The present results demonstrated that cultured mouse astrocytes exposed to 1.0% DMSO for 24 h exhibit impairments of the mitochondrial integrity and DYm, although their general growth profile is not altered compared to those in control medium. This result suggests that mitochondrial membrane is vulnerable to DMSO, which might be due to its relatively high membrane fluidity. Mitochondria are the center of cell metabolism and energy transformation; and their malfunction decreases cell viability. In agreement with this notion, we demonstrated that DMSO inhibits astrocyte viability in a dose-dependent manner, accompanied with mitochondrial structural and functional disruption. Astrocytes exposed to DMSO at concentrations of 1.0% also increases Cyt c release and activated caspase 3 expression, and decreases anti-apoptotic protein Bcl-2 expression, supporting the review that rupture of mitochondria is an initial trigger of apoptotic cascades. Furthermore, the present results indicated that DMSO dose-dependently increases mitochondriaderived ROS production, which is consistent with the notion that degenerated mitochondria are the primary site of ROS production. Taken together, these results reveal that mitochondrial impairment is a primary event in the astrocyte toxicity of DMSO. Glutamate, the major excitatory amino acid neurotransmitter in the brain, can become potentially toxic when it over-accumulates in the synaptic space. As mentioned earlier, astrocytes are responsible for maintaining brain glutamate homeostasis via glutamate transporters. Oxidative Mitomycin C stress inhibits glutamate transporter expression and function, which has been implicated as a main pathogenesis for glutamate excitotoxicity in a variety of pathological conditions, including brain ischemia, traumatic brain injury, epilepsy and neurodegeneration. The present results have demonstrated that DMSO causes down-regulation of GLT1 and GLAST in cultured astrocytes. In addition to increased ROS production, decreased cell viability and mitochondrial dysfunction may impair glutamate transporter synthesis by astrocytes. High concentration of DMSO has been shown to degrade membrane structure and disturb Rolipram secondary protein structures within membrane proteins.