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Nixon PF. Glutamate Export at the Choroid Plexus in Health, Thiamin Deficiency, and Ethanol Intoxication: Review and Hypothesis. Alcohol Clin Exp Res 2008; 32:1339-49. [DOI: 10.1111/j.1530-0277.2008.00727.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Kelly PA, Faulkner AJ, Burrow AP. The effects of the GABA agonist muscimol upon blood flow in different vascular territories of the rat cortex. J Cereb Blood Flow Metab 1989; 9:754-8. [PMID: 2584272 DOI: 10.1038/jcbfm.1989.108] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Local cerebral blood flow was measured in five regions of rat cortex immediately following intravenous administration of the gamma-aminobutyric acid (GABA) agonist muscimol. In contrast to recent observations, no increases in blood flow were found at either of the two time points analysed, and the data revealed that decreases in blood flow previously reported 30 min after muscimol treatment were in evidence as early as 30 s. These results are totally consistent with the conclusion that the overall effects of GABA agonists in the intact animal are to reduce blood flow in line with reduced metabolic demand in the neuropil. However, the heterogeneity of the reductions in cortical blood flow found here possibly suggests a biological role for vascular GABA systems in providing a mitigating influence on fluctuating tissue perfusion.
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Affiliation(s)
- P A Kelly
- Department of Clinical Neurosciences, University of Edinburgh, Scotland
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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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Palmer GC. Neurochemical coupled actions of transmitters in the microvasculature of the brain. Neurosci Biobehav Rev 1986; 10:79-101. [PMID: 2874536 DOI: 10.1016/0149-7634(86)90020-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The discovery that monoamine nerves end on the central microvessels of the choroid plexus, pia-arachnoid and parenchyma has prompted an intense investigation as to their physiological and neuropathological roles. The source of the monoamine fibers to the pial vessels and choroid plexus was shown to be the superior cervical ganglion. Ganglionic stimulation causes vasoconstriction or vasodilation of pial vessels, an event depending upon the functional ratio of alpha to beta adrenergic receptors. Moreover, stimulation of the superior cervical ganglion evokes an inhibition of cerebrospinal fluid formation in choroid plexus. The locus coeruleus is the site of adrenergic nerve supply to the parenchymal capillaries and stimulation of this nucleus increases capillary permeability to small molecules and water. Neurotransmitter receptors (adrenergic, histamine, adenosine, dopamine, prostacyclin, prostaglandins and specific amino acids or neuropeptides) have been identified on microvessels and in many instances these transmitter actions are coupled to cyclic AMP synthesis. Moreover, cyclic AMP has been shown to increase the rate of capillary endothelial pinocytosis and produce brain edema. In small vessels containing smooth muscle cells cyclic AMP production improves cerebral blood flow via an initiation of vasodilatory processes. The presence of receptors for serotonin and acetylcholine have likewise been demonstrated to occur on cerebral microvessels. Limited information is available as to the receptor coupled actions of these two transmitters, but cholinergic mechanisms may act to restrict catecholamine-induced formation of cyclic AMP. Altered sensitivity of microvessels to neurotransmitters has been demonstrated following conditions of stroke, hypertension, aging, diabetes and X-irradiation.
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Abstract
Significant amounts of gamma-aminobutyric acid (GABA), an endogenous amino acid, are present in mammalian peripheral tissues. This finding led to the suggestion that GABA may act as a neurotransmitter in the peripheral nervous system as it does in the central nervous system. This review deals with recent identification of GABA in the autonomic nervous system and the possible functional role of GABA in neuronal and non-neuronal tissues. The identification of GABA in the autonomic nervous system has paved the way for new approaches in pharmacological investigations.
