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Effects of Dizocilpine, Midazolam and Their Co-Application on the Trimethyltin (TMT)-Induced Rat Model of Cognitive Deficit. Brain Sci 2021; 11:brainsci11030400. [PMID: 33809889 PMCID: PMC8004281 DOI: 10.3390/brainsci11030400] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 03/10/2021] [Accepted: 03/18/2021] [Indexed: 12/20/2022] Open
Abstract
Research of treatment options addressing the cognitive deficit associated with neurodegenerative disorders is of particular importance. Application of trimethyltin (TMT) to rats represents a promising model replicating multiple relevant features of such disorders. N-methyl-D-aspartate (NMDA) receptor antagonists and gamma-aminobutyric acid type A (GABAA) receptor potentiators have been reported to alleviate the TMT-induced cognitive deficit. These compounds may provide synergistic interactions in other models. The aim of this study was to investigate, whether co-application of NMDA receptor antagonist dizocilpine (MK-801) and GABAA receptor potentiator midazolam would be associated with an improved effect on the TMT-induced model of cognitive deficit. Wistar rats injected with TMT were repeatedly (12 days) treated with MK-801, midazolam, or both. Subsequently, cognitive performance was assessed. Finally, after a 17-day drug-free period, hippocampal neurodegeneration (neuronal density in CA2/3 subfield in the dorsal hippocampus, dentate gyrus morphometry) were analyzed. All three protective treatments induced similar degree of therapeutic effect in Morris water maze. The results of histological analyses were suggestive of minor protective effect of the combined treatment (MK-801 and midazolam), while these compounds alone were largely ineffective at this time point. Therefore, in terms of mitigation of cognitive deficit, the combined treatment was not associated with improved effect.
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Liu J, Wu YY, Yu XL, Jia HY, Mao QY, Fang JQ. Temporal effect of acupuncture on amino acid neurotransmitters in rats with acute cerebral ischaemia. Acupunct Med 2019; 37:252-258. [PMID: 31342771 DOI: 10.1136/acupmed-2017-011417] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Acupuncture stimulation at GV26 during the acute phase of cerebral ischaemia can effectively reduce brain damage induced by ischaemic injury. However, the time course of the effects of acupuncture stimulation has not yet been thoroughly studied. OBJECTIVE To investigate the effects of manual acupuncture (MA) on glutamic acid (Glu) and γ-aminobutyric acid (GABA) expression in the cerebrospinal fluid of rats with middle cerebral artery occlusion (MCAO) and determine whether there is a temporal effect of acupuncture on the treatment of cerebral ischaemia. METHODS We performed thread occlusion of the right middle cerebral artery in rats to establish an animal model of MCAO. Simultaneously, during acupuncture treatment, microdialysis was used to continuously and dynamically observe immediate alterations in amino acid metabolism with acupuncture stimulation after cerebral ischaemia in vivo in this rat model of MCAO. RESULTS We found that, in comparison with an untreated MCAO group, Glu content was significantly decreased during the first acupuncture stimulation and during the course of the acupuncture treatment in the MCAO+MA group (MCAO vs MCAO+MA: day 1, P=0.032; day 2, P=0.021; day 3, P=0.017). These findings were also seen after the end of treatment when acupuncture was no longer applied (MCAO vs MCAO+MA: day 7, P=0.009). Measurements of GABA content following cerebral ischaemic injury showed that GABA peaks 24 hours after damage, falls thereafter and decreases to baseline levels on day 7. In the MCAO+MA group, GABA content on days 1 to day 2 was lower than in the MCAO group (MCAO+MA vs MCAO: day 1, P=0.003; day 2, P=0.001), although it was higher than in the control group (MCAO+MA vs control: day 1, P=0.024; day 2, P=0.009). GABA content on day 3 and day 7 was higher in the MCAO+MA group than in the MCAO group and the control group (MCAO+MA vs MCAO: day 3, P=0.008; day 7, P=0.013; MCAO+MA vs control: day 3, P=0.002; day 7, P=0.009). CONCLUSION Acupuncture stimulation at GV26 can effectively decrease excessive release of Glu induced by ischaemia and maintain the endogenous inhibitory activity of GABA. This phenomenon was seen during the entire course of acupuncture treatment and continued for some time after the end of acupuncture treatment.
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Affiliation(s)
- Jing Liu
- 1 The Third Affiliated Hospital, Zhejiang Chinese Medical University, Hangzhou, China.,2 The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
| | - Yuan-Yuan Wu
- 1 The Third Affiliated Hospital, Zhejiang Chinese Medical University, Hangzhou, China.,2 The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
| | - Xiao-Lei Yu
- 1 The Third Affiliated Hospital, Zhejiang Chinese Medical University, Hangzhou, China.,2 The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
| | - Hong-Yang Jia
- 1 The Third Affiliated Hospital, Zhejiang Chinese Medical University, Hangzhou, China.,2 The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
| | - Qun-Yan Mao
- 1 The Third Affiliated Hospital, Zhejiang Chinese Medical University, Hangzhou, China.,2 The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
| | - Jian-Qiao Fang
- 1 The Third Affiliated Hospital, Zhejiang Chinese Medical University, Hangzhou, China.,2 The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
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Colin O, Labreuche J, Deguil J, Mendyk AM, Deken V, Cordonnier C, Deplanque D, Leys D, Bordet R. Preadmission use of benzodiazepines and stroke outcomes: the Biostroke prospective cohort study. BMJ Open 2019; 9:e022720. [PMID: 30782684 PMCID: PMC6340422 DOI: 10.1136/bmjopen-2018-022720] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVES We tested the hypothesis that stroke outcomes in patients with preadmission use of benzodiazepine are worse. METHOD In a prospective cohort study, we recruited patients with acute ischaemic stroke. Mortality, functional outcomes and cognition were evaluated at 8 and 90 days after stroke. RESULTS 370 patients were included. 62 (18.5%) of the 336 remaining patients were treated with benzodiazepines when stroke occurred, and they did not receive any other psychotropic drug. The mortality rate was higher in benzodiazepines users than non-users at day 8 (2.2% vs 8.1%, p=0.034) and day 90 (8.1% vs 25.9%, p=0.0001). After controlling for baseline differences using propensity-score matching, only the difference in mortality rate at day 90 was of borderline of significance, with a matched OR of 3.93 (95% CI, 0.91 to 16.98). In propensity-score-adjusted cohort, this difference remained significant with a similar treatment effect size (adjusted OR, 3.50; 95% CI, 1.57 to 7.76). A higher rate of poor functional outcome at day 8 and day 90 defined bymodified Rankin scale (mRS) ≥2 or by theBarthel index (BI) <95 was found in benzodiazepines users. In propensity-score-adjusted cohort, only the difference in mRS≥2 at day 90 remained significant (adjusted OR, 1.89; 95% CI, 1.02 to 3.48). In survivors at day 8 and at day 90, there was no significant difference in cognitive evaluation. CONCLUSION Our study has shown that preadmission use of benzodiazepines could be associated with increased post-stroke mortality at 90 days. These findings do not support a putative neuroprotective effect of γ-aminobutyric acidA receptors agonists and should alert clinicians of their potential risks. TRIAL REGISTRATION NUMBER NCT00763217.
