Effect of Chondroitinase ABC Enzyme on Glial Fibrillary Acidic Protein, Chondroitin Sulfated Proteoglycans and Chondroitin ۴-Sulfate Levels in an Animal Model of Spinal Cord Injury

Background: Following spinal cord injury, reactive astrocytes upregulate chondroitin sulfate proteoglycans (CSPGs) which act as a barrier to neuronal repair and regeneration. Therefore, enzymatic digestion of CSPGs by chondroitinase ABC (cABC) is a key strategy in the treatment of spinal cord injury. Furthermore, cABC has been shown to attenuate post spinal cord injury inflammation and may decrease astrocytes activation. Thus, this study was conducted to investigate the effect of cABC on astrocytes level through measuring glial fibrillary acidic protein (GFAP) in an animal model of spinal cord injury. Methods: spinal cord injury was performed through contusion method. Sixty male rats (۲۲۰-۲۵۰ g) were divided into three groups. The first group was just subjected to spinal cord injury. In the second group, phosphate buffered saline (۶ µl) was immediately injected in lesion site after spinal cord injury. The third group received cABC (۶ µl, ۱۰ U/ml) intrathecally after spinal cord injury. Then, GFAP, CSPGs and chondroitin ۴-sulfate (C۴S) levels were measured at ۴ hours and ۱, ۳ and ۷ days after spinal cord injury using immunohistochemical method. Results: GFAP level increased in all groups until ۷ days post spinal cord injury, but no significant difference was observed between enzyme- treated group and two other groups at similar time point (p˃۰.۰۵). CSPGs level increased significantly in the first and second groups whereas it decreased considerably in enzyme- treated group. In addition, due to enzymatic digestion of CSPGs, C۴S level in the third group increased significantly. Conclusion: cABC enzyme decreased CSPGs level through degradation without any…… considerable effect on their source which is reactive astrocytes.

Keywords:

Spinal cord injury , Chondroitinase ABC , Reactive astrocytes , Glial fibrillary acidic protein , Chondroitin sulfate proteoglycans