaluate in vivo the role of the transport step in hepatic amino acid metabolism. To vary hepatic utilization of amino acids, rats were adapted to diets containing various concentrations of casein (5, 15, and 60%). In rats fed 5 or 15% casein diets, Gln and Glu were released by the liver, and there was a significant uptake of Ala. Hepatic fluxes of amino acids increased considerably after adaptation to high-casein diet (up to 1.55 mumol.min-1.g liver-1 for Ala), because of the rise in afferent concentrations as well as enhanced uptake percentage (peaking at 60–75% for most glucogenic amino acids). Adaptation to a high-protein diet led to induction of not only system A but also of most of the other transport systems (Gly, anionic, T, y+, and to a lesser extent system N); only systems ASC and L were unchanged. The study of amino acid repartition between liver and plasma with different diets indicates that transport could modulate utilization of Ala, Ser, Thr, Gly, Gln, and Asp. For Arg and Asn, present in very low concentrations in liver under any condition, the transport step should be the major locus of control of their metabolism. For amino acids chiefly transported by nonconcentrative systems, such as aromatic amino acids, cellular metabolism could also be limited by the transport process. In conclusion, during adaptation to a high-protein diet, there is apparently a coordinated adaptation of amino acid transport and of their intracellular metabolism. For some amino acids, induction of catabolic enzymes seems greater than that of transport, so that the transport step may play an important role in control of metabolic fluxes. For example, concentration of amino acids such as Thr may be markedly depressed in rats adapted to a high-protein diet.

scholarly journals THE EFFECT OF HIGH PROTEIN DIETS ON EXPERIMENTAL RENAL HYPERTENSION

1941 ◽  
Vol 74 (6) ◽  
pp. 591-600 ◽  
Author(s):  
H. Philipsborn ◽  
L. N. Katz ◽  
S. Rodbard
Keyword(s):  
Blood Pressure ◽  
Renal Hypertension ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Low Protein ◽  
Experimental Renal Hypertension ◽  
High Protein Diets ◽  
Protein Diets

The effect of high and low protein diets were studied on fourteen dogs in twenty-four different experiments. In only two of these animals, both with moderate renal excretory failure, was a reversible rise in blood pressure elicited by a high protein diet. The possible mechanisms involved in meeting an increased excretory load are discussed.

scholarly journals A proposito di…diete iperproteiche: proviamo a discuterne

2014 ◽  
Vol 26 (3) ◽  
pp. 262-266
Author(s):  
Luisa Paschino
Keyword(s):  
Sono State ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
High Protein Diets ◽  
Protein Diets

Con l'aumento costante della prevalenza di sovrappeso e obesità in tutto il mondo, è sempre maggiore l'interesse e l'utilizzo di diete iperproteiche da parte della popolazione generale per contrastare tale fenomeno. Tuttavia, vi sono ancora oggi forti dubbi sulla sicurezza a lungo termine delle High-Protein diets, soprattutto per quanto riguarda il possibile sviluppo e la progressione della patologia renale. Le diete iperproteiche sono state associate a ipertrofia renale, iperfiltrazione glomerulare, accelerazione della CKD, aumento della proteinuria, maggior rischio di nefrolitiasi e varie alterazioni metaboliche. Mentre è ormai accettato che tali condizioni possono causare un danno renale progressivo nelle persone che già soffrono di patologia renale, meno chiaro è invece l'impatto di un elevato apporto di proteine nei soggetti sani. Una comprensione globale del rischio ad esse correlato è ancora oggi limitata dall'assenza di rigorosi studi a lungo termine sull'uomo e dalla mancanza di una definizione universalmente accettata di High-Protein diet. A tal proposito è bene non indicare diete iperproteiche nei soggetti con GFR

Renal glutamine metabolism in rats fed high-protein diets.

1978 ◽  
Vol 235 (3) ◽  
pp. E261 ◽  
Author(s):  
J T Brosnan ◽  
P McPhee ◽  
B Hall ◽  
D M Parry
Keyword(s):  
Protein Intake ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Sodium Bicarbonate Solution ◽  
Ammonia Excretion ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Glutamine Metabolism ◽  
High Protein Diets ◽  
Protein Diets

The influence of protein intake on acid excretion and renal glutamine metabolism was investigated and compared to the effects of NH4Cl-induced metabolic acidosis. Rats fed a diet containing 55% casein excreted more ammonia, phosphate, sulphate, and chloride than did rats fed a 13% casein diet, but, when they were given an 0.1 M NaHCO3 solution to drink, ammonia excretion was no longer elevated. Renal phosphate-dependent glutaminase and phosphoenolpyruvate carboxykinase activities, ammoniagenesis by isolated mitochondria, and the rate of renal gluconeogenesis were all elevated in the rats fed the high-protein diet but not if these rats also drank the sodium bicarbonate solution. Increased glutaminase and phosphoenolpyruvate carboxykinase activities, mitochondrial ammoniagenesis, and gluconeogenesis were all evident in rats made acidotic with NH4Cl. It is concluded that these metabolic adaptations evident in the kidneys of rats fed the high-protein diet are due to the acidogenic effects of increased protein intake.

scholarly journals Fermented Feed Supplement Relieves Caecal Microbiota Dysbiosis and Kidney Injury Caused by High-Protein Diet in the Development of Gosling Gout

Animals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2139
Author(s):  
Yumeng Xi ◽  
Yuanpi Huang ◽  
Ying Li ◽  
Junshu Yan ◽  
Zhendan Shi
Keyword(s):  
Dietary Protein ◽  
Kidney Injury ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Feed Supplement ◽  
Protein Levels ◽  
Fermented Feed ◽  
High Protein Diets ◽  
Protein Diets

Firstly, forty-eight 1-day-old goslings were randomly allocated to four groups and were fed diets containing crude protein (CP) at different concentrations: 160, 180, 200, and 220 g/kg in Experiment One. We found a dose-dependent relationship between the dietary protein levels and morbidity of gosling gout. The concentration of serum uric acid (UA), creatinine (Cr), and urea nitrogen (UN), and the activity of xanthine oxidase in the 220CP groups were significantly higher than those in the low-protein diet groups. Beneficial microbes, including Akkermansia, Lactococcus, and Butyricicoccus were enriched in the ceca of healthy goslings, while the microbes Enterococcus, Enterobacteriaceae, and Bacteroides were enriched in those with gout. Then, we explored the effects of fermented feed on gosling gout caused by high-protein diets in Experiment Two. A total of 720 1-day-old goslings were randomly allotted to four experimental groups: CN (162.9 g/kg CP), CNF (167.5 g/kg CP, replacing 50 g/kg of the basal diet with fermented feed), HP (229.7 g/kg CP, a high-protein diet), and HPF (230.7 g/kg CP, replacing 50 g/kg of the high-protein diet with fermented feed). We found that the cumulative incidence of gout increased in the HP group compared with that in the control, but decreased in the HPF group compared to that in the HP group. Similarly, the concentration of serum UA in the HP group was higher than that in the CN group, but decreased in the HPF group. Meanwhile, compared with the HP group, using fermented feed in diets decreased the abundance of Enterococcus in the ceca of goslings, while increasing the abundance of Lactobacillus. These results suggest that appropriate dietary protein levels and the fermented feed supplement might relieve the kidney injury and gut microbiota dysbiosis caused by high-protein diets in the development of gosling gout.

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