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Affiliation(s)
- Olivier Colin
- Univ Lille; Inserm; CHU Lille; UMR-S 1171 “Degenerative and Vascular Cognitive Disorders”, Lille, France
- Univ Poitiers, Centre d’Investigation Clinique CIC1402 INSERM & Neurology Unit, CHU Poitiers, Poitiers, France
| | | | - Julie Deguil
- Univ Lille; Inserm; CHU Lille; UMR-S 1171 “Degenerative and Vascular Cognitive Disorders”, Lille, France
| | - Anne-Marie Mendyk
- Univ Lille; Inserm; CHU Lille; UMR-S 1171 “Degenerative and Vascular Cognitive Disorders”, Lille, France
| | - Valérie Deken
- Univ Lille; Inserm; CHU Lille; EA2694, Lille, France
| | - Charlotte Cordonnier
- Univ Lille; Inserm; CHU Lille; UMR-S 1171 “Degenerative and Vascular Cognitive Disorders”, Lille, France
| | - Dominique Deplanque
- Univ Lille; Inserm; CHU Lille; UMR-S 1171 “Degenerative and Vascular Cognitive Disorders”, Lille, France
| | - Didier Leys
- Univ Lille; Inserm; CHU Lille; UMR-S 1171 “Degenerative and Vascular Cognitive Disorders”, Lille, France
| | - Régis Bordet
- Univ Lille; Inserm; CHU Lille; UMR-S 1171 “Degenerative and Vascular Cognitive Disorders”, Lille, France
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Abstract
BACKGROUND Gamma aminobutyric acid (GABA) receptor agonists have been shown to have a neuroprotectant effect in reducing infarct size and improving functional outcome in animal models of cerebrovascular disease. However, the sedative effects of GABA receptor agonists have limited their wider application in people with acute stroke, due to the potential risk of stupor. This is an update of a Cochrane Review first published in 2013, and previously updated in 2014 and 2016. OBJECTIVES To determine the efficacy and safety of GABA receptor agonists in the treatment of acute stroke. SEARCH METHODS We searched the Cochrane Stroke Group Trials Register (accessed May 2018), the Cochrane Central Register of Controlled Trials (CENTRAL) 2018, Issue 4 (accessed May 2018), MEDLINE (from 1949 to May 2018), Embase (from 1980 to May 2018), CINAHL (from 1982 to May 2018), AMED (from 1985 to May 2018), and 11 Chinese databases (accessed May 2018). In an effort to identify further published, unpublished, and ongoing trials we searched ongoing trial registers, reference lists, and relevant conference proceedings, and contacted authors and pharmaceutical companies. SELECTION CRITERIA We included randomized controlled trials (RCTs) investigating GABA receptor agonists versus placebo for people with acute stroke (within 12 hours after stroke onset), with the primary outcomes of efficacy and safety. DATA COLLECTION AND ANALYSIS Two review authors independently screened the titles and abstracts of identified records, selected studies for inclusion, extracted eligible data, cross-checked the data for accuracy, and assessed the risk of bias. We used the GRADE approach to assess the quality of the evidence. MAIN RESULTS We included five trials with 3838 participants (acute ischemic or hemorrhagic stroke patients, 3758 analyzed). Most of the participants recruited had acute ischaemic stroke, with limited data available from participants with other stroke subtypes, including total anterior circulation syndrome (TACS). The methodological quality of the included trials was generally good, with an unclear risk for selection bias only. For death and dependency at three months, pooled results did not find a significant difference for chlormethiazole versus placebo (risk ratio (RR) 1.03, 95% confidence interval (CI) 0.96 to 1.11; four trials; 2909 participants; moderate-quality evidence) and for diazepam versus placebo (RR 0.94, 95% CI 0.82 to 1.07; one trial; 849 participants; moderate-quality evidence). The most frequent adverse events related to chlormethiazole were somnolence (RR 4.56, 95% CI 3.50 to 5.95; two trials; 2527 participants; moderate-quality evidence) and rhinitis (RR 4.75, 95% CI 2.67 to 8.46; two trials; 2527 participants; moderate-quality evidence). AUTHORS' CONCLUSIONS This review provides moderate-quality evidence that fails to support the use of GABA receptor agonists (chlormethiazole or diazepam) for the treatment of people with acute stroke. More well-designed RCTs with large samples of participants with total anterior circulation syndrome are required to determine if there are benefits for this subgroup. Somnolence and rhinitis are frequent adverse events related to chlormethiazole.
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Affiliation(s)
- Jia Liu
- Xuanwu Hospital, Capital Medical UniversityDepartment of NeurologyChangchun Street 45BeijingChina100053
| | - Jing Zhang
- Xuanwu Hospital, Capital Medical UniversityDepartment of NeurologyChangchun Street 45BeijingChina100053
| | - Lu‐Ning Wang
- Chinese PLA General HospitalDepartment of Geriatric NeurologyFuxing Road 28Haidian DistrictBeijingChina100853
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Glial GABA Transporters as Modulators of Inhibitory Signalling in Epilepsy and Stroke. ADVANCES IN NEUROBIOLOGY 2017; 16:137-167. [PMID: 28828609 DOI: 10.1007/978-3-319-55769-4_7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Imbalances in GABA-mediated tonic inhibition are involved in several pathophysiological conditions. A classical way of controlling tonic inhibition is through pharmacological intervention with extrasynaptic GABAA receptors that sense ambient GABA and mediate a persistent GABAergic conductance. An increase in tonic inhibition may, however, also be obtained indirectly by inhibiting glial GABA transporters (GATs). These are sodium-coupled membrane transport proteins that normally act to terminate GABA neurotransmitter action by taking up GABA into surrounding astrocytes. The aim of the review is to provide an overview of glial GATs in regulating tonic inhibition, especially in epilepsy and stroke. This entails a comprehensive summary of changes known to occur in GAT expression levels and signalling following epileptic and ischemic insults. Further, we discuss the accumulating pharmacological evidence for targeting GATs in these diseases.
