Trigeminal neuralgia (TN) is a type of neuropathic pain characterized by intense pain; although anticonvulsants are used as an option to relieve pain, adverse side effects can decrease patient adherence. In this context, a low dose of naltrexone is effective in relieving pain in other pain conditions. Thus, the objective of the present study was to evaluate the analgesic effect of low-dose naltrexone on facial mechanical allodynia in a rat model of TN, as well as its effect(s) on biomarkers in the central nervous system (tumor necrosis factor-alpha, brain-derived neurotrophic factor [BDNF], interleukin [IL]-10, and toll-like receptor-4). Fifty-nine adult male Wistar rats (CEUA-HCPA#2017-0575) were allocated to following groups: control; sham-pain + vehicle; sham-pain + carbamazepine (100 mg/kg); sham-pain + naltrexone (0.5 mg/kg); pain + vehicle; pain + carbamazepine; and pain + naltrexone. TN was induced using chronic constriction of the infraorbital nerve. Facial allodynia was assessed using von Frey test. Drugs were administered by gavage 14 days after surgery for 10 days. At baseline, the mechanical threshold was similar between groups (P > 0.05; generalized estimating equation). Seven days after surgery, facial allodynia was observed in sham-TN and pain-TN groups (P < 0.05). Fourteen days after surgery, only pain-TN groups exhibited facial allodynia. The first dose of low-dose naltrexone or carbamazepine partially reversed facial allodynia. After 10 days of treatment, both drugs completely reversed it. Spinal cord levels of BDNF and IL-10 were modulated by low-dose naltrexone. Thus, low-dose naltrexone may be suitable to relieve TN; however, the exact mechanisms need to be clarified.

三叉神经痛（TN）是一种以强烈疼痛为特征的神经性疼痛。尽管可以使用抗惊厥药来缓解疼痛，但不良副作用会降低患者的依从性。在这种情况下，低剂量的纳曲酮可有效缓解其他疼痛情况下的疼痛。因此，本研究的目的是评估低剂量纳曲酮在TN大鼠模型中对面部机械性异常性疼痛的镇痛作用，以及其对中枢神经系统生物标志物（肿瘤坏死因子-α）的镇痛作用。 α，脑源性神经营养因子[BDNF]，白介素[IL] -10和toll样受体4）。将59只成年雄性Wistar大鼠（CEUA-HCPA＃2017-0575）分为以下组：假痛+车辆；假痛+卡马西平（100 mg / kg）; 假痛+纳曲酮（0.5 mg / kg）; 疼痛+车辆；疼痛+卡马西平；和疼痛+纳曲酮。TN是使用眶下神经的慢性收缩引起的。使用von Frey检验评估面部异常性疼痛。术后14天通过管饲法给药10天。在基线时，各组之间的机械阈值相似（P> 0.05；广义估计方程）。手术7天后，假手术组和疼痛手术组观察到面部异常性疼痛（P <0.05）。手术后第十四天，仅疼痛TN组表现出面部异常性疼痛。低剂量纳曲酮或卡马西平的第一剂可部分逆转面部异常性疼痛。经过10天的治疗，这两种药物都将其完全逆转。低剂量纳曲酮可调节BDNF和IL-10的脊髓水平。因此，小剂量纳曲酮可能适合缓解TN。然而，