Expression Of MOR In Spinal Dorsal Horn In Sufentanil Induced Hyperalgesia In Rats With Incisional Pain

The discovery of opioid drugs has a milestone in the treatment of pain,which mainly acts on the analgesic effect of mu opioid receptor(MOR)in the body.As early as 1970 s and 1980 s,it was found that the use of opioids could enhance the pain sensation of patients,which as known as opioid inducedhyperalgesia(OIH).The use of long effect opioids such as sufentanil,or opioid agonist antagonist like dezocine to relieve the hyperalgesia induced by remifentanil,has also been demonstrated in a series of researches.But,there are still lots of questions that has no answer.Acting on the same ? receptor of opioid,do the application of such drugs only conceal the clinical manifestations of hyperalgesia? Moreover,as it further aggravates histopathologic changes in hyperalgesia.Objective To investigate the effect of clinical dose of sufentanil on the hyperalgesia,the dose and the way of administration,in order to investigate the changes in the expression of MOR receptor in the spinal dorsal horn of sufentanil induced hyperalgesia rats with incisional pain.Methods By observing the effect of different doses of sufentanil on the pain threshold,the effect of the clinical dose of sufentanil on the induced hyperalgesia and the degree of hyperalgesia;the effect of the same dose of sufentanil on the severity of hyperalgesia in rats;naloxone(opioid m receptor antagonists),sufentanil(opioid m receptor agonist),dezococine,evaluate the effect of opioid receptor different drugs on the pain threshold of rats;determine the level of MOR expression in the spinal dorsal horn cells at the peak pain sensitivity of rats and the pain perception.The correlation of allergies.80 male SD rats of grade SPF,weighing 200 g to 250 g,42~49 days old,were divided into 8 groups by random number table method(n=10): small dose sufentanil incisional pain group(SL): sufentanil(via tail vein)was slowly injected into rats according to the standard of 3mg/kg;middle dose sufentanil incisional pain group(SM): 12.5mg/kg.The rats were slowly injected with sufentanil(via the tail vein);large equal dose sufentanil incisional pain group(SH): sufentanil(sufentanil)was slowly injected into rats according to the standard of 25mg/kg;and the incision pain group(C): the volume of saline in the rat tail vein was injected into the rats.Naloxone incisional pain group(N): Naloxone was slowly injected into the rats by the standard 5mg/kg standard via the tail vein;and the pain group of dizoxine(D): Dizoxine was slowly injected to the tail vein rats according to the standard of 25mg/kg.Before infusion of 24 h,2h,6h and 7 days after the injection(D1,D2,D3,D4,D5,D6,D7),the paw withdrawal threshold(PWT)and paw withdrawal latency(PWL)were measured,and cold pain threshold was measured with cold acetone method.64 PF male SD rats,weighing 200 g to 250 g,42~49 days old,were divided into 6 groups(n=6),sufentanil low dose group(SL),sufentanil medium dose group(SM),Shufinta Ni Gogh dose(SH),dizoxin group(D group),naloxone group(N group),control group(C group),and fourth days post operation.Spinal cord dorsal horn cells were killed,and the expression level of MOR was determined by Westen Blot.The expression of MOR is reduced in the pain sensitive group,and the degree of reduction is correlated with the degree of pain.There was no significant difference between naloxone group and low dose group compared with blank control group.Results Compared with group C,PWT in SM and SH groups decreased significantly,and PWL shortened.(P <0.05),and reached peak value on the 5th day after operation,and SH had more severe hyperalgesia than SM.There was no statistical significance in group SL compared with group C.(P >0.05).Compared with the SH group,the same dose of sufentanil was injected intravenously in different ways,and there was no statistical difference in the pain threshold of rats(P >0.05).Compared with the C group,the threshold of mechanical foot response threshold(PWT)and the latent period(PWL)of rats decreased significantly(P<0.05),but there was no statistical difference between group D and N group(P> 0.05).Conclusion Medium and high dose of sufentanil can induce hyperalgesia in rats with incision pain;Its induced anaphylaxis was dose related,and had nothing to do with the way of administration;The expression of MOR in spinal cord tissue of rats was decreased in D5.