Risk assessment of di-(2-ethylhexyl) phthalate plus a high-fat diet in the rat kidney

Abstract

Di-(2-ethylhexyl) phthalate (DEHP) is used in food packaging and medical products, resulting in unintentional human ingestion. Concurrently, a high fat (HF)-oriented diet is very popular for many people worldwide. Here we investigated the regulatory role of renin-angiotensin system in kidney dysfunction. The HF diet-fed rats were fed a HF diet plus different doses of 10, 100 and 300 mg/kg bw DEHP for 35 days by gavage. Serum lipid contents and protein activities of renin-angiotensin system (RAS) components were measured using biochemical methods and ELISA; key metabolic genes and proteins of the kidney were determined by RT-PCR and western blotting techniques. Kidney morphology was examined through hematoxylin-eosin (HE) staining. Kidney weight to body weight ratio and mRNA expression of kidney damage markers were significantly increased following DEHP plus HF administration, which corresponded histologically with glomerular basement membrane thickening and glomerular swelling. Furthermore, DEHP treatment plus a HF diet induced dyslipidemia, accompanied by increased levels of renin-angiotensin system components, such as ACE protein, MAS-1 protein, serum renin and aldosterone. In addition, mRNA expression levels of pro-inflammatory cytokines were significantly upregulated in the kidneys. Pearson correlation analysis revealed that higher kidney ACE expression and ACE/ACE-2 ratio were positively associated with TG, TC and LDL-C levels. These data suggest that combined exposure to DEHP exposure plus a HF diet feeding may induce renal damage through overactivation of RAS.