Expression of mRNA for Monocyte Chemoattractant Protein-1 in the Sciatic Nerve and Hindlimb Muscle Following Denervation

ABSTRACT

Migration of inflammatory cells into damaged tissue is essential to host defense mechanisms and immune responses. Monocyte chemoattractant protein-1(MCP-1), a member of the CC or beta-chemokine family is a powerful leukocyte recruitment factor that is relatively specific for monocyte/macrophage. The purpose of present study was to evaluate temporal change of expression of mRNA for MCP-1 in the sciatic nerve and hindlimb muscle of Sprague-Dawley rat. The mid-portion of the sciatic nerve was exposed, cut under aseptic condition and then animals were sacrificed 1, 2, 3, 7, 14 days after denervation of the sciatic nerve. Semiquantitative RT-PCR method and image analysis system were used to analyze change in expression of mRNA for MCP-1. Expression of mRNA for MCP-1 in the distal stump of the denervated sciatic nerve was up-regulated within 1 day and peaked on the second day following transection of the sciatic nerve. Thereafter high expression of mRNA for MCP-1 lasted for 7 days after transection of the nerve. However the expression of mRNA for MCP-1 was rapidly decreased on the 14th day after denervation. Temporal change of expression of mRNA for MCP-1 in the proximal portion of the denervated sciatic nerve was very similar with that of distal one. The gastrocnemius muscle also showed significant increase in expression of mRNA for MCP-1 on the 1st day with maximal expression on the 7th day after denervation of the sciatic nerve. In contrast, the expression of mRNA for MCP-1 in the soleus muscle was lower than the gastrocnemius muscle in the course of the denervation-induced atrophy. Additionally alpha-lipoic acid, a potent antioxidant that is used in treatment for diabetic neuropathy, suppressed significantly expression of mRNA for MCP-1 in the denervated sciatic nerve but not in atrophied hindlimb muscles.