The distribution and time-dependent expression of MAGL during skeletal muscle wound healing in rats

Abstract

Monoacylglycerol lipase (MAGL) is widely distributed in mammals and largely responsible for metabolizing 2-arachidonoylglycerol (2-AG). Little is known about its expression in skeletal muscles after trauma. A preliminary study on time-dependent expression and distribution of MAGL was performed by immunohistochemical staining, Western blotting and quantitative real-time PCR (qPCR) during skeletal muscle wound healing in rats. An animal model of skeletal muscle contusion was established in 40 Sprague-Dawley male rats. Samples were taken at 1, 3, 5, 7, 9, 13, 17 and 21 days after contusion, respectively (5 rats in each posttraumatic interval). 5 rats were employed as control. Weak immunoreactivity of MAGL was observed in the sarcoplasm of myofibers in control rats. Intensive immunoreactivties of MAGL were observed in polymorphonuclear cells (PMNs), roundshaped mononuclear cells (MNCs), spindle-shaped fibroblastic cells (FBCs) and regenerated multinucleated myotubes in the injured tissue. Subsequently, neutrophils, macrophages and myofibroblasts were identified as MAGL-positive cells by double immunofluorescent procedure. MAGL expression was remarkably up-regulated after contusion by qPCR and Western blot analysis. The results demonstrate that the expression of MAGL is distributed in certain cell types and time-dependently expressed in skeletal muscles after trauma, suggesting that MAGL may be involved in inflammatory response, fibrogenesis and muscle regeneration during skeletal muscle wound healing.