Role of spinal peroxynitrite in remifentanil-induced hyperalgesia in rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the role of spinal peroxynitrite in remifentanil-induced hyperalgesia in rats.Methods Thirty-two male Sprague-Dawley rats, weighing 240-260 g, aged 2-3 months, were randomly divided into 4 groups (n =8 each) using a random number table control group (group C), remifentanil group (group R), hydrogen-rich saline group (group C + H), and remifentanil + hydrogen-rich saline group (group R+H).In group C, normal saline was infused for 60 min at a rate of 0.1 ml · kg-1 · min-1.In group R, remifentanil was infused for 60 min at a rate of 1.0 μg · kg-1 · min-1.In group R+H, remifentanil was infused for 60 min at a rate of 1.0 μg · kg-1 · min-1 ,and hydrogen-rich saline 10 ml/kg was intraperitoneally injected at 10 min before iv infusion.At 24 h before iv infusion and 6, 24 and 48 h after iv infusion (T0-3) , the mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured.All the rats were sacrificed after the last measurement of pain thresholds, the lumbar segment (L4-6) of the spinal cord was removed for determination of the nitrated manganese superoxide dismutase (MnSOD) expression (by immunoprecipitation and Western blot analysis), 3-nitrotyrosine (3-NT) expression (by Western blot) and spinal MnSOD activity (by spectrophotometer).Results Compared with group C, the MWT was significantly decreased, and TWL was shortened at T1-T3, the expression of spinal 3-NT and nitrated MnSOD was up-regulated, and MnSOD activity was decreased in R and R+H groups, and no significant change was found in the parameters mentioned above in group C+H.Compared with group R, the MWT was significantly increased, and TWL was prolonged at T1-T3, the expression of spinal 3-NT and nitrated MnSOD was down-regulated, and MnSOD activity was increased in group R + H.Conclusion Spinal peroxynitrite is involved in the mechanism underlying remifentanil-induced hyperalgesia through inhibiting the activity of MnSOD in rats.