Regulation of GABA Metabolism in Discrete Rabbit Brain Regions under Methoxypyridoxine—Regional Differences in Cofactor Saturation and the Preictal Activation of Glutamate Decarboxylase Activity
Abstract: The activities of the enzymes of the GABA system, glutamate decarboxylase (GAD) and GABA-transaminase, were measured in discrete regions of the rabbit brain before the onset and during the course of sustained epileptiform seizures induced by the vitamin B6, analogue methoxypyridoxine (MP)....
Ausführliche Beschreibung
Autor*in: |
Nitsch, Cordula [verfasserIn] |
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E-Artikel |
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Erschienen: |
Oxford, UK: Blackwell Publishing Ltd ; 1980 |
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Online-Ressource |
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Reproduktion: |
2006 ; Blackwell Publishing Journal Backfiles 1879-2005 |
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Übergeordnetes Werk: |
In: Journal of neurochemistry - Oxford : Wiley-Blackwell, 1956, 34(1980), 4, Seite 0 |
Übergeordnetes Werk: |
volume:34 ; year:1980 ; number:4 ; pages:0 |
Links: |
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DOI / URN: |
10.1111/j.1471-4159.1980.tb09653.x |
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10.1111/j.1471-4159.1980.tb09653.x doi (DE-627)NLEJ240327233 DE-627 ger DE-627 rakwb Nitsch, Cordula verfasserin aut Regulation of GABA Metabolism in Discrete Rabbit Brain Regions under Methoxypyridoxine—Regional Differences in Cofactor Saturation and the Preictal Activation of Glutamate Decarboxylase Activity Oxford, UK Blackwell Publishing Ltd 1980 Online-Ressource nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier Abstract: The activities of the enzymes of the GABA system, glutamate decarboxylase (GAD) and GABA-transaminase, were measured in discrete regions of the rabbit brain before the onset and during the course of sustained epileptiform seizures induced by the vitamin B6, analogue methoxypyridoxine (MP). GAD activities were measured in a reaction mixture alternatively containing the cofactor pyridoxal-5′-phosphate (PLP) in excess or containing no PLP (holoenzyme of GAD). A comparison between these two estimations showed that the apoenzyme of GAD is only partially saturated with cofactor and that the degree of saturation varied from brain area to brain area, being highest in cerebellar cortex and lowest in substantia nigra. Holoenzyme activity fell steeply after administration of 100 mg/kg MP. The regional degree of enzyme inhibition by MP was a function of the saturation of the apoenzyme with cofactor; i.e., a low rate of saturation resulted in a high degree of inhibition, and vice versa. That GAD from the regio inferior of the hippocampus did not fit into the scheme (strong inhibition is present although the degree of saturation is high) is discussed in view of the role of the hippocampus in seizure genesis and generalization. Inhibition of GAD activity by MP was completely reversible in vitro by excess PLP. Before the onset of seizures but not during their course, apoenzyme activity surpassed control levels. This preictal activation is significant in regio inferior of hippocampus, in superior colliculus, and in cerebellar cortex. GABA-transaminase activities were not significantly altered. The present study demonstrates that only investigation during the preictal period and in regional brain areas can reveal changes specific for the drug and perhaps representing the cause for seizure development, without being masked by additional alterations resulting from the severe functional and metabolic derangement during the ictal events. Thereby, it was disclosed that a decrease in vivo in the level of the enzyme product, GABA, is able to activate GAD. 2006 Blackwell Publishing Journal Backfiles 1879-2005 |2006|||||||||| Glutamate decarboxylase, regional activity In Journal of neurochemistry Oxford : Wiley-Blackwell, 1956 34(1980), 4, Seite 0 Online-Ressource (DE-627)NLEJ243927584 (DE-600)2020528-4 1471-4159 nnns volume:34 year:1980 number:4 pages:0 http://dx.doi.org/10.1111/j.1471-4159.1980.tb09653.x text/html Verlag Deutschlandweit zugänglich Volltext GBV_USEFLAG_U ZDB-1-DJB GBV_NL_ARTICLE AR 34 1980 4 0 |
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10.1111/j.1471-4159.1980.tb09653.x doi (DE-627)NLEJ240327233 DE-627 ger DE-627 rakwb Nitsch, Cordula verfasserin aut Regulation of GABA Metabolism in Discrete Rabbit Brain Regions under Methoxypyridoxine—Regional Differences in Cofactor Saturation and the Preictal Activation of Glutamate Decarboxylase Activity Oxford, UK Blackwell Publishing Ltd 1980 Online-Ressource nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier Abstract: The activities of the enzymes of the GABA system, glutamate decarboxylase (GAD) and GABA-transaminase, were measured in discrete regions of the rabbit brain before the onset and during the course of sustained epileptiform seizures induced by the vitamin B6, analogue methoxypyridoxine (MP). GAD activities were measured in a reaction mixture alternatively containing