Feeding, Stress, Exercise and the Supply of Amino Acids to the Brain

Author(s):  
G. Curzon
Keyword(s):  
1966 ◽  
Vol 101 (3) ◽  
pp. 591-597 ◽  
Author(s):  
R M O'Neal ◽  
R E Koeppe ◽  
E I Williams

1. Free glutamic acid, aspartic acid, glutamic acid from glutamine and, in some instances, the glutamic acid from glutathione and the aspartic acid from N-acetyl-aspartic acid were isolated from the brains of sheep and assayed for radioactivity after intravenous injection of [2-(14)C]glucose, [1-(14)C]acetate, [1-(14)C]butyrate or [2-(14)C]propionate. These brain components were also isolated and analysed from rats that had been given [2-(14)C]propionate. The results indicate that, as in rat brain, glucose is by far the best precursor of the free amino acids of sheep brain. 2. Degradation of the glutamate of brain yielded labelling patterns consistent with the proposal that the major route of pyruvate metabolism in brain is via acetyl-CoA, and that the short-chain fatty acids enter the brain without prior metabolism by other tissue and are metabolized in brain via the tricarboxylic acid cycle. 3. When labelled glucose was used as a precursor, glutamate always had a higher specific activity than glutamine; when labelled fatty acids were used, the reverse was true. These findings add support and complexity to the concept of the metabolic; compartmentation' of the free amino acids of brain. 4. The results from experiments with labelled propionate strongly suggest that brain metabolizes propionate via succinate and that this metabolic route may be a limited but important source of dicarboxylic acids in the brain.


2020 ◽  
Vol 21 (20) ◽  
pp. 7490
Author(s):  
Jing Xu ◽  
Youseff Jakher ◽  
Rebecca C. Ahrens-Nicklas

Maple syrup urine disease (MSUD) is an autosomal recessive disorder caused by decreased activity of the branched-chain α-ketoacid dehydrogenase complex (BCKDC), which catalyzes the irreversible catabolism of branched-chain amino acids (BCAAs). Current management of this BCAA dyshomeostasis consists of dietary restriction of BCAAs and liver transplantation, which aims to partially restore functional BCKDC activity in the periphery. These treatments improve the circulating levels of BCAAs and significantly increase survival rates in MSUD patients. However, significant cognitive and psychiatric morbidities remain. Specifically, patients are at a higher lifetime risk for cognitive impairments, mood and anxiety disorders (depression, anxiety, and panic disorder), and attention deficit disorder. Recent literature suggests that the neurological sequelae may be due to the brain-specific roles of BCAAs. This review will focus on the derangements of BCAAs observed in the brain of MSUD patients and will explore the potential mechanisms driving neurologic dysfunction. Finally, we will discuss recent evidence that implicates the relevance of BCAA metabolism in other neurological disorders. An understanding of the role of BCAAs in the central nervous system may facilitate future identification of novel therapeutic approaches in MSUD and a broad range of neurological disorders.


1980 ◽  
Vol 68 (3) ◽  
pp. 443-452 ◽  
Author(s):  
Jeno Toth ◽  
Abel Lajtha

1999 ◽  
Vol 344 (3) ◽  
pp. 667-675 ◽  
Author(s):  
Shin-ichiro SANO ◽  
Hiroshi OHNISHI ◽  
Misae KUBOTA

BIT/SHPS-1/SIRPα/P84 is a unique molecule with a high degree of homology with immune antigen recognition molecules (immunoglobulin, T-cell receptor and MHC), and is highly expressed in the brain. The extracellular region contains three immunoglobulin-like domains (V-type, C1-type and C1-type), and the intracellular region contains two signalling motifs that interact with SHP-2 protein tyrosine phosphatase. BIT-coated plates support cell-substrate adhesion and neurite extension of neurons, and BIT participates in neuronal signal transduction. Diversity of the V-type domain sequences of human BIT has been reported. In the present study we analysed the structure of the mouse BIT gene (Bit). The protein coding region consists of eight exons corresponding to a signal peptide, a V-type domain, a C1-type domain, a C1-type domain, a transmembrane region and three parts of one cytoplasmic region. The two signalling motifs are encoded in one exon. Four splicing forms of mouse BIT were revealed. We also found the sequence diversity in three mouse strains, namely BALB/c, 129/Sv and C57BL/6. The substitution patterns of amino acids and nucleotides indicate positive pressure to alter the amino acids in the V-type domain in evolution. Immunoblot analyses showed that mouse BIT and human BITα are predominantly expressed in the brain. On the bases of these findings we discuss the possibility that BIT contributes to the genetic individuality and diversity of the brain.


1970 ◽  
Vol 10 (3) ◽  
pp. 313-322 ◽  
Author(s):  
L. Battistin ◽  
A. Lajtha

1989 ◽  
Vol 169 (5) ◽  
pp. 1771-1778 ◽  
Author(s):  
E Levy ◽  
C Lopez-Otin ◽  
J Ghiso ◽  
D Geltner ◽  
B Frangione

Cystatin C is an inhibitor of lysosomal cysteine proteases and consists of 120 amino acids. A variant of cystatin C lacking the first NH2-terminal residues and having one amino acid substitution at position 68 forms amyloid deposits mainly in the walls of brain arteries, causing fatal strokes in Icelandic patients with familial cerebral hemorrhage secondary to a form of an autosomal dominant amyloidosis. To understand the molecular basis of the genetic defect, the gene encoding cystatin C was isolated from genomic DNA libraries made from normal tissue and the brain of an Icelandic patient with hereditary cerebral hemorrhage with amyloidosis (HCHWA-I). The data indicate that the cystatin C gene encodes a polypeptide of 146 amino acids, of which the first 26 correspond to a secretory peptide signal sequence. The gene contains two intervening sequences that interrupt the coding region at amino acids 55 and 93. Comparison with genes encoding salivary cystatins and kininogen proteins show sequence homology and conservation of exon-intron structure. Except for a mutation in the second exon (CAG instead of CTG in the normal gene, resulting in the substitution of glutamine for a leucine residue), the gene cloned from the brain of the Icelandic patient is identical to the normal cystatin C gene. Thus, HCHWA-I is the first familial type of amyloidosis related to a point mutation in a gene encoding for an inhibitor. The mutation in the structural gene encoding cystatin C appears to be the primary defect in this inherited disorder causing amyloid fibril formation and accumulation followed by cerebral hemorrhage.


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