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A study on the involvement of GABA-transaminase in MCT induced pulmonary hypertension. Pulm Pharmacol Ther 2016; 36:10-21. [DOI: 10.1016/j.pupt.2015.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 11/04/2015] [Accepted: 11/12/2015] [Indexed: 12/15/2022]
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2
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Synchronization by food access modifies the daily variations in expression and activity of liver GABA transaminase. BIOMED RESEARCH INTERNATIONAL 2014; 2014:590581. [PMID: 24809054 PMCID: PMC3997914 DOI: 10.1155/2014/590581] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 03/03/2014] [Accepted: 03/11/2014] [Indexed: 02/05/2023]
Abstract
Daytime restricted feeding (DRF) is an experimental protocol that influences the circadian timing system and underlies the expression of a biological clock known as the food entrained oscillator (FEO). Liver is the organ that reacts most rapidly to food restriction by adjusting the functional relationship between the molecular circadian clock and the metabolic networks. γ-Aminobutyric acid (GABA) is a signaling molecule in the liver, and able to modulate the cell cycle and apoptosis. This study was aimed at characterizing the expression and activity of the mostly mitochondrial enzyme GABA transaminase (GABA-T) during DRF/FEO expression. We found that DRF promotes a sustained increase of GABA-T in the liver homogenate and mitochondrial fraction throughout the entire day-night cycle. The higher amount of GABA-T promoted by DRF was not associated to changes in GABA-T mRNA or GABA-T activity. The GABA-T activity in the mitochondrial fraction even tended to decrease during the light period. We concluded that DRF influences the daily variations of GABA-T mRNA levels, stability, and catalytic activity of GABA-T. These data suggest that the liver GABAergic system responds to a metabolic challenge such as DRF and the concomitant appearance of the FEO.
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Schousboe A, Waagepetersen HS. GABA: Homeostatic and pharmacological aspects. PROGRESS IN BRAIN RESEARCH 2007; 160:9-19. [PMID: 17499106 DOI: 10.1016/s0079-6123(06)60002-2] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The central nervous system (CNS) operates by a fine-tuned balance between excitatory and inhibitory signalling. In this context, the inhibitory neurotransmission may be of particular interest as it has been suggested that such neuronal pathways may constitute 'command pathways' and the principle of 'dis-inhibition' leading ultimately to excitation may play a fundamental role (Roberts, E. (1974). Adv. Neurol., 5: 127-143). The neurotransmitter responsible for this signalling is gamma-aminobutyrate (GABA) which was first discovered in the CNS as a curious amino acid (Roberts, E., Frankel, S. (1950). J. Biol. Chem., 187: 55-63) and later proposed as an inhibitory neurotransmitter (Curtis, D.R., Watkins, J.C. (1960). J. Neurochem., 6: 117-141; Krnjevic, K., Schwartz, S. (1967). Exp. Brain Res., 3: 320-336). The present review will describe aspects of GABAergic neurotransmission related to homeostatic mechanisms such as biosynthesis, metabolism, release and inactivation. Additionally, pharmacological and therapeutic aspects of this will be discussed.
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Affiliation(s)
- Arne Schousboe
- Department of Pharmacology and Pharmacotherapy, The Faculty of Pharmaceutical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark.
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Schor DSM, Struys EA, Hogema BM, Gibson KM, Jakobs C. Development of a Stable-Isotope Dilution Assay for γ-Aminobutyric Acid (GABA) Transaminase in Isolated Leukocytes and Evidence That GABA and β-Alanine Transaminases Are Identical. Clin Chem 2001. [DOI: 10.1093/clinchem/47.3.525] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Background: Several methods have been published for measuring γ-aminobutyric acid transaminase (GABA-T) activity, but these methods are either impracticable because of the use of radioisotopes or insufficiently sensitive to determine small enzyme activities in leukocyte extracts. We developed a direct and sensitive enzyme method.
Methods: We developed a stable-isotope dilution method for the measurement of [15N]glutamic acid derived from [15N]GABA and α-ketoglutaric acid, catalyzed by GABA-T. The method for analysis of [15N]glutamic acid comprised a solid-phase extraction procedure to isolate this analyte from incubation samples. After derivatization, [15N]glutamic acid was quantified by gas chromatography–mass spectrometry relative to its 2H5-labeled internal standard. In addition to [15N]GABA, [15N]β-alanine was a cosubstrate.
