The Antidepressant Effect Of Small Doses Of Tramadol And Dexmedetomidine In Rats With Neuropathic Pain

Objective: To evaluate the antidepressant effect of the comitant use of tramadol(TRA) and dexmedetomidine(DEX) in neuropathic pain rats.Methods: Chronic constrictive injury of the sciatic nerve and sham operation were performed on healthy, male, Wistar rats, weighing 200-300 g. The chronic neuropathic pain model rats and sham-operated were randomly divided into four groups respectively: TRA(OT, ST), DEX(OD, SD), TRA + DEX(OT + D, ST + D), Saline group(OC, SC). After 14 days’ recovery, saline, TRA(20 mg/kg/day), DEX(20 μg/kg/day) or TRA(5 mg/kg/day) + DEX(5 μg/kg/day) were administrated intraperitoneally at 8:00 a.m. for 14 days. Mechanical Withdrawal Threshold(MWT) and Forced Swimming Test(FST) were detected in three days before surgery, 14 days after surgery and 14 days after administration respectively. The serum cortisol level was detected 14 days after administration.Results: The MWT of the model rats was significantly decreased compared with the sham group 14 days after the operation, and the immobility time in FST was also significantly prolonged. After 14 days drug administration, MWT of the OT and OT + D group were increased, and the immobility time in FST was shorter than those before drug administration. For the OD group, the MWT increased significantly than before, while the FST immobility time did not change obviously. When compared to OD and OT, the FST immobility time of OT + D was significantly shorter(P <0.05). There was no significant difference on MWT and the FST immobility time before administration and after in sham group. The cortisol levels of OT + D group was higher than OT and OD.Conclusion: The antidepressant effect of small doses comitant use of tramadol and dexmedetomidine on rats of neuropathic pain was better than that was used alone.