潜艇脱险中极快速减压后大鼠小胶质细胞与神经元凋亡的变化

Apoptosis of microglia and neurons in rats following hazardous fast decompression simulating escape from submerged submarine

目的研究成年大鼠极快速减压致中枢神经损伤后脑组织内小胶质细胞的变化及其与损伤后神经元凋亡的关系。方法采用1MPa暴露5·5min、50s快速减压制备SD大鼠中枢减压损伤模型,在减压后6、24、48、72h取材,分别用FITC标记的凝集素B4(IB4)标记小胶质细胞和原位末端TUNEL法标记凋亡神经元细胞。结果快速减压后6h组可见少量IB4阳性小胶质细胞;24h组达高峰(P<0·01);48h组阳性小胶质细胞数量有所下降,但仍高于6h组(P<0·01);72h组阳性小胶质细胞数量明显下降。6h组仅见少量散在TUNEL阳性细胞;48h组达高峰(P<0·01);72组阳性细胞数量有所下降,但仍高于6h组(P<0·01)。凝集素阳性小胶质细胞分布区域与神经元凋亡分布区域一致,达到高峰的时间前者先于后者,两者的变化趋势相同(r=0·645,P<0·01)。结论不安全极快速减压致中枢型减压病的中枢神经损伤中存在神经元凋亡和小胶质细胞的活化,激活的小胶质细胞可能参与了快速减压后的神经元凋亡过程。

Objective To investigate the relationship of apoptosis of microglia and neuron in adult rats following fast decompression. Methods A model of decompression sickness in rat was reproduced by exposure to 1MPa 5.5min followed by rapid decompression （50s）. Brain tissues were collected at Oh, 6h, 24h, 48h and 72h after decompression. The microglia were examined after histochemical staining with FITC-conjugated Isolectin-B4. Cell apoptosis was detected by in situ end labeling TUNEL methods. Results A few IB4-positive microglia could be seen in the brain tissue collected 6h after decompression, and the number of lB4-positive microglia was greatest at 24h （P〈0. 01）, and it decreased at 48h （still higher than that at 6h, P〈0. 01）, restored in 72h. There were a few TUNEL positive cells in brain tissue 6h after decompression, their number peaked in 48h （P〈0. 01）, then it decreased at 72h, but it was still more than that at 6h （P〈0. 05）. The apoptosis cells appeared to be neurons by their morphology. The IB4 positive microgIia and the apoptosis neurons were located in the same region in the brain, having a similar trend of changes, though the former change preceded that of the latter. There was positive correlation between them. Conclusion Apoptosis of the neurons and active microglia appeared in the process of the brain injury, and they were induced by hazardous fast decompression. The active microglia may play an important role in apoptosis of neurons after fast decompression.