砷染毒大鼠生精细胞凋亡及端粒酶活力的变化

目的观察不同剂量的染砷(As2O3)大鼠生精细胞凋亡及端粒酶活力表达的变化。方法将40只健康雄性清洁级SD大鼠随机分成4组,分别为低、中、高剂量(0.375、0.75、1.5 mg/kg)砷染毒组和对照组,以灌胃法连续染毒16周后计算各组大鼠精子头计数,并计算睾丸脏器系数、每日精子生成量(DSP)。采用TUNEL原位细胞杂交方法检测大鼠生精细胞凋亡,免疫组化法检测大鼠生精细胞端粒酶活力的表达。结果与对照组比较,中剂量组(0.75 mg/kg)和高剂量组(1.5 mg/kg)睾丸精子头计数和DSP均显著降低(P<0.01),生精细胞凋亡指数(AI)显著升高(P<0.01),生精细胞端粒酶活力表达明显降低(P<0.01);每日精子生成量与生精细胞凋亡呈负相关(r=-0.563,P<0.01);生精细胞凋亡与端粒酶活力呈负相关(r=-0.896,P<0.01)。结论一定剂量的As2O3可通过抑制生精细胞端粒酶活力,促进生精细胞凋亡而导致精子生成量减少,产生雄性生殖毒性。     

染氟大鼠血清雌二醇水平与生精细胞端粒酶逆转录酶表达关系的研究

目的了解氟中毒大鼠雌激素水平与生精细胞端粒酶表达的关系。方法将30只雄性SD大鼠随机分为对照组、低剂量染毒组、高剂量染毒组,分别按0、10和20mg/kg体重的染毒剂量隔日腹腔注射氟化钠(NaF)溶液39天后,用放射免疫法测定大鼠血清中雌二醇含量,用原位杂交法检测端粒酶逆转录酶(TERT)表达情况。同时镜检成熟精子质量和睾丸组织病理学改变。结果染毒各组大鼠血清雌二醇含量低于对照组(P<0·05);且随着染毒剂量的增加,雌二醇含量逐渐降低。染毒各组大鼠生精细胞TERT阳性表达率分别低于对照组(P<0·05);且随着染毒剂量的增加,TERT阳性表达率逐渐降低。各染毒组大鼠精子数量和精子存活率低于对照组(P<0·05);精子畸形率高于对照组(P<0·05);随着染毒剂量的增加,精子数量、精子存活率降低(P<0·05),精子畸形率升高(P<0·05)。各染毒组大鼠血清雌二醇含量与生精细胞TERT表达率均呈正相关,低剂量染毒组r=0·941,P<0·01;高剂量染毒组r=0·929,P<0·01。结论NaF很可能是通过雌激素/雌激素受体-端粒酶逆转录酶-精子途径对生殖系统造成损害的,各染毒组大鼠血清雌激素含量与生精细胞TERT表达率呈显著正相关。     

锰对大鼠生精细胞凋亡及p53和Bcl-2表达的影响

目的 研究氯化锰对大鼠生精细胞凋亡及p53、Bcl-2表达的影响.方法 将24只健康雄性SD大鼠随机分为3组,即15和30 mg/kg染锰组和0 mg/kg(阴性对照)组,腹腔注射给药,每天1次,每周5 d,连续4周.停药2周后,称重并应用电镜和原位末端脱氧核苷酸转移酶标记法(TUNEL法)检测睾丸生精细胞凋亡;免疫组化S-P法检测生精细胞p53和B淋巴细胞瘤/白血病-2(B-cell lymphoma/leukemia-2,Bcl-2)蛋白的表达.结果 电镜下各组大鼠可见生精细胞凋亡表现;15和30 mg/kg组生精细胞凋亡指数(apoptosis index,AI)和p53阳性细胞率均明显高于对照组,差异有统计学意义(P＜0.01),且30 mg/kg组高于15 mg/kg组,差异有统计学意义(P＜0.01).30 mg/kg组Bcl-2阳性细胞率明显低于0和15 mg/kg组,差异有统计学意义(P＜0.01).结论 锰可诱导大鼠生精细胞凋亡,p53表达上调和Bcl-2表达下调可能是生精细胞凋亡增加的重要原因之一.     

