The anti-inflammatory effect of melatonin in SH-SY5Y neuroblastoma cells exposed to sublethal dose of hydrogen peroxide

Brain inflammaging is considered as one of the underlying factors of neurodegenerative diseases. The present study aimed to investigate the effects of melatonin, an endogenous indoleamine mainly synthesized by the pineal gland, on hydrogen peroxide (H2O2)-induced inflammaging state in SH-SY5Y cells. Our data showed that p21(ciP1) and p16(INK4a), cell cycle arrest markers, and the number of senescence-associated beta-galactosidase (SA-beta gal) staining increased significantly in H2O2-treated cells. Melatonin treatment could reverse this effect. Flow cytometry analysis showed a significantly higher percentage in the G0/G1 phase and a lower proportion in the S phase of H2O2 treated cells. Cells pretreated with H2O2 showed a dramatic decrease in the formation of Ki67 immunoactivity while the treatment with melatonin increased Ki67-positive cell. Both mRNA and protein expression levels of the pro-inflammatory cytokines, interleukin-1 beta (IL-1 beta), IL-6 and, tumor necrosis factor-alpha (TNF-alpha) which were increased after induction with H2O2, could be attenuated by melatonin. In addition, melatonin decreased the phospho-nuclear factor kappa B (pNF-kappa B) expression and prevented its nuclear translocation, as well as abrogated the reduction of nuclear factor erythroid 2-related factor 2 (Nrf2) in SH-SY5Y cells exposed to H2O2. The present data suggested the importance of melatonin on ameliorating inflammation in SH-SY5Y cells.