Activation of cerebral peroxisome proliferator-activated receptors gamma promotes neuroprotection by attenuation of neuronal cyclooxygenase-2 overexpression after focal cerebral ischemia in rats Yi Zhao, Andreas Patzer, Thomas Herdegen, Peter Gohlke and Juraj Culman 1 Institute of Pharmacology, University Hospital of Schleswig-Holstein, Campus Kiel, Kiel, Germany 1 Correspondence: Institute of Pharmacology, University Hospital of Schleswig-Holstein, Campus Kiel Hospitalstrasse 4 24105 Kiel, Germany. E-mail: juraj.culman@pharmakologie.uni-kiel.de Up-regulation of cyclooxygenase (COX)-2 exacerbates neuronal injury after cerebral ischemia and contributes to neuronal cell death. The present study clarifies the function of cerebral peroxisome-proliferator-activated receptor(s) gamma (PPARγ) in the expression of COX-2 in neurons of the rat brain after middle cerebral artery occlusion (MCAO) with reperfusion by immunohistochemistry, Western blot, and immunofluorescence staining. In peri-infarct cortical areas the PPARγ was located in both microglia and neurons, whereas COX-2 was almost exclusively expressed in neurons. PPARγ immunolabeling reached the peak 12 h after MCAO, whereas the number of COX-2 immunostained cells gradually rose and reached its peak at 48 h. Intracerebroventricular infusion of pioglitazone, an agonist of the PPARγ, over a 5-day period before and 2 days after MCAO, reduced the infarct size, the expression of tumor necrosis factor α (TNF-α), COX-2, and the number of cells positively stained for COX-1 and COX-2 in the peri-infarct cortical regions. COX-2 induction was also attenuated in the ipsilateral but not in the contralateral hippocampus. In primary cortical neurons expressing the PPARγ, pioglitazone suppressed COX-2 expression in response to oxidative stress. This protective effect was reversed after cotreatment with GW 9662, a selective antagonist of the PPARγ, clearly demonstrating a PPARγ-dependent mechanism. Our data provide evidence that activation of neuronal PPARγ considerably contributes to neuroprotection by prevention of COX-2 up-regulation in vitro and in peri-infarct brain areas.—Zhao, Y., Patzer, A., Herdegen, T., Gohlke, P., Culma, J. Activation of cerebral peroxisome proliferator-activated receptors gamma (PPARγ) promotes neuroprotection by attenuation of neuronal cyclooxygenase-2 overexpression after focal cerebral ischemia in rats. Key Words: cerebral ischemia • PPARγ • pioglitazone • cyclooxygenase-2 • cyclooxygenase-1 • rat
/lp/fed-of-american-socs-for-experimental-biology/activation-of-cerebral-peroxisome-proliferator-activated-receptors-dIncu2MmF7