the cofactor pyridoxal-5′-phosphate (PLP) in excess or containing no PLP (holoenzyme of GAD). A comparison between these two estimations showed that the apoenzyme of GAD is only partially saturated with cofactor and that the degree of saturation varied from brain area to brain area, being highest in cerebellar cortex and lowest in substantia nigra. Holoenzyme activity fell steeply after administration of 100 mg/kg MP. The regional degree of enzyme inhibition by MP was a function of the saturation of the apoenzyme with cofactor; i.e., a low rate of saturation resulted in a high degree of inhibition, and vice versa. That GAD from the regio inferior of the hippocampus did not fit into the scheme (strong inhibition is present although the degree of saturation is high) is discussed in view of the role of the hippocampus in seizure genesis and generalization. Inhibition of GAD activity by MP was completely reversible in vitro by excess PLP. Before the onset of seizures but not during their course, apoenzyme activity surpassed control levels. This preictal activation is significant in regio inferior of hippocampus, in superior colliculus, and in cerebellar cortex. GABA-transaminase activities were not significantly altered. The present study demonstrates that only investigation during the preictal period and in regional brain areas can reveal changes specific for the drug and perhaps representing the cause for seizure development, without being masked by additional alterations resulting from the severe functional and metabolic derangement during the ictal events. Thereby, it was disclosed that a decrease in vivo in the level of the enzyme product, GABA, is able to activate GAD. 2006 Blackwell Publishing Journal Backfiles 1879-2005 |2006|||||||||| Glutamate decarboxylase, regional activity In Journal of neurochemistry Oxford : Wiley-Blackwell, 1956 34(1980), 4, Seite 0 Online-Ressource (DE-627)NLEJ243927584 (DE-600)2020528-4 1471-4159 nnns volume:34 year:1980 number:4 pages:0 http://dx.doi.org/10.1111/j.1471-4159.1980.tb09653.x text/html Verlag Deutschlandweit zugänglich Volltext GBV_USEFLAG_U ZDB-1-DJB GBV_NL_ARTICLE AR 34 1980 4 0 |
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10.1111/j.1471-4159.1980.tb09653.x doi (DE-627)NLEJ240327233 DE-627 ger DE-627 rakwb Nitsch, Cordula verfasserin aut Regulation of GABA Metabolism in Discrete Rabbit Brain Regions under Methoxypyridoxine—Regional Differences in Cofactor Saturation and the Preictal Activation of Glutamate Decarboxylase Activity Oxford, UK Blackwell Publishing Ltd 1980 Online-Ressource nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier Abstract: The activities of the enzymes of the GABA system, glutamate decarboxylase (GAD) and GABA-transaminase, were measured in discrete regions of the rabbit brain before the onset and during the course of sustained epileptiform seizures induced by the vitamin B6, analogue methoxypyridoxine (MP). GAD activities were measured in a reaction mixture alternatively containing the cofactor pyridoxal-5′-phosphate (PLP) in excess or containing no PLP (holoenzyme of GAD). A comparison between these two estimations showed that the apoenzyme of GAD is only partially saturated with cofactor and that the degree of saturation varied from brain area to brain area, being highest in cerebellar cortex and lowest in substantia nigra. Holoenzyme activity fell steeply after administration of 100 mg/kg MP. The regional degree of enzyme inhibition by MP was a function of the saturation of the apoenzyme with cofactor; i.e., a low rate of saturation resulted in a high degree of inhibition, and vice versa. That GAD from the regio inferior of the hippocampus did not fit into the scheme (strong inhibition is present although the degree of saturation is high) is discussed in view of the role of the hippocampus in seizure genesis and generalization. Inhibition of GAD activity by MP was completely reversible in vitro by excess PLP. Before the onset of seizures but not during their course, apoenzyme activity surpassed control levels. This preictal activation is significant in regio inferior of hippocampus, in superior colliculus, and in cerebellar cortex. GABA-transaminase activities were not significantly altered. The present study demonstrates that only investigation during the preictal period and in regional brain areas can reveal changes specific for the drug and perhaps representing the cause for seizure development, without being masked by additional alterations resulting from the severe functional and metabolic derangement during the ictal events. Thereby, it was disclosed that a decrease in vivo in the level of the enzyme product, GABA, is able to activate GAD. 2006 Blackwell Publishing Journal Backfiles 1879-2005 |2006|||||||||| Glutamate decarboxylase, regional activity In Journal of neurochemistry Oxford : Wiley-Blackwell, 1956 34(1980), 4, Seite 0 Online-Ressource (DE-627)NLEJ243927584 (DE-600)2020528-4 1471-4159 nnns volume:34 year:1980 number:4 pages:0 http://dx.doi.org/10.1111/j.1471-4159.1980.tb09653.x text/html Verlag Deutschlandweit zugänglich Volltext GBV_USEFLAG_U ZDB-1-DJB GBV_NL_ARTICLE AR 34 1980 4 0 |
