细菌脂多糖联合高体积分数氧对未成熟大鼠脑发育的影响

摘要

Objective To investigate the effects of lipopolysaccharide (LPS) and / or normobaric hyperoxia on brain development of neonatal rat and the possible mechanisms.Methods One hundred and twenty postnatal day 2 (P2) SD rats were randomly assigned into 4 groups:air group,LPS group,hyperoxia group,LPS + hyperoxia group.General condition and body weight of the rats in each group were observed and recorded every day.The expression of active Caspase-3 and nuclear factor-κappaB P65 (NF-κB P65) in the brain were detected by immunohistochemistry staining on P7,and the level of IL-6 and 8-iso-PGF2α in the brain homogenate were measured by enzyme-linked immunosorbent assay(ELISA).The expression of myelin basic protein (MBP) in the brain was detected by immunohistochemistry staining on P12.Results The expressions of Caspase-3 and NF-κB P65 had the same trends:the number of positive cells from high to low was in LPS + hyperoxia group,LPS group/hyperoxia group,air group.There were significant differences between the first three groups and air group(all P ＜ 0.05).There were also significant differences between LPS + hyperoxia group and LPS group or hyperoxia group(all P ＜0.01).MBP in the brain had the completely reverse expression:from high to low order was in air group,hyperoxia group,LPS group,LPS + hyperoxia group.There were significant differences between the last three groups and air group (all P ＜ 0.05).There were also significant differences between LPS + hyperoxia group and LPS group or hyperoxia group(all P ＜0.01).The level of IL-6 in the brain from high to low order respectively was in LPS + hyperoxia group,LPS group,hyperoxia group,air group;and 8-iso-PGF2α was also in LPS + hyperoxia group,hyperoxia group,LPS group,air group,Significant differences were found among the four groups (all P ＜ 0.05).Conclusions Both postnatal infection and normobaric hyperoxia may induce premature rat brain injury,and increase the number of apoptosis cell and reduce the expression of MBP.The combination of infection and normobaric hyperoxia may aggravate the degree of brain damage of neonatal rat.NF-κB pathway mediated by Toll-like receptor may be involved in inflammation and oxidative stress,and may mediate Caspase-3 related apoptosis of nerve cell and white matter injury.%目的 探讨细菌脂多糖(LPS)、高体积分数氧(高氧)单独或联合应用对新生大鼠脑发育的影响及其相关机制.方法 2日龄(P2)新生SD大鼠120只随机分为4组:空气组、LPS组、高氧组、LPS+高氧组,分别观察各组大鼠的一般情况,记录其每日体质量.7日龄(P7)时,免疫组织化学法检测各组大鼠脑组织中半胱氨酸天冬氨酸蛋白酶3(Caspase-3)、核转录因子P65(NF-κB P65)的表达情况,ELISA法检测各组大鼠脑组织中IL-6、8-异-前列腺素F2α(8-iso-PGF2α)水平；12日龄(P12)时,免疫组织化学法检测各组大鼠脑组织碱性髓鞘蛋白(MBP)的表达.结果不同处理组中Caspase-3及NF-κB P65表达水平高低依次为LPS+高氧组、LPS组/高氧组、空气组,前3组与空气组相比差异均有统计学意义(P均＜0.05),且LPS+高氧组与高氧组、LPS组相比差异亦均有统计学意义(P均＜0.01)；MBP的表达水平高低依次为空气组、高氧组、LPS组、LPS+高氧组,后3组与空气组相比差异均有统计学意义(P均＜0.05),且LPS+高氧组与高氧组、LPS组相比差异亦均有统计学意义(P均＜0.01).各组新生大鼠IL-6表达水平高低依次为LPS+高氧组、LPS组、高氧组、空气组；8-iso-PGF2α表达水平高低依次为LPS+高氧组、高氧组、LPS组、空气组,而且各组之间比较差异均有统计学意义(P均＜0.05).结论 感染及高氧均可致新生大鼠脑损伤,导致神经细胞凋亡和MBP表达减少,且感染与高氧同时存在时能加重二者单独作用时脑损伤的程度.其机制可能为炎性反应及氧化应激通过Toll样受体后发生协同作用,激活核转录因子NF-κB P65,并通过Caspase-3介导神经细胞凋亡及脑白质损伤.