Effect of immunosuppressant to neuropathic pain

我们采用Bennett和Xie （Pain 33, 1988）的慢性收缩模型，研究环孢素是否能减轻术后70天大鼠的机械异常性痛和超敏反应。此外，我们比较了环孢素与倍他米松在治疗神经性疼痛状态中的抗炎作用。取术后第2天von Frey毛测量的触觉异常性痛大鼠62只，30只随机分为6组，每组n=5只。四组腹腔注射环孢素（0.01、0.1、1、10 mg/kg）。第五组给予倍他米松磷酸钠1 mg/kg，第六组给予等量生理盐水。于坐骨神经收缩后第2天开始注射，每天注射，连续20天。观察触觉异常性痛、机械性痛觉过敏和热痛觉过敏70 d。所有组均在神经收缩的单侧和对侧出现触觉异常痛。生理盐水组和0.01 mg/kg环孢素注射组均出现对侧热痛觉过敏。类似的对侧机械过敏未见。环孢素对触觉异常性痛、热超敏和机械超敏有剂量效应，倍他米松对触觉异常性痛的缓解作用较弱。服用倍他米松的大鼠在最后一天的体重增加比其他组要少。这些结果提示环孢素治疗神经性疼痛的可能效果。即使在神经损伤后开始使用环孢素治疗，似乎也是有效的。

Using the chronic constriction model of Bennett and Xie (Pain 33, 1988), we investigated whether cyclosporine attenuates mechanical allodynia and hypersensitivity of rats for 70 days after surgery. In addition, we compared cyclosporine to betamethasone, which has potent anti-inflammatory effect, in treating neuropathic pain state.Thirty rats of 62, which showed tactile allodynia measured with von Frey hair at 2nd day after surgery, was randomly allocated to 6 groups (n=5 in each groups). Four groups received cyclosporine (0.01, 0.1, 1 and 10 mg/kg) intraperitoneally. The fifth group received betamethasone sodium phosphate 1 mg/kg, and the sixth group received equal volume of saline. Those injections were started on 2 days after sciatic nerve constriction and given daily for 20 days. Tactile allodynia, mechanical hyperalgesia and heat hyperalgesia were assessed for 70 days.Tactile allodynia was observed on both ipsi- and contralateral side of nerve constriction in all groups. Contralateral heat hyperalgesia was observed in saline and 0.01 mg/kg of cyclosporine injected groups. Similar contralateral mechanical hypersensitivity was not seen. Cyclosporine alleviated tactile allodynia, heat hypersensitivity and mechanical hypersensitivity in dose response manner, although betamethasone showed less potent effect. Body weight gain was less in betamethasone received rats than other groups on the last treatment day.These results indicate possible effects of cyclosporine to treat neuropathic pain. The treatment with cyclosporine seems to be effective even if it was started after nerve injury.