Effects of naloxone on acute diffuse axonal injury in rats

Objective To observe the effects of the naloxone on the pathological damage of the acute diffuse axonal injury(DAI) in rats.Methods A total of 99 male Wistar rats were randomly divided into control group(sham injury),injury group and naloxone intervention group(2.0 mg/kg of naloxone were administered intraperitoneally 45 minutes after trauma).The DAI models were made by modified Marmarou' method(impact-acceleration model).The neurological scores were estimated and pathological changes were observed at various times after cerebral injury in rats(2,6,24 and 72 hours).Results The severest neurological dysfunction occurred immediately in rats after DAI.The neurological scores of interventional group were significantly improved at 6 hours and 24 hours,compared with those of injury group(P0.05).The worst degree of pathological damage was seen at 24 hours by Glees.The light microscopy showed severe derangement of medullary fibers and large numbers of formation of retraction balls in injury group at this time point,but relatively normal fiber arrangements and low-density retraction balls in the naloxone intervention group at the same time point.Obvious separation of myelin layer and axonotmesis were observed in injury group,but rare axonotmesis in naloxone intervention group.Conclusion Early use of high dose of naloxone may provide remarkable protection against the experimental DAI in the early stage.