No induction of p53 phosphorylation and few focus formation of phosphorylated H2AX suggest efficient repair of DNA damage during chronic low-dose-rate irradiation in human cells

Human fibroblast cells obtained from a normal individual and immortalized by introduction of the hTERT gene were irradiated with 0 to 5 Gy of acute high-dose-rate radiation (1.8 Gy/min) or chronic low-dose-rate radiation (0.3 mGy/min) in the G0 phase, and p53 activation was studied. After high-dose-rate irradiation, a dose-dependent induction of Ser15 phosphorylation was observed, whereas after low-dose-rate irradiation almost none was observed. Then we analyzed the focus formation of phosphorylated histone H2AX protein, which is closely correlated with the induction of double-strand breaks. High-dose-rate radiation induced a significant number of foci in a dose-dependent manner, whereas, low-dose-rate radiation could induce only a few foci even at the highest dose. These results strongly suggest that DNA damage induced by low-dose-rate radiation such as a double-strand break is efficiently repaired during chronic irradiation.     

苞叶雪莲水提物对小鼠生殖细胞辐射防护作用的研究

目的 初步研究苞叶雪莲水提物对小鼠生殖细胞的辐射防护作用。方法 以辐射损伤小鼠作为研究对象,分别给予不同剂量的苞叶雪莲水提物灌胃14d后接受4Gy的X射线一次性全身照射,后继续灌胃,在照射后第35天处死小鼠,测量小鼠精子畸形率。结果 各给药组+照射组与照射组相比较,低剂量、中剂量、高剂量小鼠精子畸形率低于照射组。其中,中剂量组和高剂量组明显低于照射组,差异有统计学意义,P<0.05。结论 苞叶雪莲水提物中的活性成分对小鼠的生殖细胞有一定程度的防辐射损伤作用。     

玉米赤霉醇染毒对雄性小鼠睾丸及生精功能的影响

目的研究玉米赤霉醇对小鼠生精功能的影响及可能机制。方法选择健康性成熟的雄性昆明种小鼠40只,随机分为对照组和染毒组(玉米赤霉醇25、50、100mg/kg),连续灌胃染毒35天后脱臼处死。检测睾丸、附睾、精囊腺重量及脏器系数,附睾尾精子数、精子的形态结构及活力,并观察睾丸组织病理学改变。结果玉米赤霉醇各染毒组小鼠的精囊腺系数及精子计数均低于对照组,差异有显著性(P<0.05);50、100mg/kg组精子活动率下降,与对照组比较差异有显著性(P<0.05);睾丸组织有明显的病理改变,生精上皮细胞排列疏松、紊乱,层次减少,成熟精子数明显减少。结论在本实验剂量条件下,玉米赤霉醇对小鼠生精功能有毒性作用。     

低剂量~（12）C~（6＋）离子辐射诱导的小鼠骨髓细胞适应性反应实验研究

目的研究低剂量重离子辐射（LDR）对小鼠造血系统的适应性反应特征。方法对小鼠给予大剂量（2.0 Gy）12C＋6射线照射前预先采用0.050,0.075 Gy 12C＋6离子束全身照射,其中一批小鼠24 h处死,测定外周血指标、脏器系数、骨髓细胞微核率、骨髓DNA含量;第二批小鼠接受大剂量（2.0 Gy）全身辐照后观察其30 d存活情况。结果与大剂量直接照射组相比,0.050Gy低剂量照射组小鼠外周血白细胞明显升高,骨髓DNA含量升高,小鼠骨髓细胞的微核率降低（均P〈0.05~0.01）,其余指标无统计学差异。0.075 Gy低剂量照射后小鼠外周血白细胞与照射对照组比较有一定下降,其余指标无明显差异。结论低剂量碳离子束照射能拮抗大剂量照射后引起的骨髓细胞损伤,对造血组织产生适应性反应,对重离子治疗肿瘤及放射防护具有一定参考意义。     

Induction of rhodanese, a detoxification enzyme, in livers from mice after long-term irradiation with low-dose-rate gamma-rays

