Effect Of Dexmedetomidine Pretreatment On Inflammatory Visceral Pain

Objective:To investigate the effect dexmedetomidine pretreatment on inflammatory visceral pain.Methods:Forty healthy male Wistar rats,weighing 200-300g,aged 6-8 weeks,were randomly divided into 5 groups(n=8 each)using a random number table:control group(group C);visceral pain group(group VP);dexmedetomidine 1μg/kg group(Dex1);dexmedetomidine 5μg/kg group(Dex2);dexmedetomidine 10μg/kg group(Dex3).Group VP and groups Dex were intraperitoneally injected(IP)0.9%acetic acid 10ml·kg~-11 to get visceral pain.Group C were intraperitoneally injected equal volume saline.Dexmedetomidine 1μg/kg、5μg/kg and 10μg/kg were separately injected in Dex group 1、2 and 3 via the tail vein at 15 min before intraperitoneal injection,while the equal volume of normal saline was given instead in C and VP group.The degree of visceral pain was assessed by number of writhes of the body with in 60 min after IP acetic acid and expressed by visceral pain index.Blood samples were collected from the hearts for determination of TNF-αconcentration in serum at 180min VP model.The animals were then sacrificed and colons were obtained for examination of pathological findings with light microscope.Results:Compared with group C,the VPI and serum TNF-αconcentration were significantly increased in VP and Dex1,2group(P<0.05).The serum TNF-αconcentration was significantly higher(P<0.05),and no significant change was found in Dex3.Pathological changes of group VP and groups Dex were all accentuated.Compared with group VP,the VPI and serum TNF-αconcentration were significantly decreased(P<0.05),pathological changes were weaker in group Dex1-3.Compared with group Dex1,the VPI and serum TNF-αconcentration were significantly decreased(P<0.01),pathological changes were weaker in group Dex2,3.Compared with group Dex2,the VPI and serum TNF-αconcentration were significantly decreased(P<0.01),pathological changes were weaker in Dex3.Conclusion:Dexmedetomidine pretreatment can mitigate visceral pain.