Spinal Cord Injury Induced Changes Of Nuclear Receptors Ppar Alpha And Lxr Beta And Modulation With Oleic Acid/Albumin Treatment

In previous studies with animal models of spinal cord injury (SCI) pharmacological activation of peroxisome proliferator activated receptors (PPAR) and liver X receptors (LXR) were used to reduce tissue damage and promote behavioral recovery in animal models. We have studied the endogenous expression of the transcription factors PPAR alpha and LXR beta in the chronic stage after SCI in rats. The immunohistochemical investigation revealed a long lasting increase in the level of PPAR alpha in white matter in the vicinity of the lesion site. The source of this signal was identified in a subpopulation of astrocytes outside of the glial scar area. Intrathecal injections of oleic acid/albumin reduced the lesion-induced PPAR alpha immunoreactivity. In addition, ependymal cells displayed a prominent PPAR alpha signal in the non-injured spinal cord, and continued to express the receptor as they proliferated and migrated within the damaged tissue. The nuclear receptor LXR beta was detected at similar levels after SCI as in sham operated animals. We found high levels of immunoreactivity in the gray matter, while in the white matter it was present in subpopulations of astrocytes and oligodendrocytes. Macrophages that had accumulated within the center of the lesion contained LXR beta in their cell nuclei. Possible endogenous functions of PPAR alpha and LXR beta after SCI are discussed, specifically the control of fatty acid and cholesterol metabolism and the regulation of inflammatory reactions. (C) 2013 Elsevier B.V. All rights reserved.