Sadahiro Iwabuchi

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Glutamate (Glu) is a major excitatory neurotransmitter of the mammalian central nervous system and under normal conditions plays an important role in information processing in the brain. Therefore, extracellular Glu is subject to strong homeostasis. Astrocytes in the brain have been considered to be mainly responsible for the clearance of extracellular Glu.(More)
Glucose is a necessary source of energy to sustain cell activities and homeostasis in the brain, and enhanced glucose transporter (GLUT) activities are protective of cells during energy depletion including brain ischemia. Here we investigated whether and if so how the astrocytic expression of GLUTs crucial for the uptake of glucose changes in ischemic(More)
The opening of pannexin-1 (Px1) hemichannels is regulated by the activity of P2X(7) receptors (P2X(7)Rs). At present, however, little is known about how extracellular ATP-sensitive P2X(7)Rs regulates the opening and closure of Px1 hemichannels. Several lines of evidence suggest that P2X(7)Rs are activated under pathological conditions such as ischemia,(More)
Astrocytes become hypertrophic reactive in response to the ischemic stress, and they contribute to either protect or exacerbate neuronal damage, depending on the depth or duration of the stress. Astrocytes have more resistance to the ischemic stress than neurons, which is apparently due to active anerobic metabolic pathway in the emergency situation. We(More)
TorsinA is an evolutionarily conserved AAA+ ATPase, and human patients with an in-frame deletion of a single glutamate (ΔE) codon from the encoding gene suffer from autosomal-dominant, early-onset generalized DYT1 dystonia. Although only 30-40% of carriers of the mutation show overt motor symptoms, most experience enhanced excitability of the central(More)
Application of a brief period of ischemia, i.e. preconditioning treatment of the middle cerebral artery territory, has been known to produce ischemic tolerance, reducing cerebral infarction volume in the penumbra region after lethal ischemia. However, little is known about the molecular mechanisms responsible for preconditioning-induced ischemic tolerance.(More)
Extracellular adenosine 5'-triphosphate (ATP) activates specific G protein-coupled purinoceptors (P2Y), and ATP-P2Y signaling pathways induces intracellular Ca(2+) mobilization resulting in changes in the gene expression of a variety of proteins in astrocytes. This study investigated whether the exposure of cultured astrocytes to sublethal ischemia produced(More)
Waves of elevated intracellular free calcium that propagate between neighboring astrocytes are important for the intercellular communication between astrocytes as well as between neurons and astrocytes. However, the mechanisms responsible for the initiation and propagation of astrocytic calcium waves remain unclear. In this study, intercellular calcium(More)
Increased activities of cytoplasmic calcium and the excitatory neurotransmitter glutamate have been independently implicated in dystonia pathophysiology. However, cellular-level evidence linking these two features is not available. Here we show that glutamate-dependent changes in neuronal calcium dynamics occur in a knock-in mouse model of DYT1 dystonia,(More)