Age dependence of excitatory-inhibitory balance following stroke

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• 作者：Silvio Schmidt^a ; ^{silvio.schmidt@med.uni-jena.de} ; Claus Bruehl^a ; ^b ; Christiane Frahm^a ; Christoph Redecker^a ; Otto W. Witte^a
• 关键词：Brain excitability ; Aging ; Photothrombosis ; GABAA receptor ; Stroke
• 刊名：Neurobiology of Aging
• 出版年：2012
• 出版时间：July, 2012
• 年：2012
• 卷：33
• 期：7
• 页码：1356-1363
• 全文大小：1257 K

文摘

The mechanisms which mediate cortical map plasticity and functional recovery following stroke remain a matter of debate. Readjustment of the excitatory-inhibitory balance may support cortical map plasticity in perilesional areas. Here we studied cortical net inhibition in the vicinity of photothrombotically-induced cortical lesions in young adult (3 months) and aged (24 months) male rats. Field potentials were recorded in cortical layer II/III following application of paired-pulse stimulation at layer VI/white matter in coronal brain slices. Additionally, we analyzed the regional distribution of 5 major gamma-aminobutyric acid A (GABA_A) receptor subunits (¦Á1, ¦Á2, ¦Á3, ¦Á5, and ¦Ã2) by immunohistochemistry. Paired-pulse inhibition in the perilesional parietal cortex was decreased in young rats but was increased in aged rats. As a consequence of the diminished intrinsic net inhibition in aged control animals, the excitatory-inhibitory balance was readjusted to an age-independent similar level in young and aged lesioned rats in a homeostatic-like fashion. These physiological changes in neuronal activity were accompanied by age-specific laminar alterations of the gamma-aminobutyric acid A (GABA_A) receptor subunit composition, most prominently of the subunit ¦Á5. The present study suggests that the mechanisms underlying functional reorganization in aged animals may be distinctly different from those in young animals.