异丙苯过氧化氢体内致大鼠睾丸和附睾过氧化的初步研究

Peroxidative Damage Induced by Cumene Hydroperoxide in Testis and Epididymis of Rats in vivo

目的:建立异丙苯过氧化氢(cHP)体内过氧化模型,探讨cHP体内过氧化对大鼠睾丸组织和附睾精子的影响,及对精子核DNA断裂的影响。方法:90日龄雄性W istar大鼠52只,设cHP 1/10 LD50、1/6 LD50、1/4 LD503个剂量组和对照组,cHP 1/10 LD50、1/6 LD50组和对照组每组大鼠12只,1/4 LD50组大鼠16只。用无菌生理盐水稀释70%cHP水剂配制,按2 m l/kg经腹腔每日1次注射,对照组给同体积生理盐水,观察一般中毒症状和体征。连续1周,最后1次给药24 h后处死动物。分光光度法测定睾丸组织匀浆、附睾头部和尾部精子丙二醛含量,用单细胞凝胶电泳检测睾丸生精上皮细胞、附睾头部和尾部精子核DNA断裂发生率,计数附睾尾部精子活动率,睾丸和附睾常规石蜡切片,苏木精-伊红染色观察病理变化。结果:给予cHP大鼠活动稍差,无死亡,1/6 LD50、1/4 LD50 cHP组体重降低明显(P<0.001)。1/6 LD50、1/4 LD50 cHP组大鼠睾丸和附睾精子丙二醛浓度均明显高于对照组,附睾尾部精子活动率均明显降低,睾丸生精上皮细胞和附睾头部精子核DNA断裂发生率明显高于对照组,附睾尾部精子核DNA断裂的发生率与对照组差异无显著性(P>0.05)。1/10 LD50 cHP组大鼠体重变化、睾丸丙二醛浓度、附睾尾部精子活动率、睾丸生精上皮细胞和附睾精子核DNA断裂与对照组比较,差异均无显著性(P>0.05)。结论:1/6 LD50、1/4 LD50 cHP能在体内使大鼠睾丸和附睾精子发生过氧化,并使细胞核DNA发生断裂,核DNA断裂的主要部位可能在睾丸组织,对附睾尾部精子核DNA断裂无明显影响。

Objective： To establish an oxidative stress model induced by cumene hydroperoxide（cliP） in testis and epididymis of rats in vivo, and to understand the peroxidative damage of oxidative stress in testis, epididymal sperm and its propensity to induce nuclear DNA damage during spermatogenesis and sperm maturation in vivo. Methods： An organic hydroperoxide, cliP, 70% aqueous, diluted by 0.9% NaCl, was employed as model prooxidant. Ninty-day-old male Wistar rats were divided into a control and three cliP groups, and were administered intraperitonealy 0, 1/10, 1/6 and 1/4 LD50 cliP per day respectively at a dose of 2 ml/kg, for 7 consecutive days and were observed for any toxic symptoms and mortality. Twenty-four hours after the last dose, rats were sacrificed and induction of oxidative stress was ascertained by monitoring the degree of lipid peroxidation expressed as nano molar of malondialdehyde （MDA） in testicular homogenate and epididymal sperm. Nuclear DNA damage in testes and epididymal sperms was determined by comet assay. Motility of caudal sperms was counted and the morphology of testes and epididymis was observed under light microscope. Results： Rats of cliP administered groups were less vigorous than those of the control, but there were not death of rats during treatment. 1/10 LD50 per day for 7 consecutive days resulted in only a marginal increase in testicular MDA levels. However, 1/6 and 1! 4 LD50 per day for 7 days of cliP administered to adult rats induced marked oxidative stress in testis and epididymal sperms as evidenced by a marked increase in MDA or nuclear DNA damage in testis and caput sperms, as well as significant decreases both in the body weight and motility of caudal sperms. While the nuclear DNA damage caput sperms of 1/6 and 1/4 LD50 cliP administered rats increased significantly, nuclear DNA damage in caudal sperms showed no treatment related alterations. Conclusion： Oxidative stress in testis and epididymal sperms can be safely induced by applying multiple doses of cliP （ 1/6 and 1/4 LD50 per day for seven consecutive days）. DNA damage caused by cliP induced oxidative stress may occurred mainly in testes.