亚低温对颅脑损伤后脑血管内皮细胞紧密连接开放的影响

目的　观察颅脑损伤后早期亚低温治疗对脑毛细血管内皮细胞紧密连接开放的影响 ,阐明亚低温降低伤后血脑屏障通透性的可能机制。　方法　Wistar大鼠 90只 ,随机分为常温对照组 (10只 )、常温损伤组 (40只 )和亚低温治疗组 (40只 )。在镧示踪法电镜下分别观察亚低温及常温条件下颅脑损伤后内皮细胞紧密连接的开放及其程度 ;用干 -湿重法测定常温损伤组及亚低温治疗组伤后不同时相脑组织含水量并行统计学分析。　结果　常温损伤组伤后 3h紧密连接初步开放 ,2 4～ 4 8h紧密连接开放达高峰 ,72h紧密连接仍大量开放。亚低温治疗组紧密连接仅轻度开放 ;亚低温治疗组脑组织含水量较常温损伤组明显减少 ,伤后 3,2 4 ,72h差异有显著性意义(P <0 .0 5 ) ,伤后 4 8h差异有非常显著性意义 (P <0 .0 1)。　结论　亚低温有减轻颅脑损伤后血脑屏障毛细血管内皮细胞紧密连接的开放程度及减轻脑水肿的作用 ,亚低温减轻伤后内皮细胞紧密连接开放是降低伤后血脑屏障通透性机制之一。

Effect of mild hypothermia on the opening of tight junction of cerebral endothelial cells following traumatic brain injury

Objective To observe the effect of early mild hypothermia on the opening of tight junction of cerebral endothelial cells following traumatic brain injury in order to illustrate possible mechanism of low permeability of blood brain barrier (BBB) treated by mild hypothermia. Methods A total of 90 Wistar rats were randomly divided into normothermia control group (n=10),normothermia injury group (n=40) and mild hypothermia group (n=40). The opening state and its extent of tight junction were observed using lanthanum trace labeling with electron microscope. At the same time,water content of cerebral tissue at different phases in normothermia injury group and mild hypothermia group was measured by means of dry-wet weight and analyzed statistically. Results The tight junction was under preliminary opening three hours after trauma and reached the maximum opening within 24-48 hours after trauma,lasting for 72 hours in the normothermia injury group. However,slight opening appeared only in the mild hypothermia group. Water content of cerebral tissue in the mild hypothermia group lessened obviously in contrast to that in the normothermia injury group,with significant difference 3,24 and 72 hours after trauma ( P < 0.05) and with very significant difference 48 hours after trauma ( P < 0.01). Conclusions Mild hypothermia plays important role in alleviating tight junction opening of capillary endothelial cells of BBB and brain edema after trauma. Mild hypothermia alleviating tight junction opening of capillary endothelial cells is one of mechanisms of lowered permeability of BBB after trauma.