scholarly journals The effects of chronic hyperphenylalaninaemia on mouse brain protein synthesis can be prevented by other amino acids

1982 ◽  
Vol 206 (2) ◽  
pp. 407-414 ◽  
Author(s):  
P Binek-Singer ◽  
T C Johnson
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Polypeptide Chain ◽  
Amino Acid Mixture ◽  
Chain Elongation ◽  
Acid Mixture ◽  
Brain Protein ◽  
Brain Protein Synthesis ◽  
The Brain

A prolonged elevation in the concentrations of circulating phenylalanine was maintained in newborn mice by daily injections of phenylalanine and a phenylalanine hydroxylase inhibitor, alpha-methylphenylalanine. The result of this chronic hyperphenylalaninaemia was an accumulation of vacant or inactive monoribosomes that persisted for 18 h of each day. An elongation assay in vitro with brain postmitochondrial supernatants demonstrated that, in addition, there was an equally prolonged decrease in the rates of polypeptide-chain elongation by the remaining brain polyribosomes. Analyses of the free amino acid composition in the brains of hyperphenylalaninaemic mice showed a loss of several amino acids from the brain, particularly the large, neutral amino acids, which are co- or counter-transported across plasma membranes with phenylalanine. When a mixture of these amino acids (leucine, isoleucine, valine, threonine, tryptophan, tyrosine, methionine) was injected into hyperphenylalaninaemic mice, there was an immediate cessation of monoribosome accumulation in the brain and there was no inhibition of the rates of polypeptide-chain elongation. Although the concentrations of the large, neutral amino acids in the brain were partially preserved by treatment of hyperphenylalaninaemic mice with the amino acid mixture, the elevated concentrations of phenylalanine remained unaltered. The amino acid mixture had no detectable effect on brain protein synthesis in the absence of the hyperphenylalaninaemic condition.

An abundant supply of amino acids enhances the metabolic effect of exercise on muscle protein

1997 ◽  
Vol 273 (1) ◽  
pp. E122-E129 ◽  
Author(s):  
G. Biolo ◽  
K. D. Tipton ◽  
S. Klein ◽  
R. R. Wolfe
Keyword(s):  
Amino Acids ◽  
Blood Flow ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Protein Kinetics ◽  
Amino Acid Infusion

Six normal untrained men were studied during the intravenous infusion of a balanced amino acid mixture (approximately 0.15 g.kg-1.h-1 for 3 h) at rest and after a leg resistance exercise routine to test the influence of exercise on the regulation of muscle protein kinetics by hyperaminoacidemia. Leg muscle protein kinetics and transport of selected amino acids (alanine, phenylalanine, leucine, and lysine) were isotopically determined using a model based on arteriovenous blood samples and muscle biopsy. The intravenous amino acid infusion resulted in comparable increases in arterial amino acid concentrations at rest and after exercise, whereas leg blood flow was 64 +/- 5% greater after exercise than at rest. During hyperaminoacidemia, the increases in amino acid transport above basal were 30-100% greater after exercise than at rest. Increases in muscle protein synthesis were also greater after exercise than at rest (291 +/- 42% vs. 141 +/- 45%). Muscle protein breakdown was not significantly affected by hyperminoacidemia either at rest or after exercise. We conclude that the stimulatory effect of exogenous amino acids on muscle protein synthesis is enhanced by prior exercise, perhaps in part because of enhanced blood flow. Our results imply that protein intake immediately after exercise may be more anabolic than when ingested at some later time.

scholarly journals The effect of elevated plasma phenylalanine levels on protein synthesis rates in adult rat brain

1994 ◽  
Vol 302 (2) ◽  
pp. 601-610 ◽  
Author(s):  
D S Dunlop ◽  
X R Yang ◽  
A Lajtha
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Free Amino ◽  
Specific Activity ◽  
Brain Protein ◽  
Free Amino Acid Pool ◽  
Plasma Phenylalanine ◽  
Specific Activities ◽  
Brain Protein Synthesis ◽  
The Brain

