Ahlbom E, Grandison L, Zhivotovsky B, Ceccatelli S
Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden.
Endocrinology. 1998 May;139(5):2465-71. doi: 10.1210/endo.139.5.5985.
After lactation, there is a massive loss of pituitary lactotrophs. The aim of this study was to investigate the events and mechanisms involved in the remodeling of the anterior pituitary after termination of lactation. Animals were analyzed at day 7 of lactation and at 4 and 7 days after pup removal. Field-inversion gel electrophoresis was used to detect high-molecular-weight DNA fragments, a characteristic feature of apoptosis. Bax and Bcl-2, proteins involved in regulation of cell survival, were studied by immunohistochemistry and Western blot analysis. In addition, the expression of Bax, Bcl-2, Bcl-X(L), and p53 messenger RNA (mRNA) was analyzed by in situ hybridization. Four days after termination of lactation, a peak in high-molecular-weight DNA fragments and an increase in Bax, along with a decrease in Bcl-2 proteins, were observed, in comparison with lactation and with 7 days post lactation. The mRNAs for Bax and p53 also were increased, whereas no changes were detected in Bcl-2 and Bcl-X(L) mRNA levels. In summary, these findings indicate that the cell remodeling of the anterior pituitary, after the termination of lactation, occurs through the process of apoptosis and involves changes in Bax, Bcl-2, and p53.
哺乳期结束后，垂体催乳细胞大量减少。本研究的目的是调查哺乳期结束后垂体前叶重塑所涉及的事件及机制。在哺乳期第7天以及幼崽被移除后的第4天和第7天对动物进行分析。采用脉冲场凝胶电泳检测高分子量DNA片段，这是细胞凋亡的一个特征。通过免疫组织化学和蛋白质印迹分析研究参与细胞存活调节的蛋白质Bax和Bcl-2。此外，通过原位杂交分析Bax、Bcl-2、Bcl-X(L)和p53信使核糖核酸（mRNA）的表达。与哺乳期以及哺乳期后第7天相比，在哺乳期结束后第4天，观察到高分子量DNA片段出现峰值，Bax增加，同时Bcl-2蛋白减少。Bax和p53的mRNA也增加，而Bcl-2和Bcl-X(L)的mRNA水平未检测到变化。总之，这些发现表明，哺乳期结束后垂体前叶的细胞重塑是通过细胞凋亡过程发生的，并且涉及Bax、Bcl-2和p53的变化。