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Alborch E, Torregrosa G, Terrasa JC, Estrada C. GABA receptors mediate cerebral vasodilation in the unanesthetized goat. Brain Res 1984; 321:103-10. [PMID: 6093926 DOI: 10.1016/0006-8993(84)90685-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The effects of gamma-aminobutyric acid (GABA) and muscimol upon cerebral blood flow were evaluated in the unanesthetized goat. Cerebral blood flow was continuously measured by means of an electromagnetic flow probe chronically implanted on the internal maxillary artery after occlusion and thrombosis of the distal extracerebral vessels. Administration of GABA (1-100 micrograms) directly into the cerebral circulation produced dose-dependent increases in cerebral blood flow, without accompanying systemic effects. Muscimol mimicked the effects of GABA at doses 10 times lower. Administration of picrotoxin (1-3 mg) into the internal maxillary artery did not significantly change cerebral blood flow, but inhibited in a dose-dependent manner the vasodilation induced by GABA. Selective blockade of beta-adrenergic or muscarinic cholinergic receptors by propranolol or atropine, respectively, did not modify the cerebrovascular response to the GABAergic agonists. These results indicate that GABA increases total cerebral blood flow, acting on specific receptor sites in the cerebral blood vessels. The absence of influence of picrotoxin on resting cerebral blood flow suggests that the GABAergic receptors are not tonically activated under physiological conditions.
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Abstract
Evidence supporting the hypothesis that GABA-ergic mechanisms are involved in controlling mammalian cardiovascular function has been reviewed and analyzed. In vivo and in vitro studies with GABA-agonists and GABA-antagonists have revealed that activation of GABA-receptors is involved in the control of blood pressure and heart rate. Further studies conducted with agents that modify central and/or peripheral GABA-ergic systems could lead to the discovery of drugs that might be useful for treating certain cardiovascular disorders in man, such as hypertension and stroke, and should increase our understanding of the pathophysiological bases of such disorders.
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Hamel E, Krause DN, Roberts E. Characterization of glutamic acid decarboxylase activity in cerebral blood vessels. J Neurochem 1982; 39:842-9. [PMID: 7097288 DOI: 10.1111/j.1471-4159.1982.tb07969.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Glutamic acid decarboxylase activity associated with cerebral blood vessels appears to be part of a specific cerebrovascular system involving gamma-aminobutyric acid. This activity was characterized kinetically and pharmacologically and compared with that in brain and several nonneuronal tissues. Formation of gamma-aminobutyric acid from [14C]glutamate was measured in a soluble extract of pia-arachnoid blood vessels isolated from bovine brain. The vascular activity was like brain glutamate decarboxylase in that it required pyridoxal phosphate, was completely inhibited by aminooxyacetic acid, and had a similar affinity for glutamate. Cerebrovascular decarboxylase activity differed, however, from brain decarboxylase in that it was less sensitive to sulfhydryl reagents, was stimulated by 3-mercaptopropionic and cysteic acids, and was competitively inhibited by cysteine sulfinic acid. The glutamate decarboxylase activity of the cerebral vessels was similar to that in renal cortex and mesenteric blood vessels in its responses to sulfhydryl reagents and 3-mercaptopropionic acid. These findings are consistent with previous suggestions of a nonneuronal form of the enzyme and offer the possibility that synthesis of gamma-aminobutyric acid in cerebral blood vessels can be manipulated independently from that in neuronal tissue.
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Goodyer PR, Mills M, Scriver CR. Properties of gamma-aminobutyric acid synthesis by rat renal cortex. BIOCHIMICA ET BIOPHYSICA ACTA 1982; 716:348-57. [PMID: 7115757 DOI: 10.1016/0304-4165(82)90027-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Substantial synthesis of gamma-aminobutyric acid occurs in rat renal cortex. Renal glutamate decarboxylase activity (24.3 +/- 2.9 (S.E.) nmols/mg protein per h) is 15% of that in brain; renal gamma-aminobutyric acid content (39.5 +/- 5.3 (S.E.) nmols/g wet wt.) is 5% of the whole brain concentration. Properties of glutamate decarboxylase were studied in homogenates of rat renal cortex and rat brain under conditions for which gamma-aminobutyric acid formation from [2,3-3H]glutamate and CO2 release from [1(-14)C]glutamate were equal. Several properties of renal glutamate decarboxylase distinguish it from the corresponding brain enzyme: (1) renal glutamate decarboxylase is selectively inhibited by cysteine sulfinic acid (Ki = 5X10(-5) M); (2) renal glutamate decarboxylase is less sensitive (Ki = 3-5X10(-5) M) to inhibition by aminooxyacetic acid than is the brain enzyme (Ki = 1X10(-6) M); (3) brain but not renal glutamate decarboxylase activity can be substantially stimulated in vitro by the addition of exogenous pyridoxal 5'-phosphate; (4) renal glutamate decarboxylase is significantly decreased in renal cortex from rats on a low-salt diet. Proximal tubules are enriched in glutamate decarboxylase compared to the activity in whole renal cortex or glomeruli (42, 22 and 14 nmols/mg protein per h, respectively). We speculate that renal gamma-aminobutyric acid synthesis does not reflect the presence of GABAergic renal nerves, but may serve a function in proximal tubular cells.
