Legrand P, Catheline D, Fichot M C, Lemarchal P
Laboratoire de Biochimie, Ecole Nationale Supérieure Agronomique, Rennes, France.
J Nutr. 1997 Feb;127(2):249-56. doi: 10.1093/jn/127.2.249.
The relationship between endogenous oleic acid produced by hepatic delta9-desaturase and the secretion of VLDL-triglycerides was investigated in a primary culture of chicken hepatocytes. When the fatty acid compositions of the secreted and intracellular triglycerides (TG) (or triacylglycerols) were compared, an imbalance between monoenes and saturated fatty acids was observed, with the secreted TG being significantly more unsaturated than the intracellular TG. The addition of a mixture of cyclopropenic fatty acids (specific inhibitors of fatty acid desaturation) to the culture medium of cells 24 h before measurement of their delta9-desaturase activity and TG secretion rate caused a significant impairment of both desaturase activity and TG secretion, without affecting total TG synthesis. However, the addition of oleic acid to the culture medium of cells treated with cyclopropenic fatty acids restored the TG secretion rate. Palmitic acid did not restore the TG secretion rate and linoleic acid partly restored the TG secretion rate. Finally, even in the presence of oleic acid in the culture medium of secreting cells, those which had been treated with cyclopropenic fatty acids had a significantly lower TG secretion rate than nontreated cells. Taken together, these results show that TG secretion is highly dependent on the delta9-desaturase activity and suggest that oversecretion of VLDL-TG in chickens and subsequent fattening could originate in a high hepatic delta9-desaturation of saturated fatty acids.
在鸡肝细胞原代培养中研究了肝脏Δ9-去饱和酶产生的内源性油酸与极低密度脂蛋白甘油三酯（VLDL-甘油三酯）分泌之间的关系。比较分泌型和细胞内甘油三酯（TG，即三酰甘油）的脂肪酸组成时，观察到单烯酸和饱和脂肪酸之间存在失衡，分泌型TG的不饱和程度明显高于细胞内TG。在测量细胞的Δ9-去饱和酶活性和TG分泌率前24小时，向细胞培养基中添加环丙烯脂肪酸混合物（脂肪酸去饱和的特异性抑制剂），导致去饱和酶活性和TG分泌均显著受损，但不影响总TG合成。然而，向用环丙烯脂肪酸处理的细胞培养基中添加油酸可恢复TG分泌率。棕榈酸不能恢复TG分泌率，亚油酸部分恢复TG分泌率。最后，即使在分泌细胞的培养基中存在油酸，用环丙烯脂肪酸处理过的细胞的TG分泌率仍显著低于未处理细胞。综上所述，这些结果表明TG分泌高度依赖于Δ9-去饱和酶活性，并提示鸡中VLDL-TG的过度分泌及随后的育肥可能源于肝脏中饱和脂肪酸的高Δ9-去饱和作用。
