GABA neurons survive focal ischemic injury.
Focal cerebral lesions in rat brain induced by photothrombosis lead to an impaired inhibitory neurotransmission. A reduced gamma-aminobutyric acid (GABA)-mediated inhibition has been revealed by electrophysiological recordings associated with a diminished immunostaining of GABA handling proteins. Changes were found in ipsi- as well as in contralateral brain areas. Inhibition is mediated by interneurons using GABA as neurotransmitter. These cells use GAD (glutamate decarboxylase) to synthesize GABA. To analyze the vulnerability of GABAergic neurons in rats with a lesioned hindlimb area, cells expressing GAD65/67 mRNA were labeled using in situ hybridization. Positive somata were counted 7 and 30 days after focal ischemia in different cortical (hindlimb cortex, frontal cortex, primary and secondary somatosensory cortex) and hippocampal subsectors (pyramidal cell layer, stratum oriens and stratum radiatum/lacunosum-moleculare). The lesioned hemispheres were compared with the intact brain sides and with control brains. GABAergic interneurons survived the injury for up to 30 days in all investigated brain regions. Therefore it is unlikely that a loss of GABAergic neurons contributes to the reduced inhibition.
Frahm
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Department of Neurology, Friedrich-Schiller-University, Erlanger Allee 101, 07745 Jena, Germany. christiane.frahm@med.uni-jena.de
Haupt
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Witte
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D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D002470:Cell Survival / Q000502:physiology; D002540:Cerebral Cortex / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D005968:Glutamate Decarboxylase / Q000235:genetics; D006624:Hippocampus / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D007150:Immunohistochemistry; D007395:Interneurons / Q000166:cytology / Q000378:metabolism*; D020767:Intracranial Thrombosis / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D007527:Isoenzymes / Q000235:genetics; D009433:Neural Inhibition / Q000502:physiology*; D009434:Neural Pathways / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D007527:Isoenzymes; D012333:RNA, Messenger; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase; C401141:glutamate decarboxylase 2