乳铁蛋白对神经病理性痛大鼠脊髓小胶质细胞活化的影响研究

Effects of lactoferrin on microglial activation in the spinal cord in the rat model of neuropathic pain

目的探讨乳铁蛋白对神经病理性痛大鼠脊髓背角小胶质细胞活化的影响.方法雄性 SD 大鼠32只,体质 量200-220g,按照数字表法随机分为4组（对照组、神经病理性痛组、米诺环素组、乳铁蛋白组）,每组8只.对照组大鼠仅分离坐骨神经,不结扎,肌鞘内注射生理盐水8μl;其余3组大鼠采用结扎坐骨神经的方法制备神经病理性痛模型.神经病理性 痛组鞘内仅注射生理盐水8μl;乳铁蛋白组鞘内注射乳铁蛋白100μl,米诺环素组鞘内注射米诺环素（小胶质细胞特异性活化 抑制剂）100pg.给药后每隔30 mm以热刺激法测试大鼠热缩爪潜伏期,共180 mm,测量7 次后,常规处死大鼠取脊髓背角, 采用免疫荧光法检测小胶质细胞特异性标记物Iba-1的表达,并进行统计学分析.结果与对照组比较,神经病理性痛组缩爪潜伏期明显延长,差异有统计学意义（P 〈0. 05 ）;与神经病理性痛组相比,米诺环素组和乳铁蛋白组缩爪潜伏期延长,差异有 统计学意义（P 〈0. 05）;而米诺环素组与乳铁蛋白组爪潜伏期比较差异无统计学意义（ P〉0.05）,可间接证明乳铁蛋白可通过 抑制脊髓小胶质细胞活化减轻大鼠神经病理性痛.与对照组比较,神经病理性痛组、米诺环素组和乳铁蛋白组脊髓背角Iba-1 表达明显减少,差异有统计学意义（P〈0.05）;与神经病理性痛组相比,米诺环素组和乳铁蛋白组脊髓背角Iba-1表达也明显 减少,差异有统计学意义（P 〈0.05 ）;而米诺环素组与乳铁蛋白组缩爪潜伏期比较,差异无统计学意义（ P 〉0. 05 ）,可直接证明 乳铁蛋白可通过抑制脊髓小胶质细胞活化减轻大鼠神经病理性痛.结论乳铁蛋白可通过抑制大鼠脊髓小胶质细胞活化减 轻神经病理性痛,对临床麻醉镇痛过程有一定的指导价值.

Objective To investigate the effects of lactoferrin on microglial activation in the spinal cord in the rat model of neuropathic pain （ NP）. Methods Thirty-two male SD rats with the weight of 200 -220 g were randomly divided into 4 groups, i. e. the control group, the neuropathic pain group, the minocycline group and the lactoferrin group, each consisting of 8 animals. The sciat-ic nerve was only exposed but not ligated in the animals of the control group, and 8μl of normal saline were injected intrathecally. The neuropathic pain model was produced by placing loosely constrictive ligatures around the common sciatic nerve in the animals of the oth-er groups. Eight 8μl of normal saline were injected intrathecally in the animals of the neuropathic pain group. One hundred 8μl of lacto-ferrin were given intrathecally in the animals of the lactoferrin group, while the same amount of minocycline was also given intrathecally in the animals of the minocycline group. Following medication, the paw withdrawal latency （PWL） was detected every 30 minutes by u-sing thermal nociceptive stimulus with a total of 180 minutes. After detections for 7 times, the rats were sacrificed for the collection of spinal dorsal horn. The expression of Iba-1 was determined by immunofluorescence, and then statistical analyses were made according-ly. Results PWL for the animals of the neuropathic pain group was obviously prolonged, as compared with that of the control group, and statistical significance could be seen, when comparisons were made between them（P 〈0. 05）. PWL for the animals of both the minocycline group and the lactoferrin group was prolonged, as compared with that of the neuropathic pain group, also with statistical signif-icance （ P 〈 0. 05）. No statistical significance could be noted in PWL for the animals of the minocycline group and the lactoferrin group, when comparisons were made between them（P 〉0. 05） . This was an indirect indication that lactoferrin could alleviate neuropathic pain through the inhibition of the activation of spinal microglia. The expression levels of Iba-1 in the animals of the minocycline group and the lactoferrin group, as well as the neuropathic pain group, were significantly decreased, and statistical significance could be seen, when it was compared with that of the control group （P 〈0. 05）. The expression levels of Iba-1 in the animals of the minocycline group and the lactoferrin group were also significantly decreased, as compared with that of the neuropathic pain group, also with statistical signifi- cance（P 〈0. 05 ）. No statistical significance was shown in PWL, when comparisons were made between the minocycline group and the lactoferrin group （ P 〉 0. 05 ）. This was also an indirect indication that lactoferrin could alleviate neuropathic pain through the inhibition of the activation of spinal microglia. Conclusion Lactoferrin could alleviate neuropathic pain through the inhibition of the activation of spinal microglia, which had certain medical value in the clinical practice of anesthesia.