S-腺苷L-甲硫氨酸对围产期暴露全氟辛烷磺酸大鼠生殖毒性的拮抗作用

Antagonistic effects of S-adenosyl L-methionine on PFOS induced reproductive and genetic toxicity in rats

目的探讨早期低剂量接触全氟辛烷磺酸盐(perfluorooctane sulfonate,PFOS)对大鼠生殖功能和生长发育的影响及S-腺苷L-甲硫氨酸(S adenosyl L methionine,SAM)和5-杂氯脱氧胞嘧啶(decitabine,DAC)对其的干预作用。方法将40只健康出生5 d(PND5)SPF级SD大鼠随机分为4组,每组10只,雌雄各半,分别为对照(0.2%Tween-80生理盐水)组、PFOS染毒组、SAM干预组和DAC干预组。PFOS染毒组、SAM干预组和DAC干预组分别染毒5 mg/kg的PFOS;SAM干预组和DAC干预组分别同时给与16 mg/kg的SAM和0.15 mg/kg的DAC干预;采用颈部皮下注射方式进行染毒,每天1次,28 d后,每3 d 1次,持续染毒至出生后60 d(PND60)。每天观察F0代大鼠的一般情况并测定体重。待F0代大鼠成年后,将雌、雄大鼠按1∶1合笼交配。待F1代大鼠成年后,各组选取6只大鼠,以雌∶雄为2∶1进行合笼,孕期和哺乳期(PND28)母鼠的染毒方法同前。观察各代大鼠的生育能力和仔鼠的发育情况,并观察F1代大鼠睾丸组织形态结构变化。结果与对照组比较,PFOS组、SAM干预组和DAC干预组F0代母鼠的受孕率均较低,死产率较高,存活率较低;PFOS组和DAC干预组F0代母鼠的畸胎率和产后死亡率均较高,差异均有统计学意义(P<0.01,P<0.05)。与PFOS染毒组比较,SAM干预组F0代母鼠的受孕率、存活率较高,死产率、畸胎率较低;DAC干预组F0代母鼠的死产率、存活率较低,产后死亡率较高,差异均有统计学意义(P<0.01,P<0.05)。与对照组比较,PFOS染毒组和DAC干预组F1代仔鼠出生体重均较低,毛发长出时间均延长,差异有统计学意义(P<0.05,P<0.01);PFOS染毒组和SAM干预组、DAC干预组F1代仔鼠的开眼时间和自主采食出现时间均延长,差异有统计学意义(P<0.05),而耳廓伸展时间无明显改变。与PFOS染毒组比较,SAM干预组F1代仔鼠的出生体重较高,开眼时间和自主采食出现时间均缩短,差异有统计学意义(P<0.05,P<0.01);DAC干预组F1代仔鼠出生体重、耳廓伸展时间、毛发长出时间、开眼时间和自主采食出现时间均无明显改变。与对照组比较,PFOS染毒组和DAC干预组、SAM干预组F1代雄性大鼠睾丸生精细胞层次减少和生精上皮细胞排列松散的异常生精小管百分比均增加,差异均有统计学意义(P<0.05,P<0.01)。与PFOS染毒组比较,SAM干预组F1代雄性大鼠睾丸生精细胞层次减少和生精上皮细胞排列松散的异常生精小管百分比均下降,差异均有统计学意义(P<0.05);而DAC干预组以上2指标均无明显变化。F1代仔鼠正常饲养两个月后,PFOS染毒组有2雄4雌仔鼠;DAC干预组有3雄4雌仔鼠,其雌鼠均未受孕;而SAM干预组有4雄4雌仔鼠,雌鼠均受孕,但均因难产死亡。结论围产期PFOS慢性暴露能引起大鼠生长发育迟缓,生育力下降,并遗传子代,致子代不孕不育,这与损害雄性大鼠的睾丸组织结构和生殖功能有关。DAC可进一步加重PFOS引起的生殖发育毒性,而SAM可明显抑制PFOS暴露产生的生殖毒性作用。影响体内甲基化代谢可能是干预PFOS的生殖毒性作用的新途径。

Objective To detect the potential effects of S-adenosyl L-methionine（SAM） and decitabine（DAC） on the reproductive and developmental toxicity induced by perfluorooctane sulfonate（PFOS）. Methods Forty SD of PND5 SD rats were randomly divided into control,PFOS,PFOS ＋SAM and PFOS ＋DAC groups, ten in each group, half male and female. The rats were subcutaneously injected on neck with PFOS（5 mg/kg body weight） in PFOS, PFOS ＋SAM and PFOS ＋DAC group, with equivalent of 0.2% Tween-80 saline in control group, co-treated with SAM（16 mg/kg body weight） or DAC（0.15 mg/kg body weight） in PFOS＋SAM or PFOS＋DAC group, once a day for 28 d, then once three days till PND60. The F0 adult rats（male ∶female=1∶1） were put into a cage for mating. The adult F1 rats（female∶male= 2∶1）,six rats in each group,were put into a cage for mating. The treatments of PFOS and SAM or DAC to maternal rats during pregnancy and lactation were the same as before. The fertility of maternal rats and development of neonates were detected. The morphology of male testis was also observed. Results Compared with the control group,the pregnancy rates and viability were significantly lower and the mortality rates were higher in PFOS, PFOS＋SAM and PFOS＋DAC groups. The teras rates and postpartum mortality were higher in PFOS and PFOS＋DAC groups. Compared with PFOS group, the pregnancy rates and viability of neonates in F0 rats were higher,in PFOS＋SAM group.The birth weights of rats（F1） in PFOS and PFOS＋DAC group were significantly lower, the time of hair appear,opening of eyes and independent foraging were later than those in control rats,whereas,those of which were quite the same as in PFOS ＋SAM group and control group. After normal feeding for two months, there was offspring of two male and four female in PFOS group,three male and four female in PFOS＋DAC group, both of which female rats were infertility, however, there were neonates of four male and four female in PFOS ＋SAM group, in which female got pregnant, but dystocia. Conclusion The toxic effects of perinatal exposure to PFOS may induce rats retardation, fertility decline and heredity to next generation to infertility, which is related to impairment of testis structure and function of reproduction. DAC may increase the reproductive and developmental toxicity of PFOS, however, SAM may significantly inhibit its toxicities, and the effect of internal methylation metabolism may be a potential intervention way.