The Damage Of Di-(2-ethylhcxyl) Phthaiate And Bisphenol A Mixed On Testis In Rats And Its Mechanism

ObjectivesPlastics are widely used in modern life,and their unbound chemicals bisphenol A and phthalates can leach out into the surrounding environment.BPA and PAEs have recently attracted the special attention of the scientific community,regulatory agencies and the general public because of their high production volume,widespread use of plastics,and endocrine-disrupting effects.Considering the environmental pollutants in actual life is mixture,and human exposure channels,so the research on the toxicological effects of single pollutant is no longer meet the actual needs.This study was designed to observe the reproductive toxicity on male rats when they are exposed to DEHP and BPA,and explore the damage mechanism of this two substance.MethodsThree weeks old SD rats were randomly divided into four groups,25 rats in each group.DEHP exposure group,BPA exposure group,D+B exposure group were treated with 750mg/kg DEHP,100mg/kg BPA,750mg/kg DEHP+100mg/kg BPA,adopting corn oil as excipients.The negative control group received corn oil.Four groups were exposed adopting administration by gavage the volume of 5ml/kg consecutively for 6 weeks,1 times/day.Each group were randomly divided into three stage according to initial body weight,and then rats were killed in the first week,third week and sixth week,each stage of each treatment group treatment 8 animal.The weight coefficient of testis,sperm count,serum sex hormone(T,E2)levels and testicular tissue pathology and lipid peroxidation were measured.Such as malondialdehyde(MDA),hydrogen peroxide(H2O2),superoxide dismutase(SOD),glutathione peroxidase(GSH-Px),and the expression of oxidative stress related genes:SOD,GSH-Px,Nrf2,HO-1,Gclc,Txnrd.Results1.The body weight of DEHP group and D+B group were significantly lower than the control group(P<0.05);testis organ coefficient of DEHP group was lower than in third weeks and sixth weeks,the control group(P<0.05);testis coefficient of D+B group were lower than the control group and BPA group in the three stage,the difference was statistically significant(P<0.05).2.The number of sperm in each treatment group were lower than the control group,DEHP group and D+B group the number of sperm was significantly lower,the difference was statistically significant(P<0.05).3.T of rats in the D+B group were significantly lower than the control group on third weeks and sixth weeks(P<0.05);the content of E2 after first weeks in the BPA group and D+B group than in the control group,the difference was statistically significant(P<0.05).4.DEHP and D+B group in seminiferous tubule vacuolization on first week,cells related to spermatogenesis significantly decreased;third weeks,DEHP group and D+B seminiferous tubule atrophy,most germ cells disappeared,seminiferous tube constituted by Sertoli cells only slightly;BPA expansion of seminiferous tube;sixth weeks,DEHP seminiferous tubule atrophy,seminiferous tubule germ cells mostly disappeared and the changes of D+B group and DEHP group,but severe than that in DEHP group,BPA seminiferous tubules spermatogenic epithelial cells mostly disappeared,only a small amount of visible elongated sperm cells;the control group of male spermatogenic stage tubular well developed.5.The content of MDA and H2O2 in the three treatment groups increased in first and third weeks.The content of MDA and H2O2 in D+B group was higher tharn that of control group.DEHP group and D+B group MDA was significantly higher than that of the control group on sixth weeks(P<0.05).The content of SOD were decreased significantly in the D+B group on three stage(P<0.05).The content of GSH-Px in DEHP group and D+B group appeared significantly increased(P<0.05).6.The expression of each treatment group SOD1 showed a significant decline in the first and third weeks(P<0.05),SOD3 increase change,D+B group of three stages was significantly higher than that in the other three groups,the difference was significantly(P<0.05);the results of GSH-Px and SOD3 have the same changing trend.DEHP group HO-1 was significantly higher than that in control group at first weeks(P<0.05),but Gclc was significantly lower than the control(P<0.05);D+B group Gclc were significantly decreased compared with the control group in the three stage(P<0.05);the content of Txnrd in DEHP group and D+B group were significantly lower than the control group(P<0.05);The content of Nrf2 in all treatment groups were significantly lower than the control group on the first week(P<0.05).But group BPA were significantly higher than the control group on third and sixth weeks,at the same time,group D+B were significantly lower than those of the other three groups,the difference was significantly(P<0.05).ConclusionsAlone and mixed exposed to DEHP and BPA interference normal development of rats;lead to testicular dysplasia,testicular seminiferous tubule atrophy,spermatogenic cells decreased;inhibition of sex hormone synthesis related enzymes,and then changes the T and E2 level of rats;affect spermatogenesis,resulting in decreased number of sperm;induce lipid peroxidation,and activation of keapl-Nrf2 signaling pathway in vivo.The combined effects of DEHP and BPA increased the damage of antioxidation system of testis,oxidative stress damage the body's homeostasis ability,which led to injury of testis.