Results: GABA-T-deficient lymphoblasts showed diminished enzyme activity, with both [15N]GABA and [15N]β-alanine as substrate. Vigabatrin inhibited the enzyme activity for both substrates.
Conclusions: The activity of GABA-T can be accurately determined by our procedure using 15N-labeled substrate, measuring the formation of [15N]glutamic acid. Our results with [15N]β-alanine indicate that GABA and β-alanine transaminases are identical.
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Affiliation(s)
- Danielle S M Schor
- Metabolic Unit, Department of Clinical Chemistry, University Hospital Vrije Universiteit, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands
| | - Eduard A Struys
- Metabolic Unit, Department of Clinical Chemistry, University Hospital Vrije Universiteit, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands
| | - Boris M Hogema
- Metabolic Unit, Department of Clinical Chemistry, University Hospital Vrije Universiteit, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands
- Department of Molecular and Medical Genetics, Biochemical Genetics Laboratory, Oregon Health Sciences University, Portland, OR 97201
| | - K Michael Gibson
- Department of Molecular and Medical Genetics, Biochemical Genetics Laboratory, Oregon Health Sciences University, Portland, OR 97201
| | - Cornelis Jakobs
- Metabolic Unit, Department of Clinical Chemistry, University Hospital Vrije Universiteit, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands
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Jeon SG, Bahn JH, Jang JS, Park J, Kwon OS, Cho SW, Choi SY. Human brain GABA transaminase tissue distribution and molecular expression. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:5601-7. [PMID: 10951220 DOI: 10.1046/j.1432-1327.2000.01626.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Human brain gamma-aminobutyrate transaminase is differentially expressed in a tissue-specific manner. mRNA master dot-blot analysis for 50 different human tissues, including different brain regions and fetal tissues, provided a complete map of the tissue distribution. Genomic Southern analysis revealed that the gamma-aminobutyrate transaminase gene is a single copy, at least 15 kb in size. In addition, human brain gamma-aminobutyrate transaminase cDNA was expressed in Escherichia coli using a pGEX expression vector system. Catalytically active gamma-aminobutyrate transaminase was expressed in large quantities and the purified recombinant enzyme had kinetic parameters that were indistinguishable from those isolated from other mammalian brains. The human enzyme was inactivated by a well-known antiepileptic drug vigabatrin. Values of Ki and kinact were 1 mM and 0.35 min-1, respectively. Results from inactivation kinetics suggested that human gamma-aminobutyrate transaminase is more sensitive to the vigabatrin drug than the enzyme isolated from bovine brain.
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Affiliation(s)
- S G Jeon
- Department of Genetic Engineering, Hallym University, Chunchon, Korea
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Cavallotti D, Artico M, Cavallotti C, De Santis S, Leali FT. Interleukin 1beta and GABA-transaminase activity in rat thymus. INTERNATIONAL JOURNAL OF IMMUNOPHARMACOLOGY 2000; 22:719-28. [PMID: 10884592 DOI: 10.1016/s0192-0561(00)00035-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The occurrence and distribution of 4-aminobutyrate:2 oxoglutarate transaminase (GABA-t) activity were examined in the rat thymus of normal and immunostimulated rats using biochemical and histoenzymatical methods. Specific GABA-t reactivity was confined primarily to the arteries and, to a lesser extent, to the veins. Only a few activities could be observed in association with the subcapsular and medullar part of the parenchyma and nerve fibers. GABA-t was considered a linking enzyme between the immune and the nervous system and it was studied with the aim of analyzing the relationships between these two systems. Our findings indicate that the GABA-t activity in the thymus is specifically located in the wall of the blood vessels. Moreover, our results demonstrate the presence of a GABA-t activity in the peripheral blood vessels. Treatment with interleukin 1beta induces an increase of protein content of the amounts of GABA-t biochemically assayed and of the levels of histoenzymatically stained GABA-t. Furthermore, staining of the different structures of the thymus in treated or untreated rats shows that the significant modifications concern the parenchyma, the structures resembling nerve fibers and finally, the whole thymus. On the contrary, the highest activity of the GABA-t is located in the walls of arteries, veins and lymphatic vessels.
