Chronic expression of PPAR-delta by oligodendrocyte lineage cells in the injured rat spinal cord.
The transcription factor peroxisome proliferator-activated receptor (PPAR)-delta promotes oligodendrocyte differentiation and myelin formation in vitro and is prevalent throughout the brain and spinal cord. Its expression after injury, however, has not been examined. Thus, we used a spinal contusion model to examine the spatiotemporal expression of PPAR-delta in naïve and injured spinal cords from adult rats. As previously reported, PPAR-delta was expressed by neurons and oligodendrocytes in uninjured spinal cords; PPAR-delta was also detected in NG2 cells (potential oligodendrocyte progenitors) within the white matter and gray matter. After spinal cord injury (SCI), PPAR-delta mRNA and protein were present early and increased over time. Overall PPAR-delta+ cell numbers declined at 1 day post injury (dpi), likely reflecting neuron loss, and then rose through 14 dpi. A large proportion of NG2 cells expressed PPAR-delta after SCI, especially along lesion borders. PPAR-delta+ NG2 cell numbers were significantly higher than naive by 7 dpi and remained elevated through at least 28 dpi. PPAR-delta+ oligodendrocyte numbers declined at 1 dpi and then increased over time such that >20% of oligodendrocytes expressed PPAR-delta after SCI compared with approximately 10% in uninjured tissue. The most prominent increase in PPAR-delta+ oligodendrocytes was along lesion borders where at least a portion of newly generated oligodendrocytes (bromodeoxyuridine+) were PPAR-delta+. Consistent with its role in cellular differentiation, the early rise in PPAR-delta+ NG2 cells followed by an increase in new PPAR-delta+ oligodendrocytes suggests that this transcription factor may be involved in the robust oligodendrogenesis detected previously along SCI lesion borders.
Almad
Akshata
A
The Neuroscience Graduate Studies Program, The Ohio State University, Columbus, Ohio 43210, USA.
McTigue
Dana M
DM
D000818:Animals; D002452:Cell Count; D019070:Cell Lineage; D005260:Female; D009413:Nerve Fibers, Myelinated / Q000378:metabolism; D036421:Nerve Fibers, Unmyelinated / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D009836:Oligodendroglia / Q000378:metabolism*; D047494:PPAR delta / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000378:metabolism*; D013119:Spinal Cord Injuries / Q000378:metabolism*; D013234:Stem Cells / Q000378:metabolism*; D013997:Time Factors
D047494:PPAR delta; D012333:RNA, Messenger