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Elias AN, Valenta LJ, Szekeres AV, Grossman MK. Regulatory role of gamma-aminobutyric acid in pituitary hormone secretion. Psychoneuroendocrinology 1982; 7:15-30. [PMID: 6124990 DOI: 10.1016/0306-4530(82)90052-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Hamel E, Krause DN, Roberts E. Specific cerebrovascular localization of glutamate decarboxylase activity. Brain Res 1981; 223:199-204. [PMID: 7284804 DOI: 10.1016/0006-8993(81)90824-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Glutamate decarboxylase (GAD) activity and GABA levels, determined with a [3H]muscimol radioreceptor assay, were found to be significantly higher in cerebral blood vessels from the piaarachnoid membrane as compared to extracranial vessels (aorta, mesenteric and femoral arteries, and vena cava). A cerebrovascular localization for GABA and GAD is consistent with earlier studies suggesting that an indigenous GABA system is involved in cerebral vascular function.
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DeFeudis F. GABA and “neuro-cardiovascular” mechanisms. Neurochem Int 1981; 3:113-22. [DOI: 10.1016/0197-0186(81)90029-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/1981] [Accepted: 04/10/1981] [Indexed: 01/09/2023]
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Edvinsson L, Larsson B, Skärby T. Effect of the GABA receptor agonist muscimol on regional cerebral blood flow in the rat. Brain Res 1980; 185:445-8. [PMID: 6244058 DOI: 10.1016/0006-8993(80)91084-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Krause DN, Wong E, Degener P, Roberts E. GABA receptors in bovine cerebral blood vessels: binding studies with [3H]muscimol. Brain Res 1980; 185:51-7. [PMID: 6243504 DOI: 10.1016/0006-8993(80)90669-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
[3H]Muscimol, a potent GABA agonist used to label GABA receptor sites in brain and invertebrate striated muscle, was found to bind specifically to sites in a crude membrane fraction prepared from bovine cerebral blood vessels. Specific [3H]muscimol binding was saturable of high affinity (Kd = 41 nM), and was selectively inhibited by GABA, specific GABA agonists, and the antagonist bicuculline with potencies similar to what has been found for GABA receptors in mammalian brain. GABA and several GABA agonists including muscimol have been reported to dilate isolated cerebral arteries, but not peripheral blood vessels. The pharmacology of the [3H]muscimol binding site correlated well with that of the vasodilatory response. No significant specific [3H]muscimol binding was detected in aorta and mesenteric arteries. The characteristics of the cerebrovascular muscimol binding site thus are indicative of a physiologically relevant GABA receptor associated with cerebral blood vessels. These findings suggest a direct role for GABA in cerebral vascular function.