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10.1111/j.1471-4159.1980.tb09653.x doi (DE-627)NLEJ240327233 DE-627 ger DE-627 rakwb Nitsch, Cordula verfasserin aut Regulation of GABA Metabolism in Discrete Rabbit Brain Regions under Methoxypyridoxine—Regional Differences in Cofactor Saturation and the Preictal Activation of Glutamate Decarboxylase Activity Oxford, UK Blackwell Publishing Ltd 1980 Online-Ressource nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier Abstract: The activities of the enzymes of the GABA system, glutamate decarboxylase (GAD) and GABA-transaminase, were measured in discrete regions of the rabbit brain before the onset and during the course of sustained epileptiform seizures induced by the vitamin B6, analogue methoxypyridoxine (MP). GAD activities were measured in a reaction mixture alternatively containing the cofactor pyridoxal-5′-phosphate (PLP) in excess or containing no PLP (holoenzyme of GAD). A comparison between these two estimations showed that the apoenzyme of GAD is only partially saturated with cofactor and that the degree of saturation varied from brain area to brain area, being highest in cerebellar cortex and lowest in substantia nigra. Holoenzyme activity fell steeply after administration of 100 mg/kg MP. The regional degree of enzyme inhibition by MP was a function of the saturation of the apoenzyme with cofactor; i.e., a low rate of saturation resulted in a high degree of inhibition, and vice versa. That GAD from the regio inferior of the hippocampus did not fit into the scheme (strong inhibition is present although the degree of saturation is high) is discussed in view of the role of the hippocampus in seizure genesis and generalization. Inhibition of GAD activity by MP was completely reversible in vitro by excess PLP. Before the onset of seizures but not during their course, apoenzyme activity surpassed control levels. This preictal activation is significant in regio inferior of hippocampus, in superior colliculus, and in cerebellar cortex. GABA-transaminase activities were not significantly altered. The present study demonstrates that only investigation during the preictal period and in regional brain areas can reveal changes specific for the drug and perhaps representing the cause for seizure development, without being masked by additional alterations resulting from the severe functional and metabolic derangement during the ictal events. Thereby, it was disclosed that a decrease in vivo in the level of the enzyme product, GABA, is able to activate GAD. 2006 Blackwell Publishing Journal Backfiles 1879-2005 |2006|||||||||| Glutamate decarboxylase, regional activity In Journal of neurochemistry Oxford : Wiley-Blackwell, 1956 34(1980), 4, Seite 0 Online-Ressource (DE-627)NLEJ243927584 (DE-600)2020528-4 1471-4159 nnns volume:34 year:1980 number:4 pages:0 http://dx.doi.org/10.1111/j.1471-4159.1980.tb09653.x text/html Verlag Deutschlandweit zugänglich Volltext GBV_USEFLAG_U ZDB-1-DJB GBV_NL_ARTICLE AR 34 1980 4 0 |
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regulation of gaba metabolism in discrete rabbit brain regions under methoxypyridoxine—regional differences in cofactor saturation and the preictal activation of glutamate decarboxylase activity |
title_auth |
Regulation of GABA Metabolism in Discrete Rabbit Brain Regions under Methoxypyridoxine—Regional Differences in Cofactor Saturation and the Preictal Activation of Glutamate Decarboxylase Activity |
abstract |
Abstract: The activities of the enzymes of the GABA system, glutamate decarboxylase (GAD) and GABA-transaminase, were measured in discrete regions of the rabbit brain before the onset and during the course of sustained epileptiform seizures induced by the vitamin B6, analogue methoxypyridoxine (MP). GAD activities were measured in a reaction mixture alternatively containing the cofactor pyridoxal-5′-phosphate (PLP) in excess or containing no PLP (holoenzyme of GAD). A comparison between these two estimations showed that the apoenzyme of GAD is only partially saturated with cofactor and that the degree of saturation varied from brain area to brain area, being highest in cerebellar cortex and lowest in substantia nigra. Holoenzyme activity fell steeply after administration of 100 mg/kg MP. The regional degree of enzyme inhibition by MP was a function of the saturation of the apoenzyme with cofactor; i.e., a low rate of saturation resulted in a high degree of inhibition, and vice versa. That GAD from the regio inferior of the hippocampus did not fit into the scheme (strong inhibition is present although the degree of saturation is high) is discussed in view of the role of the hippocampus in seizure genesis and generalization. Inhibition of GAD activity by MP was completely reversible in vitro by excess PLP. Before the onset of seizures but not during their course, apoenzyme activity surpassed control levels. This preictal activation is significant in regio inferior of hippocampus, in superior colliculus, and in cerebellar cortex. GABA-transaminase activities were not significantly altered. The present study demonstrates that only investigation during the preictal period and in regional brain areas can reveal changes specific for the drug and perhaps representing the cause for seizure development, without being masked by additional alterations resulting from the severe functional and metabolic derangement during the ictal events. Thereby, it was disclosed that a decrease in vivo in the level of the enzyme product, GABA, is able to activate GAD. |