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Affiliation(s)
- D Cavallotti
- II Neurologic Clinic, University "La Sapienza", Rome, Italy
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Koo YK, Nandi D, Silverman RB. The multiple active enzyme species of gamma-aminobutyric acid aminotransferase are not isozymes. Arch Biochem Biophys 2000; 374:248-54. [PMID: 10666304 DOI: 10.1006/abbi.1999.1623] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Purified gamma-aminobutyric acid aminotransferase (GABA-AT) from pig brain under certain conditions gave a single band on 12% NaDodSO(4)-PAGE, whereas two or three distinct bands were observed on 7.5% native PAGE. These multiple active species were isolated by 5% preparative gel electrophoresis and characterized by N-terminal sequencing and MALDI-TOF mass spectrometry. The results indicate that these active enzyme species are not GABA-AT isozymes in pig brain, but are the products of proteolysis of the N-terminus of GABA-AT, differing by 3, 7, and 12 residues from the full sequence (as deduced from the cDNA), respectively. Conditions for obtaining the nontruncated GABA-AT were found, and the potential cause for the proteolysis was determined. It was found that Na(2)EDTA inhibits the N-terminal cleavage during GABA-AT preparation from pig brain. The presence of Triton X-100 in the homogenization step is partially responsible for this proteolysis, and Mn(2+) strongly enhances the protease activity, suggesting the presence of a membrane-bound matrix metalloprotease that causes the N-terminal cleavage.
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Affiliation(s)
- Y K Koo
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA
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8
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Abstract
Over the last two decades, there have been several studies suggesting the major inhibitory amino acid neurotransmitter gamma-aminobutyric acid (GABA) is involved directly and/or indirectly in the pathogenesis of many neurologic diseases and psychiatric disorders. GABA is mainly degradated to succinic semialdehyde in a reaction catalyzed by the enzyme GABA-transaminase (GABA-T). Inhibition of this enzyme produces considerable elevation of GABA contents in the brain, and such elevation has been found to correlate with pharmacologic and behavioral effects. We focus attention, from the basic aspects, on brain and platelet GABA-T activities in various species, with a special reference to neuropsychiatric disorders. It seems that the activity of GABA-T in the brain and/or in the blood platelets is correlated to certain neuropsychiatric disorders such as alcoholism, epilepsy, and Alzheimer's disease. In animal and human studies, platelet GABA-T was identified with similar kinetic and inhibitor characteristics to those of the brain. Therefore, in this way, studies of the activity of the enzyme GABA-T in relation to neuropsychiatric disorders could be undertaken to understand, diagnose, and treat GABA-related disorders of the central nervous system.
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Affiliation(s)
- F M Sherif
- Department of Pharmacology, Faculty of Pharmacy, University of Al-Fateh for Medical Sciences, Tripoli, Libya
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Sherif FM. GABA-transaminase in brain and blood platelets: basic and clinical aspects. Prog Neuropsychopharmacol Biol Psychiatry 1994; 18:1219-33. [PMID: 7863013 DOI: 10.1016/0278-5846(94)90089-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Several lines of evidence suggest that the major inhibitory neuro-transmitter, gamma-aminobutyric acid (GABA) is involved, both directly and indirectly, in the pathogenesis of certain neurological and psychiatric disorders. The main enzyme responsible for GABA catabolism is gamma-aminobutyrate aminotransferase (GABA-T). Inhibition of this enzyme produces a considerable elevation of brain GABA concentrations, and such elevation has been correlated with many pharmacological effects. There seems to be that, as is discussed below, GABA-T activity in the brain and/or blood platelets is related to some neuro-psychiatric disorders such as alcoholism, epilepsy and Alzheimer's disease. GABA-T has been identified in the blood platelets with similar characteristics to those of brain GABA-T. In this way, studies on GABA-T activity in neuro-psychiatric disorders could be performed to understand, diagnosis and treat GABA-related disorders of the central nervous system (CNS).
