Facultad de Medicina, Instituto de Investigaciones en Reproducción, Universidad de Buenos Aires, Paraguay 2155, Buenos Aires, Argentina.
Endocrine. 2011 Feb;39(1):21-7. doi: 10.1007/s12020-010-9407-4. Epub 2010 Nov 11.
We have previously reported that Fas activation induces apoptosis of anterior pituitary cells from rats at proestrus but not at diestrus and in an estrogen-dependent manner. In this study, we evaluated the effect of Fas activation on apoptosis of lactotropes and somatotropes during the estrous cycle and explored the action of gonadal steroids on Fas-induced apoptosis. Also, we studied whether changes in Fas expression are involved in the apoptotic response of anterior pituitary cells. Fas activation increased the percentage of TUNEL-positive lactotropes and somatotropes at proestrus but not at diestrus. FasL triggered apoptosis of somatotropes only when cells from ovariectomized rats were cultured in the presence of 17 β-estradiol (E2). Progesterone (P4) blocked the apoptotic action of the Fas/FasL system in lactotropes and somatotropes incubated with E2. Both E2 and P4 increased the percentage of cells expressing Fas at the cell membrane. Our results show that Fas activation induces apoptosis of lactotropes and somatotropes at proestrus but not at diestrus. Gonadal steroids may be involved in the apoptotic response of lactotropes and somatotropes, suggesting that Fas activation is implicated in the renewal of these pituitary subpopulations during the estrous cycle. The effect of gonadal steroids on Fas expression may be only partially involved in regulation of the Fas/FasL apoptotic pathway in the anterior pituitary gland.
我们之前曾报道过，Fas 激活以雌激素依赖的方式诱导发情前期大鼠垂体前叶细胞凋亡，但不在发情期诱导。在这项研究中，我们评估了 Fas 激活对发情周期中催乳素细胞和生长激素细胞凋亡的影响，并探讨了性腺类固醇对 Fas 诱导的凋亡的作用。此外，我们研究了 Fas 表达的变化是否参与了垂体前叶细胞的凋亡反应。Fas 激活增加了发情前期 TUNEL 阳性催乳素细胞和生长激素细胞的百分比，但在发情期则没有。只有当从卵巢切除大鼠的细胞在 17β-雌二醇（E2）存在的情况下培养时，FasL 才会引发生长激素细胞的凋亡。孕酮（P4）阻断了 E2 孵育的催乳素细胞和生长激素细胞中 Fas/FasL 系统的凋亡作用。E2 和 P4 均增加了表达 Fas 的细胞在细胞膜上的百分比。我们的结果表明，Fas 激活诱导发情前期催乳素细胞和生长激素细胞凋亡，但不在发情期诱导。性腺类固醇可能参与催乳素细胞和生长激素细胞的凋亡反应，提示 Fas 激活参与发情周期中这些垂体亚群的更新。性腺类固醇对 Fas 表达的影响可能仅部分参与调节垂体前叶中的 Fas/FasL 凋亡途径。
