孕期酒精暴露诱导神经鞘磷脂合成酶2基因敲除小鼠海马苔藓细胞凋亡

Prenatal alcohol exposure induces the mossy cell apoptosis in hippocampus of sphingomyelin synthase 2 knockout mice

目的探讨神经酰胺对孕期酒精暴露所诱导的小鼠神经细胞凋亡的影响。方法建立神经鞘磷脂合成酶2基因敲除(SMS2-/-)小鼠和野生型(WT)小鼠的孕期酒精暴露模型,将出生后的不同基因型仔鼠(共360只)分为对照组和酒精组。用酶学法检测生后0 d(P0)仔鼠血清神经鞘磷脂(SM)含量,利用免疫荧光染色法观察对照组与模型组各年龄点仔鼠齿状回苔藓细胞凋亡数量的变化,免疫印迹法检测P7、P14仔鼠海马组织Caspase-8、Caspase-3激活蛋白的相对表达量。结果酒精暴露后仔鼠血清SM水平降低,且具有剂量依赖性(F=41.08,P<0.05);SMS2-/-仔鼠血清SM水平低于同组WT仔鼠(F=53.34,P<0.01)。酒精诱导WT和SMS2-/-仔鼠苔藓细胞凋亡(F=15.61,P<0.05),有剂量依赖性和长时程效应,与同年龄、相同处理条件的WT仔鼠相比,SMS2-/-仔鼠苔藓细胞凋亡数量较多(F=11.72,P<0.05)。Western blotting检测结果与免疫荧光结果一致。结论 SMS2基因缺失使血清SM水平降低,可引起神经酰胺在体内蓄积;神经酰胺促进酒精暴露诱导神经细胞凋亡的过程;孕期酒精暴露主要通过死亡受体途径诱导神经细胞凋亡的发生。

Objective To investigate the role of eeramide regulation on the alcohol-induced neuronal cells apoptosis in mice. Methods Using sphingomyelin synthase 2 knockout （SMS_2^-/- ） mice and wide-type （WT） miee to establish the model of prenatal alcohol exposure. A total of 360 pups from control the group and ethyl alcohol （EtoH） treatment group was used in the study. The levels of serum sphingomyelin （SM） was detected with enzymatic method in P0. Apoptosis of mossy cells in hippocampus were investigated after alcohol exposure with immunofluorescent labeling. The expression of activated Caspase-8 and activated Caspase-3 in hippocampus were tested with Western blotting analysis. Results In WT and SMS_2^-/- mice, prenatal alcohol exposure down-regulated the SM levels with dose-dependency （F = 41.08, P〈0.05）. The SM level of serum in SMS_2^-/- pups was significantly lower than that of WT pups（F=53.34, P〈 0.01 ） In both WT and / number of SMS_2^-/-pups, the apoptosis moss cells in hippoeampus was increased after prenatal alcohol exposure with dose dependency （F = 15.61 , P 〈 0.05） , and then decreased with the growing age. However, compared with the WT pups, the number of apoptosis neurons in hippocampus of SMS_2^-/-pups increased more than WT mice （ F = 11.72, P 〈 0. 05 ）. Western blotting supported the results of immunofluoreseent labeling. Conclusion The reduction of SM level in SMS_2^-/- mice leads to the ceramide aceumulation in brain tissue. Ceramide is involved in prenatal alcohol exposed neuronal apoptosis in the process, and may promote apoptosis. Alcohol exposure during pregnancy, mainly through the death receptor pathway, induces neuronal apoptosis.