Peroxisome proliferator-activated receptor gamma (
PPARgamma) plays a role in regulating a myriad of biological processes in virtually all brain cell types, including neurons. We and others have reported recently that drugs which activate
PPARgamma are effective in reducing damage to brain in distinct models of
brain disease, including
ischemia. However, the cell type responsible for
PPARgamma-mediated protection has not been established. In response to
ischemia,
PPARgamma gene is robustly upregulated in neurons, suggesting that neuronal
PPARgamma may be a primary target for
PPARgamma-agonist-mediated neuroprotection. To understand the contribution of neuronal
PPARgamma to ischemic injury, we generated conditional neuron-specific
PPARgamma knock-out mice (N-
PPARgamma-KO). These mice are viable and appeared to be normal with respect to their gross behavior and brain anatomy. However, neuronal
PPARgamma deficiency caused these mice to experience significantly more brain damage and oxidative stress in response to
middle cerebral artery occlusion. The primary cortical neurons harvested from N-
PPARgamma-KO mice, but not astroglia, exposed to
ischemia in vitro demonstrated more damage and a reduced expression of numerous key gene products that could explain increased vulnerability, including SOD1 (
superoxide dismutase 1),
catalase,
glutathione S-transferase, uncoupling protein-1, or
transcription factor liver X receptor-alpha. Also,
PPARgamma agonist-based
neuroprotective effect was lost in neurons from N-
PPARgamma neurons. Therefore, we conclude that
PPARgamma in neurons play an essential protective function and that
PPARgamma agonists may have utility in neuronal self-defense, in addition to their well established anti-inflammatory effect.