硫辛酸对全氟辛酸致雄性大鼠生殖毒性的保护作用

Protective effect of lipoic acid on reproductive toxicity induced by pentadecafluorooctanoic acid in male rats

[背景]全氟辛酸(PFOA)对生殖健康的损害越来越受到人们的重视,硫辛酸(LA)是否可以缓解PFOA所致的生殖损伤尚不明确。[目的]探讨LA对PFOA致雄性大鼠生殖毒性是否具有保护作用。[方法]6周龄雄性SD大鼠40只,随机分为5组,每组8只。各组处理如下:正常对照组,玉米油(0.2%体重);LA对照组,100 mg·kg^-1 LA;PFOA染毒组,10 mg·kg^-1 PFOA;低剂量LA干预组,10 mg·kg^-1 PFOA+50 mg·kg^-1 LA;高剂量LA组,10 mg·kg^-1 PFOA+100 mg·kg^-1 LA。灌胃染毒7周后,腹主动脉取血,留取睾丸、附睾,计算脏器系数。采用计算机辅助精子分析系统进行精子数量的检测,HE染色进行睾丸组织的病理学观察,分光光度法检测睾丸内琥珀酸脱氢酶(SDH)、乳酸脱氢酶(LDH)活性,酶联免疫吸附试验(ELISA)法检测大鼠血清中睾酮和卵泡刺激素(FSH)含量,Western blotting法检测各组大鼠睾丸组织中卵泡刺激素受体(FSHR)蛋白表达水平。[结果]PFOA染毒组大鼠睾丸脏器系数较正常对照组和LA对照组增高分别为(9.41±0.40)‰、(7.50±0.66)‰,(8.21±0.94)‰(P<0.05),附睾精子数量降低[(10.63±2.07)×106,(21.00±3.89)×106,(17.63±5.01)×106;P<0.05]。睾丸组织病理学结果显示:PFOA染毒组较正常对照组大鼠生精小管内生精细胞层次减少,生精细胞排列紊乱,生精上皮出现较多的空泡化改变,间质细胞数量减少且排列紊乱;而各剂量LA干预组病变明显减轻。PFOA染毒组大鼠血浆SDH、LDH活性较正常组大鼠下降[(1.15±0.44)、(1.74±0.58)U·g^-1;(1.82±0.64)、(2.58±0.64)U·g^-1;P<0.05],而经100 mg·kg^-1 LA干预后SDH活性有明显逆转,且差异有统计学意义(P<0.05)。此外,PFOA染毒组大鼠与正常对照组相比,睾丸内睾酮水平降低,FSH水平升高,睾丸组织FSHR蛋白表达量降低(P<0.05),而LA干预后可明显看到FSH水平下降,且高剂量LA效果更加明显,同时也减轻了睾丸组织FSHR蛋白的下降程度。[结论]PFOA对雄性大鼠具有生殖毒性效应,而适量的LA补充可以缓解PFOA所致的生殖损伤。

[Background]The reproductive damage induced by pentadecafluorooctanoic acid(PFOA)has raised increasing concerns,but if lipoic acid(LA)alleviates the damage is unknown.[Objective]This experiment investigates whether LA could protect against the reproductive toxicity of PFOA in male rats.[Methods]Forty male SD rats aged six weeks were randomly divided into five groups(eight rats in each group):blank control group(corn oil),LA control group(100 mg·kg^-1 LA),PFOA exposure group(10 mg·kg^-1 PFOA),low-dose LA intervention group(10 mg·kg^-1 PFOA+50 mg·kg^-1 LA),and high-dose LA intervention group(10 mg·kg^-1 PFOA+100 mg·kg^-1 LA).After seven weeks of administration by gavage,blood samples were collected from abdominal aorta,testes and epididymis were harvested,and viscera coefficients were calculated.The sperm count was measured using computer aided sperm analysis system.Pathological observation of testicular tissues was conducted after HE staining.The activities of succinic acid dehydrogenase(SDH)and lactate dehydrogenase(LDH)in testis were detected by spectrophotometry,the contents of testosterone(T)and follicle-stimulating hormone(FSH)in serum by enzyme-linked immunosorbent assay(ELISA),and the protein expression level of follicle-stimulating hormone receptor(FSHR)in rat testis by Western blotting.[Results]The testicular organ coefficient of the PFOA exposure group was higher than those of the blank control group and the LA control group[(9.41±0.40)‰,(7.50±0.66)‰,(8.21±0.94)‰;P<0.05],and the epididymal sperm count was lower[(10.63±2.07)×106,(21.00±3.89)×106,(17.63±5.01)×106;P<0.05].The results of testicular histopathology showed reduced layers of disordered spermatogenic cells in the rat spermatogenic tubule of the PFOA exposure group compared with the blank control group,along with more vacuolization changes in the spermatogenic epithelium and less and disarranged leydig cells;while these lesions in the LA intervention groups were significantly reduced.The activities of SDH and LDH decreased after the PFOA treatment compared with the blank control group[(1.15±0.44),(1.74±0.58)U·g^-1;(1.82±0.64),(2.58±0.64)U·g^-1;P<0.05],but the activity of SDH reversed after the 100 mg·kg^-1 LA intervention(P<0.05).In addition,compared with the blank control group,the rats in the PFOA exposure group had lower T levels,higher FSH levels,and lower FSHR protein expression levels in the testicular tissues(P<0.05),and the rats after LA intervention showed lower FSH levels(far bigger falls for the high-dose LA intervention group)and alleviated reduction of FSHR protein expression levels.[Conclusion]PFOA has a reproductive toxicity effect on male rats,while appropriate LA supplementation can protect against the reproductive injury caused by PFOA.