THE ACTION OF SERICIN PROTEIN ON INITIAL NERVE REPAIR, ASSOCIATED OR NOT WITH SWIMMING IN WISTAR RATS

ABSTRACT Objective: To analyze the effects of sericin treatment, associated or not with swimming with load exercise, on initial sciatic nerve repair after compression in Wistar rats. Methods: Forty animals were divided into five groups: control, injury, injury-sericin, injury-swimming and injury-sericin-swimming. During the axonotmesis procedure, the sericin was applied to the injury-sericin and injury-sericin-swimming groups. The injury-swimming and injury-sericin-swimming groups performed the swimming with load exercise for five days, beginning on the third postoperative day (PO), and were evaluated for function, nociception and allodynia. Euthanasia was performed on the 8th PO day and fragments of the nerve were collected and prepared for quantitative and descriptive analysis in relation to the total amount of viable nerve fibers and non-viable nerve fibers, nerve fiber diameter, axon diameter and myelin sheath thickness. Results: There was no significant improvement in the sciatic functional index up to the eighth day. The Von Frey test of the surgical scar and plantar fascia indicated a reduction in pain and allodynia for the injury-swimming and injury-sericin-swimming groups. The morphological analysis presented similar characteristics in the injury-sericin, injury-swimming and injury-sericin-swimming groups, but there was a significant difference in the number of smaller non-viable nerve fibers in the injury-swimming and injury-sericin-swimming groups as compared to the others. Conclusions: Isolated sericin protein presented proinflammatory characteristics. There was improvement of allodynia and a decrease in the pain at the site of the surgical incision, possibly linked to an aquatic effect. There was no acceleration of nerve repair on the eighth day after the injury. Level of Evidence I; High quality randomized clinical trial with or without statistically significant difference, but with narrow confidence intervals.

摘要
研究目的：分析丝胶（sericin）单独或联合负重游泳运动，对Wistar大鼠坐骨神经（sciatic nerve）压迫损伤后初期修复的影响。
实验方法：选取40只实验动物，随机分为5组：对照组、损伤组、损伤-丝胶组、损伤-游泳组及损伤-丝胶-游泳组。在轴突断伤（axonotmesis）手术过程中，向损伤-丝胶组与损伤-丝胶-游泳组的损伤部位施加丝胶。损伤-游泳组与损伤-丝胶-游泳组于术后第3天（postoperative day，PO）起进行为期5天的负重游泳运动，随后对其运动功能、痛觉及痛觉超敏（allodynia）进行评估。于术后第8天实施安乐死，采集神经组织标本，针对存活神经纤维与非存活神经纤维总数量、神经纤维直径、轴突直径及髓鞘厚度开展定量与描述性分析。
实验结果：截至术后第8天，坐骨神经功能指数（sciatic functional index）未出现显著改善。对手术瘢痕与足底筋膜进行冯·弗雷（Von Frey）丝测试结果显示，损伤-游泳组与损伤-丝胶-游泳组的痛觉及痛觉超敏症状均有所减轻。形态学分析表明，损伤-丝胶组、损伤-游泳组及损伤-丝胶-游泳组的组织特征相似，但相较于其余组别，损伤-游泳组与损伤-丝胶-游泳组的小型非存活神经纤维数量存在显著差异。
研究结论：单独使用丝胶蛋白表现出促炎特性。手术切口部位的痛觉超敏症状得到改善，疼痛程度有所降低，这一效应可能与水环境运动相关。截至损伤后第8天，未观察到神经修复过程出现加速。证据等级：I级；高质量随机对照试验（randomized clinical trial），无论是否存在统计学显著性差异，但置信区间较窄。