Changes in motor function and expression of insulin-like growth factor-1 of skeletal muscle and peripheral nerve of rats after chronic spinal cord compression

Abstract

Objective To observe the changes in motor function and expression of insulin-like growth factor-1 (IGF-1) of peripheral nerve and skeletal muscle in rats after chronic spinal cord compression. Methods A total of 50 Wistar rats were randomly divided into normal group (n=10), sham operation group (group A,n=10) and chronic compressive group (goup B,n=30). The rats in group B were given gradual compression on the posterior spinal cord using blunt plastics screw. Compression degree reached 20% (n=10), 40% (n=10) and 60% (n=10) respectively after two months. The rats were killed, and gastrocnemius muscle cells were removed. The expression levels of IGF-1 protein and mRNA in peripheral nerve and skeletal muscle were detected by immunohistochemistry and hybridization respectively after chronic compressive spinal cord injury. Results The rat hind limb paralysis was exacerbated with the increase of the compression. In the sciatic nerve and skeletal muscle, the expression levels of IGF-1 protein and mRNA were: (236.9±3.2), (231.5±2.9), (245.6±3.4), (246.6±2.7) in 20% group; (205.3±2.7), (202.2±3.4), (209.4±2.6), (214.6±2.5) in 40% group; (215.4±3.5), (219.3±4.1), (231.9±2.3), (238.5±2.7) in 60% group. The expression levels of IGF-1 protein and mRNA in peripheral nerve and skeletal muscle were significantly up-regulated after compression (P<0.05). Conclusion The results indicate that body transfers the protective factor to relieve injury of CNS. Key words: Spinal cord injury; IGF-1; Peripheral nerve; Skeletal muscle