Contribution Of Intraperitioneal Injection Of Dexmedeto-midine And Small Dose Of Ketamine To The Hyperalgesia And BDNF MRNA In Spinal Cord Of Rats With Spared Nerve Injury

Objective: To study the Contribution of intraperitioneal injection ofDexmedetomidine and small dose of Ketamine to the hyperalgesia and BDNF proteinin the spinal cord of rats with spared nerve injury(SNI) and to explore the therapeuticeffects of them on the neuropathic pain and the effects of potential mechanism ofneuropathic pain induced by BDNF. Methods：Forty-five male SD rats weighing250~300g were randomly divided into five groups as follows(n=9each)：shamoperation group(S)，control group(C), ketamine group(K),dexmedetomidine group(D)and combined group(K+D).In S group sciatic nerves were exposed but not seperated，and other groups were set up with the mold of SNI.From the second day afteroperation，ketamine10mg/kg (2mL),dexmedetomidine40ug/kg(2ml),ketamine5mg/kg+dexmedetomidine20ug/kg (2mL) were injection intraperitoneally into K, D, K+Dgroup respectively and normal saline2mL was injection into S and C group once aday for21days. Results50%PWMT of group C,K,D and K+D were all reducedobviously after operation,compared with those before operation and group S;50%PWMT of group K+D was significantly higher than group K and D.The expression ofBDNF mRNA in group C,K,D and K+D was higher than group S;the reduction ofgroup K+D was more obviously than other groups.Conclusion Dexmedetomidine andlow dose of Ketamine all have evident analgesic effects.The combined injection ofDexmedetomidine and low dose of Ketamine produce synergistic abirritation and theunderlying mechanism was correlated with the expression of BDNF mRNA in thespinal cord.