Mechanistic exploration of methylglyoxal-induced hepatotoxicity involving oxidative stress, apoptosis, and gluconeogenic modulation.

Methylglyoxal (MG) is a precursor of advanced glycation end-products produced during glycolysis. MG accumulation is linked to various pathophysiological conditions through the production of reactive oxygen species (ROS). This investigation uncovers the mechanism of MG-induced hepatotoxicity in vitro and in vivo. We assessed MG's dose- and time-dependent cytotoxicity (0.001-10 μM) in HepG2 cells using the cell viability assay. We examined the protective effects of N-acetylcysteine (NAC) against MG toxicity using MTT reagent, monitoring ROS generation, apoptosis (via flow cytometry), and mitochondrial membrane potential (with JC1 dye staining). For the in vivo study, BALB/c mice received MG (290 mg/kg and 400 mg/kg) at 6 h and 14 h intervals to induce hepatotoxicity. We conducted liver histopathology and protein expression analysis for apoptotic markers (Bax, Bcl-2, and caspase-3) and gluconeogenesis regulators (SIRT1, PGC1α, and glucose 6-phosphatase or G6Pase) in both cell lines and liver tissues. MG caused significant dose- and time-dependent toxicity in HepG2 cells by promoting cell death, increasing ROS and apoptosis, and altering the mitochondrial membrane potential at 5 μM. NAC (5 and 10 mM) protected against MG-induced toxicity. In mice, MG led to elevated spleen and liver weight, aspartate transferase (AST), alanine transaminase (ALT), glucose, malondialdehyde, and decreased superoxide dismutase levels. MG upregulated pro-apoptotic and gluconeogenic proteins in HepG2 cells, while NAC significantly reduced their levels. MG also increased the expression of proteins involved in apoptosis and gluconeogenesis. MG-induced caspase-dependent hepatotoxicity was mediated by the production of ROS and the activation of gluconeogenesis via SIRT1-dependent PGC1α activation.