Attenuation of alcohol-induced apoptosis of hepatocytes in rat livers by polyenylphosphatidylcholine (PPC).
Attenuation of alcohol-induced apoptosis of hepatocytes in rat livers by polyenylphosphatidylcholine (PPC).
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DOI：
10.1111/j.1530-0277.2000.tb04592.x
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发表时间：
2000-02
期刊：
影响因子：
--
通讯作者：
Li Mi;K. Mak;C. Lieber
中科院分区：
文献类型：
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作者：
Li Mi;K. Mak;C. Lieber
饮酒增加肝细胞凋亡。这种作用似乎是通过诱导肝细胞色素P-4502 E1（CYP 2 E1）及其产生自由基介导的，这导致脂质过氧化作用增强，从而启动细胞凋亡。因为多烯磷脂酰胆碱（PPC），大豆提取物中富含多不饱和磷脂酰胆碱，减少乙醇特异性CYP 2 E1的诱导，并对抗氧化应激，我们假设PPC补充可能会减弱乙醇摄入引起的肝细胞凋亡。方法28只雄性Sprague道利大鼠，采用Lieber-DeCarli流质饲料喂养，含36%能量的酒精或等热量的碳水化合物。一半的大鼠被给予PPC（3克/升），而另一半则接受相同数量的亚油酸酯（作为红花油）和胆碱作为酒石酸氢盐。在取出肝脏前90分钟，灌胃给予额外剂量的酒精（3 g/kg）。我们通过TUNEL（末端转移酶dUTP缺口末端标记）分析评估福尔马林固定、石蜡包埋的肝切片中的细胞凋亡。凋亡肝细胞通过阳性TUNEL染色结合核质浓缩或染色质边集来鉴定。在每只大鼠中，使用Image-Pro Plus计算机软件通过光学显微镜计数20，000至60，000个肝细胞，并将细胞凋亡的发生率表示为总肝细胞的百分比。结果：与对照组大鼠相比，酒精喂养导致肝细胞凋亡增加4.5倍; PPC补充剂使酒精诱导的细胞凋亡减少到不到一半。在无酒精的情况下，对照组和补充PPC的大鼠之间的细胞凋亡发生率没有差异。对照组大鼠肝小叶内细胞凋亡呈随机分布，而酒精诱导的细胞凋亡在小静脉周围区明显增加。PPC补充剂显著降低了这种影响。结论PPC可抑制乙醇诱导的肝细胞凋亡，其机制可能与其抑制乙醇诱导的CYP 2 E1诱导的抗氧化作用有关。
BACKGROUND Alcohol consumption increases apoptosis of hepatocytes. This effect appears to be mediated by the induction of hepatic cytochrome P-4502E1(CYP2E1) and its generation of free radicals, which results in an enhanced lipid peroxidation that initiates apoptosis. Because polyenylphosphatidylcholine (PPC), a soybean extract rich in polyunsaturated phosphatidylcholines, decreases the induction of ethanol-specific CYP2E1 and opposes oxidative stress, we hypothesized that PPC supplementation may attenuate hepatocyte apoptosis caused by ethanol ingestion. METHODS Twenty-eight male Sprague Dawley rats were pair-fed Lieber-DeCarli liquid diets containing 36% of energy as alcohol or an isocaloric amount of carbohydrate for 28 days. Half of the rats were given PPC (3 g/liter), whereas the other half received the same amount of linoleate (as safflower oil) and of choline as the bitartrate. An additional dose of alcohol (3 g/kg) was given intragastrically 90 min before the livers were removed. We assessed apoptosis in formalin-fixed, paraffin-embedded liver sections by using the TUNEL (terminal transferase dUTP nick end labeling) assay. Apoptotic hepatocytes were identified by positive TUNEL staining in conjunction with condensation of nucleoplasm or margination of chromatin. In each rat, 20,000 to 60,000 hepatocytes were counted by light microscopy by using Image-Pro Plus computer software, and the incidence of apoptosis was expressed as the percentage of total hepatocytes. RESULTS Alcohol feeding resulted in a 4.5-fold increase in apoptosis of hepatocytes compared to pair-fed control rats; PPC supplementation decreased the alcohol-induced apoptosis to less than half. No difference in the incidence of apoptosis between the control and PPC-supplemented rats was found in the absence of alcohol. Apoptosis was distributed randomly in the liver lobules of the rats fed the control diet, whereas the alcohol-induced apoptosis was significantly increased in the perivenular area. PPC supplementation strikingly reduced this effect. CONCLUSIONS PPC attenuates alcohol-induced apoptosis of hepatocytes; this effect may provide a mechanism for PPC's protection against liver injury, possibly in association with its antioxidative action via the down-regulation of ethanol-mediated CYP2E1 induction.