锰对大鼠睾丸抗氧化能力及生精细胞凋亡的影响研究

目的:研究氯化锰对SD大鼠睾丸抗氧化能力和生精细胞凋亡的影响。方法:24只健康雄性SD大鼠随机分为3组。染锰组给予MnCl2.4H2O(15mg/kg、30mg/kg)4周,对照组给予生理盐水,各组给药途径均为腹腔注射,每天1次,每周5天。应用原位末端脱氧核苷酸转移酶标记技术检测睾丸生精细胞凋亡;化学比色法检测睾丸组织超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶活性。结果:生精细胞凋亡指数染锰组明显高于对照组,且随染锰剂量的增加而升高(P<0.01);睾丸组织超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶活性均染锰组明显低于对照组(P<0.01)。结论:锰诱导的抗氧化能力下降可能是大鼠生精细胞凋亡增加的重要原因之一。     

氟对原代培养大鼠海马细胞周期及细胞凋亡和核因子-κB表达的影响

目的 探讨氟对原代大鼠海马细胞存活、细胞周期、凋亡和核因子-κB(NF-κB)表达的影响.方法 原代培养大鼠海马细胞分别暴露于20、40和80μg/ml氟化钠24 h后,采用噻唑蓝(MTT)、流式细胞术(FCM)、逆转录PCR(RT-PCR)分别检测大鼠海马细胞存活情况、细胞周期分布、凋亡率、NF-κB表达水平.结果 与对照组比较,80 μg/ml剂量组海马细胞存活率下降(P＜0.05);40、80 μg/ml剂量组凋亡率和S期细胞百分率皆显著高于对照组(P＜0.05),各剂量组NF-κB mRNA显著高于对照组(P＜0.05).结论 一定剂量氟可抑制海马细胞存活,诱导NF-κB mRNA表达和凋亡发生.氟对发育中海马细胞NF-κB表达水平的影响可能是氟神经毒性的机制之一.     

食管癌端粒酶表达与其活性关系

目的探讨食管癌端粒酶亚基因表达及其与端粒酶活性的关系。方法采用端粒末端重复序列扩增技术检测29例食管鳞癌组织及其相应癌旁正常组织、47例食管鳞状上皮不典型增生组织的端粒酶活性;采用逆转录聚合酶链反应技术检测端粒酶各亚单位基因mRNA的表达。结果端粒酶活性阳性检出率、亚单位基因端粒酶逆转录酶(mTERT)mRNA表达在食管癌、不典型增生组织和癌旁正常组织之间差异有统计学意义(P<0.001);而端粒酶亚单位基因hTR或TP1mRNA在3种食管组织中表达差异无统计学意义(P>0.05)。在105例食管癌组织、癌旁正常组织和不典型增生组织中hTERTmRNA表达与端粒酶活性呈显著正相关(P<0.001);而hTR或TP1mRNA表达与端粒酶活性无明显相关(P>0.05)。结论端粒酶在食管癌的发生发展过程中可能起关键性作用:hTERT与端粒酶活性密切相关;端粒酶有望成为食管癌的生物标志物。     

谷胱甘肽拮抗锰致雄性大鼠生殖损伤的研究

目的:研究谷胱甘肽(GSH)对锰致雄性大鼠睾丸氧化损伤的拮抗作用。方法:将48只健康雄性SD大鼠随机分为3组进行急性和亚急性染毒。染锰组腹腔注射30mg/kgMnCl2.4H2O染毒1周(急性染毒)和4周(亚急性染毒),GSH拮抗组染毒后再给予2周1mmol/kgGSH,对照组染毒后给予生理盐水。TUNEL法检测生精细胞凋亡;化学比色法检测睾丸丙二醛和谷胱甘肽过氧化物酶活性。结果:急性锰染毒时,染锰组生精细胞凋亡指数和睾丸丙二醛含量高于对照组和GSH拮抗组(P<0.01);各组间谷胱甘肽过氧化物酶活性无差异。亚急性锰染毒时,染锰组生精细胞凋亡指数和睾丸丙二醛含量高于对照组和GSH拮抗组(P<0.01),GSH拮抗组高于对照组(P<0.01);染锰组睾丸谷胱甘肽过氧化物酶活性低于对照组和GSH拮抗组(P<0.01)。结论:及时补充谷胱甘肽可通过抑制脂质过氧化作用而拮抗锰引起的雄性大鼠生精细胞凋亡。     

