围产期反复感染对未成熟鼠脑发育的影响

Effect of perinatal recurrent infection on the brain development in immature mice

摘要:

目的 探讨围产期反复感染对未成熟脑发育的影响及相关机制.方法 将6只C57BL6 孕小鼠随机分为宫内感染组、反复感染组与正常对照组.母鼠于妊娠第18天单次腹腔注射LPS(0.5 mg/kg)制成宫内感染脑损伤模型;反复感染组取宫内感染母鼠所生仔鼠,于生后3~12 d每日腹腔注射单剂LPS(0.5 mg/kg)制成围产期反复感染脑损伤模型;对照组用等量生理盐水替代LPS在上述相同时间点给予母鼠和仔鼠腹腔注射.各组仔鼠于生后13 d分别评估早期神经行为改变.评估完成后处死取脑组织检测脑重变化;焦油紫染色进行神经病理学评估;Western blot检测肿瘤坏死因子-α(TNF-α)、半胱氨酸蛋白酶-3(Caspase-3)和髓鞘碱性蛋白(MBP)的表达变化.结果 与对照组和宫内感染组相比,围产期反复感染组仔鼠脑重下降(P<0.05),且表现出较为明显的神经病理学改变.Western blot结果显示反复感染组TNF-α和Caspase-3的表达水平均高于宫内感染组与正常对照组(均P<0.01);而MBP表达量却低于宫内感染组与正常对照组(P<0.01).神经行为学检测结果显示,生后13 d时反复感染组小鼠步态反射、翻正反射与负向趋地反射完成时间均长于宫内感染组与正常对照组(均P<0.05).结论 围产期反复感染加重未成熟脑组织内的炎症反应与神经细胞凋亡,是导致未成熟脑白质损伤的重要危险因素.

Abstract:

Objective To study the effects of perinatal recurrent infection on the brain development in immature mice. Methods Six pregnant C57BL6 mice were randomly assigned to three groups: intrauterine infection, perinatal recurrent infection and control. The intrauterine infection group was intraperitoneally injected with LPS (0.5 mg/kg) on the 18th day of pregnancy. The perinatal recurrent infection group was injected with LPS (0.5 mg/kg) on the 18th day of pregnancy and their offsprings were intraperitoneally injected with the same dose of LPS daily from postnatal day 3 to 12. The control group was administered with normal saline at the same time points as the recurrent infection group. The short-time neurobehaviors were assessed on postnatal day 13. The mice were then sacrificed to measure brain weights and neuropathological changes using cresyl violet staining. Western blot was used to evaluate the expression of TNF-α, Caspase-3 and myelin basic protein (MBP). Results The brain weights of the recurrent infection group were significantly lower than the control and intrauterine infection groups (P<0.05) and the recurrent infection group displayed significant neuropathological changes. Perinatal recurrent infection resulted in increased expression levels of TNF-α and Caspase-3, and decreased expression level of MBP compared with the intrauterine infection and control groups (P<0.01). The neurobehavior test showed that the recurrent infection group used longer time in gait reflex, right reflex and geotaxis reflex compared with the control and intrauterine infection groups on postnatal day 13 (P<0.05). Conclusions Perinatal recurrent infection may exacerbate inflammatory response and cell death in the immature brain, which may be one of the important factors for perinatal brain injury.