The health effects of low-dose radiation exposure are of public concern. Although molecular events in the cellular response to high-dose-rate radiation exposure have been fully investigated, effects of long-term exposure to extremely low-dose-rate radiation remain unclear. Protein expression was analyzed by two-dimensional electrophoresis in livers from mice irradiated for 485 days (22 hr/day) at low-dose-rates of 0.032 microGy/min, 0.65 microGy/min and 13 microGy/min (total doses of 21 mGy, 420 mGy and 8000 mGy, respectively). One of the proteins that showed marked changes in expression was identified as rhodanese (thiosulfate sulfurtransferase). Rhodanese expression was increased after irradiation at 0.65 microGy/min and 13 microGy/min, while its expression was not changed at 0.032 microGy/min. Rhodanese is a detoxification enzyme, probably related to the regulation of antioxidative function. However, antioxidative proteins, such as superoxide dismutase (SOD)1 (also known as Cu,Zn-SOD) and SOD2 (also known as Mn-SOD), which can be induced by high-dose-rate radiation, were not induced at any low-dose-rates tested. These findings indicate that rhodanese is a novel protein induced by low-dose-rate radiation, and further analysis could provide insight into the effects of extremely low-dose-rate radiation exposure.     

Neurobehavioral effects of acute low-dose whole-body irradiation

Radiation exposure has multiple effects on the brain, behavior and cognitive functions. It has been reported that high-dose (>20 Gy) radiation-induced behavior and cognitive aberration partly associated with severe tissue destruction. Low-dose (<3 Gy) exposure can occur in radiological disasters and cerebral endovascular treatment. However, only a few reports analyzed behavior and cognitive functions after low-dose irradiation. This study was undertaken to assess the relationship between brain neurochemistry and behavioral disruption in irradiated mice. The irradiated mice (0.5 Gy, 1 Gy and 3 Gy) were tested for alteration in their normal behavior over 10 days. A serotonin (5-HT), Dopamine, gamma-Aminobutyric acid (GABA) and cortisol analysis was carried out in blood, hippocampus, amygdala and whole brain tissue. There was a significant decline in the exploratory activity of mice exposed to 3 Gy and 1 Gy radiation in an open field test. We observed a significant short-term memory loss in 3 Gy and 1 Gy irradiated mice in Y-Maze. Mice exposed to 1 Gy and 3 Gy radiation exhibited increased anxiety in an elevated plus maze (EPM). The increased anxiety and memory loss patterns were also seen in 0.5 Gy irradiated mice, but the results were not statistically significant. In this study we observed that neurotransmitters are significantly altered after irradiation, but the neuronal cells in the hippocampus were not significantly affected. This study suggests that the low-dose radiation-induced cognitive impairment may be associated with the neurochemical in low-dose irradiation and unlike the high-dose scenario might not be directly related to the morphological changes in the brain.     

大豆异黄酮对辐射小鼠骨髓细胞的防护作用

目的研究大豆异黄酮(SI)对辐射小鼠骨髓细胞的防护作用,为SI应用于抗电离辐射药物和功能食品的研究提供依据。方法24只雄性昆明小鼠,随机分为正常对照组、辐射对照组和辐射补充0.5%SI组,喂养2周后,后两者给予4.0Gyγ射线照射。照射后7d处死小鼠,分离双侧股骨,观察骨髓细胞(BMC)形成细胞集落的能力。体外实验取正常组小鼠的股骨,制成BMC单细胞悬液,4.0Gyγ射线照射,测定BMC的细胞周期和3H-TdR掺入量。结果辐射使小鼠BMC的粒-巨细胞集落形成单位(CFU-GM)和成纤维细胞集落形成单位(CFU-F)明显减少,辐射补充SI组BMC的CFU-GM〔(26.0±6.9)个/105BMC〕和CFU-F〔(23.4±8.6)个/106BMC〕明显高于辐射对照组〔相应为(17.3±4.4)个/105BMC和(15.6±4.9)个/106BMC)(P0.05)〕。体外实验结果表明,辐射使细胞周期的G0-G1期细胞数量明显增加,S和G2-M期细胞明显减少,细胞的3H-TdR掺入量明显减少;补充SI组与辐射对照组相比,G0-G1期细胞数量明显减少(P0.05),S和G2-M期的细胞数明显增加(P0.05),细胞的3H-TdR掺入量明显增加(P0.05)。结论大豆异黄酮对小鼠骨髓细胞辐射损伤有一定的防护作用。     