烟草烟雾对大鼠生精细胞凋亡及血清睾酮和抑制素B水平的影响

目的探讨烟草烟雾对大鼠生精细胞凋亡及血清睾酮、抑制素B表达的影响。方法将40只8周龄雄性SD大鼠随机分成4组,分别为对照组及轻、中、重度吸烟组(每天分别暴露于4、8、12支香烟烟雾,早晚各1次),连续染毒8周后成功建立大鼠被动吸烟毒性模型。采用TUNEL法检测睾丸生精细胞凋亡数,分别以直接化学发光和ELISA法检测大鼠血清中睾酮、抑制素B的表达水平。结果对照组及轻、中、重度吸烟组大鼠生精细胞凋亡指数分别为(6.62±0.58)%,(7.08±1.02)%,(8.71±0.76)%,(10.17±1.18)%,各染毒组生精细胞凋亡指数均高于对照组,差异有统计学意义(P0.01)。各染毒组大鼠血清睾酮、抑制素B水平均低于对照组,且均随染毒剂量的增加而降低,差异有统计学意义(P0.05)。结论烟草烟雾可诱导大鼠睾丸生精细胞凋亡,并影响血清抑制素B及睾酮分泌。     

饮食限制对大鼠抗氧化能力及端粒酶活性的影响

目的探讨饮食限制对成年大鼠血清超氧化物歧化酶(SOD)、丙二醛(MDA)、总抗氧化能力(T-AOC)及血液端粒酶活性的影响。方法 SD成年雌、雄性大鼠共48只,随机分为100%进食组(对照组)、80%进食组(限制20%组)、60%进食组(限制40%组)、50%进食组(限制50%组)4组,喂养90d。测量体重,测定血清SOD活性、MDA含量、T-AOC及端粒酶活性。结果除对照组大鼠体重增加外,限制20%组、限制40%组、限制50%组大鼠体重均明显下降(P<0.05)。各组大鼠SOD活性无明显区别;实验组大鼠限制20%组、限制40%组、限制50%组的MDA含量与对照组相比明显降低(P<0.05),限制20%组、限制40%组的T-AOC水平与对照组相比明显升高;端粒酶活性结果显示实验组与对照组相比均无明显变化。结论饮食限制可提高大鼠的抗氧化能力,但对端粒酶活性无明显影响。     

硒对镉诱导大鼠肝细胞端粒酶活力作用研究

目的 研究硒对镉诱导的大鼠肝细胞端粒酶活力、癌基因c-myc和p53表达的影响.方法 80只雄性SD大鼠随机分为16组,包括对照组,2.5、5.0和10.0 μmol/kg亚硒酸钠组,5.0、10.0和20.0μmol/kg氯化镉组,9个硒镉联合作用组.氯化镉采用腹腔注射染毒、亚硒酸钠采用灌胃染毒.用端粒重复序列扩增法(TRAP)检测端粒酶活力,用逆转录聚合酶链反应法检测c-myc和p53表达.结果 3个镉单独作用组的大鼠肝细胞端粒酶活力、c-myc和p53表达较对照组明显增高,差异有统计学意义(P＜0.05).硒镉联合作用组中,当2.5和5.0μmol/kg亚硒酸钠分别与5.0、10.0和20.0μmol/kg氯化镉联合作用时,大鼠肝细胞端粒酶活力、c-myc和p53 mRNA水平较相应剂量的镉单独作用组下降;当10.0 μmol/kg亚硒酸钠分别与5.0、10.0和20.0 μmol/kg氯化镉联合作用时,大鼠肝细胞端粒酶活力、c-myc和53 mRNA水平与相应剂量的镉单独作用组比较,差异无统计学意义(P＞0.05).结论 相对较低剂量的硒对镉引起的大鼠肝细胞端粒酶活力增高具有抑制作用,其抑制作用可能是通过降低c-myc和p53表达.     

