Sciatic nerve crush evokes a biphasic TGF-beta and decorin modulation in the rat spinal cord

Inherent property of the motoneurons of the peripheral nervous system is their ability to recover, at least in part, upon injury. To this end different factors are expressed and are thought to play important role in the regeneration processes. These factors are diverse, and range from transcription factors and chemokines, to molecules of the extracellular matrix. Transforming growth factor beta (TGF-beta) is a protein with diverse actions controlling cell growth and proliferation. In the extracellular matrix it is found bound to decorin a proteoglycan involved in cell adhesion and cell signaling. In the present study we investigate the expression of TGF-beta and decorin at different time points, in the regenerating sciatic nerve of a seven day old rat, having suffered nerve crush injury, over a period of one month.

To achieve this, we evoked injury to male Wistar rats by exposing and applying pressure to the sciatic nerve using watchmaker's forceps. After that at 12 h, 24 h, 48 h, 72 h, one week, and one month intervals we investigated the gene expression of decorin using RT-PCR, and followed the expression of TGF-beta molecule by immunohistochemistry in frozen sections of the L4-L5 region of the rat spinal cord.

We report that both decorin mRNA and TGF- protein exhibit a concerted, biphasic expression after 12 hours and one month having the animal suffered the nerve crush.

Our data reveal a biphasic modulation of TGF-beta protein and decorin mRNA expression at lumbar segment of the spinal cord of animals having suffered unilateral sciatic nerve crush. We postulate that their concerted expression both at an early and a late phase after the nerve injury is of importance and can be part of a repair or neuroprotective mechanism as yet unclarified.