Up-regulation of Robo1 in dorsal root ganglia after sciatic nerve transection in rats

Abstract

Roundabout (Robo) receptors have many important roles including mediating the migration of the growth cone and neurons, promoting axonal growth and development of nerve fascicles, and guiding the growth direction of central nervous system by binding Slit. To better understand the role of Robo in peripheral nervous system, this study investigated the expression profile of Robo1 in the dorsal root ganglia (DRG) of adult rats following sciatic nerve transection (SNT). Adult Sprague-Dawley rats that were untreated (n = 8), or received SNT (n = 40), were analyzed. DRG from each treatment group at days three, seven, 14, 21, and 28 post-SNT were collected and assayed by real-time PCR and immunohistochemistry. Expression of Robo1 and 2 was performed, with staining also evaluated in relation to neuron diameters. We found that both mRNA and protein levels of Robo1 were detected in normal DRG, and these levels increased following SNT. Increases were initially detected at day three post-SNT, then peaked between day seven and 14, then gradually returned to basal levels by day 21 post-SNT. Neither normal, nor SNT DRG exhibited co-localization of Robo1 and 2, and this observation was independent of neuron diameter. These results suggest that Robo1 in DRG is upregulated following sciatic nerve transection in rats.