维生素E类似物对NEFA处理的奶牛乳腺上皮细胞乳脂乳蛋白合成和氧化应激的影响

Effects of vitamin E analogs on milk fat and milk protein synthesis and oxidative stress in NEFA-treated cow mammary epithelial cells

应用高浓度非酯化脂肪酸(non-esterified fatty acids,NEFA)处理MAC-T细胞并添加α生育酚,采用Western blot技术检测乳脂乳蛋白合成相关关键蛋白的表达,并利用生化试剂盒检测细胞中TG和MDA含量,通过酶活试剂盒检测细胞SOD、CAT和GSH-Px酶活性。结果显示,在1.2 mmol/L NEFA作用下,MAC-T细胞β-casein蛋白表达以及乳蛋白合成相关蛋白mTor和S6K1磷酸化水平降低,细胞TG含量和合成相关蛋白SREBP1蛋白表达升高,同时氧化产物MDA含量升高,抗氧化酶SOD、CAT和GSH-Px活性降低,表明高浓度NEFA可以诱导奶牛乳腺上皮细胞发生氧化应激,并抑制乳蛋白合成,促进乳脂合成。用1.2 mmol/L NEFA处理细胞并添加10μmol/Lα生育酚,发现α生育酚可以缓解NEFA导致的β-casein蛋白水平下降,恢复mTor和S6K1磷酸化水平,降低细胞TG含量和SREBP1蛋白表达。同时,α生育酚还可以降低细胞MDA含量,升高SOD、CAT和GSH-Px的活性。结果表明,维生素E类似物可以降低高NEFA引起的乳腺上皮细胞氧化应激水平,缓解NEFA对乳脂乳蛋白合成的影响。

MAC-T cells were treated with high concentrations of non-esterified fatty acids(NEFA)andα-tocopherol.Western blot was used to detect the expression of key proteins related to milk fat and milk protein synthesis.Biochemical kits were used to detect the contents of TG and MDA,and enzyme activity kits were used to detect SOD,CAT and GSH-Px enzymatic activities.Results showed that compared with control group,the protein abundance ofβ-casein,the phosphorylation levels of milk protein synthesis related proteins mTor and S6K1 were lower in the 1.2 mmol/L NEFA group,and the content of TG and the protein abundance of milk fat synthesis related protein SREBP1 were higher.Furthermore,the content of MDA was significantly increased in the 1.2 mmol/L NEFA group,but the activities of antioxidant enzymes SOD,CAT and GSH-Px were decreased.The above results indicated that high concentrations of NEFA could induce oxidative stress in cow mammary epithelial cells,inhibit milk protein synthesis,and promote milk fat synthesis.Importantly,loμmol/Lα-tocopherol could alleviate the decrease ofβ-casein protein abundance caused by NEFA,restore the phosphorylation levels of mTor and S6K1,and reduce the protein expression of SREBP1 and TG content in cells.Also,α-tocopherol could reduce the content of MDA and increase the activities of SOD,CAT and GSH-Px in MAC-T cells.In conclusion,vitamin E analogs can reduce the oxidative stress and alleviate the disorder of milk fat and milk protein synthesis caused by high NEFA in mammary epithelial cells.