Background Intravitreal injection of α-crystallin can promote axons from optic nerve regeneration after crushing in rats. we have previously demonstrated that α-crystallin can counteract the effect of myelin inhibitory factors and stimulate neurite growth. And a common crucial signaling event for myelin inhibitory factors is the activation of RhoA.
Objectives  To investigate whether α-crystallin counteract the inhibitory effect of myelin inhibitory factors through regulation of RhoA/Rock signaling pathway. 
Methodsbα-Crystallin(10^-4g/L) was injected into rat vitreous at the time of optic nerve crushed. The RhoA protein activity and the expression of RhoA and Rock were evaluated after 3 days of optic nerve axotomy. Rock downstream effectors, phosphorylated cofilin and phosphorylated myosin light chain were detected when retinal neurons were culture for 3 days. Axonal regeneration and neurites growth of cultured cells were observed also. 
Results Our results showed that α-Crystallin decreased the RhoA protein activity(P<0.05). However, the effect of α-crystallin was slighter than that of C3 transferase(P<0.05). Compared to BSA, α-crystallin treatment decreased the phosphorylation of both cofilin (P<0.01) and MLC significantly (P<0.01).  However, the expression of RhoA and Rock did not been affected by α-crystallin. Tow weeks after vitreous injection of α-crystallin, many axons regenerated beyond the crush site, and extended toward the central direction. Whereas, in the BSA experiments, several axons were found in the crush site, but no axons were beyond the crush site. We also analyzed axonal outgrowth by retinal neurons cultured on culture plates coated with the myelin. The numbers of neurons with neurites were counted and the longest neurite was measured on day 1, 3 and 5. Most cells initiated neurite in α-crystallin group. However, only several cells initiated neurite in BSA group. And the neurite length was longer significantly in α-crystallin administration than in BSA administration
Conclusion These findings indicated that α-crystallin could counteract the effect of myelin inhibitory factors through regulation of RhoA/Rock signaling pathway.