Trx、REG3G和AZGP1蛋白在60Co γ射线全身辐照大鼠尿液中的表达和剂量相关性研究

目的探索⁶⁰Coγ射线全身照射后大鼠尿液中硫氧还蛋白(Trx)、再生胰岛来源3γ蛋白(REG3G)和锌-α2糖蛋白(AZGP1)表达水平变化。方法30只Sprague Dawley(SD)大鼠随机分为0、0.5、1、3、5、8 Gy共6组,每组5只,给予⁶⁰Coγ射线照射(剂量率1.0 Gy/min),收集照射后1 d、3 d、5 d大鼠尿液,用ELISA方法定量检测尿液中Trx、REG3G和AZGP1蛋白的表达水平。结果照射后1 d,三种蛋白表达水平均升高,且与照射剂量有关。Trx蛋白5 Gy组照射后1 d较0 Gy组表达增高,8 Gy组照射后3 d、5 d较0 Gy组表达增高,差异具有统计学意义(P<0.05)。REG3G蛋白5Gy组照射后3 d较0 Gy组表达增高,8 Gy组照射后5 d较0 Gy组表达增高,差异具有统计学意义(P<0.05)。AZGP1蛋白5 Gy组照射后1 d较0 Gy组表达增高,差异具有统计学意义(P<0.05)。结论大鼠尿液中Trx和REG3G蛋白在全身照射后特定时间点有较为良好的剂量-效应关系。     

Impacts of psychological stress on high dose-rate radiation acute effects in a mouse experimental model

Psychological stress affects health. Radiation workers in the medical field or astronauts living in space have possible risks of exposure to radiation, and psychological stress is considered to be easily induced in them due to activities performed in small areas or stress conditions. The impact of psychological stress on the effects of radiation was evaluated in senescence-accelerated mouse prone 10 (SAMP10) mice and ddY mice using a confrontational housing model, which makes dominant and subordinate mice in a cage live together without severe quarrel. Mice of ddY and SAMP10 have been previously demonstrated to be influenced in terms of acute and late effects, respectively, under psychological stress by this model. In SAMP10 mice, irradiation with 4 Gy induced the death of irradiated mice under psychological stress. In ddY mice, irradiation with 5 Gy X-rays alone had almost no effect on the mouse survival, but irradiation in conditions of psychological stress promoted acute death of irradiated mice. In addition, hypocellular bone marrow was also observed histopathologically in irradiated ddY mice under stress. Psychological stress may promote damage caused by radiation through modulation of radio-sensitivity in bone marrow in mice. This model would be useful for evaluation of modulation of radiation-induced various effects by psychological stress.     

Effects on rat testis of 1.95-GHz W-CDMA for IMT-2000 cellular phones

In recent years concern has arisen whether carrying a cellular phone near the reproductive organs such as the testes may cause dysfunction and particularly decrease in sperm development and production, and thus fertility in men. The present study was performed to investigate the effects of a 1.95 GHz electromagnetic field on testicular function in male Sprague-Dawley rats. Five week old animals were divided into 3 groups of 24 each and a 1.95-GHz wide-band code division multiple access (W-CDMA) signal, which is used for the freedom of mobile multimedia access (FOMA), was employed for whole body exposure for 5 hours per day, 7 days a week for 5 weeks (the period from the age of 5 to 10 weeks, corresponding to reproductive maturation in the rat). Whole-body average specific absorption rates (SAR) for individuals were designed to be 0.4 and 0.08 W/kg respectively. The control group received sham exposure. There were no differences in body weight gain or weights of the testis, epididymis, seminal vesicles, and prostate among the groups. The number of sperm in the testis and epididymis were not decreased in the electromagnetic field (EMF) exposed groups, and, in fact, the testicular sperm count was significantly increased with the 0.4 SAR. Abnormalities of sperm motility or morphology and the histological appearance of seminiferous tubules, including the stage of the spermatogenic cycle, were not observed. Thus, under the present exposure conditions, no testicular toxicity was evident.     

