Abnormal amino acid metabolism and brain protein synthesis during neural development

1978 ◽  
Vol 3 (4) ◽  
pp. 381-399 ◽  
Author(s):  
Joseph V. Hughes ◽  
Terry C. Johnson
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Neural Development ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Brain Protein ◽  
Brain Protein Synthesis

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.

scholarly journals Rates of protein synthesis in skin and bone, and their importance in the assessment of protein degradation in the perfused rat hemicorpus

1981 ◽  
Vol 194 (1) ◽  
pp. 373-376 ◽  
Author(s):  
V R Preedy ◽  
P J Garlick
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Degradation ◽  
Muscle Tissue ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Muscle Protein ◽  
Muscle Metabolism ◽  
Muscle Protein Degradation

The perfused rat hemicorpus preparation, which has frequently been used to study muscle metabolism, contains 39% by weight of non-muscle tissue such as skin and bone. Both the concentration of RNA and the incorporation of [U-14C]tyrosine into protein indicate that the non-muscle components are more active in protein synthesis than is muscle. These observations have important implications for studies of amino acid metabolism, and in particular for the measurement of muscle protein degradation in the hemicorpus.

scholarly journals Reducing plasma HIV RNA improves muscle amino acid metabolism

2005 ◽  
Vol 288 (1) ◽  
pp. E278-E284 ◽  
Author(s):  
Kevin E. Yarasheski ◽  
Samuel R. Smith ◽  
William G. Powderly
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Hiv Rna ◽  
Muscle Protein Synthesis Rate

We reported (Yarasheski KE, Zachwieja JJ, Gischler J, Crowley J, Horgan MM, and Powderly WG. Am J Physiol Endocrinol Metab 275: E577–E583, 1998) that AIDS muscle wasting was associated with an inappropriately low rate of muscle protein synthesis and an elevated glutamine rate of appearance (Ra Gln). We hypothesized that high plasma HIV RNA caused dysregulation of muscle amino acid metabolism. We determined whether a reduction in HIV RNA (≥1 log) increased muscle protein synthesis rate and reduced Ra Gln and muscle proteasome activity in 10 men and 1 woman (22–57 yr, 60–108 kg, 17–33 kg muscle) with advanced HIV (CD4 = 0–311 cells/μl; HIV RNA = 10–375 × 103 copies/ml). We utilized stable isotope tracer methodologies ([13C]Leu and [15N]Gln) to measure the fractional rate of mixed muscle protein synthesis and plasma Ra Gln in these subjects before and 4 mo after initiating their first or a salvage antiretroviral therapy regimen. After treatment, median CD4 increased (98 vs. 139 cells/μl, P = 0.009) and median HIV RNA was reduced (155,828 vs. 100 copies/ml, P = 0.003). Mixed muscle protein synthesis rate increased (0.062 ± 0.005 vs. 0.078 ± 0.006%/h, P = 0.01), Ra Gln decreased (387 ± 33 vs. 323 ± 15 μmol·kg fat-free mass−1·h−1, P = 0.04), and muscle proteasome chymotrypsin-like catalytic activity was reduced 14% ( P = 0.03). Muscle mass was only modestly increased (1 kg, P = not significant). We estimated that, for each 10,000 copies/ml reduction in HIV RNA, ∼3 g of additional muscle protein are synthesized per day. These findings suggest that reducing HIV RNA increases muscle protein synthesis and reduces muscle proteolysis, but muscle protein synthesis relative to whole body protein synthesis rate is not restored to normal, so muscle mass is not substantially increased.

scholarly journals Brain Protein Synthesis and Cell Proliferation in Sulfur Amino Acid Restricted Mice

2021 ◽  
Vol 35 (S1) ◽  
Author(s):  
Wenceslao Martinez ◽  
Qian Zhang ◽  
Emily Mirek ◽  
Jordan Levy ◽  
William Jonsson ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Sulfur Amino Acid ◽  
Brain Protein ◽  
Brain Protein Synthesis

Role of Leucine in Protein Metabolism During Exercise and Recovery

2002 ◽  
Vol 27 (6) ◽  
pp. 646-662 ◽  
Author(s):  
Donald K. Layman
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Branched Chain Amino Acids ◽  
New Findings ◽  
Branched Chain

Exercise produces changes in protein and amino acid metabolism. These changes include degradation of the branched-chain amino acids, production of alanine and glutamine, and changes in protein turnover. One of the amino acid most affected by exercise is the branched-chain amino acid leucine. Recently, there has been an increased understanding of the role of leucine in metabolic regulations and remarkable new findings about the role of leucine in intracellular signaling. Leucine appears to exert a synergistic role with insulin as a regulatory factor in the insulin/phosphatidylinositol-3 kinase (PI3-K) signal cascade. Insulin serves to activate the signal pathway, while leucine is essential to enhance or amplify the signal for protein synthesis at the level of peptide initiation. Studies feeding amino acids or leucine soon after exercise suggest that post-exercise consumption of amino acids stimulates recovery of muscle protein synthesis via translation regulations. This review focuses on the unique roles of leucine in amino acid metabolism in skeletal muscle during and after exercise. Key words: branched-chain amino acids, insulin, protein synthesis, skeletal muscle

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