Analysis of the muscle tissue of Wistar rats submitted to the sciatic nerve compression model and cryotherapy

ABSTRACT Objective: To evaluate the effects of right sciatic nerve compression and cryotherapy on muscle tissue. Methods: We used 42 male Wistar rats, subdivided in the following Groups Control, Injury 3, Injury 8 and Injury 15 submitted to nerve compression and euthanized in the 3rd, 8th and 15th day after surgery. The Cryotherapy Injury 3 was entailed treatment with cryotherapy by immersion of the animal in recipient for 20 minutes during 1 day, then animals were euthanized at the 3rd day after surgery, and the Cryotherapy Injury 8 and the Cryotherapy Injury 15 was treated for 6 days, and euthanized at the 8th and 15th day after surgery. Functional evaluation was performed by the grasping strength of the right pelvic limb. The right tibialis anterior muscles were evaluated for mass, smaller diameter and cross-sectional area. In the Cryotherapy Injury 8 and the Cryotherapy Injury 15 groups, the hydroxyproline was dosed in the right soles. Results: In the compression there was a significant difference in the Injury Groups compared with the Control Group (p<0.05). In the smaller diameter, the compression in Control Group was higher than Injury 8 (p=0.0094), Injury 15 (p=0.002) and Cryotherapy Injury 15 (p<0.001) groups. The comparison between groups with euthanasia in the same post-operative period, a significant difference (p=0.0363) was seen in day 8th after surgery, and this result in Cryotherapy Injury Group was greater than Injury Group. In the fiber area, Control Group was also higher than the Injury 8 (p=0.0018), the Injury 15 (p<0.001) and the Cryotherapy Injury 15 (p<0.001). In hydroxyproline, no significant difference was seen between groups. Conclusion: Nerve damage resulted in decreased muscle strength and trophism, the cryotherapy delayed hypotrophy, but this effect did not persist after cessation of treatment.

摘要 研究目的：评估右侧坐骨神经压迫联合冷冻治疗对肌肉组织的影响。
研究方法：选取42只雄性Wistar大鼠，分为对照组、单纯损伤3天组、单纯损伤8天组、单纯损伤15天组，各组均接受坐骨神经压迫造模，分别于术后第3、8、15天实施安乐死。其中冷冻治疗损伤3天组：于造模后1天内将大鼠浸入容器中接受冷冻治疗20分钟，于术后第3天安乐死；冷冻治疗损伤8天组与冷冻治疗损伤15天组连续治疗6天，分别于术后第8、15天安乐死。采用右侧后肢抓握力量测试进行功能评估；检测右侧胫骨前肌(tibialis anterior)的质量、最小直径及横截面积。针对冷冻治疗损伤8天组与冷冻治疗损伤15天组，检测右侧足底的羟脯氨酸(hydroxyproline)含量。
研究结果：坐骨神经压迫造模后，各单纯损伤组与对照组相比存在显著统计学差异（p<0.05）。在肌肉最小直径方面，对照组显著高于单纯损伤8天组（p=0.0094）、单纯损伤15天组（p=0.002）及冷冻治疗损伤15天组（p<0.001）。按术后相同安乐死时间点进行组间比较，术后第8天组间存在显著统计学差异（p=0.0363），冷冻治疗组的指标高于单纯损伤组。在肌纤维横截面积方面，对照组同样显著高于单纯损伤8天组（p=0.0018）、单纯损伤15天组（p<0.001）及冷冻治疗损伤15天组（p<0.001）。羟脯氨酸检测未发现组间显著统计学差异。
研究结论：坐骨神经损伤可导致肌肉力量下降及营养代谢异常，冷冻治疗可延缓肌肉萎缩，但该效应在治疗停止后未能持续。