脂质过氧化在胰腺纤维化形成中的作用

The role of lipid peroxidation in formation of pancreatic fibrosis.

目的研究脂质过氧化对胰腺星状细胞（pancreatic stellate cells，PSC）活化的影响及其在胰腺纤维化形成中的作用。方法实验大鼠每周2次腹腔内注射二乙基二硫代氨基甲酸盐（diethyldithiocarbamate，DDC），共10周建立胰腺纤维化模型。分别于注射后第2，4，6，8，10周处死大鼠，检测胰腺组织中丙二醛（MDA）含量，各时间点胰腺组织a-平滑肌肌动蛋白（a—SMA）、转化生长因子-β1（TGF-β1）的表达，逆转录聚合酶链反应（RT—PCR）检测α1-Ⅰ型胶原（Col Ⅰ α1）、TGF-β1 mRNA水平。结果注射DDC后，胰腺组织内MDA含量逐步升高，8周时高达（6．21±0．70）nmol／mg prot（P〈0．01）。4周时可见明显的细胞外基质沉积和纤维化形成，8周时小叶及小叶内广泛纤维化，大量腺体萎缩，形成瘢疤组织。α-SMA、TGF-β1的阳性表达在2周时已出现，4周时明显增加，且阳性细胞多位于胰腺小叶间及腺泡旁纤维化区域。胰腺组织Col Ⅰ α1mRNA在造模2周时少量表达，4周表达增加，8周后维持在较高水平；对照组TGF-β1mRNA表达水平较低，TGF-β1mRNA在造模4周时表达明显增强，与对照组相比有显著性差异（P〈0．05），6周后表达增加不明显。结论随着造模时间的延长，胰腺组织MDA含量的增加与胶原纤维形成、TGF-β1表达及活化PSC的增加相一致，提示脂质过氧化产物通过激活PSC及刺激TGF-β1的分泌，增加胰腺组织中胶原的沉积，促进胰腺纤维化的形成。

Objective To clarify the effect of lipid peroxidation on activation of pancreatic stellate cells （PSC） and its role in the formation of pancreatic fibrosis. Methods Wistar rats were randomly divided into 2 groups., model group and normal group. Rats in the model group were injected intraperitoneally with diethyldithiocarbamate （DDC） twice every week for 10 weeks, and rats in the normal group were injected with 0. 9% sodium chloride solution. Rats were sacrificed at 2, 4, 6, 8 and 10 weeks after drug administration. The content of pancreatic malondialdehyde （MDA） was measured by the thibabituric acid method. Expression of α-smooth muscle actin （α-SMA） was detected by immunohistochemistry, and expression of collagen Ⅰ α1 mRNA and transforming growth factor-β （TGF-β1） was detected by RT-PCR at each time point. Results The MDA content increased progressively after drug administration, and 4 weeks later, deposition of extracellular matrix （ECM） and formation of fibrosis were visible. The peak time was at the 8th week. Immunohistochemistry showed that the number of cells expressing α-SMA and TGF-β1 increased significantly, and these cells located at fibrotic areas principally at the 4th week. The results of RT-PCR showed that there was a little expression of TGF-β1 and Col Ⅰ α1 mRNA in the normal group, and the expression level increased significantly at the 4th week. Conclusions The content of pancreatic MDA was consistent with increase of fibrogenesis and activation of PSC. The production of lipid peroxidation may promote deposition of collagen and formation of fibrosis by stimulating the activation of PSC and the secretion of TGF-β1.