褪黑素对新生大鼠缺氧缺血性脑损伤时免疫功能的影响

Effect of melatonin on immune function of neonatal rats with hypoxic-ischemic brain damage

目的:探讨新生大鼠缺氧缺血性脑损伤(hypoxic-ischemic brain damage,HIBD)时脾脏中肿瘤坏死因子α(TNF-α),白细胞介素6(IL-6)表达的变化及外源性褪黑素(MT)对其产生的影响。方法:选用7日龄的Sprague-Dawley大鼠,随机分为生理对照组、假手术组、模型组(HIBD组)、MT治疗组。建立新生鼠HIBD模型后,于不同时间点取脾脏组织,使用逆转录聚合酶链式反应(RT-PCR)的方法,对脾脏中TNF-α、IL-6、褪黑素受体1(MT1)mRNA的表达进行半定量检测。结果:假手术组脾脏TNF-α、IL-6、MT1的mRNA表达在24 h内均无显著变化,与生理对照组相比差异无统计学意义。HIBD组和MT治疗组TNF-α的mRNA表达在2 h升高,8 h达到高峰,随后下降,24 h内均显著高于假手术组(P<0.01),MT治疗组在24 h内各时间点TNF-αmRNA的表达均显著低于HIBD组(P<0.01)。HIBD组脾脏中IL-6的mRNA表达在8 h开始上升,24 h升高更显著。MT治疗组中脾脏IL-6 mRNA的表达在24 h内不断升高,各时间点均显著高于HIBD组(P<0.01)。脾脏中MT1的表达在HIBD组未见明显变化,而在MT治疗组,MT1在2 h较HIBD组明显下降(P<0.01),在4 h降至最低,8 h开始回升。结论:新生大鼠缺氧缺血性脑损伤时,脾脏TNF-α,IL-6的表达上调,而褪黑素可以抑制TNF-α的表达而增加IL-6的表达,缺氧缺血性脑损伤对脾脏褪黑素受体的表达没有显著影响,而外源性褪黑素对褪黑素受体mRNA的表达有下调作用。

Objective：To explore the changes of expressions of tumor necrosis factor-α（TNF-α） and interleukin 6（IL-6） in spleen of neonatal rats with hypoxic-ischemic brain damage（HIBD） and the effect of exogenous melatonin on them.Methods：7-day-old Sprague-Dawley rats were divided into physiological control group,sham operation group,model group（HIBD group） and melatonin treatment group randomly;the splenic tissues were obtained at different time points after establishing neonatal rat models of HIBD;reverse transcriptase-polymerase chain reaction（RT-PCR） was used to detect the expressions of TNF-α,IL-6 and melatonin receptor l（MT1） mRNA semiquantitatively.Results：There was no obvious changes in expressions of TNF-α,IL-6 and MT1 mRNA in sham group within 24 hours,compared with physiological control group,there was no significant difference;in HIBD group and melatonin treatment group,the expression of TNF-α mRNA increased at 2 hours,peaked at 8 hours,and then decreased,the expression levels of TNF-α mRNA within 24 hours in HIBD group and melatonin treatment group were significantly higher than that in sham group（P0.01）;the expression levels of TNF-α mRNA at all time points within 24 hours in melatonin treatment group were significantly lower than those in HIBD group（P0.01）;in HIBD group,the expression of IL-6 mRNA increased at 8 hours,and peaked at 24 hours;in melatonin treatment group,the expression of IL-6 mRNA increased uninterruptedly within 24 hours,the expression levels of IL-6 mRNA at all time points within 24 hours in melatonin treatment group were significantly higher than those in HIBD group（P0.01）;in HIBD group,there was no obvious changes in expression of MT1 in splenic tissues,but in melatonin treatment group,the decrease amplitude of MT1 within 2 hours was larger than that in HIBD group（P0.01）,the expression of MT1 decreased to minimum level,and then rose again at 8 hours.Conclusion：The expression levels of TNF-α and IL-6 in spleen increase in neonatal rats with HIBD,melatonin can inhibit the expression of TNF-α and promote the expression of IL-6,HIBD has no significant effect on expression of MT1,but exogenous melatonin can down-regulate the expression of MT1 mRNA.