巨噬细胞与坐骨神经非冻结性冷损伤

The analysis of macrophages in non-freezing cold Injury of the sciatic nerves

目的观察非冻结性冷损伤后坐骨神经超微结构的动态变化,探讨炎性细胞在神经损伤中的作用。方法 20只雄性wistar大鼠随机分成持续低温组与间断低温组。每只大鼠一侧坐骨神经给予低温作用,另一侧坐骨神经作为常温对照。持续低温组给予坐骨神经3～5℃,2小时低温处理;间断低温组给予3～5℃,1小时低温处理,待其恢复体温1小时后,再次给予3～5℃,1小时低温处理。冷损伤后1天、3天时分别观察坐骨神经超微结构变化及炎性细胞活动。结果①持续冷损伤后1天,坐骨神经多数有髓纤维即发生"空轴索"改变;无髓纤维基本正常。神经内膜血管内皮肿胀管腔狭窄,管腔内未见血小板激活与红细胞淤滞;②持续冷损伤后3天,有髓纤维病变继续加重,而无髓纤维仍保持正常。神经内膜血管病变同前;③间断冷损伤后1天,有髓纤维病变的同时伴随少量无髓纤维退变。第3天时观察到巨噬细胞侵犯、吞噬有髓纤维。结论非冻结性冷损伤时温度波动可以增强血液再灌注,加速氧自由基的产生,这可能是间断低温后出现巨噬细胞活动的主要原因,它将使坐骨神经有髓纤维变性更加严重。

Objective We observed the ultrastructural change of rat＇s sciatic nerves in non-freezing cold injury by electron microscope, and discuss the effect of inflammatory cell on nerve injury. Methods 20 male wistar rats were randomly divided into continuous cooling group and intermittent cooling group. One side of sciatic nerves was cooled, and the other side was control. The sciatic nerves of the continuous group received 3-5℃ for 2 hours. Those of the intermittent cooling group received 3-5℃ for 1 hour, after rewarming to normal body temperature for 1 hour, and then received 3-5℃ for 1 hour again. The bilateral sciatic nerves of each group were harvested on the 1st and 3rd day after cooling. The ultrastructure of nerves were examined by electron microscopy. Results On the 1st day after 2 h of continuous cooling, most of the myelinated fibres in sciatic nerves showed ＂empty＂ axons, with normal unmyelinated fibres. On the 3rd day, myelinated fibre degeneration became more widespread with normal unmyelinated fibres. The vasculature was similar to that of the 1st day. In the intermittent cooling group, degenerative myelinated and unmyelinated fibers could be seen on the 1st day. Until the 3rd day, myelinated fibres were damaged and phagocytosed by macrophages. Conclusion Temperature fluctuation can enhance reperfusion injury and accelerate the formation of oxygen free radical. It may be the main reason for macrophages activation, and then promote degeneration in myelinated fibres of sciatic nerves.