RESUMO
Objective:To study the effects of arsenic exposure on necroptosis pathway and inflammatory response of mouse myocardial cells.Methods:Sixty male C57BL/6J mice were randomly divided into control group (group C) and low, medium, and high dose arsenic exposure groups (groups L, M, H) based on body weight using a random number table method. Each group had 15 mice, and they drank 0.00, 0.15, 1.50, and 15.00 mg/L arsenic trioxide (As 2O 3) solution prepared with deionized water. The exposure period was 12 weeks. Hematoxylin-eosin (HE) staining and Masson trichrome staining of paraffin-embedded heart tissues were used to observe the histopathology changes of the heart. Transmission electron microscopy (TEM) was used to evaluate the ultrastructural changes of myocardial cells. The quantitative real-time PCR (qRT-PCR) was used to detect the mRNA expression of inflammatory genes [tumor necrosis factor (TNF)-α and interleukin(IL)-6] and the genes involved in necroptosis pathway [receptor-interacting protein (RIP) 1, RIP3 and mixed-lineage kinase domain-like protein (MLKL)]. Protein expressions of RIP1 and RIP3 in the heart were assessed by western blotting. Results:Histopathological examination results showed there were myocardial necrosis, inflammatory cells infiltration and fibroblasts hyperplasia and other changes in groups M and H. TEM analysis revealed marked ultrastructural changes in groups M and H, including fractured myofibril, fractured Z lines of sarcomere, and swollen mitochondria with fractured cristae. Compared with group C (1.00 ± 0.00), the mRNA expression of RIP1 in group H was significantly up-regulated (1.41 ± 0.06, P < 0.05); the mRNA expressions of RIP3 (1.29 ± 0.14, 1.56 ± 0.08), MLKL (1.23 ± 0.05, 1.36 ± 0.07), TNF-α (2.20 ± 0.10, 2.23 ± 0.18) and IL-6 (1.87 ± 0.16, 1.63 ± 0.15) were significantly up-regulated in groups M and H ( P < 0.05). The protein expressions of RIP1 (0.43 ± 0.04, 0.50 ± 0.04) and RIP3 (0.68 ± 0.02, 0.84 ± 0.05) in groups M and H were higher than those in group C (0.25 ± 0.01, 0.45 ± 0.04, P < 0.05). Conclusion:Subchronic arsenic exposure induces histopathological changes such as myocardial necrosis and fibrosis in mice, inducing necroptosis and inflammatory reactions in myocardial cells.