Analgesic effect of intrathecal injection of dexmedetomidine on selective damage of sciatic nerve branch in a rat model

Deng Hai-hong; Ma Song-mei; Xiao Xiao-shan

doi:10.3969/j.issn.2095-4344.2014.27.015

Abstract：BACKGROUND:Dexmedetomidine is an effective high-selectivityα2-adrenoceptor agonist that has sedative, analgesic, anxiolytic effects, but slightly affects respiration. <br> OBJECTIVE:To observe the analgesic effect of dexmedetomidine on selective damage of sciatic nerve branch in a rat model by intrathecal injection. <br> METHODS:A total of 36 male Sprague-Dawley rats were randomly divided into normal control group, physiological saline group and dexmedetomidine group. A rat model of selective damage of sciatic nerve branch was established by knotting off the common peroneal nerve and tibial nerve in the physiological saline group and dexmedetomidine group. Rats in the dexmedetomidine group were daily injected with dexmedetomidine 3μg/kg by intrathecal injection within 14 days after injury. Rats in the physiological saline group were injected with physiological saline. <br> RESULTS AND CONCLUSION:Compared with the physiological saline group, the mechanical withdrawal threshold and the thermal withdrawal latency were significantly increased in the dexmedetomidine group (P<0.05). Neuronal nitric oxide synthase mRNA and protein expression levels were significantly decreased in the spinal dorsal horn (P<0.05). The injury to spinal dorsal horn neurons was obviously lessened. Moreover, neuronal nitric oxide synthase mRNA and protein expression levels and the injury to spinal dorsal horn neurons were similar between 14 days after administration and normal control group. Results indicated that intrathecal injection of dexmedetomidine could inhibit the expression of neuronal nitric oxide synthase in the spinal dorsal horn and relieve the pain induced by sciatic nerve injury.