Colitti M, Stradaioli G, Stefanon B
Department of Animal Production Sciences, Faculty of Veterinary Medicine, University of Udine, Italy.
J Dairy Sci. 2000 Feb;83(2):345-50. doi: 10.3168/jds.S0022-0302(00)74885-5.
The objective of this study was to investigate the effect of alpha-tocopherol deprivation on mammary gland involution and apoptosis in sheep. Two groups of four single lamb ewes were used. The control group received 100 mg/d of RRR-alpha-tocopherol supplementation and the experimental group received no vitamin E supplementation. After 3 mo of suckling, ewes were dried off, and blood samples from the jugular vein and tissue biopsies from the mammary gland were collected at d 1, 3, 5, and 8 after dry-off. The experimental group had lower plasma concentrations of alpha-tocopherol (1.8 vs. 4.2 micromol/L), lower glutathione peroxidase activity in erythrocytes, and higher concentration of malondialdehyde in plasma than the control group. Immunohistochemical analysis of tissue samples resulted in marked differences of bcl-2 and bax protein expressions during involution and between groups. The bax expression was decreased by alpha-tocopherol deprivation at 1, 3, and 5 d, but not at 8 d, while the bcl-2 score was higher only at 8 d (1.5 vs. 0.0 for experimental and control groups, respectively). As a result, the bcl-2 to bax ratios were increased for the experimental group at 1 and 8 d. During involution, apoptotic counts increased (from 0.12 to 4.06%), but no effects were detected in relation to bcl-2 to bax ratio and alpha-tocopherol. These results indicate that alpha-tocopherol can control bcl-2 expression, but not apoptosis in cells of the mammary gland during involution.
本研究的目的是调查α-生育酚缺乏对绵羊乳腺退化和细胞凋亡的影响。使用了两组，每组四只单羔母羊。对照组每天补充100毫克RRR-α-生育酚，实验组不补充维生素E。哺乳3个月后，母羊停止哺乳，并在停止哺乳后的第1、3、5和8天采集颈静脉血样和乳腺组织活检样本。实验组的α-生育酚血浆浓度较低（1.8对4.2微摩尔/升），红细胞中的谷胱甘肽过氧化物酶活性较低，血浆中的丙二醛浓度高于对照组。组织样本的免疫组织化学分析显示，在退化过程中以及两组之间，bcl-2和bax蛋白表达存在显著差异。在第1、3和5天，α-生育酚缺乏会使bax表达降低，但在第8天不会，而bcl-2评分仅在第8天较高（实验组和对照组分别为1.5对0.0）。结果，实验组在第1天和第8天的bcl-2与bax比值增加。在退化过程中，凋亡细胞计数增加（从0.12%增至4.06%），但未检测到与bcl-2与bax比值和α-生育酚相关的影响。这些结果表明，α-生育酚可以控制bcl-2的表达，但在退化过程中对乳腺细胞的凋亡没有影响。