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Abstract
BACKGROUND Gamma aminobutyric acid (GABA) receptor agonists have been shown to have a neuroprotectant effect in reducing infarct size and improving functional outcome in animal models of cerebrovascular disease. However, the sedative effects of GABA receptor agonists have limited their wider application in people with acute stroke, due to the potential risk of stupor. This is an update of a Cochrane review first published in 2013, and previously updated in 2014. OBJECTIVES To determine the efficacy and safety of GABA receptor agonists in the treatment of acute stroke. SEARCH METHODS We searched the Cochrane Stroke Group Trials Register (accessed March 2016), the Cochrane Central Register of Controlled Trials (CENTRAL) 2016, Issue 3, part of the Cochrane Library (accessed March 2016), MEDLINE (from 1949 to March 2016), Embase (from 1980 to March 2016), CINAHL (from 1982 to March 2016), AMED (from 1985 to March 2016), and 11 Chinese databases (accessed March 2016). In an effort to identify further published, unpublished, and ongoing trials we searched ongoing trials registers, reference lists, and relevant conference proceedings, and contacted authors and pharmaceutical companies. SELECTION CRITERIA We included randomized controlled trials (RCTs) investigating GABA receptor agonists versus placebo for people with acute stroke (within 12 hours after stroke onset), with the primary outcomes of efficacy and safety. DATA COLLECTION AND ANALYSIS Two review authors independently screened the titles and abstracts of identified records, selected studies for inclusion, extracted eligible data, cross-checked the data for accuracy, and assessed the risk of bias. MAIN RESULTS We included five trials with 3838 participants (3758 analyzed). The methodological quality of the included trials was generally good, with an unclear risk for selection bias only. Four trials (N = 2909) measured death and dependency at three months for chlormethiazole versus placebo; pooled results did not find a significant difference (risk ratio (RR) 1.03, 95% confidence interval (CI) 0.96 to 1.11). One trial (N = 849) measured this outcome for diazepam versus placebo (RR 0.94, 95% CI 0.82 to 1.07). The most frequent adverse events related to chlormethiazole were somnolence (RR 4.56, 95% CI 3.50 to 5.95; two trials; N = 2527) and rhinitis (RR 4.75, 95% CI 2.67 to 8.46; two trials; N = 2527). AUTHORS' CONCLUSIONS This review provides moderate-quality evidence that fails to support the use of GABA receptor agonists (chlormethiazole or diazepam) for the treatment of people with acute stroke. More well-designed RCTs with large samples of participants with total anterior circulation syndrome are required to determine if there are benefits for this subgroup. Somnolence and rhinitis are frequent adverse events related to chlormethiazole.
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Affiliation(s)
- Jia Liu
- Xuanwu Hospital, Capital Medical UniversityDepartment of NeurologyChangchun Street 45BeijingChina100053
| | - Lu‐Ning Wang
- Chinese PLA General HospitalDepartment of Geriatric NeurologyFuxing Road 28Haidian DistrictBeijingChina100853
| | - Xin Ma
- Xuanwu Hospital, Capital Medical UniversityDepartment of NeurologyChangchun Street 45BeijingChina100053
| | - Xunming Ji
- Xuanwu Hospital, Capital Medical UniversityDepartment of NeurosurgeryBeijingChina100053
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Alleviation of glutamate mediated neuronal insult by piroxicam in rodent model of focal cerebral ischemia: a possible mechanism of GABA agonism. J Physiol Biochem 2014; 70:901-13. [DOI: 10.1007/s13105-014-0358-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 09/17/2014] [Indexed: 12/17/2022]
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Abstract
BACKGROUND Gamma aminobutyric acid (GABA) receptor agonists have been shown to have a neuroprotectant effect in reducing infarct size and improving functional outcome in animal models of cerebral ischemia. However, the sedation effects of GABA receptor agonists have limited their wider application in acute stroke patients due to the potential risk of stupor. OBJECTIVES To determine the efficacy and safety of GABA receptor agonists in the treatment of acute stroke. SEARCH METHODS We searched the Cochrane Stroke Group Trials Register (February 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 5), MEDLINE (1949 to June 2014), EMBASE (1980 to June 2014), CINAHL (1982 to June 2014), AMED (1985 to June 2014) and 11 Chinese databases (June 2014). In an effort to identify further published, unpublished and ongoing trials we searched ongoing trials registers, reference lists and relevant conference proceedings, and contacted authors and pharmaceutical companies. SELECTION CRITERIA We included randomized controlled trials (RCTs) investigating GABA receptor agonists versus placebo for acute stroke patients (within 12 hours after stroke onset), with the outcomes of death or dependency, functional independence and adverse events. DATA COLLECTION AND ANALYSIS Two review authors independently screened the titles and abstracts of identified records, selected studies for inclusion, extracted eligible data, cross-checked the data for accuracy and assessed the methodological quality. MAIN RESULTS We included five trials with 3838 patients. The methodological quality of the included trials was generally good, with low risk of bias. Four trials measured death and dependency at three months in chlormethiazole versus placebo without significant difference (risk ratio (RR) 1.03, 95% confidence interval (CI) 0.95 to 1.11). One trial measured this outcome between diazepam and placebo (RR 0.94, 95% CI 0.82 to 1.07). In the subgroup analysis of total anterior circulation syndrome (TACS), a higher percentage of functional independence was found in the chlormethiazole group (RR 1.33, 95% CI 1.09 to 1.64). The frequent adverse events related to chlormethiazole were somnolence (RR 4.56, 95% CI 3.50 to 5.95) and rhinitis (RR 4.75, 95% CI 2.67 to 8.46). AUTHORS' CONCLUSIONS This review does not provide the evidence to support the use of GABA receptor agonists (chlormethiazole or diazepam) for the treatment of patients with acute ischemic or hemorrhagic stroke. Chlormethiazole appeared to be beneficial in improving functional independence in patients with TACS according to the subgroup analysis, but this result must be interpreted with great caution. More well-designed RCTs with large samples of TACS would be required for further confirmation. However, somnolence and rhinitis are frequent adverse events related to chlormethiazole.
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Affiliation(s)
- Jia Liu
- Department of Geriatric Neurology, Chinese PLA General Hospital, Fuxing Road 28, Beijing, China, 100853
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9
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Huang WS, Muo CH, Chang SN, Chang YJ, Tsai CH, Kao CH. Benzodiazepine use and risk of stroke: a retrospective population-based cohort study. Psychiatry Clin Neurosci 2014; 68:255-62. [PMID: 24829937 DOI: 10.1111/pcn.12117] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
AIM The aim of this study was to investigate the possible association between benzodiazepine (BZD) use and risk of incident stroke by utilizing data from 2000 to 2003 from the National Health Insurance system of Taiwan. METHODS Study subjects consisted of 38,671 patients with new BZD use and 38,663 people without BZD use who were frequency-matched for age, sex and baseline comorbidity with BZD users. All subjects had no history of stroke. Each study patient's case was followed until a new diagnosis of stroke was made or until the patient was censored by loss to follow up, death, or termination of insurance. The study lasted until the end of 2009. A Cox proportional hazards regression model was used to estimate the incidences and hazard ratios (HR) of stroke. RESULTS The HR of hemorrhagic stroke was significantly lower in the BZD group when compared with the non-BZD group. For patients aged 20-39 years, the HR of ischemic stroke was significantly higher in the BZD group when compared with the non-BZD group. Compared to the non-BZD group, patients with a lower annual dosage (<1 g) or duration (<30 days) of BZD use had a lower risk of stroke in the elder group (P < 0.0001) and patients with a higher annual dosage (≥ 4 g) or duration (≥ 95 days) of BZD use had a higher risk of stroke in all age groups (P < 0.0001). CONCLUSIONS Our findings may suggest neuroprotection under lower-dosage BZD use and neurotoxicity under higher-dosage BZD use.
