Alterations in protein expression patterns of spinal peroxisome proliferator-activated receptors after spinal cord injury

Abstract

Objectives: Peroxisome proliferator-activated receptors (PPARs) control wound healing processes in damaged tissues. PPAR agonists have neuroprotective effects in spinal cord injury (SCI); however, isotype-specific roles of PPARs are not well understood. Therefore, we evaluated protein expression changes for three isotypes of PPARs at different time points and locations relative to the epicenter after SCI in rats. Methods: A 10-g rod was dropped on the spinal cord which located at the T10 vertebra of rats from a height of 6.25, 12.5, or 50 mm using New York University impactor. We collected the spinal cord at 6, 12, 24, and 72 h and 1, 3, and 5 weeks after SCI. The protein expression of PPARs was analyzed using western blot. Results: The protein expression of PPAR-alpha declined gradually up to 5 weeks at the epicenter. PPAR-beta/delta expression increased from 3 days to 5 weeks at the caudal region, but decreased at the epicenter in the severe injury group. PPAR-gamma expression increased significantly at all regions in all three injury groups up to 5 weeks after SCI and increased to a greater extent in the severe injury group. In addition, PPAR-beta/delta controlled protein expression of PPAR-alpha positively, and -gamma negatively. Conclusions: The present results suggest that different PPAR isotypes have varied protein expression patterns at the epicenter and in adjacent regions after SCI. Our results suggest that PPARs may have overlapping but distinct roles. These findings will be useful for further studies investigating PPARs in neurological disorders including SCI.