【作者】 王文祥；

【导师】 廖惠珍； 吴小南；

【作者基本信息】 福建医科大学 ， 流行病与卫生统计学， 2004， 硕士

【摘要】 目的: 研究茶多酚对亚慢性镉致雄性生殖毒性的拮抗作用及其可能的机理,为茶多酚防治环境低剂量镉暴露所致雄性(男性)生殖损害提供科学实验依据。方法:(1)建立镉的亚慢性生殖毒性模型: 24只清洁级雄性SD大鼠按体重随机区组分为4组——对照组、低剂量染镉组、中剂量染镉组、高剂量染镉组。染毒剂量分别为0、0.10mg, 0.20mg,0.40mg/kg.bw(以Cd计),每周染毒5次,连续5周,第36天处死各组实验动物。取出睾丸组织称重,并取左侧睾丸组织作病理形态学检查, 同时取附睾尾作精子数量、活动率及畸形率测定。 (2)茶多酚对亚慢性镉致雄性大鼠生殖毒性的拮抗作用及其机理探讨:60只清洁级雄性大鼠按体重大小随机分为6组----对照组、单染镉组、镉+低剂量茶多酚组、镉+中剂量茶多酚组、镉+高剂量茶多酚组、茶多酚组。对照组和茶多酚组给予生理盐水皮下注射,其余各组以0.4mg/kg.BW Cd2+ 皮下注射染毒,每周5次,连续5周;染毒的同时分别给予不同的干预因素:阴性对照组与单染镉组给予双蒸水;镉+低剂量茶多酚组、镉+中剂量茶多酚组、镉+高剂量茶多酚组分别给予50、100、200 mg/kg.d茶多酚,茶多酚组给予100 mg/kg.d茶多酚,连续灌胃5周;干预结束后,收集24h尿液、粪便,并抠眼球取血分离血清。最后处死大鼠取肝、肾、睾丸等样品进行相关指标的测定。 结果:(1)茶多酚对亚慢性镉致雄性大鼠生殖毒性的拮抗作用:亚慢性镉暴露可使大鼠精子活动率下降(P<0.05),睾丸组织LDH-X酶活力受抑(P<0.05);精子生成量下降(P<0.05);精子畸形率升高(P<0.05);血清睾酮水平降低<WP=4>(P<0.05);病理组织学检查睾丸轻度水肿,曲精小管管腔精子较少。中高剂量茶多酚可以部分拮抗镉所致精子活动率和精子生成量的下降(P<0.05),精子畸形率的上升(P<0.05),部分恢复血清睾酮水平(P<0.05),抑制镉所致的睾丸脏器系数的升高和曲精管腔精子数的减少。(2)茶多酚拮抗镉致雄性大鼠生殖毒性的机理:①茶多酚对染镉大鼠睾丸氧化应激的影响; 亚慢性染镉可提高睾丸组织MDA含量,升高GSH-PX酶活力,耗尽GSH含量, 并降低SOD酶活力(P<0.05),而中高剂量茶多酚可明显拮抗镉所致的睾丸氧化应激,降低睾丸组织MDA含量,恢复SOD酶活力,并提高GSH含量(P<0.05)。提示茶多酚可拮抗镉致睾丸氧化应激,其机制可能与茶多酚直接捕获自由基、促进细胞GSH的合成,并恢复抗氧化酶SOD活力有关。②茶多酚对染镉大鼠体内镉蓄积的影响:中高剂量干预组肝镉和睾丸镉含量下降(P<0.05),尿镉和粪镉排出量增加(P<0.05),且具有明显的剂量-效应关系。而肾镉未见显著性差异(p>0.05);茶多酚尚可降低正常大鼠肝脏镉含量(P<0.05)。提示茶多酚可促进体内蓄积镉排出,且茶多酚在促排镉的同时并不加重肝肾损伤。结论:亚慢性低剂量镉暴露可损伤雄性大鼠生殖系统生精功能的异常和睾酮合成的抑制是亚慢性低剂量镉暴露所致生殖损伤的首要表现氧化应激和内分泌干扰作用是亚慢性低剂量镉暴露致生殖损伤的重要机制茶多酚可拮抗亚慢性低剂量镉暴露所致生殖损伤抗氧化和促排镉作用是茶多酚拮抗亚慢性低剂量镉暴露所致生殖损伤的重要机制更多还原

