摘要目的 探讨轻度低温对脓毒症模型大鼠脓毒症相关性脑病的保护作用,并寻找合适的轻度低温时间. 方法164只雄性SD大鼠行盲肠结扎穿孔术或假手术后分为假手术组(Sham组,20只)和手术组,根据维持温度及时间将手术组分为常温组[Norm组,(37.0±0.2)℃,43只]和轻度低温组[(34.0±0.5)℃,轻度低温6 h组(Hypo 6组,41只),轻度低温12 h组(Hypo 12组,33只),轻度低温24 h组(Hypo 24组,27只)].手术前10 d,大鼠头部放置电极.每只大鼠分别在术前及术后24 h行脑电图及神经生物学监测,术后24 h处死大鼠采血行ELISA检测血浆中S100β蛋白表达以判断脑损伤程度. 结果每组最终存活大鼠20只,其中Sham组、Norm组、Hypo 6组、Hypo 12组、Hypo 24组存活率分别为100%(20/20)、46.51%(20/43)、48.78%(20/41)、60.61%(20/33)、74.07%(20/27).与Sham组比较,其余各组存活率明显降低(P<0.05),手术组中,Hypo 24组存活率明显高于Norm组和Hypo 6组,差异有统计学意义(P<0.05).存活大鼠术后24 h神经生物学评分,手术组大鼠均明显低于Sham组(P<0.05);手术组中,Hypo 24组神经生物学评分明显高于Norm组及Hypo 6组(P<0.05),但与Hypo 12组比较,差异无统计学意义(P＞0.05),Hypo 12组与Norm组及Hypo 6组比较,差异无统计学意义(P＞0.05).手术组大鼠脑电图δ波百分比及血浆中S100β蛋白含量均明显高于Sham组(P<0.05).在手术组中,脑电图δ波百分比及血浆中S100β蛋白含量两项指标Hypo 24组分别与Norm组、Hypo 6组比较,差异有统计学意义(P<0.05),与Hypo 12组比较,差异无统计学意义(P＞0.05),Hypo 12组分别与Norm组、Hypo 6组比较,差异无统计学意义(P＞0.05).根据神经生物学评分、脑电图监测判断,Norm组、Hypo 6组、Hypo 12组、Hypo 24组存活大鼠分别有13、13、11、8只大鼠出现脓毒症相关性脑病,在存活大鼠中发生率分别为65%、65%、55%、40%,与Sham组比较,差异有统计学意义(P<0.05);手术组各组间发病率差异无统计学意义(P＞0.05). 结论 轻度低温不能够降低脓毒症大鼠脓毒症相关性脑病的发病率,可减轻脓毒症大鼠的脑损伤程度,且随着轻度低温时间的延长作用更明显,具有一定脑保护作用.

abstractsObjective To investigate the protective effect of mild hypothermia on septic rats and to find suitable hypothermia duration time. Methods After cecal ligation and puncture (or sham), male Sprague-Dawley rats were divided into a sham operation group (Sham group, n=20), a normal temperature group [Norm group, (37.0±0.2) °C, n=43], and hypothermia group (34.0±0.5) °C[a hypothermia 6 h group (Hypo 6 group, n=41), a hypothermia 12 h group (Hypo 12 group, n=33), a hypothermia 24 h group (Hypo 24 group, n=27)], and the electrodes were placed on the head 10 days before the operation. Electrocardiogram (EEG) and behavioral tests were performed before and 24 h after surgery. The blood samples were collected 24 h after surgery. The blood levels of S100β protein were detected by enzyme-linked immunosorbent assay (ELISA) to determine the degree of brain damage. Results Twenty rats in each group survived. The survival rates of Sham group, Norm group and Hypo 6, 12 and 24 groups were 100% (20/20), 46.51% (20/43), 48.78% (20/41), 60.61% (20/33) and 74.07% (20/27), the survival rate of Hypo 24 group was significantly higher than that of Norm group and Hypo 6 group (P<0.05), no significantly difference was found when compared with Hypo 12 group (P＞0.05). Compared with the Sham group, rats in Norm group and Hypo groups presented remarkably lowerd neurobiological scores 24 h after surgery (P<0.05). Meanwhile, markly higher neurobiological scores were found in the Hypo 24 group, compared with those in the Norm group and Hypo 6 group (P<0.05), there was no significantly difference when compared with Hypo 12 group (P＞0.05), and no significant difference was found between Hypo 12 and Hypo 6 groups (P＞0.05). Compared with the sham groups, remarkly higher levels of plasma S100β protein and EEG δ waves were detected in the operation group (P<0.05), in the operation group, the amount of S100β and EEG δ waves in Hypo 24 group was significantly lower than those in Norm group and Hypo 6 group (P<0.05), There was no significantly difference when compared with Hypo 12 group (P＞0.05), and no significant difference between Hypo 6 and Hypo 12 groups (P＞0.05). According to the biological score and EEG monitoring results, sepsis-associated encephalopathy was was detected in 13 (65%), 13 (65%), 11 (55%), and 8 (40%) rats in the Norm group, Hypo 6, 12, 24 groups, and no statistically significant differences in the incidence was found among the groups (P＞0.05). Conclusions Although mild hypothermia cannot reduce the incidence of sepsis-associated encephalopathy in rats with sepsis, it can reduce there brain damage, and protect the brain as hypothermia time extends.