【摘要】：核事故受照人員以及臨床上接受放射治療的腫瘤患者,會(huì)出現(xiàn)各種輻射損傷,其中造血系統(tǒng)對(duì)輻射高度敏感,尤其是造血干細(xì)胞(HSCs)損傷會(huì)導(dǎo)致持久性骨髓抑制甚至個(gè)體死亡,目前尚無(wú)有效治療手段,因此研發(fā)造血系統(tǒng)輻射損傷預(yù)防和治療藥物具有重要的社會(huì)意義和臨床價(jià)值。我們前期研究發(fā)現(xiàn)氧化應(yīng)激水平升高是介導(dǎo)亞致死劑量(6-6.5 Gy)受照小鼠造血干細(xì)胞衰老、骨髓長(zhǎng)期抑制的主要機(jī)制。應(yīng)用抗氧化制劑具有一定的治療作用。二甲雙胍是廣泛應(yīng)用的Ⅱ型糖尿病治療藥物,近年來(lái)研究發(fā)現(xiàn)有抗氧化和抗衰老的作用,具有防止糖尿病心血管并發(fā)癥及腫瘤預(yù)防作用。本項(xiàng)研究通過(guò)體外、體內(nèi)照射模型,探討二甲雙胍對(duì)輻射引起的造血免疫損傷的防護(hù)作用,尤其是在接受4 Gy全身照射(TBI)小鼠HSCs功能損傷的保護(hù)作用,并探討其作用機(jī)制。為觀察二甲雙胍對(duì)造血免疫細(xì)胞輻射損傷的保護(hù)作用,分離C57BL/6小鼠骨髓、胸腺及脾臟細(xì)胞,加入不同濃度二甲雙胍孵育30 min后接受不同劑量γ射線照射,孵育過(guò)夜后進(jìn)行細(xì)胞活力測(cè)定,結(jié)果顯示二甲雙胍對(duì)照射引起的造血免疫細(xì)胞損傷具有一定的保護(hù)作用。為了研究二甲雙胍對(duì)TBI小鼠造血免疫系統(tǒng)輻射損傷的保護(hù)作用,我們將C57BL/6小鼠分為對(duì)照組、照射組和照射給藥組,在30d生存率實(shí)驗(yàn)中,二甲雙胍能夠提高接受致死劑量(7.2 Gy)TBI小鼠的生存率。利用4 Gy全身照射模型,探討了二甲雙胍不同劑量、不同給藥時(shí)間對(duì)骨髓細(xì)胞輻射損傷的保護(hù)作用,確定小鼠受照前24 h灌胃給藥250mg/kg劑量,受照后持續(xù)給藥7 d,能夠提高受照小鼠外周血細(xì)胞計(jì)數(shù)、骨髓有核細(xì)胞計(jì)數(shù)和脾結(jié)節(jié)計(jì)數(shù)；CFU-GM和CAFC實(shí)驗(yàn)表明4 Gy照射可以引起造血祖細(xì)胞和造血干細(xì)胞功能損傷,而二甲雙胍能夠提高受照小鼠造血祖細(xì)胞和造血干細(xì)胞的增殖能力,骨髓競(jìng)爭(zhēng)移植實(shí)驗(yàn)表明,二甲雙胍可以提高受照小鼠造血干細(xì)胞長(zhǎng)期再植能力。二甲雙胍輻射防護(hù)機(jī)制研究發(fā)現(xiàn),二甲雙胍能夠降低受照小鼠造血細(xì)胞中活性氧(ROS)水平,qRT-PCR實(shí)驗(yàn)表明二甲雙胍可以降低受照小鼠造血細(xì)胞中NOX4mRNA表達(dá)水平,這與二甲雙胍能夠降低受照小鼠造血細(xì)胞中ROS水平有關(guān)。對(duì)造血細(xì)胞的p16mRNA表達(dá)和凋亡水平的研究表明,二甲雙胍可以降低受照小鼠造血細(xì)胞中p16mRNA表達(dá)水平、不影響細(xì)胞的凋亡率,提示二甲雙胍對(duì)造血系統(tǒng)輻射損傷的防護(hù)作用與改善輻射誘導(dǎo)造血細(xì)胞的衰老有關(guān),而與凋亡途徑無(wú)關(guān)。全基因組表達(dá)譜芯片分析結(jié)果顯示,接受4 Gy照射小鼠HSCs中mTOR、S6K、S6基因的表達(dá)均上調(diào),說(shuō)明照射可能激活了HSCs中mTOR信號(hào)通路,而給藥后能夠抑制這些基因表達(dá)的上調(diào),提示二甲雙胍可能能夠抑制受照小鼠HSCs中mTOR通路的活性�？傊�,我們首次系統(tǒng)地研究了二甲雙胍對(duì)造血免疫系統(tǒng)輻射損傷的防護(hù)作用,初步闡明了二甲雙胍對(duì)4 Gy受照小鼠造血干細(xì)胞的損傷有保護(hù)作用,闡明了這一保護(hù)作用與二甲雙胍能夠降低造血干細(xì)胞氧化應(yīng)激水平和衰老有關(guān),降低造血干細(xì)胞氧化應(yīng)激水平與二甲雙胍調(diào)節(jié)NOX4mRNA表達(dá)水平有關(guān)。也有可能與二甲雙胍對(duì)mTOR通路調(diào)節(jié)作用有關(guān)。我們的研究提示二甲雙胍有可能成為臨床上造血系統(tǒng)輻射損傷防護(hù)藥,對(duì)改善腫瘤放療患者預(yù)后和提高意外輻射事故受害人員生存率都具有潛在的應(yīng)有價(jià)值。
[Abstract]:In patients with a nuclear accident and a tumor with a clinically acceptable radiation treatment, various radiation damage may occur, in which the hematopoietic system is highly sensitive to radiation, in particular hematopoietic stem cells (HSCs), which may lead to persistent bone marrow suppression, or even death of the individual, and there is no effective means of treatment at this time, Therefore, the research and development of the radiation damage prevention and treatment medicine of the hematopoietic system has important social significance and clinical value. We found that the level of oxidative stress in the early stage of our study was the main mechanism of mediating sublethal dose (6-6.5 Gy) on the aging of hematopoietic stem cells and long-term inhibition of bone marrow. The antioxidant preparation has certain therapeutic effect. Dimethyldicyandiamide is widely used in the treatment of type II diabetes. In recent years, the effects of anti-oxidation and anti-aging have been found, and it has the function of preventing the cardiovascular complications of diabetes and the prevention of tumor. In this study, by in vitro and in vivo irradiation model, the protective effect of the dimethoxy-2 on the hematopoietic immune injury induced by radiation, in particular the protective effect of the function injury of the HSCs in the mice receiving the whole body irradiation (TBI) of 4 Gy, was discussed, and its mechanism of action was discussed. In order to observe the protective effect of the dimethoxy dicyandiamide on the radiation injury of the hematopoietic immune cells, the bone marrow, thymus and spleen cells of the C57BL/6 mice were isolated, and the cells of the bone marrow, the thymus and the spleen of the C57BL/6 mice were isolated and incubated for 30 min with different