Received for publication October 17, 2006.
Revised December 12, 2006.
Accepted for publication December 12, 2006.

Neuroprotective Efficacy of Peroxisome Proliferator-Activated Receptor delta (PPAR-) Selective Agonists, L-165041 and GW501516, in Vitro and in Vivo

Abstract

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear receptor superfamily, and function as ligand-modulated transcription factors that regulate gene-expression in many important biological processes. The PPAR subtype has the highest expression in the brain and is postulated to play a major role in neuronal cell function, however, the precise physiological roles of this receptor remain to be elucidated. Herein we show that the high-affinity PPAR agonists L-165041 and GW501516 protect against cytotoxin-induced SH-SY5Y cell injury in vitro, and both ischemic brain injury and MPTP neurotoxicity in vivo. In the SH-SY5Y studies, treatment with L-165041 or GW501516 significantly and concentration-dependently attenuated cell death following thapsigargin, MPP⁺ or staurosporine exposure, with the extent of damage correlated with the level of caspase-3 inhibition. In the transient (90 min) middle cerebral artery occlusion model of ischemic brain injury in rats, intracerebroventricular infusion of L-165041 or GW501516 significantly attenuated the ischemic brain damage measured 24 h after reperfusion. Moreover, the PPAR agonists also significantly attenuated MPTP-induced depletion of striatal dopamine and related metabolite contents in mouse brain. These results demonstrate that subtype-selective PPAR agonists possess anti-apoptotic properties in vitro, which may underlie their potential neuroprotective potential in in vivo experimental models of cerebral ischemia and Parkinson's disease (PD). These findings suggest that PPAR agonists could be useful tools for understanding the role of PPAR in other neurodegenerative disorders, as well as attractive therapeutic candidates for stroke and neurodegenerative diseases such as PD.

Key words: GW501516, L-165041, MCAo, MPTP, PPAR, thapsigargin

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