| Background and objective:"White pollution" has swept the world with production and consumption of plastic products.The marine biology professor Richard Thompson of Plymouth University put forward the concept of "microplastics",and microplastics(MPs)are generally defined as plastic particles in the environment smaller than 5 mm.Ingestion of microplastics can cause a variety of damage on physiological functions of aquatic organisms,and they can even transfer in the food chains.Microplastics are attracting more and more attention as a potential threat to the ecological environment and human health,but effect of microplastics on terrestrial organisms was seldom reported.This study investigated the effect of polyvinyl chloride(PVC),polystyrene(PS)and polycarbonate(PC)microplastics on metabolism,liver function and reproductive paraments of rats with high-fat diet.Methods:PVC,PS and PC resin powder were sieved by 150μm sieve to made three kinds of microplastics.Then the PVC,PS and PC microplastics were added in high-fat diet by 2%(w/w)to made PVC-diet,PS-diet and PC-diet,respectively.Thirty-four 6-week-age Wistar rats(male and female)were picked and randomly divided into control group(C group)and microplastics groups(PVC group,PS group,PC group),feed with high-fat diet,PVC-diet,PS-diet and PC-diet for 60 days.Glucose tolerance test(OGTT)and insulin tolerance test(ITT)were administered at week 8.After fasting overnight,the rats were executed and the serum were collected to test serum glucose,TC,TG,LDL-C,HDL-C,testosterone,estradiol,progesterone,aspartate aminotransferase(AST),alanine aminotransferase(ALT).Liver,spleen,pancreas,kidney,gonads and fat samples were collected and weighed,to calculate relative organ weights.UPLC-Q/TOF MS was applied to identify changes of liver metabolite profiles and find the metabolic variables related to the intervention.Results:On the aspect of energy metabolism,the results of OGTT and ITT showed no adverse change in the microplastics groups,and the serum metabolic indexes did not show significant difference compared with control group.As for the liver function,the morphological examination showed the microplastics ingestion may cause liver damage,especially for the male rats,while the AST and ALT of microplastics groups showed no obvious change compared with control group.To the aspect of reproductive and endocrine,the morphological examination of testicles in microplastics groups showed interstitial edema,and the organ coefficient of testis and epididymis increased significantly(P<0.05 or P<0.01).Meanwhile,the estradiol of male rats in PVC group decreased significantly(P<0.05),while estradiol of female rats in PVC was significantly increased(P<0.01),compared with their control group respectively.UPLC-Q/TOF MS results confirmed the PVC,PS and PC microplastics can lead 11 kinds of metabolites changed with same trends significantly compared with control group.And the rhodopsin and thiamine in the liver of PVC group was significantly decreased compared with control group(P<0.05).Conclusion:The results of OGTT,ITT and energy metabolism indexes showed that PVC,PS and PC microplastics in this study did not have harmful effects on blood glucose and insulin sensitivity of high-fat diet rats,and they would not disturb the energy metabolism.The morphology analysis of liver and AST,ALT results showed the microplastics ingestion may cause liver damage,the liver damage still at low grade and longer intervention may cause more severe liver damage.The microplastics could lead to the compensatory increase of sex gland in male rats,which suggested that microplastics had more obvious effects on male reproductive system.PVC microplastics ingestion would disrupt the reproductive endocrine of high-fat diet rats,and the mechanism of reproductive endocrine disorder of male rats may relate to the decrease of rhodopsin and thiamine in the liver. |
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