Critical Role of the Astrocyte for Functional Remodeling in Contralateral Hemisphere of Somatosensory Cortex after Stroke

• DOI: 10.1523/jneurosci.2657-12.2013
• Publication Date: 2013-03-13T16:54:54Z
• Authors: Yusuke Takatsuru; Kei Eto; Ryosuke Kaneko; Hiroko Masuda; Noriaki Shimokawa; Noriyuki Koibuchi; Junichi Nabekura
• Keywords: Male; Neurons; Analysis of Variance; Aspartic Acid; Microdialysis; Glycine; Glutamic Acid; Motor Activity; Functional Laterality; Excitatory Amino Acid Transporter 1; Mice, Inbred C57BL; Disease Models, Animal; Mice; 03 medical and health sciences; 0302 clinical medicine; Excitatory Amino Acid Transporter 2; Gene Expression Regulation; Astrocytes; Physical Stimulation; Aminomethyltransferase; Animals; Calcium

After ischemic stroke, the corresponding area contralateral to the lesion may partly compensate for the loss of function. We previously reported the remodeling of neuronal circuits in the contralateral somatosensory cortex (SSC) during the first week after infarction for processing bilateral information, resulting in functional compensation. However, the underlying processes in the contralateral hemisphere after stroke have not yet been fully elucidated. Recent studies have shown that astrocytes may play critical roles in synaptic reorganization and functional compensation after a stroke. Thus, we aim to clarify the contribution of astrocytes using a rodent stroke model.In vivocalcium imaging showed a significantly large number of astrocytes in the contralateral SSC responding to ipsilateral limb stimulation at the first week after infarction. Simultaneously, extracellular glutamine level increased, indicating the involvement of astrocytes in the conversion of glutamate to glutamine, which may be an important process for functional recovery. This hypothesis was supported further by the observation that application of (2S,3S)-3-{3-[4-(trifluoromethyl)benzoylamino]benzyloxy} aspartate, a glial glutamate transporter blocker, disturbed the functional recovery. These findings indicate the involvement of astrocytes in functional remodeling/recovery in the area contralateral to the lesion. Our study has provided new insights into the mechanisms underlying synaptic remodeling after cerebral infarction, which contributes to the development of effective therapeutic approaches for patients after a stroke.