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Affiliation(s)
- Wei-Shih Huang
- Department of Neurology; China Medical University Hospital; Taichung Taiwan
- Graduate Institute of Clinical Medical Science; School of Medicine; College of Medicine; China Medical University; Taichung Taiwan
| | | | | | - Yen-Jung Chang
- Management Office for Health Data; Taichung Taiwan
- Department of Health Promotion and Health Education; National Taiwan Normal University; Taipei Taiwan
| | - Chon-Haw Tsai
- Department of Neurology; China Medical University Hospital; Taichung Taiwan
- Graduate Institute of Clinical Medical Science; School of Medicine; College of Medicine; China Medical University; Taichung Taiwan
| | - Chia-Hung Kao
- Department of Nuclear Medicine and PET Center; China Medical University Hospital; Taichung Taiwan
- Graduate Institute of Clinical Medical Science; School of Medicine; College of Medicine; China Medical University; Taichung Taiwan
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Abstract
BACKGROUND Gamma aminobutyric acid (GABA) receptor agonists have been shown to have a neuroprotectant effect in reducing infarct size and improving functional outcome in animal models of cerebral ischemia. However, the sedation effects of GABA receptor agonists have limited their wider application in acute stroke patients due to the potential risk of stupor. OBJECTIVES To determine the efficacy and safety of GABA receptor agonists in the treatment of acute stroke. SEARCH METHODS We searched the Cochrane Stroke Group Trials Register (January 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 1), MEDLINE (1949 to March 2012), EMBASE (1980 to March 2012), CINAHL (1982 to March 2012), AMED (1985 to March 2012) and 11 Chinese databases (March 2012). In an effort to identify further published, unpublished and ongoing trials we searched ongoing trials registers, reference lists and relevant conference proceedings, and contacted authors and pharmaceutical companies. SELECTION CRITERIA We included randomized controlled trials (RCTs) investigating GABA receptor agonists versus placebo for acute stroke patients (within 12 hours after stroke onset), with the outcomes of death or dependency, functional independence and adverse events. DATA COLLECTION AND ANALYSIS Two review authors independently screened the titles and abstracts of identified records, selected studies for inclusion, extracted eligible data, cross-checked the data for accuracy and assessed the methodological quality. MAIN RESULTS We included five trials with 3838 patients. The methodological quality of the included trials was generally good, with low risk of bias. Four trials measured death and dependency at three months in chlormethiazole versus placebo without significant difference (risk ratio (RR) 1.03, 95% confidence interval (CI) 0.95 to 1.11). One trial measured this outcome between diazepam and placebo (RR 0.94, 95% CI 0.82 to 1.07). In the subgroup analysis of total anterior circulation syndrome (TACS), a higher percentage of functional independence was found in the chlormethiazole group (RR 1.33, 95% CI 1.09 to 1.64). The frequent adverse events related to chlormethiazole were somnolence (RR 4.56, 95% CI 3.50 to 5.95) and rhinitis (RR 4.75, 95% CI 2.67 to 8.46). AUTHORS' CONCLUSIONS This review does not provide the evidence to support the use of GABA receptor agonists (chlormethiazole or diazepam) for the treatment of patients with acute ischemic or hemorrhagic stroke. Chlormethiazole appeared to be beneficial in improving functional independence in patients with TACS according to the subgroup analysis, but this result must be interpreted with great caution. More well-designed RCTs with large samples of TACS would be required for further confirmation. However, somnolence and rhinitis are frequent adverse events related to chlormethiazole.
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Affiliation(s)
- Jia Liu
- Department of Geriatric Neurology, Chinese PLA General Hospital, Beijing, China.
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Chi OZ, Hunter C, Liu X, Chi Y, Weiss HR. Effects of GABA(A) receptor blockade on regional cerebral blood flow and blood-brain barrier disruption in focal cerebral ischemia. J Neurol Sci 2010; 301:66-70. [PMID: 21094956 DOI: 10.1016/j.jns.2010.10.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 10/14/2010] [Accepted: 10/22/2010] [Indexed: 11/18/2022]
Abstract
In cerebral ischemia, transmission by the inhibitory neurotransmitter, γ-aminobutyric acid (GABA) is altered. This study was performed to determine whether blockade of GABA(A) receptor would affect regional cerebral blood flow (rCBF) and blood-brain barrier (BBB) permeability in a focal ischemic area of the brain. Rats were anesthetized with isoflurane and mechanically ventilated. Fifteen minutes after a permanent middle cerebral artery (MCA) occlusion, one half of the rats were infused with bicuculline 1mg/kg/min iv for 2 min followed by 0.1mg/kg/min iv to the end of the experiment. The other half were infused with normal saline. At one hour after MCA occlusion, rCBF was determined using ¹⁴C-iodoantipyrine and BBB permeability was determined by measuring the transfer coefficient (Ki) of ¹⁴C-α-aminoisobutyric acid. With MCA occlusion, rCBF was decreased in the ischemic cortex (IC) (-70%) in the control rats. In the bicuculline treated rats, the rCBF of the IC was lower (-48%) than the contralateral cortex but higher than the rCBF of the IC of the control rats (+55%). MCA occlusion increased Ki in the IC of the control rats (+72%) and bicuculline administration increased Ki further (+53%) in the IC. Blockade of GABA(A) receptors did not significantly affect rCBF or BBB permeability in the non-ischemic brain regions under isoflurane anesthesia. Our data demonstrated that blockade of GABA(A) receptors increased rCBF and enhanced the BBB disruption in focal cerebral ischemia. Our data suggest that GABA(A) receptors are involved, at least in part, in modulating rCBF and BBB disruption in focal cerebral ischemia.
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Affiliation(s)
- Oak Z Chi
- Department of Anesthesia, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, New Brunswick, NJ 08901-1977, USA.
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Jochum T, Reinhard M, Boettger MK, Piater M, Bär KJ. Impaired cerebral autoregulation during acute alcohol withdrawal. Drug Alcohol Depend 2010; 110:240-6. [PMID: 20456871 DOI: 10.1016/j.drugalcdep.2010.03.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 03/17/2010] [Accepted: 03/17/2010] [Indexed: 10/19/2022]
Abstract
Heavy alcohol consumption increases the risk for all major types of stroke and is associated with autonomic dysfunction during alcohol withdrawal syndrome (AWS). Cerebral autoregulation is the mechanism by which cerebral perfusion is maintained stable, representing an intrinsic protective system of the cerebral circulation. Here, we aimed to analyze the influence of acute AWS on cerebral hemodynamics in alcohol-dependent patients. We investigated 20 men in the unmedicated acute state of AWS and repeated the investigation 24h after initiation of clomethiazole treatment. Dynamic cerebral autoregulation (dCA) was assessed by the correlation coefficient index and transfer function analysis (phase and gain) from oscillations of arterial blood pressure and cerebral blood flow velocity (CBFV). The vasomotor reserve (VMR) was measured by the CO(2)-reactivity test. In addition, we assessed autonomic modulation by means of heart rate variability and baroreflex sensitivity. We observed impaired dynamic autoregulation as shown by a multivariate analysis of variance (p<0.038) including all parameters of dCA. Similar results were found for VMR at admission (p<0.05). Pair-wise comparison between baseline and treatment with clomethiazole revealed a significant improvement for the systolic correlation coefficient index (Sx; p<0.001). Furthermore, we found a strong association of autonomic dysfunction and impaired autoregulation indicated by a correlation between the LF/HF ratio and Sx (p<0.001). In conclusion, cerebral autoregulation and VMR are disturbed during acute AWS. Influences of autonomic dysbalance and mental state during withdrawal are suggested. The finding of an affected autoregulation during acute withdrawal might indicate an increased risk for cerebro-vascular disease.