Expression of GAT1 in Male Reproductive System and its Effects on Reproduction in Mice

The present study was carried out to identify GABA (γ-aminobutyric acid) transport protein I (GAT1) in male reproductive organs and to study the effect of GAT1 overexpression on the male reproductive system in GAT1 transgenic mice (TG). Expression and location of GAT1 in testes, epididymis, and sperm of wild-type (WT) mice were identified by immunohistochemistry and western-blot. Histological changes of testes, epididymis, and sperm of transgenic mice overexpressing GAT1 were detected by immunofluorenscent staining and haematoxylin and eosin (HE) staining. GAT1 expression was detected in the testes, epididymis, and sperm of non-transgenic mice. Vacuolization and deformity of spermatogenic cells were observed in the transgenic mice, but the epididymis was unremarkable. Immunofluorenscent staining showed that the number of diastrophic and decapitated sperm increased significantly in transgenic mice to 46.9% from 7.3% in nontransgenic mice. These results suggest that abnormal expression of GAT1 could result in spermiogenesis function injury, sperm paramorphia and dysgenesis.     

Effects on rat testis of 1.95-GHz W-CDMA for IMT-2000 cellular phones

In recent years concern has arisen whether carrying a cellular phone near the reproductive organs such as the testes may cause dysfunction and particularly decrease in sperm development and production, and thus fertility in men. The present study was performed to investigate the effects of a 1.95?GHz electromagnetic field on testicular function in male Sprague-Dawley rats. Five week old animals were divided into 3 groups of 24 each and a 1.95-GHz wide-band code division multiple access (W-CDMA) signal, which is used for the freedom of mobile multimedia access (FOMA), was employed for whole body exposure for 5 hours per day, 7 days a week for 5 weeks (the period from the age of 5 to 10 weeks, corresponding to reproductive maturation in the rat). Whole-body average specific absorption rates (SAR) for individuals were designed to be 0.4 and 0.08 W/kg respectively. The control group received sham exposure. There were no differences in body weight gain or weights of the testis, epididymis, seminal vesicles, and prostate among the groups. The number of sperm in the testis and epididymis were not decreased in the electromagnetic field (EMF) exposed groups, and, in fact, the testicular sperm count was significantly increased with the 0.4 SAR. Abnormalities of sperm motility or morphology and the histological appearance of seminiferous tubules, including the stage of the spermatogenic cycle, were not observed. Thus, under the present exposure conditions, no testicular toxicity was evident.     

Effects of ionizing radiation on differentiation of murine bone marrow cells into mast cells

Mast cells, immune effector cells produced from bone marrow cells, play a major role in immunoglobulin E–mediated allergic responses. Ionizing radiation affects the functions of mast cells, which are involved in radiation-induced tissue damage. However, whether ionizing radiation affects the differential induction of mast cells is unknown. Here we investigated whether bone marrow cells of X-irradiated mice differentiated into mast cells. To induce mast cells, bone marrow cells from X-irradiated and unirradiated mice were cultured in the presence of cytokines required for mast cell induction. Although irradiation at 0.5 Gy and 2 Gy decreased the number of bone marrow cells 1 day post-irradiation, the cultured bone marrow cells of X-irradiated and unirradiated mice both expressed mast cell–related cell-surface antigens. However, the percentage of mast cells in the irradiated group was lower than in the unirradiated group. Similar decreases in the percentage of mast cells induced in the presence of X-irradiation were observed 10 days post irradiation, although the number of bone marrow cells in irradiated mice had recovered by this time. Analysis of mast cell function showed that degranulation of mast cells after immunoglobulin E–mediated allergen recognition was significantly higher in the X-irradiated group compared with in the unirradiated group. In conclusion, bone marrow cells of X-irradiated mice differentiated into mast cells, but ionizing radiation affected the differentiation efficiency and function of mast cells.     

硒对辐射所致过氧化脂质含量及谷胱甘肽过氧化物酶活性的影响

以肝、脾组织中过氧化脂质(LPO)含量及谷胱甘肽过氧化物酶(GSHL-Px)活性为指标探讨硒的辐射防护效应。实验结果表明:BALB/C纯系雄性小鼠经3Gy ~(60)Co γ射线照射后3天,肝、脾组织LPO生成量比未照射者均显著增多,而GSH-Px活性却都显著降低;但于照射前连续7天每日经口灌胃亚硒酸钠溶液0.2ml(含硒12.5μg)的实验组动物,肝、脾组织LPO含量均明显少于照射对照组,而GSH-Px活性都显著高于照射对照组,结果提示,通过降低LPO含量和增加GSH-Px活性,硒对小鼠可能有辐射防护作用。     

