Sharma K, Mehra Raj D
Department of Anatomy, All India Institute of Medical Sciences, Ansari Nagar, New Delhi-110029, India.
Brain Res. 2008 Apr 14;1204:1-15. doi: 10.1016/j.brainres.2008.01.080. Epub 2008 Feb 12.
Recently we reported that chronic treatment with 17beta-estradiol (E2) or tamoxifen (TAM) regulates the ovariectomy-induced downregulation of the key molecules linked to hippocampal synaptic plasticity and signal transduction pathway. We now report modulation of the antiapoptotic (Bcl-2) and proapoptotic (Bax) proteins in the hippocampus of both the ovariectomized (OVX) rats as well as those given E2 or TAM subcutaneously as a daily dose for four weeks post-ovariectomy. Forty bilaterally OVX animals were divided into four groups of 10 each, namely i) OVX+E2 (0.1 mg/kg body weight), ii) OVX+TAM (0.05 mg/kg body weight), iii) OVX+vehicle (0.1 ml of sesame oil) and iv) OVX controls. An additional group of 10 animals constituted the ovary intact controls. Following culmination of treatment regimen, brain tissues of five animals from each group were processed for immunohistochemical staining of Bcl-2 and Bax on perfusion fixed cryo-sections. The remaining animals in each group were utilized for protein and Western blot analyses using unfixed hippocampal tissue. The results revealed that chronic administration of both E2 and TAM prevented the ovariectomy-induced downregulation of Bcl-2 and upregulation of Bax expression while restoring the Bcl-2/Bax ratio as observed in the ovary intact rats. Furthermore, TUNEL assay demonstrated a decline in the percentage of TUNEL positive cells in E2 or TAM treated groups. Confocal microscope studies of ERalpha and the apoptotic markers revealed that these two proteins co-reside in the same ERalpha positive hippocampal neurons. Thus, long-term E2 or TAM therapy modulates the apoptotic proteins and affords neuroprotection to the hippocampal neurons. Furthermore the estrogen-like effects of TAM point towards its potential as a beneficial therapeutic agent for neurodegenerative disorders, particularly in the postmenopausal women.
最近我们报道，用17β-雌二醇（E2）或他莫昔芬（TAM）进行长期治疗可调节卵巢切除诱导的与海马突触可塑性和信号转导通路相关的关键分子的下调。我们现在报告，在卵巢切除（OVX）大鼠以及卵巢切除术后每天皮下注射E2或TAM四周的大鼠海马中，抗凋亡蛋白（Bcl-2）和促凋亡蛋白（Bax）的调节情况。40只双侧卵巢切除的动物被分为四组，每组10只，即：i）OVX + E2（0.1 mg/kg体重），ii）OVX + TAM（0.05 mg/kg体重），iii）OVX +赋形剂（0.1 ml芝麻油）和iv）OVX对照组。另外10只动物组成卵巢完整对照组。治疗方案结束后，对每组5只动物的脑组织进行灌注固定冷冻切片的Bcl-2和Bax免疫组织化学染色。每组其余动物用于使用未固定的海马组织进行蛋白质和蛋白质印迹分析。结果显示，E2和TAM的长期给药可防止卵巢切除诱导的Bcl-2下调和Bax表达上调，同时恢复卵巢完整大鼠中观察到的Bcl-2/Bax比值。此外，TUNEL分析表明，E2或TAM处理组中TUNEL阳性细胞的百分比下降。对ERα和凋亡标志物的共聚焦显微镜研究表明，这两种蛋白共存在于相同的ERα阳性海马神经元中。因此，长期E2或TAM治疗可调节凋亡蛋白并为海马神经元提供神经保护。此外，TAM的雌激素样作用表明其作为神经退行性疾病，特别是绝经后女性有益治疗剂的潜力。