concentrations of dimethyldiisopropyl alcohol and then irradiated with different doses of X-ray, and the cell viability was measured after the incubation overnight. The results showed that the dimethoxy-2-2 was a protective effect on the damage of the hematopoietic immune cells caused by the irradiation. In order to study the protective effect of the dimethoxy dicyandiamide on the radiation damage of the hematopoietic immune system in the TBI mice, the C57BL/6 mice were divided into the control group, the irradiation group and the irradiation group. In the 30-day survival experiment, the survival rate of the TBI mice receiving the lethal dose (7.2Gy) was increased. The protective effects of different doses and different administration time on the radiation injury of bone marrow cells were discussed by using a 4 Gy whole-body irradiation model. The mice were given a dose of 250 mg/ kg for 24 h before the irradiation, and 7 days after the irradiation, the peripheral blood cell count of the irradiated mice can be improved. Bone marrow nucleated cell count and spleen nodule count; CFU-GM and CAFC experiment showed that 4 Gy irradiation could cause functional damage of hematopoietic progenitor cells and hematopoietic stem cells, and the proliferation ability of hematopoietic progenitor cells and hematopoietic stem cells in irradiated mice can be improved, and the bone marrow competition transplantation experiment shows that, The ability of the long-term replantation of the hematopoietic stem cells of the irradiated mice can be improved. The results of the study on the radiation protection mechanism of dimethoxy-2-(2-(2-)-2-(2-(2-)-2-(2-(2-)-2-(2-(2-)-2-(2-)-(2-(2-)-(2-)-(2-)-(2-)-(2-)-(2-)-(2-(2-)- This is related to the reduction of the level of ROS in the hematopoietic cells of the irradiated mice. The study of the expression of p16mRNA and the level of apoptosis in the hematopoietic cells showed that the expression of p16mRNA in the hematopoietic cells of the irradiated mice can be reduced, and the apoptosis rate of the cells is not affected, and the protective effect of the dimethoxy dicyandiamide on the radiation damage of the hematopoietic system is related to the improvement of the aging of the radiation-induced hematopoietic cells. Regardless of the pathway of apoptosis. The results of the whole genome analysis showed that the expression of mTOR, S6K and S6 in the HSCs irradiated by 4 Gy was up-regulated, indicating that the irradiation could activate the mTOR signaling pathway in the HSCs, and the upregulation of the expression of these genes can be inhibited after administration. It is suggested that the dicyandiamide may be able to inhibit the activity of the mTOR pathway in the HSCs of the irradiated mice. In conclusion, we first systematically studied the protective effect of the dimethoxy dicyandiamide on the radiation damage of the hematopoietic immune system. This protective effect is related to the reduction of the oxidative stress level and the aging of the hematopoietic stem cells, and the level of the oxidative stress of the hematopoietic stem cells is related to the level of the NOx4mRNA expression regulated by the dimethoxy-2-1. It is also possible to be related to the regulation of the mTOR pathway with the di-dimethoxy. Our study suggests that the disidiolone has the potential to be a protective agent for radiation damage in the clinical hemopoietic system, and it is of potential value to improve the prognosis of patients with tumor radiotherapy and to improve the survival rate of patients with accidental radiation accident.
【學(xué)位授予單位】：北京協(xié)和醫(yī)學(xué)院
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2013
【分類(lèi)號(hào)】：R818

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 董小英;張如意;;二甲雙胍對(duì)糖尿病大鼠心肌病變的抗氧化保護(hù)作用[J];寧夏醫(yī)學(xué)院學(xué)報(bào);2008年02期

，

本文編號(hào)：2445532