染料木黄酮的雌激素活性对辐照小鼠免疫功能的影响

目的研究染料木黄酮(genistein,Gen)的雌激素效应对辐射损伤的防护作用,为抗辐射功能食品的开发和对原有辐射防护剂的改进提供实验依据。方法观察应用他莫西芬(ERα阻断剂)和Faslodex(ERβ阻断剂)阻断受照小鼠雌激素受体(ER)活化情况下,Gen对接受4Gy全身照射小鼠血白细胞和淋巴细胞计数、血清溶血素及迟发型变态反应的影响。结果Gen可以降低辐照小鼠的血白细胞和淋巴细胞的减少幅度,增强免疫功能;他莫西芬与Gen合用对小鼠血白细胞和淋巴细胞计数及免疫功能无明显影响,表明他莫西芬不能阻断Gen对辐照的保护作用。Faslodex与Gen合用则仍降低受照小鼠血白细胞和淋巴细胞数量,也抑制免疫功能。表明Faslodex能阻断Gen的保护作用。结论Gen通过激活ERβ途径,增强辐射小鼠的免疫功能。     

Effects of dose rates on radiation-induced replenishment of intestinal stem cells determined by Lgr5 lineage tracing

An understanding of the dynamics of intestinal Lgr5⁺ stem cells is important for elucidating the mechanism of colonic cancer development. We previously established a method for evaluating Lgr5⁺ stem cells by tamoxifen-dependent Lgr5-lineage tracing and showed that high-dose-rate radiation stimulated replenishment of colonic stem cells. In this study, we evaluated the effects of low-dose-rate radiation on stem cell maintenance. Tamoxifen (4OHT)-injected Lgr5-EGFP-IRES-Cre^ERT2 × ROSA-LSL-LacZ mice were used, LacZ-labeled colonic crypts were enumerated, and the loss of LacZ⁺ crypts under low-dose-rate radiation was estimated. After 4OHT treatment, the number of LacZ-labeled Lgr5⁺ stem cells was higher in the colon of infant mice than in adult mice. The percentage of LacZ-labeled crypts in infant mice rapidly decreased after 4OHT treatment. However, the percentage of labeled crypts plateaued at ∼2% at 4 weeks post-treatment and remained unchanged for up to 7 months. Thus, it will be advantageous to evaluate the long-term effects of low-dose-rate radiation. Next, we determined the percentages of LacZ-labeled crypts irradiated with 1 Gy administered at different dose rates. As reported in our previous study, mice exposed to high-dose-rate radiation (30 Gy/h) showed a marked replenishment (P = 0.04). However, mice exposed to low-dose-rate radiation (0.003 Gy/h) did not exhibit accelerated stem-cell replenishment (P = 0.47). These findings suggest the percentage of labeled crypts can serve as a useful indicator of the effects of dose rate on the stem cell pool.     

补肾单药和复方对急性电离辐射损伤后小鼠外周血作用的研究

目的 探究补肾单药（CP）和复方（KS）对急性电离辐射损伤后小鼠造血的调控作用。方法 9~10周龄C57BL/6小鼠分成空白对照组、照射组、照射+KS和照射+CP 4组,照射组、照射+KS和照射+CP三组进行5.5 Gy ¹³⁷Cs-γ射线单次全身照射,剂量率1 Gy/min。照射后,照射+KS组按1.5 g/kg体重灌服KS药液,照射+CP组按2.7 g/kg体重灌服CP药液,其余两对照组灌服等体积生理盐水。每月取血监测血常规。另取小鼠按同样方式分组,照射后连续给药一个月,检测间充质干细胞集落形成。结果 照射+KS组和照射+CP组在前两个月的白细胞和淋巴细胞高于照射组,集落数也多于照射组。结论 KS和CP可以促进电离辐射损伤后小鼠的造血恢复。     

Inhibitory effects of prior low-dose x-irradiation on ischemia-reperfusion injury in mouse paw