Neither methionine nor nitrous oxide inactivation of methionine synthase affect the concentration of 5,10-methylenetetrahydrofolate in rat liver

5,10-Methylenetetrahydrofolate occupies a key position in folate-dependent one-carbon metabolism. It is involved directly in the biosynthesis of deoxythymidine, it can be converted to 10-formyltetrahydrofolate for purine synthesis and it may be reduced to 5-methyltetrahydrofolate for methylation of homocysteine to methionine. We have developed a HPLC method for measuring 5,10-methylenetetrahydrofolate in liver and we have used this method to investigate two conditions that perturb one-carbon metabolism: 1) administration of methionine and 2) administration of the anesthetic gas, nitrous oxide (N(2)O). Rats were given 1.3 mmol/kg of methionine, and folate coenzymes in liver were measured. As expected, giving methionine resulted in an apparent increase in the concentration of 10-formyl- and tetrahydrofolate and an apparent decrease in 5-methyltetrahydrofolate concentration at 30 and 60 min. After 120 min, the concentrations of these coenzymes appeared to revert to control values. There was no apparent change in the concentration of 5,10-methylenetetrahydrofolate. Exposing rats to an atmosphere containing N(2)O results in inactivation of methionine synthase and accumulation of 5-methyltetrahydrofolate at the expense of other folate coenzymes. In liver from rats breathing N(2)O, 5-methyltetrahydrofolate increased, whereas there was no change in 5- or 10-formyltetrahydrofolates (P > 0.7 and P > 0.8, respectively). Tetrahydrofolate was not detected in liver from the N(2)O group, whereas it constituted 24% of folates in the control group. The concentration of 5,10-methylenetetrahydrofolate was not significantly affected by N(2)O (P > 0.18). These results suggest that the concentration of 5,10-methylenetetrahydrofolate is tightly regulated in liver.     

Effects of oral acute administration and subchronic feeding of several levels of D-psicose in rats

The effects of oral acute administration and subchronic (34 d) feeding of several levels of D-psicose, a C3-epimer of D-fructose, were studied in rats. In the acute administration test, five groups of eight male Wistar rats (3 wk old) were orally given D-psicose in doses of 8, 11, 14, 17, and 20 g/kg. Three rats receiving 14 g/kg, three rats receiving 17 g/kg and eight rats receiving 20 g/kg of D-psicose died within 2 d after administration. The calculated LD50 values were 16.3 g/kg by the Behrens-Karber method and 15.8 g/kg by the Litchfield-Wilcoxon method. In the subcronic feeding test, eight groups of seven male Wistar rats (3 wk old) were fed diets containing 0 (control), 10, 20, 30, and 40% for 34 d. One rat fed 30% D-psicose diet and five rats fed 40% D-psicose diet died during the experimental period. Body weight gain, food intake and food efficiency were more extensively suppressed by the higher D-psicose diets. The weights of heart, spleen and abdominal adipose tissue were smaller in the order of dietary D-psicose concentration. Cecal weight increased with increasing D-psicose concentration in the diets. Cecal hypertrophy was observed in rats fed 10-40% D-psicose diets. These results suggest that D-psicose differs in nutritional characteristics from D-glucose or D-fructose. The feeding of diets extremely high in D-psicose seems to be harmful to the intestinal tract.     

Gender effects on adrenergic receptor expression and lipolysis in white adipose tissue of rats

OBJECTIVE: To investigate the effects of short-term (15 days) cafeteria-diet feeding on the expression of alpha- and beta-adrenergic receptors (AR) and its association with lipolytic stimulation in isolated retroperitoneal white adipocytes. RESEARCH METHODS AND PROCEDURES: Six female and 6 male Wistar rats (4 weeks old) were fed a cafeteria diet plus standard diet for 15 days. The remaining 12 age- and sex-matched rats received a standard diet only. White retroperitoneal adipose tissue was isolated and used for the determination of both alpha(2) and beta-AR expression and for in vitro studies of lipolytic activity. RESULTS: In female control rats, we found higher lipolytic capacities located at the postreceptor level and a lower alpha(2)/beta(3)-AR ratio than male rats. Cafeteria-diet feeding for 15 days decreased lipolytic activity in both male and female rats and altered the alpha(2A)- and beta(3)-AR protein levels with an increase of alpha(2A)-AR in males and a beta(3)-AR decrease in females. DISCUSSION: Our results indicate that a 15-day cafeteria-diet feeding induced an increase in the alpha(2)/beta(3)-AR balance and impaired adipose tissue lipolytic activity, which was higher in males and may contribute to the development of increased fat mass. The higher functionality of alpha(2)-AR, together with the minor role developed by beta(3)-AR and lower lipolytic capacities located at the postreceptor level in cafeteria-diet-fed male rats compared with female rats, may be responsible for the gender-dependent differences observed in this study.     

