Background Di(2-ethylhexyl) phthalate (DEHP) is the highest consumed and the most widely used phthalic acid ester, their effects on lipid metabolism have attracted the attention of many scholars. However, the associated mechanism is still unclear.
Objective To observe the effect of DEHP on lipid metabolism in rats, probe its possible mechanism, and provide a research basis for the effect of DEHP on human lipid metabolism.
Methods Forty healthy male SD rats were randomly divided into 4 groups: solvent control (0 mg·kg−1 DEHP), low DEHP (187 mg·kg−1), medium DEHP (375 mg·kg−1), and high DEHP (750 mg·kg−1) groups. DEHP was administered by oral gavage for 6 d per week, consecutively 8 weeks. The rats were weighed once a week during the exposure period. At 24 h after the last exposure, the rats were anesthetized with 20% urethane and sacrificed by apical puncture. Rat livers were harvested and weighed before hematoxylin-eosin (HE) histopathological observation. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the mRNA levels of lipid metabolism-related genes Janus kinase 3 (JAK3), signal transducer and activator of transcription 5b (STAT5b), and peroxisome proliferator-activated receptor γ (PPARγ) in liver, and Western blot was used to detect the expression levels of lipid metabolism-related proteins JAK3, STAT5b, and PPARγ in liver.
Results Compared with the control group, there was no significant difference in the body weight gain of the rats in each group (P>0.05). The liver organ coefficients of the DEHP exposure groups were higher than that of the control group (P<0.001), and increased with higher DEHP dosages. The level of high-density lipoprotein cholesterol (HDL-C) in serum decreased in all DEHP exposure groups (P<0.05), and the level of low-density lipoprotein cholesterol (LDL-C) in serum increased in the high DEHP group (P<0.05). The results of liver histopathological morphology showed that the hepatocytes of each DEHP group were enlarged and edematous in varying degrees, with loose stroma and irregular arrangement of cells, which were manifested as inflammatory cell infiltration and fatty degeneration of liver cells. Compared to the control group, the mRNA levels of JAK3, STAT5b, and PPARγ in liver tissues of rats in each DEHP group decreased (P<0.001). Compared to the control group, the relative expression levels of JAK3 in each DEHP group decreased (P<0.05), and the relative expression levels of STAT5b and PPARγ in the medium and high DEHP groups decreased (P<0.05).
Conclusion DEHP exposure can induce abnormal lipid metabolism in rats, and the mechanism may be related to DEHP inhibiting the activation of JAK3/STAT5b/PPARγ signaling pathway.
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