Increasing the plasma phenylalanine concentration to levels as high as 0.560-0.870 mM (over ten times normal levels) had no detectable effect on the rate of brain protein synthesis in adult rats. The average rates for 7-week-old rats were: valine, 0.58 +/- 0.05%/h, phenylalanine, 0.59 +/- 0.06%/h, and tyrosine, 0.60 +/- 0.09%/h, or 0.59 +/- 0.06%/h overall. Synthesis rates calculated on the basis of the specific activity of the tRNA-bound amino acid were slightly lower (4% lower for phenylalanine) than those based on the brain free amino acid pool. Similarly, the specific activities of valine and phenylalanine in microdialysis fluid from striatum were practically the same as those in the brain free amino acid pool. Thus the specific activities of the valine and phenylalanine brain free pools are good measures of the precursor specific activity for protein synthesis. In any event, synthesis rates, whether based on the specific activities of the amino acids in the brain free pool or those bound to tRNA, were unaffected by elevated levels of plasma phenylalanine. Brain protein synthesis rates measured after the administration of quite large doses of phenylalanine (> 1.5 mumol/g) or valine (15 mumol/g) were in agreement (0.62 +/- 0.01 and 0.65 +/- 0.01%/h respectively) with the rates determined with infusions of trace amounts of amino acids. Thus the technique of stabilizing precursor-specific activity, and pushing values in the brain close to those of the plasma, by the administration of large quantities of precursor, appears to be valid.

Stimulated amino acid imbalance and histidine transport in rat brain slices

1975 ◽  
Vol 229 (1) ◽  
pp. 229-234 ◽  
Author(s):  
J Lutz ◽  
JK Tews ◽  
AE Harper
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Brain Slices ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Large Neutral Amino Acids ◽  
Neutral Amino Acids ◽  
Low Protein ◽  
Amino Acid Imbalance ◽  
The Brain

Histidine concentration in the brain decreases rapidly when rats are fed a low protein diet in which an amino acid imbalance is created by addition of an amino acid mixture devoid of histidine. Competition for histidine transport into the brain was suggested as an explanation for this effect. Therefore, animo acid mixtures simulating composition of plasma from rats fed basal or histidine-imbalanced diets were added to media to evaluate their effects on uptake of histidine by brain slices during a 60-min incubation period. At the concentrations actually found in plasma, the unbalanced mixture decreased histidine uptake significantly more than did the basal mixture. Two distinct inhibition patterns were observed with different groups of amino acids: a linear decrease in histidine uptake with a mixture of the small neutral, hydroxyl, basic, and acidic amino acids, and a hyperbolic decrease with a mixture of large neutral amino acids, and a hyperbolic decrease with a mixture of large neutral amino acids. Inhibition of histidine transport by the complete mixtures reflected these two effects. Plasma patterns and concentrations of competitive amino acids as well as the concentration of histidine appear to be factors involved in decreasing histidine transport into the brain.

Oral amino acids stimulate muscle protein anabolism in the elderly despite higher first-pass splanchnic extraction

1999 ◽  
Vol 277 (3) ◽  
pp. E513-E520 ◽  
Author(s):  
Elena Volpi ◽  
Bettina Mittendorfer ◽  
Steven E. Wolf ◽  
Robert R. Wolfe
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
The Elderly ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Healthy Elderly ◽  
First Pass

Muscle protein synthesis and breakdown and amino acid transport were measured in 7 healthy young (30 ± 2 yr) and 8 healthy elderly (71 ± 2 yr) volunteers in the postabsorptive state and during the oral administration of an amino acid mixture withl-[ ring-2H5]phenylalanine infusion, femoral artery and vein catheterization, and muscle biopsies. Phenylalanine first-pass splanchnic extraction was measured by addingl-[ ring-13C6]phenylalanine to the mixture. In the postabsorptive state, no differences in muscle amino acid kinetics were detected between young and elderly volunteers. Phenylalanine first-pass splanchnic extraction was significantly higher in the elderly ( P < 0.003) during ingestion of amino acids, but the delivery to the leg increased to the same extent in both groups. Phenylalanine transport into the muscle, muscle protein synthesis, and net balance increased significantly ( P < 0.01) and similarly in both the young and the elderly. We conclude that, despite an increased splanchnic first-pass extraction, muscle protein anabolism can be stimulated by oral amino acids in the elderly as well as in the young.

scholarly journals Effect of co-ingestion of amino acids with rice on glycaemic and insulinaemic response

2015 ◽  
Vol 114 (11) ◽  
pp. 1845-1851 ◽  
Author(s):  
Yean Yean Soong ◽  
Joseph Lim ◽  
Lijuan Sun ◽  
Christiani Jeyakumar Henry
Keyword(s):  
Amino Acids ◽  
Blood Glucose ◽  
Amino Acid ◽  
Glycaemic Index ◽  
Amino Acid Mixture ◽  
Postprandial Blood Glucose ◽  
Acid Mixture ◽  
White Rice ◽  
Amino Acid Mixtures