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Affiliation(s)
- Thomas Jochum
- Department of Psychiatry and Psychotherapy, Philosophenweg 3, University Hospital, Jena, Germany
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Rotge JY, Aouizerate B, Tignol J, Bioulac B, Burbaud P, Guehl D. The glutamate-based genetic immune hypothesis in obsessive-compulsive disorder. An integrative approach from genes to symptoms. Neuroscience 2010; 165:408-17. [PMID: 19861150 DOI: 10.1016/j.neuroscience.2009.10.043] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Revised: 10/21/2009] [Accepted: 10/21/2009] [Indexed: 10/20/2022]
Abstract
Recent advances in multiple areas of research have contributed to the identification of several pathophysiological factors underlying obsessive-compulsive disorder (OCD). In particular, the glutamate transporter gene SLC1A1 has been associated with the diagnosis of OCD. Immunological and infectious studies have reported alterations of the immune system and the presence of immune complexes directed against the Borna disease virus in OCD patients. In addition, neuroimaging of OCD patients has demonstrated abnormalities in the anterior cingulate cortex, orbitofrontal cortex, thalamus, and the basal ganglia. Neuropsychological assessments have found several cognitive disruptions that have been identified in OCD, especially impairments in cognitive flexibility. Here, we attempt to bridge the gap between these remarkable findings through several previously unpredicted pathophysiological mechanisms. We propose an integrative hypothesis that indicates how genetic and environmental factors may contribute to the structural and functional alterations of cortico-subcortical circuits, leading to the characteristic cognitive disruptions underlying OCD symptoms.
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Affiliation(s)
- J Y Rotge
- Laboratoire Mouvement Adaptation Cognition, CNRS UMR 5227, Université Bordeaux 2, Bordeaux, France.
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Pre-ischemic treadmill training affects glutamate and gamma aminobutyric acid levels in the striatal dialysate of a rat model of cerebral ischemia. Life Sci 2009; 84:505-11. [DOI: 10.1016/j.lfs.2009.01.015] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Revised: 12/05/2008] [Accepted: 01/26/2009] [Indexed: 11/17/2022]
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15
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Thompson JW, Prentice HM, Lutz PL. Regulation of extracellular glutamate levels in the long-term anoxic turtle striatum: coordinated activity of glutamate transporters, adenosine, K (ATP) (+) channels and GABA. J Biomed Sci 2007; 14:809-17. [PMID: 17629717 DOI: 10.1007/s11373-007-9190-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Accepted: 05/10/2007] [Indexed: 11/28/2022] Open
Abstract
Early in anoxia the mammalian brain experiences an uncontrolled release of glutamate, which combined with the failure of glutamate reuptake mechanisms, leads to massive neurotoxic increases in extracellular glutamate. By contrast, the anoxia tolerant turtle (Trachemys scripta) shows no increase in extracellular glutamate levels over many hours of anoxia. During the first hours of anoxia extracellular glutamate levels are maintained by a reduction in glutamate release (mainly due to the inhibition of neuronal vesicular glutamate release), combined with continued uptake by still active glutamate transporters. The early down-regulation in glutamate release is modulated by adenosine receptors and K (ATP) (+) channels, but is not affected by GABA(A )receptors. During long-term anoxia there is a further reduction in the rate of glutamate release, reaching 30% of normoxic control values at 5 h of anoxia. Adenosine and GABA(A) receptors but not K (ATP) (+) channels regulate this reduction in glutamate release. We conclude that the reduction in glutamate release during progressive anoxia is a dynamic process requiring continuous but changing synergistic activity of K (ATP) (+) channels, adenosine and GABA(A) receptors. The fact that there is a still active glutamate release and uptake in prolonged anoxia suggests that extracellular glutamate has a vital function in the deeply hypometabolic brain.
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Affiliation(s)
- John W Thompson
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, FL 33431, USA.
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16
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Ouyang C, Guo L, Lu Q, Xu X, Wang H. Enhanced activity of GABA receptors inhibits glutamate release induced by focal cerebral ischemia in rat striatum. Neurosci Lett 2007; 420:174-8. [PMID: 17531382 DOI: 10.1016/j.neulet.2007.05.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 03/22/2007] [Accepted: 05/01/2007] [Indexed: 11/29/2022]
Abstract
Cerebral ischemia causes an excess release of glutamate, which can injure neurons. The striatum is one of the important regions vulnerable to hypoxia and ischemia. Using push-pull perfusion technique, we investigated the regulatory role of gamma-aminobutyric acid (GABA) and its receptors in modifying the amount of glutamate in rat striatum with ischemia. Perfusion with exogenous GABA (1 mM) inhibited cerebral ischemia-induced glutamate release by as much as 47%. We further characterized relative roles of subtype receptors of GABA on glutamate release by using pharmacological tools. While baclofen (500 microM), a GABA(B) receptor agonist, suppressed ischemia-induced glutamate release by 52%, GABA(B) receptor antagonist saclofen (500 microM) failed to produce a significant increase of glutamate release. The GABA(A) receptor agonist muscimol (500 microM) also reduced by 38% the release of glutamate induced by cerebral ischemia but the GABA(A) receptor antagonist bicuculline (500 microM) had very little effect. The present study demonstrates that the excessive release of glutamate or the overly activated glutamate receptor, triggered by cerebral ischemia, can be down-regulated by exogenous GABA or by increased activity of GABA receptors, especially the presynaptic GABA(B) receptors, which might be one of the important mechanisms to protect against striatum neuronal damage from over stimulation by excessive glutamate during ischemia.
