Activation of Rho after spinal cord injury and the collapse of growth cone

Abstract

Objective To investigate the mechanism of ROCK causing collapse of the growth cone after SCI through observing the activation of RhoA after SCI and the reorganization of F-actin of neuron during mimic isehcmia injury in vitro. Method The model of SCI was made by Allen's method. The activation expressive variety of RhoA was detected through Western Blot and Pull down assay;In vitro, N2a cells induced by ischemia and ischemia-reperfuaion were treated with different dilute Y-27632, cell damage was analyzed by MTT;On the other hand, the cytoskeleton of N2a cells were scanod through immunofluorescence techniques by confocal laser microscopy which stained with Fitc-phalloidin for F-actin visualization. Results The activation of RhoA proteins was increased significantly in the damaged local during the following phase of SCI. Ischemia induced a striking reorganization of actin cytoskeleton with a weakening of fluorescent intensity of the peripheral filament actin bands and formation of the long and thick stress fibers, but pretreatment of Y-27632 could reversed the changes of ultra-structure on the cellular surface, and the protection of Y-27632 was related with its concentration in determinate bound. MTT assay showed that Y-27632 could prolong the survival time of N2a cells after mimic ischemia-reperfusion for 24 h. Conclusions The activation of Rho had exceptional hoist after SCI, it is likely to induce the collapse of the growth cone through ROCK. Suppression of Rho kinase activity could promote axonal growth on inhibitory spinal cord. Key words: Rho/ROCK; Spinal cord injuries; Cytoskeletnn; Collapse