AbstractConsumption of high glycaemic index (GI) and glycaemic response (GR) food such as white rice has been implicated in the development of type 2 diabetes. Previous studies have reported the ability of individual amino acids to reduce GR of carbohydrate-rich foods. Because of the bitter flavour of amino acids, they have rarely been used to reduce GR. We now report the use of a palatable, preformed amino acid mixture in the form of essence of chicken. In all, sixteen healthy male Chinese were served 68 or 136 ml amino acid mixture together with rice, or 15 or 30 min before consumption of white rice. Postprandial blood glucose and plasma insulin concentrations were measured at fasting and every 15 min after consumption of the meal until 60 min after the consumption of the white rice. Subsequent blood samples were taken at 30-min intervals until 210 min. The co-ingestion of 68 ml of amino acid mixture with white rice produced the best results in reducing the peak blood glucose and GR of white rice without increasing the insulinaemic response. It is postulated that amino acid mixtures prime β-cell insulin secretion and peripheral tissue uptake of glucose. The use of ready-to-drink amino acid mixtures may be a useful strategy for lowering the high-GI rice diets consumed in Asia.

Liver extract and its free amino acids equally stimulate gastric acid secretion

1980 ◽  
Vol 239 (6) ◽  
pp. G493-G496 ◽  
Author(s):  
E. J. Feldman ◽  
M. I. Grossman
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Free Amino Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Liver Extract ◽  
Amino Acid Mixture ◽  
Acid Mixture

Using intragastric titration in dogs with gastric fistulas, dose-response studies were carried out with liver extract and with a mixture of amino acids that matched the free amino acids found in liver extract. All solutions were adjusted to pH 7.0 and osmolality to 290 mosmol x kg-1. Doses are expressed as the sum of the concentrations of all free amino acids. At each dose studied (free amino acid concentration: 2.8, 5.6, 11, 23, and 45 mM), acid secretion in response to the free amino acid mixture was not significantly different from that of liver extract. The peak response to both liver extract and the free amino acid mixture occurred with the 23-mM dose and represented about 60% of the maximal response to histamine. The serum concentrations of gastrin after liver extract and the amino acid mixture were not significantly different. It is concluded that in dogs with gastric fistula, gastric acid secretion and release of gastrin were not significantly different in response to liver extract and to a mixture of amino acids that simulated the free amino acid content of liver extract.

Effect of hyperinsulinemia and hyperaminoacidemia on muscle and liver protein synthesis in lactating goats

1994 ◽  
Vol 267 (6) ◽  
pp. E877-E885 ◽  
Author(s):  
I. Tauveron ◽  
D. Larbaud ◽  
C. Champredon ◽  
E. Debras ◽  
S. Tesseraud ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Skeletal Muscles ◽  
Constant Infusion ◽  
Acid Mixture ◽  
Liver Protein ◽  
Group I ◽  
Lactating Goats ◽  
Group A

The experiment was carried out to clarify the roles of insulin and amino acids on protein synthesis in fed lactating goats (30 days postpartum). Protein synthesis in the liver and various skeletal muscles was assessed after an intravenous injection of a large dose of unlabeled valine containing a tracer dose of L-[2,3,4-3H]valine. The animals were divided into three groups. Group I was infused with insulin (1.7 mumol/min) for 2.5 h under glucose, potassium, and amino acid replacement. Group A was infused with an amino acid mixture to create stable hyperaminoacidemia for 2.5 h. Group C animals were controls. The fractional synthesis rates (FSR) were 31.5 +/- 2.2, 6.5 +/- 0.4, 4.3 +/- 0.8, 4.0 +/- 1.2, 3.9 +/- 1.2, and 3.6 +/- 0.4%/day (SD) in liver, masseter, diaphragm, anconeus, semitendinosus, and longissimus dorsi, respectively, for group C. Neither hyperinsulinemia in group I nor hyperaminoacidemia in group A had not affected by hyperinsulinemia but was stimulated by hyperaminoacidemia (+30%, P < 0.05). In contrast to previous experiments in which a labeled amino acid was constantly infused, this study revealed a stimulating effect of amino acids on protein synthesis in the liver but not in skeletal muscles. As previously observed in studies with the constant-infusion method, insulin had no effect on protein synthesis.

scholarly journals Dietary γ-Aminobutyric Acid Affects the Brain Protein Synthesis Rate in Ovariectomized Female Rats

2009 ◽  
Vol 55 (1) ◽  
pp. 75-80 ◽  
Author(s):  
Kazuyo TUJIOKA ◽  
Miho OHSUMI ◽  
Kenji HORIE ◽  
Mujo KIM ◽  
Kazutoshi HAYASE ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Female Rats ◽  
Aminobutyric Acid ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Brain Protein ◽  
Brain Protein Synthesis ◽  
The Brain
Sign in / Sign up

Export Citation Format

Share Document