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Affiliation(s)
- Changhan Ouyang
- Department of Pharmacology, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430030, PR China
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17
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Schlösser RGM, Gesierich T, Wagner G, Bolz M, Gründer G, Dielentheis TF, Scherb C, Stoeter P. Altered benzodiazepine receptor sensitivity in alcoholism: a study with fMRI and acute lorazepam challenge. Psychiatry Res 2007; 154:241-51. [PMID: 17337165 DOI: 10.1016/j.pscychresns.2006.02.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2004] [Revised: 01/16/2006] [Accepted: 02/11/2006] [Indexed: 11/26/2022]
Abstract
Previous studies suggested altered sensitivity of the GABA/benzodiazepine receptor system in alcoholic patients. Expanding on these findings, the present functional magnetic resonance imaging (fMRI) study aimed to assess whether a differential modulation of cognitive brain activation by an acute GABAergic drug challenge could be detected in patients with alcoholism. Eight detoxified male patients meeting DSM-IV criteria for alcohol dependence and nine healthy male control subjects were studied with fMRI while performing a 2-back working memory task. The fMRI scans were performed 1 h after intravenous administration of saline and again 1 h after 0.03 mg/kg lorazepam I.V. After saline, a task x group interaction effect with higher task activation in alcoholic patients in the left cerebellum and the right prefrontal cortex emerged. Additionally, a differential task x drug x group interaction was identified in the right cerebellum with more pronounced reduction in cognitive activation after lorazepam in the patient group. A significant correlation between lorazepam sensitivity and duration of alcohol dependence was detected. The present findings are in line with previous studies suggesting disrupted prefrontal-cerebellar activation with potential compensatory hyperactivation of the compromised brain networks in alcoholism. Moreover, the results suggest enhanced responsivity to an acute GABAergic challenge in the right cerebellum with disease-related disruption of cerebellar functional integrity.
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Affiliation(s)
- Ralf G M Schlösser
- Department of Psychiatry, University of Jena, Philosophenweg 3, 07740 Jena, Germany.
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18
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Clarkson AN. Anesthetic-mediated protection/preconditioning during cerebral ischemia. Life Sci 2007; 80:1157-75. [PMID: 17258776 DOI: 10.1016/j.lfs.2006.12.022] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Revised: 12/04/2006] [Accepted: 12/13/2006] [Indexed: 01/22/2023]
Abstract
Cerebral ischemia is a multi-faceted neurodegenerative pathology that causes cellular injury to neurons within the central nervous system. In light of the underlying mechanisms being elucidated, clinical trials to find possible neuroprotectants to date have failed, thus highlighting the need for new putative targets to offer protection. Recent evidence has clearly shown that anesthetics can confer significant protection and or induce a preconditioning effect against cerebral ischemia-induced injury. This review will focus on the putative protection/preconditioning that is afforded by anesthetics, their possible interaction with GABA(A) and glutamate receptors and two-pore potassium channels. In addition, the interaction with inflammatory, apoptotic and underlying molecular (particularly immediately early genes and inducible nitric oxide synthase etc) pathways, the activation of K(ATP) channels and the ability to provide lasting protection will also be addressed.
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Affiliation(s)
- Andrew N Clarkson
- Department of Anatomy and Structural Biology, University of Otago, PO Box 913, Dunedin 9054, New Zealand.
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Hainsworth AH, Nelson RM, Lambert DG, Green AR, Webb TE. Glutamate receptor-mediated inhibition of L-glutamate efflux from cerebral cortex in vitro. Brain Res 2006; 1114:36-40. [PMID: 16904087 DOI: 10.1016/j.brainres.2006.07.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2005] [Revised: 07/05/2006] [Accepted: 07/13/2006] [Indexed: 11/30/2022]
Abstract
We tested whether glutamate receptor ligands affect oxygen-glucose deprivation-evoked L-glutamate efflux from adult rat cerebrocortical prisms. The uncompetitive NMDA antagonist AR-R15896AR inhibited efflux (IC50 34 microM, 87% maximal inhibition). AMPA/kainate receptor blockade (NBQX, 100 microM) or Group II metabotropic glutamate receptor activation (DCG-IV, 10 microM) inhibited efflux (41%, 67% respectively) but Group I mGluR blockade (CPCCOEt/MPEP, 10 microM) was without effect. These data support a modulatory effect of glutamate receptors on L-glutamate efflux.
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Affiliation(s)
- Atticus H Hainsworth
- Pharmacology Research Group, Leicester School of Pharmacy, De Montfort University, Leicester, LE1 9BH, UK.
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20
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Miyamoto TA, Miyamoto KJ, Miyamoto MR. Part III. Systemically administered taurine: pharmacologically activated mechanisms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2006; 583:335-51. [PMID: 17153619 DOI: 10.1007/978-0-387-33504-9_38] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
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21
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Clarkson AN, Liu H, Rahman R, Jackson DM, Appleton I, Kerr DS. Clomethiazole: mechanisms underlying lasting neuroprotection following hypoxia-ischemia. FASEB J 2005; 19:1036-8. [PMID: 15809357 DOI: 10.1096/fj.04-3367fje] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Damage after hypoxia-ischemia (HI) is observed in both cortical and subcortical regions. In this study, we employed a "Levine" rat model of HI (left carotid ligation + 1 h global hypoxia on PND-26) and used histological and electrophysiological paradigms to assess the long-term neuroprotective properties of clomethiazole (CMZ; a GABA(A) receptor modulator). Key enzymes involved in inflammation, namely nitric oxide synthase (NOS) and arginase, were also examined to assess potential CMZ mechanisms not involving GABA-R activation. Assessments were carried out 3 and 90 days post-HI. Extensive CNS lesions were evident after HI ipsilaterally at both short- and long-term intervals. CMZ significantly decreased the lesion size at 3 and 90 days (P<0.01; P<0.05). Evoked field potential analyses were used to assess hippocampal CA1 neuronal activity ex vivo. Electrophysiological measurements contralateral to the occlusion revealed impaired neuronal function after HI relative to short- and long-term controls (P<0.001, 3 and 14 days; P<0.01, 90 days), with CMZ treatment providing near complete protection (P<0.001 at 3 and 14 days; P<0.01 at 90 days). Both NOS and arginase activities were significantly increased at 3 days (P<0.01), with arginase remaining elevated at 90 days post-HI (P<0.05) ipsilaterally. CMZ suppressed the HI-induced increase in iNOS and arginase activities (P<0.001; P<0.05). These data provide evidence of long-term functional neuroprotection by CMZ in a model of HI. We further conclude that under conditions of HI, functional deficits are not restricted to the ipsilateral hemisphere and are due, at least in part, to changes in the activity of NOS and arginase.
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Affiliation(s)
- Andrew N Clarkson
- Department of Pharmacology and Toxicology, University of Otago School of Medical Sciences, Dunedin, New Zealand
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22
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Kawasaki Y, Fujita T, Kumamoto E. Enhancement of the releases of GABA and glycine during ischemia in rat spinal dorsal horn. Biochem Biophys Res Commun 2004; 316:553-8. [PMID: 15020253 DOI: 10.1016/j.bbrc.2004.02.078] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2004] [Indexed: 11/22/2022]
Abstract
The present study examined a change in spontaneous inhibitory postsynaptic currents (sIPSCs) following ischemia in substantia gelatinosa (SG) neurons of adult rat spinal cord slices by using the whole-cell patch-clamp technique. At about 10 min after superfusion of an oxygen- and glucose-free medium, sIPSCs were remarkably increased in amplitude and frequency when compared with those in the control. In a phase of the increase in sIPSC activities, GABAergic and glycinergic sIPSCs, which were observed in the presence of strychnine and bicuculline, respectively, with TTX, were increased greatly in frequency with a minimal change in their amplitudes. It is concluded that the in vitro ischemia increases the spontaneous quantal releases of GABA and glycine to SG neurons from nerve terminals; a part of this enhancement is possibly due to an increase in spontaneous activities of inhibitory interneurons. GABA released thus might serve to inhibit the release of l-glutamate from nerve terminals.
