Inhibitory effects of high-dose methylprednisolone on bacterial translocation from gut and endotoxin release following acute spinal cord injury-induced paraplegia in rats

摘要： BACKGROUND:Previous studies have shown that autonomic dysfunction results in gastrointestinal motility disorders and ultimately results in bacterial translocation following acute spinal cord in-jury (SCI). Intensive methylprednisolone dosing improves neurological recovery in SCI patients. However,it remains uncertain whether high-dose methylprednisolone inhibits bacterial translocation and endotoxin release following acute SCI. OBJECTIVE:To investigate the inhibitory effect of methylprednisolone on bacterial translocation and endotoxin release from the gut in paraplegic rats. DESIGN,TIME AND SETTING:The randomized,controlled study was performed at the Orthopedic Lab,First Affiliated Hospital,Nanchang University,China,from April to December 2008. MATERIALS:Methylprednisolone (Pfizer,USA),automatic microbial identification instrument ATB Expression and reagent ID 32 system (BioMérieux,France),Limulus test kit (ACC,USA),and optical microscope (Olympus,Japan) were used in this study. METHODS:A paraplegia model was established following SCI in 48 Wistar rats,aged 7 weeks. The rats were equally and randomly assigned to saline and methylprednisolone groups. Immediately post-injury,the methylprednisolone group was administered 30 mg/kg methylprednisolone via caudal intravenous infusion,followed by a 23-hour infusion of 5.4 mg/kg per hour. The saline group received an equal volume of saline as placebo. MAIN OUTCOME MEASURES:At 24 hours,72 hours,and 1 week after SCI,blood samples were collected for bacterial cultures,and bacteria and endotoxin were identified using ATB Expression and Limulus test kits. In addition,mesenteric lymph node,spleen,and liver samples were collected for bacterial cultures. Histological examinations of mesenteric lymph node,spleen,liver,jejunum,and ileum were performed 1 week post-injury. Locomotor function in the hind limb was evaluated using the Basso,Beattie,and Bresnahan score at pre-injury time point,as well as 24 hours,72 hours,and 1 week post-injury. RESULTS:Endotoxemia and bacterial growth were identified at 24 hours post-injury in both groups. However,plasma endotoxin levels were significantly decreased in the methylprednisolone group compared with the saline group at 72 hours and 1 week post-injury (P < 0.05). Translocated bacteria mainly comprised Bacillus coli,Enterobacter cloacae,Escherichia coli,Proteus vulgaris,and Enterococcus faecalis following SCI combined with paraplegia. Histological changes were not as severe in the methylprednisolone group compared with the saline group 1 week after injury. Basso,Beattie,and Bresnahan scores were significantly better in the methylprednisolone group compared with the saline group 1 week after injury (P < 0.05). CONCLUSION:High-dose methylprednisolone inhibited bacterial translocation from the gut and endotoxin release in rats with SCI. ... （共5页）