Protective effects of peroxisome proliferator-activated receptors gamma coactivator-1alpha against neuronal cell death in the hippocampal CA1 subfield after transient global ischemia.

Peroxisome proliferator-activated receptors gamma coactivator-1alpha (PGC-1alpha) may regulate the mitochondrial antioxidant defense system under many neuropathological settings. However, the exact role of PGC-1alpha in ischemic brain damage is still under debate. Based on an experimental model of transient global ischemia (TGI), this study evaluated the hypothesis that the activation of PGC-1alpha signaling pathway protects hippocampal CA1 neurons against delayed neuronal death after TGI. In Sprague-Dawley rats, significantly increased content of oxidized proteins in the hippocampal CA1 tissue was observed as early as 30 min after TGI, followed by augmentation of PGC-1alpha expression at 1 hr. Expression of uncoupling protein 2 (UCP2) and superoxide dismutases 2 (SOD2) in the hippocampal CA1 neurons was upregulated 4-48 hr after TGI. In addition, knock-down of PGC-1alpha expression by pretreatment with a specific antisense oligodeoxynucleotide in the hippocampal CA1 subfield downregulated the expression of UCP2 and SOD2 with resultant exacerbation of oxidative stress and augmentation of delayed neuronal cell death in the hippocampus after TGI. Overall, our results indicate that PGC-1alpha is induced by cerebral ischemia leading to upregulation of UCP2 and SOD2, thereby providing a neuroprotective effect against ischemic brain injury in the hippocampus by ameliorating oxidative stress.