The impact of brachial plexus injury on the expressions of heat shock proteins and neuronal nitric oxide synthase

Objective: To observe the expressional changes of Hsp70, Hsp27 and neuronal nitric oxide synthase(nNOS) in spinal motoneurons following different distal injury of brachial plexus and to investigate the correlation of the expressional changes and the survival and regeneration of motoneurons. Method: A total of eighteen adult male SD rats were randomly divided into three groups: musculocutaneous nerve cut group(n=7), crushed group(n=7) and control group(n=4). Two months later, motor function was assessed by Grooming test standard to evaluate the functional recovery at the experimental side. Then the C5 spinal cord were harvested and immunohistochemical examination were performed. Result: In cut group and crushed group, the functional recovery were all significant. Moreover, the percentage of above grading 4 in crushed group(86%) was better than in cut group(57%). Compared to control group, the expressions of all the three proteins at motoneurons of experimental side in the two experimental groups were increased significantly. The number of Hsp70 and Hsp27 positive motoneurons in cut group(140.61±1.25,130.08±2.38) were more than that in crushed group(143.86±1.32,138.93±1.58), but the number of nNOS positive motoneurons in crushed group(106.12±0.91) was more than that in cut group(68.18±0.63). Conclusion: The expressions of three proteins in spinal motoneurons following musculocutaneous nerve cut and crush lesion were different from the normal and it were directly correlated with the motor function recovery.