abstractGer |
Abstract: The activities of the enzymes of the GABA system, glutamate decarboxylase (GAD) and GABA-transaminase, were measured in discrete regions of the rabbit brain before the onset and during the course of sustained epileptiform seizures induced by the vitamin B6, analogue methoxypyridoxine (MP). GAD activities were measured in a reaction mixture alternatively containing the cofactor pyridoxal-5′-phosphate (PLP) in excess or containing no PLP (holoenzyme of GAD). A comparison between these two estimations showed that the apoenzyme of GAD is only partially saturated with cofactor and that the degree of saturation varied from brain area to brain area, being highest in cerebellar cortex and lowest in substantia nigra. Holoenzyme activity fell steeply after administration of 100 mg/kg MP. The regional degree of enzyme inhibition by MP was a function of the saturation of the apoenzyme with cofactor; i.e., a low rate of saturation resulted in a high degree of inhibition, and vice versa. That GAD from the regio inferior of the hippocampus did not fit into the scheme (strong inhibition is present although the degree of saturation is high) is discussed in view of the role of the hippocampus in seizure genesis and generalization. Inhibition of GAD activity by MP was completely reversible in vitro by excess PLP. Before the onset of seizures but not during their course, apoenzyme activity surpassed control levels. This preictal activation is significant in regio inferior of hippocampus, in superior colliculus, and in cerebellar cortex. GABA-transaminase activities were not significantly altered. The present study demonstrates that only investigation during the preictal period and in regional brain areas can reveal changes specific for the drug and perhaps representing the cause for seizure development, without being masked by additional alterations resulting from the severe functional and metabolic derangement during the ictal events. Thereby, it was disclosed that a decrease in vivo in the level of the enzyme product, GABA, is able to activate GAD. |
abstract_unstemmed |
Abstract: The activities of the enzymes of the GABA system, glutamate decarboxylase (GAD) and GABA-transaminase, were measured in discrete regions of the rabbit brain before the onset and during the course of sustained epileptiform seizures induced by the vitamin B6, analogue methoxypyridoxine (MP). GAD activities were measured in a reaction mixture alternatively containing the cofactor pyridoxal-5′-phosphate (PLP) in excess or containing no PLP (holoenzyme of GAD). A comparison between these two estimations showed that the apoenzyme of GAD is only partially saturated with cofactor and that the degree of saturation varied from brain area to brain area, being highest in cerebellar cortex and lowest in substantia nigra. Holoenzyme activity fell steeply after administration of 100 mg/kg MP. The regional degree of enzyme inhibition by MP was a function of the saturation of the apoenzyme with cofactor; i.e., a low rate of saturation resulted in a high degree of inhibition, and vice versa. That GAD from the regio inferior of the hippocampus did not fit into the scheme (strong inhibition is present although the degree of saturation is high) is discussed in view of the role of the hippocampus in seizure genesis and generalization. Inhibition of GAD activity by MP was completely reversible in vitro by excess PLP. Before the onset of seizures but not during their course, apoenzyme activity surpassed control levels. This preictal activation is significant in regio inferior of hippocampus, in superior colliculus, and in cerebellar cortex. GABA-transaminase activities were not significantly altered. The present study demonstrates that only investigation during the preictal period and in regional brain areas can reveal changes specific for the drug and perhaps representing the cause for seizure development, without being masked by additional alterations resulting from the severe functional and metabolic derangement during the ictal events. Thereby, it was disclosed that a decrease in vivo in the level of the enzyme product, GABA, is able to activate GAD. |
collection_details |
GBV_USEFLAG_U ZDB-1-DJB GBV_NL_ARTICLE |
container_issue |
4 |
title_short |
Regulation of GABA Metabolism in Discrete Rabbit Brain Regions under Methoxypyridoxine—Regional Differences in Cofactor Saturation and the Preictal Activation of Glutamate Decarboxylase Activity |
url |
http://dx.doi.org/10.1111/j.1471-4159.1980.tb09653.x |
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doi_str |
10.1111/j.1471-4159.1980.tb09653.x |
up_date |
2024-07-06T09:43:05.515Z |
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7.400342 |