Impact of particulate matter 2.5 on the liver function of mice

Q. Zhang, H.-Y. Zhang, X.-Q. Yu, Z.-J. Cui, Z.-W. Lv

Department of Nuclear Medicine, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China. zhai0184heyifan2@126.com

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• Nuclear Medicine

OBJECTIVE: The aim of this study was to evaluate the impact of particulate matter 2.5 (PM2.5) on liver function at the animal level and to study its impact targets.

MATERIALS AND METHODS: 60 male and female BALB/c mice of SPF grade, aged 6-8 weeks, were randomly divided into four groups, with 15 mice in each, including the normal saline control group, the PM2.5 low dose group [2 μg/(100 g/d)], the PM2.5 medium dose group [8 μg/(100 g/d)] and the PM2.5 high dose group [16 μg/(100 g/d)]. Each day, 0.9% saline or PM2.5 particles were administered through the nasal route, and samples were taken after 3 weeks of continuous exposure. Hematoxylin-eosin staining (HE) was used to observe the liver damage caused by PM2.5. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were detected by using an automatic biochemical analyzer to detect the content of liver glycogen and blood glucose. Multiple indicators were observed, including plasma tumor necrosis factor (TNF-α) and interleukin-6 (IL-6) levels, oxidative stress response indicators reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) detection, RT-PCR and Western blot detection of glycogen synthase (GS), glucokinase (GK), nuclear factor erythroid 2-related factor 2 (Nrf2) expression and phosphorylation level of phospho-c-Jun N-terminal kinases (p-JNK).

RESULTS: PM2.5 can cause damage to the liver by increasing PM2.5 concentrations, raising the metabolic rate of liver cells, resulting in a substantial amount of inflammatory infiltration and vacuolar degeneration of cells, and increasing the liver/body weight. TNF-α and IL-6 inflammatory factor expression increased (p<0.05). An increase in the serum ALT and AST levels were also observed. The blood glucose of mice increased, whereas the content of liver glycogen declined (p<0.05). ROS, MDA, and SOD levels all increased considerably. PM2.5 can drastically lower the expression of GS and GK, increase the expression of Nrf2, and raise the phosphorylation level of p-JNK (p<0.05).

CONCLUSIONS: PM2.5 can induce oxidative stress in mouse liver through the Nrf2/JNK pathway, induce liver inflammation in mice, and inhibit glycogen synthesis.

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