摘要目的:探讨褪黑素（melatonin, MEL）对脂多糖（lipopolysaccharides，LPS）诱导的SD幼鼠大脑星形胶质细胞活化及远期焦虑样行为的影响。方法:将新生鼠随机（随机数字法）分为对照组（CON）组、LPS组、LPS+MEL组。LPS组：腹腔注射P1d幼鼠LPS(1 mg/kg)制作脓毒症模型，CON组仅注射等体积生理盐水，LPS+MEL组于建模0.5 h后注射MEL溶液10 mg/kg。在各组注射后不同时间点分为3 d、7 d、28 d三个亚组。免疫荧光染色和Western Blot法检测三组3 d、7 d后胼胝体内GFAP、TNF-α的表达变化；采用旷场实验检测28 d动物焦虑样行为。细胞实验以LPS（1 μg/mL）诱导原代星形胶质细胞为细胞模型, 随机分为对照组、LPS组、LPS+MEL组和LPS+MEL+褪黑素受体抑制剂（Luzindole，LUZ）组, 采用免疫荧光观察各组GFAP、TNF-α表达情况，Western Blot法检测GFAP、TNF-α、p-NF-κBp65、NF-κBp65蛋白表达，荧光定量PCR检测对照组、LPS组、LPS+MEL组神经营养因子GDNF、BDNF mRNA的表达。计量资料多组间比较采用单因素及双因素方差分析，以 P<0.05为差异有统计学意义。 结果:与CON组相比，LPS组中央区活动时间、中央路程/总路程比例下降，MEL干预可明显改善LPS组大鼠焦虑样行为；与LPS组相比，MEL组可降低LPS注射后3 d、7 d胼胝体内GFAP、TNF-α的表达（ P<0.05）。与LPS刺激组相比，MEL可降低星形胶质细胞GFAP、TNF-α、p-NF-κBp65的表达上调( P<0.05)，该效应可被LUZ所阻断( P<0.05)。此外，与LPS组相比，MEL预处理原代星形胶质细胞可逆转LPS诱发的GDNF、BDNF表达下调( P<0.05)。 结论:褪黑素可改善LPS诱导的脓毒症新生鼠远期焦虑样行为，其作用机制可能是通过NF-κB途径抑制星形胶质细胞活化及炎症反应有关。

abstractsObjective:To investigate the effect of melatonin (MEL) influence on lipopolysaccharide (LPS)-induced long-term anxiety-like behavior and activation of astrocytes in septic neonatal rats.Methods:Sprague-Dawley rats were randomly(random number) assigned to the control group, LPS group and LPS+MEL group. Sepsis model was intraperitoneally injected with LPS (1 mg/kg), and neonatal rats in the MEL group were administered with MEL (10 mg/kg) 30 min after LPS injection. At different time points after injection, rats in each group were divided into three subgroups: 3 d, 7 d and 28 d. The expression of GFAP and TNF-α in the corpus callosum was detected by immunofluorescence staining and Western blot. Open-field test was applied to observe anxiety-like behaviors. In vitro, cultured neonatal SD rat astrocytes were divided into the control group, LPS group, LPS+MEL group, and LPS+MEL+luzindole group. Immunofluorescence staining was used to observe the expression of GFAP and TNF-α. Expression of GFAP, TNF-α, p-NF-κBp65, NF-κBp65 protein in astrocytes were assessed by Western blot. RT-qPCR was used to investigate the mRNA expression of GDNF and BDNF. One-way ANOVA and two-way ANOVA were used for comparison of multiple groups of variables. A P<0.05 was considered statistically significant. Results:LPS reduced the duration of movement in the central area and distance in the central area/total distance in open-field test, while melatonin evidently reversed the LPS-induced anxiety-like behavior. Compared with the LPS group, the expressions of GFAP and TNF-α were significantly decreased in the corpus callosum at 3 d and 7 d in the MEL group ( P< 0.05). Compared with the LPS group, MEL could significantly decrease the expression of GFAP, TNF-α and p-NF-κBp65 in astrocytes ( P< 0.05), which could be blocked by Luzindole. In addition, compared with the LPS group, MEL pretreatment could reverse the down regulation of GDNF and BDNF induced by LPS ( P<0.05). Conclusions:MEL can relieve LPS-induced long-term anxiety-like behavior in septic neonatal rats. The mechanism may be related to the inhibition of astrocyte activation and inflammatory reaction through NF - κ B pathway.