番茄红素对高同型半胱氨酸血症大鼠血管内皮功能的影响和机制研究

目的研究番茄红素(Lyc)预防高同型半胱氨酸血症(HHcy)致大鼠动脉粥样硬化(AS)的作用机制。方法50只SD雄性大鼠分为正常对照组(NC),HHcy对照组n(HC),HHcy+低(HL1)、中(HL2)、高剂量Lyc组(HL3)。NC组给予AOAC配方饲料,其余各组则给予在AOAC配方基础上添加3%L-蛋氨酸的饲料。HL1、HL2、HL3组按体重每日分别给予Lyc10、15、20mg/kgbw,实验期12w。分析血清Hcy、NO、一氧化氮合酶(NOS)、内皮素-1(ET-1),丙二醛(MDA)、·OH、H2O2,血管细胞粘附分子-1(VCAM-1)、单核细胞趋化因子-1(MCP-1)、白介素-8(IL-8)含量。处死动物,取腹主动脉做NF-κB测定和病理学检查。结果除了NC组外,HHcy各组大鼠血清Hcy含量均随时间延长而显著提高;HC组NO含量显著低于NC组,而ET-1含量显著高于NC组,HL2和HL3组NO含量显著高于HC组,而ET-1含量则明显低于HC组,各组间NOS含量无明显差异。病理学检查显示,HC组和HL1组主动脉内膜中有泡沫细胞聚集,有脂肪颗粒沉着,HL2组、HL3组和NC组主动脉内膜完整,无泡沫细胞和脂肪颗粒。HC和HL1组血清MDA和H2O2含量显著高于NC组,HL2和HL3组则明显低于HC组,HL2和HL3组H2O2含量还显著低于HL1组。与HC组相比,HL2和HL3组血清·OH含量显著降低;HC组VCAM-1、MCP-1和IL-8含量显著高于NC组,HL1、HL2和HL3组则明显低于HC组;HC组NF-κB的表达显著高于NC组,HL1、HL2和HL3组则明显低于HC组。结论Lyc可以通过直接淬灭活性氧,抑制NF-κB的激活,减少炎性因子的表达,来改善血管内皮功能,阻止AS的发生。     

脑活素对冷暴露大鼠细胞免疫功能的影响

我们采用酶水解法自猪脑制备脑活素水溶液(Cerebrolysine),分子量小于一万。每ml相当于1g脑蛋白的含氮量,含氮量为1.8594mg/ml,游离氨基酸约占85％。符合奥地利EBEWE有关脑活素(Cerebolysine)的科学资料。我们进一步用SD雄性大鼠实验观察到:低温能使~3H-UR参入为指标的淋巴细胞转化活性增强,使用我们制备的脑活素则能进一步显著提高淋转活性,增强细胞免疫功能,从而增强机体抵抗力。这一新功能迄今未见国内外报道。     

Systemic effects of orally administered p, p'-DDE on immature male Wistar rats during pubertal period

Systemic effects of p, p'-DDE (1, 1-dichloro-2, 2 bis (p-chlorophenyl) ethylene; DDE) on immature male rats were investigated in pubertal Wistar rats after oral administration of DDE. Special rat chow containing 125 ppm DDE (approximately 10 mg/kg DDE) had been administered daily for 42 d since 6 wk of age and its effects had been observed until 12 wk of age. The administration of DDE did not produce any overt signs of toxicity. Neither physical development nor sexual maturation was affected, and serum biochemistry was not impaired at the dose used in this experiment. Moreover, the male reproductive organs and epididymal sperm count were not affected by the administration of DDE during the pubertal period. Our results showed that even immature male rats were resistant to DDE exposure at the daily dose of ca. 10 mg/kg, but metabolic and immunological changes still remained uncertain. Further investigation should be conducted to reveal all the effects of DDE on immature male rats.