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Affiliation(s)
- F M Sherif
- Department of Pharmacology, University for Medical Sciences, Tripoli, Libya
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Medina-Kauwe LK, Tillakaratne NJ, Wu JY, Tobin AJ. A rat brain cDNA encodes enzymatically active GABA transaminase and provides a molecular probe for GABA-catabolizing cells. J Neurochem 1994; 62:1267-75. [PMID: 8133261 DOI: 10.1046/j.1471-4159.1994.62041267.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
cDNAs encoding gamma-aminobutyric acid aminotransferase (GABA-T) were isolated from a lambda ZAP rat hippocampal cDNA expression library by two independent cloning methods, immunological screening with an antimouse GABA-T antibody and plaque hybridization with a GABA-T cDNA probe derived by polymerase chain reaction. We have produced enzymatically active GABA-T from a rat brain cDNA containing the full-length GABA-T coding region. Our rat brain GABA-T cDNAs hybridize to mRNAs in brain and peripheral tissues, including liver, kidney, and testis. We have also detected GABA-T mRNA in GABAergic cells of rat cerebellar cortex by in situ hybridization. Our rat brain GABA-T probe hybridizes to Purkinje, basket, stellate, and Golgi II cells, the same GABAergic neurons previously shown to contain glutamate decarboxylase GAD65 and GAD67.
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Affiliation(s)
- L K Medina-Kauwe
- Molecular Biology Institute, University of California-Los Angeles 90024-1606
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11
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Tews JK, Repa JJ, Harper AE. Dietary amino acid analogs alter activities of some amino acid-metabolizing enzymes in rat liver. J Nutr Biochem 1993. [DOI: 10.1016/0955-2863(93)90047-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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12
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Abstract
The occurrence and distribution of 4-aminobutyrate:2-oxoglutarate transaminase (GABA-T) activity were examined in the guinea pig lung using biochemical and enzymehistochemical methods. Specific GABA-T reactivity was confined primarily to the arteries and to a lesser extent to the veins. No activity could be observed in association with bronchi, alveoli and nerve fibers. Our findings indicate that the GABA-T activity in the lung is specifically located in blood vessels. This study is the first to demonstrate GABA-T activity in peripheral blood vessels.
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13
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Fujimoto S, Mizutani N, Mizota C, Tamaki N. The level of beta-alanine aminotransferase activity in regenerating and differentiating rat liver. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 882:106-12. [PMID: 3085724 DOI: 10.1016/0304-4165(86)90061-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
beta-Alanine aminotransferase from rat liver was purified to electrophoretic homogeneity. The immunological and kinetic properties of this enzyme were similar to those of the enzyme from rat brain. However, the liver enzyme transaminates from beta-alanine to 2-oxoglutaric acid, while the brain enzyme transaminates from gamma-aminobutyric acid. beta-Alanine aminotransferase activity in regenerating rat liver was lower than that in control rat liver. Activity of this enzyme, as well as of other uracil-catabolizing enzymes (Weber, G., Queener, S.F. and Ferdinandus, A. (1970) in Advances in Enzyme Regulation (Weber, G., ed.), Vol. 9, pp. 63-95, Pergamon Press, Oxford), was low in newborn rat liver and increased about 5-fold, reaching the level observed in adult rat liver. beta-Alanine and prednisolone induced beta-alanine aminotransferase in rat liver.
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14
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Maderdrut JL. A radiometric microassay for gamma-aminobutyric acid (GABA) transaminase. Neurochem Res 1986; 11:465-70. [PMID: 3703111 DOI: 10.1007/bf00965019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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15
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Gibson KM, Sweetman L, Nyhan WL, Jansen I. Demonstration of 4-aminobutyric acid aminotransferase deficiency in lymphocytes and lymphoblasts. J Inherit Metab Dis 1985; 8:204-8. [PMID: 3939544 DOI: 10.1007/bf01805436] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Lysates of lymphocytes, isolated from whole blood, and Epstein-Barr virus transformed cultured lymphoblasts catalysed the transamination of 4-aminobutyric acid with 2-oxoglutaric acid as co-substrate. 4-Aminobutyric acid aminotransferase activity in lymphocyte and lymphoblast sonicates derived from 12 unrelated control individuals (6 each) was 39 +/- 19 pmol min(-1) (mg protein (-1] (mean +/- 1 SD). Activities in lysates of both types of cell derived from a Flemish patient were less than 3% of control. 4-Aminobutyric acid aminotransferase activity in sonicates derived from the parents and a healthy sibling were 15-37% of the control mean for lymphocytes and 13-20% of the control mean in lymphoblasts, respectively. Km values in a control lymphoblast sonicate were 0.63 and 0.08 mmol L(-1) for 4-aminobutyric and 2-oxoglutaric acids, respectively. These data indicate that the parents and healthy sibling are heterozygous and the patient is homozygous for a defective gene responsible for 4-aminobutyric acid aminotransferase deficiency, and that inheritance is autosomal recessive.
