Localization of the peroxisome proliferator-activated receptor in the brain

This paper describes the localization of the α-type peroxisome proliferator-activated receptor (PPARα) in the rat brain using immunocytochemistry and in situ hybridization. Expression of PPARα mRNA was highest in the granular cells of the cerebellar cortex and in the dentate gyrus, with a somewhat lower expresssion in areas CA1-CA4 of the hippocampus. PPARα mRNA was also found in some neurones of the cerebral cortex (layers II-IV) and the molecular layer of the cerebellar cortex, and in the olfactory tubercle. Immunocytochemistry revealed nuclear PPARα-immunoreactivity (-IR) in the same areas as seen with the in situ hybridization. Furthermore, PPARα-IR was also localized in oligodendrocytes, whereas the other glial cell types appeared to lack PPARα. These results suggest that peroxisome proliferators and chemicals acting similarly have effects on discrete populations of neurones. The presence of PPARα in oligodendrocytes lends further support to the suggestion that peroxisomes are important in the assembly and degradation of myelin.