Aims: To understand the roles of the RhoA/ROCK and mitogen-activated protein kinase (MAPK) pathways in high glucose (HG)-induced apoptosis and oxidative stress in cardiomyocytes.
Materials and methods: Neonatal rat cardiomyocytes were cultured in Dulbecco's modified Eagle's medium, supplemented with 5.5 or 30 mmol/L D-glucose, in the presence or absence of fasudil (50 or 100 μM), SB203580, SP600125, or PD98059 (10 μM, respectively). The percentage of early apoptotic cardiomyocytes was evaluated using flow cytometry. The superoxide dismutase activity and malondialdehyde contents in the cellular supernatants were measured. The Bax and Bcl-2 mRNA levels were determined by quantitative real-time PCR. Phosphorylation of myosin phosphatase target subunit 1 (MYPT1), p38MAPK, JNK, and ERK as well as the protein levels of Bax, Bcl-2, and cleaved caspase-3 was analysed by Western blot.
Results: Fasudil, SB203580, and SP600125 effectively inhibited the HG-induced early apoptosis increase and decreased Bax mRNA expression, the Bax/Bcl-2 protein expression ratio, and cleaved caspase-3 protein levels in the cardiomyocytes; this was accompanied by upregulation of the Bcl-2 mRNA. Moreover, fasudil markedly increased the superoxide dismutase activity level and suppressed the elevation in HG-induced malondialdehyde content and the phosphorylation of MYPT1, p38MAPK and JNK.
Conclusions: The RhoA/ROCK pathway mediates HG-induced cardiomyocyte apoptosis via oxidative stress and activation of p38MAPK and JNK in neonatal rats in vitro. Fasudil effectively ameliorates HG-induced cardiomyocyte apoptosis by suppressing oxidative stress and the p38MAPK and JNK pathways.
Keywords: JNK; Rho kinase; cardiomyocytes apoptosis; high glucose; oxidative stress; p38MAPK.
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