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23
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Harsing LG, Gigler G, Albert M, Szenasi G, Simo A, Moricz K, Varga A, Ling I, Bagdy E, Kiraly I, Solyom S, Juranyi Z. Neurotransmitter Release in Experimental Stroke Models: The Role of Glutamate-Gaba Interaction. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2004. [DOI: 10.1007/978-1-4419-8969-7_2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Marcoli M, Raiteri L, Bonfanti A, Monopoli A, Ongini E, Raiteri M, Maura G. Sensitivity to selective adenosine A1 and A2A receptor antagonists of the release of glutamate induced by ischemia in rat cerebrocortical slices. Neuropharmacology 2003; 45:201-10. [PMID: 12842126 DOI: 10.1016/s0028-3908(03)00156-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Adenosine released during cerebral ischemia is considered to act as a neuroprotectant, possibly through the inhibition of glutamate release. The involvement of A(1) and A(2A) receptors in the control of the rise of extracellular glutamate during ischemia was investigated by monitoring the effects of selective A(1) and A(2A) receptor antagonists on ischemia-evoked glutamate release in rat cerebrocortical slices.Slices were superfused with oxygen- and glucose-deprived medium and [(3)H]D-aspartate or endogenous glutamate was measured in the superfusate fractions. Withdrawal of Ca(2+) ions or addition of tetrodotoxin more than halved the ischemia-evoked efflux of [(3)H]D-aspartate or glutamate, compatible with a vesicular-like release. The glutamate transporter inhibitor DL-TBOA prevented the ischemia-evoked efflux of [(3)H]D-aspartate by about 40%, indicating a carrier-mediated efflux. The ischemia-evoked efflux of [(3)H]D-aspartate or glutamate was increased by the A(1) receptor antagonist DPCPX. The A(2A) antagonist SCH 58261 decreased [(3)H]D-aspartate or endogenous glutamate efflux (50 and 55% maximal inhibitions; EC(50): 14.9 and 7.6 nM, respectively); the drug was effective also if added during ischemia. No effect of either the A(1) or the A(2A) receptor antagonist was found on the ischemia-evoked efflux of [(3)H]D-aspartate in Ca(2+)-free medium. Our data suggest that adenosine released during cerebral ischemia can activate inhibitory A(1) and stimulatory A(2A) receptors that down- or up-regulate the vesicular-like component of glutamate release.
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Affiliation(s)
- Manuela Marcoli
- Department of Experimental Medicine, Pharmacology and Toxicology Section, University of Genoa, Viale Cembrano 4, Genoa, Italy
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Nelson RM, Lambert DG, Richard Green A, Hainsworth AH. Pharmacology of ischemia-induced glutamate efflux from rat cerebral cortex in vitro. Brain Res 2003; 964:1-8. [PMID: 12573507 DOI: 10.1016/s0006-8993(02)03691-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Simulated ischemic conditions (hypoxia-hypoglycaemia) in vitro enhanced glutamate efflux from rat cerebrocortical prisms. Here we characterised efflux mechanisms using pharmacological tools. The Na(+) channel blocker TTX (1 microM) did not affect ischemia-induced efflux, while sipatrigine (100 microM), a Na(+)/Ca(2+) channel blocker and omega-conotoxin MVIIC (2 microM), an N/P/Q type Ca(2+) channel blocker, inhibited efflux by fractions of 0.53 and 0.46, respectively (1.00 corresponding to total inhibition). Omission of extracellular Ca(2+) and addition of EGTA (2 mM) inhibited ischemia-induced efflux only during the first 25 min of incubation. A similar result was observed on omission of extracellular Ca(2+) together with addition of La(3+) (10 microM) and Mg(2+) (6 mM). TTX, sipatrigine and La(3+)/Mg(2+) all inhibited control efflux. Ischemia-induced efflux was sensitive to the volume activated anion channel inhibitor NPPB (100 microM) only after the first 25 min of incubation, with the maximal fraction inhibited being 0.54. The glutamate transporter inhibitor D,L-TBOA reduced ischemia-induced efflux throughout a 45-min incubation period, and enhanced efflux from control tissue. D,L-TBOA inhibited efflux at 30 min by a maximum fraction of 0.49, at 50 microM. These data indicate that the early phase of ischemia-induced glutamate efflux is in part Ca(2+) dependent, while the later phase involves volume activated anion currents and both phases involve excitatory amino acid transporters.
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Affiliation(s)
- Rachael M Nelson
- Pharmacology Research Group, School of Pharmacy, De Montfort University, The Gateway, Leicester LE1 9BH, UK
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Matsumoto N, Kumamoto E, Furue H, Yoshimura M. GABA-mediated inhibition of glutamate release during ischemia in substantia gelatinosa of the adult rat. J Neurophysiol 2003; 89:257-64. [PMID: 12522177 DOI: 10.1152/jn.00384.2002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
An ischemia-induced change in glutamatergic transmission was investigated in substantia gelatinosa (SG) neurons of adult rat spinal cord slices by use of the whole cell patch-clamp technique; the ischemia was simulated by superfusing an oxygen- and glucose-free medium (ISM). Following ISM superfusion, 21 of 37 SG neurons tested produced an outward current (23 +/- 4 pA at a holding potential of -70 mV), which was followed by a slow and subsequent rapid inward current; the remaining neurons had only inward currents. During such a change in holding currents, spontaneous excitatory postsynaptic currents (EPSCs) were remarkably decreased in a frequency with time (half-decay time of the frequency: about 65 s). The frequency of spontaneous EPSCs was reduced to 28 +/- 13% (n = 37) of the control level during the generation of the slow inward current (about 4 min after the beginning of ISM superfusion) without a change in the amplitude of spontaneous EPSCs. When ISM was superfused together with either bicuculline (10 microM) or CGP35348 (20 microM; GABA(A) and GABA(B) receptor antagonists, respectively), spontaneous EPSC frequency reduced by ISM recovered to the control level and then the frequency markedly increased [by 325 +/- 120% (n = 22) and 326 +/- 91% (n = 17), respectively, 4 min after ISM superfusion]; this alteration in the frequency was not accompanied by a change in spontaneous EPSC amplitude. Superfusing TTX (1 microM)-containing ISM resulted in a similar recovery of spontaneous EPSC frequency and following increase (by 328 +/- 26%, n = 12) in the frequency; strychnine (1 microM) did not affect ISM-induced changes in spontaneous EPSC frequency (n = 5). It is concluded that the ischemic simulation inhibits excitatory transmission to SG neurons, whose action is in part mediated by the activation of presynaptic GABA(A) and GABA(B) receptors, probably due to GABA released from interneurons as a result of an ischemia-induced increase in neuronal activities. This action might protect SG neurons from an excessive excitation mediated by L-glutamate during ischemia.