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Edvinsson L, Krause DN, Larsson B, Skärby T. GABA dilates cerebral arteries in vitro and increases regional cerebral blood flow in vivo. Brain Res Bull 1980. [DOI: 10.1016/0361-9230(80)90054-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Edvinsson L, Krause DN. Pharmacological characterization of GABA receptors mediating vasodilation of verebral arteries in vitro. Brain Res 1979; 173:89-97. [PMID: 226209 DOI: 10.1016/0006-8993(79)91098-9] [Citation(s) in RCA: 81] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
GABA (gamma-aminobutyric acid) produced a dose-dependent dilation of isolated cat and dog cerebral artery segments which had been given an active, tonic contraction by either prostaglandin F2 alpha or serotonin. No effect of GABA on extracranial blood vessels was observed. The GABA-induced dilation could be blocked in a dose-dependent manner by either bicuculline or picrotoxin. The latter agent appeared to act as a competitive antagonist. GABA agonists muscimol, imidazoleacetic acid, delta-aminovaleric acid, (+/-)gamma-amino-beta-hydroxybutyric acid, and beta-alanine also relaxed actively contracted cerebral arteries dose-dependently. The relative potency of these agonists was consistent with that established for GABA receptors on neurons and invertebrate striated muscle. GABA was also tested on two human cerebral arteries and found to cause a small dilation. The results support the existence of a cerebrovascular GABA receptor which may mediate an interaction between GABA and the cerebral circulatory system.
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Wu PH, Durden DA, Hertz L. Net production of gamma-aminobutyric acid in astrocytes in primary cultures determined by a sensitive mass spectrometric method. J Neurochem 1979; 32:379-90. [PMID: 216775 DOI: 10.1111/j.1471-4159.1979.tb00361.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Wu JY. A comparative study of L-glutamate decarboxylase from mouse brain and bovine heart with purified preparations. J Neurochem 1977; 28:1359-67. [PMID: 874499 DOI: 10.1111/j.1471-4159.1977.tb12332.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Kanazawa I, Iversen LL, Kelly JS. Glutamate decarboxylase activity in the rat posterior pituitary, pineal gland, dorsal root ganglion and superior cervical ganglion. J Neurochem 1976; 27:1267-9. [PMID: 12170621 DOI: 10.1111/j.1471-4159.1976.tb00341.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- I Kanazawa
- M R C Neurochemical Pharmacology Unit, Department of Pharmacology, Medical School, Hills Road, Cambridge CB2 2QD, U.K
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Wu JY, Wong E, Saito K, Roberts E, Schousboe A. Properties of L-glutamate decarboxylase from brains of adult and newborn mice. J Neurochem 1976; 27:653-9. [PMID: 9480 DOI: 10.1111/j.1471-4159.1976.tb10390.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Seiler N, Wagner G. NAD+-dependent formation of?-aminobutyrate (GABA) from glutamate. Neurochem Res 1976; 1:113-31. [DOI: 10.1007/bf00965636] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/24/1975] [Indexed: 10/26/2022]
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MacDonnell P, Greengard O. THE DISTRIBUTION OF GLUTAMATE DECARBOXYLASE IN RAT TISSUES; ISOTOPIC VS FLUORIMETRIC ASSAYS. J Neurochem 1975. [DOI: 10.1111/j.1471-4159.1975.tb03836.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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OKADA Y, TANIGUCHI H, SHIMADA C, KUROSAWA F. High Concentration of γ-aminobutyric Acid (GABA) in the Langerhans' Islets of the Pancreas. ACTA ACUST UNITED AC 1975. [DOI: 10.2183/pjab1945.51.760] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Yasuhiro OKADA
- Department of Neurochemistry, Tokyo Metropolitan Institute for Neurosciences
| | - Hiroshi TANIGUCHI
- Department of Neurochemistry, Tokyo Metropolitan Institute for Neurosciences
| | - Chicaco SHIMADA
- Department of Neurochemistry, Tokyo Metropolitan Institute for Neurosciences
| | - Fumiko KUROSAWA
- Department of Neurochemistry, Tokyo Metropolitan Institute for Neurosciences
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l-glutamic acid decarboxylase of fleshfly flight muscle, its properties and subcellular location. ACTA ACUST UNITED AC 1974. [DOI: 10.1016/0020-1790(74)90010-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Curtis DR, Johnston GA. Amino acid transmitters in the mammalian central nervous system. ERGEBNISSE DER PHYSIOLOGIE, BIOLOGISCHEN CHEMIE UND EXPERIMENTELLEN PHARMAKOLOGIE 1974; 69:97-188. [PMID: 4151806 DOI: 10.1007/3-540-06498-2_3] [Citation(s) in RCA: 124] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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