大鼠脊神经压迫后早期痛阈与神经损伤程度的联系

目的观察大鼠脊神经压迫后早期痛阈改变与神经损伤程度的联系。方法雄性SD大鼠32只,随机分为4组（每组n=8）：正常组,假手术组,70 g压迫组和180 g压迫组。正常组不作任何处理,作为对照,假手术组模型制作过程和其它两个模型组相同,但不做神经压迫,70 g压迫组和180 g压迫组分别用70 g或180 g血管夹压迫大鼠右侧颈7脊神经15 min,制作神经急性压迫损伤模型。于术前2 d和术后1、35、、7 d测右侧前足机械性痛阈和热痛阈,术后7 d处死大鼠取右侧颈7脊神经,HE染色病理分级和扫描电镜观察,比较各组痛阈改变以及神经损伤程度的变化。结果与术前相比较,正常组和假手术组术后机械性痛阈和热痛阈无明显变化（P〉0.05）;与术前以及正常组和假手术组相比,70 g压迫组术后1～7 d机械性痛阈和热痛阈明显降低（P〈0.05）,180 g压迫组术后1 d痛阈无明显变化（P〉0.05）,术后3～7 d明显升高（P〈0.05）。正常组和假手术组均未出现神经损伤病理变化,而70 g压迫组和180g压迫组出现不同程度的神经损伤,损伤病理分级180 g压迫组高于70 g压迫组（P〈0.05）。结论70 g或180 g血管夹压迫大鼠颈7脊神经后大鼠痛阈降低或升高,其机制可能与不同的压力导致不同的神经损伤程度有关。

The Relationship of Pain Threshold and Extent of Nerve Injury in the Early Stage of Rats Spinal Nerve Compression

Objective To explore the relationship of pain threshold and extent of nerve injury in the early stage following rats C7 spinal nerve compression. Methods Thirty two adult male Spraguc - Dawley rats weighing 250 - 300 g were divided into 4 groups （ n = 8 each） ： normal group, as control without any operation ; sham group, operated without nerve compression ; 70 grams force（gf） group, 70 gf applied to the fight C7 spinal nerve; 180 gf group, 180 gf applied to the fight C7 spinal nerve. Threshold thermal and mechanical pain was measured before surgery （baseline） and on the 1^sh, 3^rd , 5^th and 7^th day after surgery. On the 7^th day after surgery, all of the rats were killed and the fight C7 spinal nerve was removed for pathological test. Results During the 1^sh to the 7^th day after surgery, the mechanical and thermal pain threshold on the right forepaw of normal group and sham group maintained at the same level as the baseline（ P 〉 0.05）, but the threshold of 70 gf group was significant lower than the baseline（ P 〈 0.05）. On the 1^sh day after surgery, the mechanical and thermal pain threshold of 180 gf group was not different from the baseline（P 〉 0.05）, although on the 3^rd to the 7^th day after surgery, the threshold was significant higher than the baseline（ P 〈 0.05）. There was not any pathological sign of injury in the spinal nerve of normal group and sham group. However, there were different extents of injury in the spinal nerve of 70 gf group and 180 gf group, and the pathological grades of injury in 180 gf group were higher than in 70 gf group（ P 〈 0.05）. Conclusion 70 gf and 180 gf compression on C7 spinal nerve leaded to the rats pain threshold decrease or increase, respectively. The mechanism of it may owe to different extents of nerve injury produced by different forces.