【Abstract】 Objective: The objective of this research was to demonstrate whether Tea polyphenols could antagonize cadmium-induced male subchronic reproductive toxicity and by which mechanisms it worked. This study was also to provide the evidences for the prevention and treatment of reproductive toxicity induced by environmental cadmium exposure. Methods: (1) Establishing the model of male reproductive toxicity induced by sub-chronic cadmium exposure: 24 male Sprague-Dawley rats were randomly divided into four groups. 0、0.1、0.2 and 0.4mg cd2+/kg.bw were injected subcutaneously in different groups, five times per week for 5 weeks. After the exposure, the rats were sacrificed and the testis, epididymis were separated. Testes were selected to examine the pathology. while sperm concentration、sperm activity and sperm malformation were detected from epididymises. (2) the Antagonistic effect and mechanism of Tea Polyphenols (TP) on Cadmium -induced Subchronic Reproductive Toxicity :60 male Sprague-Dawley rats were randomly divided into six groups: control, Cd, Cd +low-dose TP, Cd +middle-dose TP, Cd +high-dose TP and TP groups. The rats in control and TP groups were injected (sc) with saline, while others with Cd at a dose of 0.4mg/kg, five days a week.. Mean while ,the rats in Cd +low-dose TP, Cd +middle-dose TP, Cd<WP=6>+high-dose TP and TP groups were given TP( 50 mg/kg, 100 mg/kg, 200 mg/kg ,100mg/kg respectively) orally once a day , while others were given distilled water instead. After five weeks , the rats were killed and the samples of serum, urine, feces, liver, kidney and testis were take for test.Results: (1) TP could antagonize cadmium-induced male subchronic reproductive toxicity: A significant reduction in the sperm population, motility, serum testosterone concentration and testicular LDH-X activity were recorded in rats treated with cadmium alone, which was accompanied by an increase of malformed sperm. Middle and high-dose TP given resulted in partial recovery of the reproductive parameters above studied (P<0.05). Through the pathological examination of the testes we could find out that: treatment with cadmium resulted in testicular edema lightly and less sperm in seminiferous tubule. However testes from rats that were treated with TP appeared to show much less cadmium-induced damage, especially in middle and high-dose TP group.(2) The mechanisms of TP antagonize cadmium-induced male subchronic reproductive toxicity:①The effects of TP on cadmium -induced testicular oxidative stress: After 5 weeks of cadmium treatment, MDA level and GSH-PX activity in testis were significantly higher (P<0.05) while SOD activity and GSH concentration were significantly lower (P<0.05) than those in the control group respectively. As compared to Cd group, middle and high dose TP taken had lower MDA level, higher GSH concentration and SOD activity in testis, which showed that TP could against testicular oxidative stress induced by cadmium.②The effects of TP on cadmium accumulation in different tissues: Compared with the control group, the administration of Cd led to a manifold increase of its level in all investigated organs such as liver, kidney and testes, the Cd concentration in urine and feces was also increased. Middle and high dose TP taken significantly decreased Cd accumulation in the testes and liver, increased Cd concentration in urine and feces as compared to Cd group. TP had no effect on the serum ALT、AST、BUN、CRE level,<WP=7>which shows that TP could promote accumulative cadmium to excretion without increasing the hurt of liver and kidney. Conclusion:1 Subchronic Cd exposure could damage male reproductive system.2 Spermatogenic lesion and inhibition of testosterone production are early events after subchronic Cd exposure.3 Oxidative stress and endocrine disruption are two important mechanisms of male reproductive toxicity induced by subchronic Cd exposure.4 Tea polyphenols could antagonize cadmium-induced male subchronic reproductive toxicity.5 Inhibition of oxidative stres更多还原