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Abstract
The activities of both mitochondrial and cytosolic forms of alanine aminotransferase are markedly increased in Huntington's disease putamen autopsy samples. This increase was not observed in rats with kainic acid lesions of the striatum, and suggests a considerable alteration of glutamate and pyruvate metabolism as a feature of Huntington's disease.
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Abstract
GABA transaminase activity is reduced in autopsied putamen samples from patients dying with Huntington's disease. Its activity is also reduced in the striatum of rats previously lesioned with kainic acid. In both cases, the reduction in GABA transaminase activity is comparable with the reduction in glutamate decarboxylase activity, supporting the suspected localization of this enzyme to GABA neurones within the basal ganglia.
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Tews JK, Repa JJ, Harper AE. Alleviation in the rat of a GABA-induced reduction in food intake and growth. Physiol Behav 1984; 33:55-63. [PMID: 6505052 DOI: 10.1016/0031-9384(84)90013-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Cold exposure and diet dilution which stimulate food intake of normal rats lessened depressions of food intake and growth induced by dietary GABA. During a 3-day adaptation to the cold, rats fed a diet containing 4.5% GABA lost weight; thereafter, food intake and growth rate differed little from those of cold control rats and were usually greater than those of normal rats fed GABA. Hepatic GABA-aminotransferase activity of cold-exposed rats fed the GABA diet increased to about twice that of normal control rats. Rats fed a control diet diluted by half with cellulose ate 50% more of this diet than of the undiluted diet but gained only 20% less weight. Rats ate twice as much of a diluted, 9% GABA diet as of an undiluted, 4.5% GABA diet (thus doubling their GABA intake) and gained three times as much weight. A novel food (condensed milk) barely lessened the adverse responses to GABA. These results show that conditions requiring rats to increase their food intake in order to maintain body weight can also increase their acceptance of a diet high in GABA.
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Tews JK, Rogers QR, Morris JG, Harper AE. Effect of dietary protein and GABA on food intake, growth and tissue amino acids in cats. Physiol Behav 1984; 32:301-8. [PMID: 6718555 DOI: 10.1016/0031-9384(84)90145-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
GABA at 5%, but not 3%, of a low protein diet depressed food intake and growth of kittens. Adaptation to high protein prevented these effects. When cats adapted to low or high protein were fed a meal containing GABA, plasma GABA concentration after 2 hr was 8-fold higher in the low than in the high protein group; clearance was almost complete within 6 hr. Concentrations of proline, branched-chain, other large neutral and basic (especially ornithine) amino acids increased more when cats were fed a high rather than a low protein meal; glycine decreased. At 6 hr, concentrations had consistently returned to initial levels only in the low protein group. Feeding the high protein diet ad lib increased tissue concentrations of threonine, proline and the branched-chain amino acids. Hepatic or renal GABA-aminotransferase activity was not altered in kittens fed the high protein diet. Kidney activity was 10-fold that of liver, which may contribute to the better tolerance of GABA by cats than by rats.
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Krantis A. The involvement of GABA-transaminase in the blood-brain barrier to radiolabelled GABA. Acta Neuropathol 1984; 64:61-7. [PMID: 6475496 DOI: 10.1007/bf00695607] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The involvement of GABA-transaminase (GABA-T) in the blood-brain barrier to GABA was investigated using a sensitive radiotracer technique which allows measurement of tracer permeation as a cerebrovascular permeability-area product, PA. In Sprague-Dawley rats subjected to peripheral GABA-T inhibition and occlusion of hepatic circulation, chromatographic (TLC) analysis together with lyophylized plasma samples showed the radioactivity measured in brain parenchyma was derived from the permeation of unchanged [3H]GABA and not its blood-borne metabolites. Permeation (PA) of i.v. injected [3H]GABA was poor in all brain regions examined. Pretreatment of these rats with various compounds known to inhibit endothelial GABA-T activity did not cause any increased permeation of [3H]GABA into the brain. These results suggest that the poor permeation of GABA into the rat brain is unrelated to the activity of GABA-T at endothelial sites.
