Activation of PPARγ by 12/15-lipoxygenase during cerebral ischemia-reperfusion injury

Peroxisome proliferator-activated receptor (PPAR) expression and activity are increased in brain ischemic injury and its agonists have shown potential for brain injury protection. The influence of 12/15-lipoxygenase (12/15-LOX) on the activity of PPAR in oxygen-glucose deprivation (OGD) and ischemia-reperfusion (I/R) was investigated. A middle cerebral artery occlusion/reperfusion model with Sprague Dawley (SD) rats was established. For I/R intervention, the rats were treated with the 12/15-LOX-derived product 12-hydroxyeicosatetraenoic acid (12-HETE) for 30 min before cerebral artery occlusion. Primary cortical neurons from SD rats were used to establish an OGD cell model. 12-HETE or a 12/15-LOX antisense oligonucleotide (asON-12/15-LOX) was added to OGD-treated neurons. Western blots, immunofluorescence and enzyme-linked immunosorbent assays detected protein. Reverse transcription-polymerase chain reaction analyzed the expression of the PPAR target genes. PPAR-DNA binding activity was determined by peroxisome proliferator responsive element luciferase reporter vectors. 12/15-LOX total protein increased significantly with I/R, and expression of 12-HETE was also upregulated. 12-HETE treatment increased PPAR protein expression and inhibited inducible nitric oxide synthase protein expression, which was upregulated with I/R. PPAR nuclear protein and 12/15-LOX total protein expression in OGD-treated neurons increased significantly. 12-HETE treatment increased the expression of PPAR nuclear protein, upregulated the mRNA levels of PPAR target genes (lipoprotein lipase and acyl-CoA oxidase) and enhanced PPAR-DNA binding activity. asON-12/15-LOX treatment inhibited 12/15-LOX and PPAR protein expression and lipoprotein lipase mRNA. Cerebral I/R injury in rats and OGD treatment in neurons promoted 12/15-LOX expression, and 12-HETE activated PPAR. Therefore, PPAR can be activated by the 12/15-LOX pathway during cerebral I/R injury.