Effect Of DEHP Combined With A High-Fat Diet On Renal Function In Rats And Its Mechanism

Di(2-ethylhexyl)phthalate(DEHP),as a plasticizer with endocrine disrupting properties,is widely known for its developmental toxicity,genetic toxicity,and reproductive toxicity.Thereby DEHP can seriously endanger the human health.Previous studies have revealed that DEHP can cause kidney damage.And obesity is one of the independent causes of chronic kidney disease.In view of this,we studied the effects of DEHP combined with a high-fat diet(HFD)on renal function in rats by means of intragastric administration.This study is aim to providing some toxicological basis for further research on possible molecular mechanisms of DEHP-induced renal injury.In this study,30 male Wistar rats were randomly divided into five groups.Rats in control group were fed a regular chow and rats of the other four groups fed a HFD were combined with the treatment of DEHP(0,0.5,10 and 100 mg/kg bw/day)for 8 weeks by gavage.In order to investigate the effects of DEHP combined with a HFD on the kidney in rats,renal function markers were measured using biochemical method and enzyme-linked immunosorbent assay(ELISA).Furthermore,m RNA expression levels of related genes were measured using reverse transcriptase-polymerase chain reaction(RT-PCR).The results showed:(1)All the doses of DEHP exposure caused significant increase in body weight and fat-body ratio in HFD rats compared with the control and HFD group.100 mg/kg bw DEHP significantly increased kidney weight and kidney-body ratio in HFD rats compared with the control group.(2)100 mg/kg bw DEHP significantly increased the contents of Scr and serum Cys-C compared with the control and HFD groups,and 10 and 100 mg/kg bw DEHP significantly increased the transcription levels of Kim-1 and NGAL compared with the control and HFD group.(3)Compared with the control group and the HFD group,100 mg/kg bw DEHP caused some pathological changes in rats,including glomerular atrophy,enlarged cystic cavity,relatively dilated renal tubules,a small amount of interstitial fibrosis and interstitial inflammatory cell infiltration.(4)Compared with the control group,100 mg/kg bw DEHP exposure caused significant up-regulation of IL-6 and TNF-α m RNA transcription levels.In order to study the mechanism of the effects of DEHP combined with a HFD on the kidney in rats,the activity of two typical signaling pathways in the renin-angiotensin(RAS)system and m RNA expression levels of sodium retention-related genes were determined.The result showed:(1)Compared with the control groups,TG and LDL-C levels in all the DEHP groups were significantly elevated,while HDL-C levels were significantly decreased.(2)Compared with the control and HFD groups,the expression levels of ACE and ACE2 were not significantly changed.In the 100 mg/kg DEHP group,the contents of renin,AngⅡ,ALD and the expression level of AT1 R m RNA in the HFD groups were significantly increased,while the content of Ang-1-7 and its receptor Mas-1 transcription level were significantly reduced.(3)Pearson correlation analysis showed that TC,TG and LDC-C were negatively correlated with Ang-1-7 and Mas-1,while LDL-C was positively correlated with AT1 R m RNA and renin levels.(4)Compared with the control group,DEHP significantly increased the m RNA expression levels of ENa C-α,ATP-α,ATP-β,NHE-3 and NKCC-2 in the kidneys of HFD rats,and significantly reduced the expression of ENa C-β expression.In summary,HFD plus DEHP exposure did promote the occurrence of obesity in rats,leading to abnormal lipid metabolism in rats.Thereby HFD plus DEHP exposure further increase the possibility of renal function abnormalities in the HFD group.Some pathological changes of the rats in the 100 mg/kg DEHP group,including glomerular atrophy,tubular dilatation,and clear tube,coincided with the fact that the kidney weight and kidney-body ratio of this group were significantly higher than those of the control and HFD groups.Exposure to different doses of DEHP can cause RAS system imbalance and increased renal water and sodium reabsorption in HFD rats.The cause of renal damage may be that the the activity of ACE2-Ang-1-7-Mas1 pathway in 0.5 mg/kg bw DEHP group was inhibited,and 10 and 100 mg/kg bw DEHP exposure caused functional damage to the kidney by increasing the activity of the ACE-AngⅡ-AT1 R pathway and inhibiting the activity of the ACE2-Ang-1-7-Mas1 pathway at the same time.It is suggested that DEHP combined with a HFD might cause dyslipidemia,sodium retention and RAS system imbalance,which lead to inflammation and renal dysfunction in rats.