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Gombos G, Aunis D. Enzymes of neurotransmitter metabolism as neuronal markers in the central nervous system. SCANDINAVIAN JOURNAL OF IMMUNOLOGY. SUPPLEMENT 1982; 9:317-38. [PMID: 6134337 DOI: 10.1111/j.1365-3083.1982.tb03771.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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23
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Fellman JH, Roth ES. Hypotaurine aminotransferase. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1982; 139:99-113. [PMID: 6800233 DOI: 10.1007/978-1-4757-0402-0_7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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25
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Schousboe A. Transport and metabolism of glutamate and GABA in neurons are glial cells. INTERNATIONAL REVIEW OF NEUROBIOLOGY 1981; 22:1-45. [PMID: 6115823 DOI: 10.1016/s0074-7742(08)60289-5] [Citation(s) in RCA: 342] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Tews JK, Riegel EA, Harper AE. Effect of dietary GABA and protein on growth, food intake and GABA metabolism in the rat. Brain Res Bull 1980. [DOI: 10.1016/0361-9230(80)90041-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Schousboe A, Saito K, Wu JY. Characterization and cellular and subcellular localization of GABA-transaminase. Brain Res Bull 1980. [DOI: 10.1016/0361-9230(80)90011-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Hammerstad J, Gronke L, Nutt J, Casey D. The effect of γ-vinyl GABA on amphetamine stereotypy in rats. Brain Res Bull 1980. [DOI: 10.1016/0361-9230(80)90100-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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29
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Wu JY, Bird ED, Chen MS, Huang WM. Abnormalities of neurotransmitter enzymes in Huntington's chorea. Neurochem Res 1979; 4:575-86. [PMID: 40150 DOI: 10.1007/bf00964435] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The activities of L-glutamate decarboxylase (GAD), GABA-transaminase (GABA-T), choline acetyltransferase (CAT), and cysteic and cysteinesulfinic acids decarboxylase (CAD/CSAD) in putamen and frontal cortex in both Huntington's chorea and normal tissues were measured. The greatest difference between Huntington's and normal tissues occurred in putamen, in which the apparent CSAD activity was reduced by 85%, while no difference was observed in frontal cortex. GAD, CAD, and CAT activities were also reduced in putamen by 65%, 63%, and 42%, respectively (P less than 0.05). Slight reduction in the enzyme activities was also observed in frontal cortex. However, these reductions appeared to be statistically insignificant (P greater than 0.05 in all cases). GABA-T showed little difference in both putamen and frontal cortex in Huntington's chorea and normal tissues. GAD and GABA-T from Huntington's tissues were indistinguishable from those obtained from normal tissues by double diffusion test and by microcomplement fixation test, which is capable of distinguishing proteins with a single amino acid substitution. Furthermore, the similarity of the complement fixation curves for GAD from Huntington's and normal tissues suggests that the decrease in GAD activity is probably due to the reduction in the number of GAD molecules, presumably through the loss of neurons, and not due to the inhibition or inactivation of GAD activity by toxic substances which might be present in Huntington's chorea.
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Wu JY, Moss LG, Chen MS. Tissue and regional distribution of cysteic acid decarboxylase. A new assay method. Neurochem Res 1979; 4:201-12. [PMID: 460520 DOI: 10.1007/bf00964144] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A sensitive and rapid assay method method for cysteic acid decarboxylase was develped which combined the selectivity of ion exchange resin (a complete retention of the substrate, cysteic acid, and exclusion of the product, taurine) with the speed of a vacuum filtration. The synthesis and purification of 35S-labeled cysteic acid were described. The validity of the assay was established by the identification of the reaction product as taurine. With this new method, the decarboxylase activity was measured in discrete regions of bovine brain. Putamen had the highest activity, 172 pmol taurine formed/min/mg protein (100%), followed by caudate nucleus, 90%; cerebral cortex, 82%; hypothalamus, 81%; cerebellar cortex, 79%; cerebellar peduncle, 59%; thalamus, 42%; brain stem, 25%; pons, 10%; and corpus callosum, 3%. The decarboxylase activity in various mouse tissues was also determined as follows: liver, 403; brain, 145; kidney, 143; spinal cord, 59; lung, 21; and spleen, 10 pmol taurine formed/min/mg. No activity could be detected in skeleton muscle and heart, suggesting a different biosynthetic pathway for taurine synthesis in these tissues. The advantages and disadvantages of the new assay method are also discussed.
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