We have reported that low-dose, unlike high-dose, irradiation enhanced antioxidation function and reduced oxidative damage. On the other hand, ischemia-reperfusion injury is induced by reactive oxygen species. In this study, we examined the inhibitory effects of prior low-dose X-irradiation on ischemia-reperfusion injury in mouse paw. BALB/c mice were irradiated by sham or 0.5 Gy of X-ray. At 4 hrs after irradiation, the left hind leg was bound 10 times with a rubber ring for 0.5, 1, or 2 hrs and the paw thickness was measured. Results show that the paw swelling thickness by ischemia for 0.5 hr was lower than that for 2 hrs. At 1 hr after reperfusion from ischemia for 1 hr, superoxide dismutase activity in serum was increased in those mice which received 0.5 Gy irradiation and in the case of the ischemia for 0.5 or 1 hr, the paw swelling thicknesses were inhibited by 0.5 Gy irradiation. In addition, interstitial edema in those mice which received 0.5 Gy irradiation was less than that in the mice which underwent by sham irradiation. These findings suggest that the ischemia-reperfusion injury is inhibited by the enhancement of antioxidation function by 0.5 Gy irradiation.     

中波紫外线致雄性小鼠生殖系统损伤

[目的]本文以小鼠为实验材料探讨中波紫外线（uhraviolet-B,UVB）对雄性小鼠生殖系统造成的光辐射损伤。[方法]将36只雄性小鼠随机分为空白对照组、2h照射组和3h照射组,每组12只,照射组用UVB（285nm）连续照射30d。照射后称其体重并将小鼠处死,取出睾丸、附睾并称重,求睾体比,检测附睾中精子活率及精子畸形率,观察睾丸组织病理学变化,测定睾丸组织超氧化物歧化酶（superoxidedismutase,SOD）活性和丙二醛（malondialdehyde,MDA）含量。[结果]照射组小鼠的体重和睾体比明显低于对照组（P〈0．01）;精子活率也下降,差异有统计学意义（P〈0．05）;精子的畸形率上升但差异无统计学意义（P〉0．05）.睾丸病理学变化：睾丸间质水肿与曲细精管分离;生精上皮排列疏松、脱落至管腔;管腔变窄;管腔中的精子数减少,并且3h照射组造成的辐射损伤更大。睾丸组织SOD活性和MDA含量变化：紫外辐射能够明显降低SOD活性、增加MDA含量（P〈0．01）,并且呈现剂量效应。[结论]UVB辐射可引起雄性小鼠体重和睾体比降低、精子活率下降、睾丸组织病变、SOD活性降低、MDA含量增加,但对小鼠的精子畸形率影响不明显,损伤主要是由于紫外线辐射产生的活性氧簇（ROS）间接引起。     

Radioprotective effects of Sipunculus nudus L. polysaccharide combined with WR-2721, rhIL-11 and rhG-CSF on radiation-injured mice

This study investigated the radioprotective effect of Sipunculus nudus L. polysaccharide (SNP) in combination with WR-2721, rhIL-11 and rhG-CSF on irradiated mice. A total of 70 Imprinting Control Region (ICR) mice were divided into seven groups: the control group, the model group and five administration groups. All groups, except the control group, were exposed to a 5 Gy ⁶⁰Co γ-ray beam. Blood parameters [including white blood cell (WBC), red blood cell (RBC) and platelet counts and hemoglobin level] were assessed three days before irradiation, and the on the 3rd, 7th and 14th days after irradiation. Spleen, thymus and testicular indices, DNA contents of bone marrow cells, bone marrow nucleated cells, sperm counts, superoxide dismutase (SOD), malondialdehyde (MDA), testosterone and estradiol levels in the serum were assessed on the 14th day after irradiation. The combined administration of SNP, WR-2721, rhIL-11 and rhG-CSF exerted synergistic recovery effects on peripheral blood WBC, RBC and platelet counts and hemoglobin levels in irradiated mice, and synergistic promotion effects on spleen, thymus, testicle, bone marrow nucleated cells and sperm counts in irradiated mice. The synergistic administration increased the serum SOD activities and serum testosterone content of irradiated mice, but synergy decreased the content of serum MDA and estradiol in irradiated mice. These results suggest that the combined administration of SNP, WR-2721, rhIL-11 and rhG-CSF should increase the efficacy of these drugs for acute radiation sickness, protect immunity, hematopoiesis and the reproductive organs of irradiated-damaged mice, and improve oxidation resistance in the body.