The matrix metalloproteinases(MMPs) constitute a family of both zinc-and calcium-dependent endopeptidases.The MMPs include 28 MMP members,function in degrading the extracellular matrix collagen components and regulating different types of cells migration and stress response.Studies show that after chronic nerve injury,MMP-9 and MMP-2 are involved in the formation and maintenance of hyperalgesia,which is an important mechanism for inducing neuropathic pain.Besides,acute or chronic morphine application induce...