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Nelson RM, Green AR, Hainsworth AH. Electrophysiological actions of gamma-aminobutyric acid and clomethiazole on recombinant GABA(A) receptors. Eur J Pharmacol 2002; 452:255-62. [PMID: 12359265 DOI: 10.1016/s0014-2999(02)02233-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Clomethiazole is a gamma-aminobutyric acid (GABA)-mimetic agent with anticonvulsant, sedative and neuroprotective properties. The pharmacological actions of clomethiazole that underlie its functional profile have not been fully explored, but are known to result from an interaction with the GABA(A) receptor. Here, we present a quantitative electrophysiological study of clomethiazole action at human recombinant GABA(A) receptors. Whole-cell currents were recorded from murine L(tk-) cells stably transfected with either alpha1, beta1 and gamma 2 or alpha1, beta2 and gamma 2 GABA(A) receptor subunits. Clomethiazole directly activated GABA(A) currents in alpha1/beta1/gamma 2- and alpha1/beta2/gamma 2-containing cells, with EC(50) values of 0.3 and 1.5 mM, respectively. A low concentration of clomethiazole (30 micro M) also potentiated the action of GABA in both cell types, equivalent to a 3-fold increase in potency and up to 1.8-fold increase in maximal current. Both direct activation and gamma-aminobutyric acid potentiation are likely to contribute to the in vivo profile of clomethiazole.
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Affiliation(s)
- Rachael M Nelson
- Pharmacology Research Group, School of Pharmacy, De Montfort University, LE1 9BH, Leicester, UK
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28
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Green AR, Hainsworth AH, Misra A, Debens TA, Jackson DM, Murray TK, Nelson RM, Cross AJ. The interaction of AR-A008055 and its enantiomers with the GABA(A) receptor complex and their sedative, muscle relaxant and anticonvulsant activity. Neuropharmacology 2001; 41:167-74. [PMID: 11489453 DOI: 10.1016/s0028-3908(01)00053-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AR-A008055 [(+/-)-1-(4-methyl-5-thiazolyl)-1-phenylmethylamine] is structurally related to clomethiazole and has been used to probe the mechanism of the neuroprotective effect of clomethiazole. Clomethiazole, (+/-)-AR-A008055 and (S)-(-)-AR-A008055 all displaced [35S]-t-butyl-bicyclophosphorothionate ([35S]TBPS) from rat cerebral cortex tissue (IC50 values: GABA, 8.1+/-0.04 microM; clomethiazole, 130+/-30 microM; (+/-)-AR-A008055, 494+/-7 microM; (S)-(-)-AR-A008055, 221+/-14 microM. (R)-(+)-AR-A008055 was without significant effect (IC50>1000 microM). None of the compounds interacted with NMDA or AMPA receptors or with sodium or calcium (N, P/Q) channels. Brain penetration of both enantiomers following their i.p. administration was excellent, with brain and plasma concentrations being similar. Clomethiazole dose-dependently inhibited spontaneous locomotor activity in rats and was approximately 10 times more sedative than either enantiomer of AR-A008055. Clomethiazole was more potent than (S)-(-)-AR-A008055 in the "pull-up" test (muscle relaxation) and in producing loss of righting reflex, while (R)-(+)-AR-A008055 had little effect. The time animals remained on a Rota-rod was of the order: clomethiazole<(S)-(-)-AR-A008055<(R)-(+)-AR-A008055. (S)-(-)-AR-A008055 (210 micromol/kg) raised seizure threshold to pentylenetetrazole (i.v.) by 119+/-21%. The (R)-(+)- enantiomer was not anticonvulsant. Overall, (S)-(-)-AR-A008055 exhibited a similar pharmacology to clomethiazole. However, its sedative and muscle relaxant effects were substantially less than clomethiazole, emphasising that these properties are not directly related to neuroprotective efficacy. The current data suggest that the proposed GABA uptake inhibitory property of (R)-(+)-AR-A008055 fails to produce significant sedative, myorelaxant or anticonvulsant activity.
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Affiliation(s)
- A R Green
- AstraZeneca R&D Charnwood, Loughborough LE11 5RH, UK.
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Nelson RM, Hainsworth AH, Lambert DG, Jones JA, Murray TK, Richards DA, Gabrielsson J, Cross AJ, Green AR. Neuroprotective efficacy of AR-A008055, a clomethiazole analogue, in a global model of acute ischaemic stroke and its effect on ischaemia-induced glutamate and GABA efflux in vitro. Neuropharmacology 2001; 41:159-66. [PMID: 11489452 DOI: 10.1016/s0028-3908(01)00052-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have investigated the neuroprotective properties of AR-A008055 [(+/-)-1-(4-methyl-5-thiazolyl-1-phenyl-methylamine], a novel compound structurally related to clomethiazole. Administration (i.p.) of (+/-)-AR-A008055 60 min after 5 min of global cerebral ischaemia in gerbils produced a dose-dependent protection of the hippocampus from damage. Both enantiomers [(R)-(+)-AR-A008055 and (S)-(-)- AR-A008055] at 600 micromol/kg produced similar protection to that following clomethiazole (600& micromol/kg) and both produced similar and sustained neuroprotection, at 4, 7 and 21 days post-insult. When infused intravenously over a 2-h period, both enantiomers produced concentration-dependent neuroprotection, with the enantiomers providing similar protection at every plasma concentration (50-200 nmol/ml). The efficacy of (S)-(-)-AR-A008055 was similar to clomethiazole, but it was slightly less potent. Ischaemia-induced glutamate efflux from rat brain cortical prisms in vitro was inhibited by both isomers (100 microM). The inhibitory effect of (R)-(+)-AR-A008055 was blocked by bicuculline (10 microM) and picrotoxin (100 microM), while the effect of (S)-(-)-AR-A008055 was only antagonised by picrotoxin. This indicated that (S)-(-)-AR-A008055, like clomethiazole, is able to open the GABA(A)-chloride channel in the absence of endogenous GABA. (R)-(+)-AR-A008055 was more potent than (S)-(-)-AR-A008055 in enhancing the concentration of GABA in the medium following 30 min exposure of tissue to the ischaemic conditions, suggesting that it is an effective GABA uptake inhibitor. This action may explain both its effect on glutamate efflux in vitro and its neuroprotective effect in vivo.
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Affiliation(s)
- R M Nelson
- Department of Pharmacology, School of Pharmacy, De Montfort University, The Gateway, Leicester LE1 9BH, UK
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30
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Paslawski T, Knaus E, Iqbal N, Coutts R, Baker G. ?-phenylethylidenehydrazine, a novel inhibitor of GABA transaminase. Drug Dev Res 2001. [DOI: 10.1002/ddr.1202] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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