Methylglyoxal induces death in human brain neuronal cells (SH-SY5Y), prevented by metformin and dapagliflozin

Diabetes mellitus is a metabolic disorder caused by a dysfunction in insulin action or secretion, leading to an elevation in blood glucose levels. It is a highly prevalent condition and as a result, the NHS spends 10 % of its entire budget on diabetes mellitus care, that is equivalent to £10 billion a year. Diabetes mellitus has been linked with vascular and neurological complications which may be associated with the progression of neurodegeneration and Alzheimer's disease. Chronic hyperglycaemia increases the production of the reactive oxidant species (ROS) such as methylglyoxal (MGO). MGO has been linked with vascular complications, neuropathy and cytotoxicity. The main aim of this study was to investigate the potential beneficial effect of antidiabetic agents such as metformin and dapagliflozin on human brain neuronal cells (SH-SY5Y) treated with MGO. SH-SY5Y cells were cultured in DMEM/F12 media and subjected overnight incubation with one of the following treatment conditions: Control (untreated); MGO (1 μM); MGO (100 μM); metformin (100 μM) + MGO (100 μM); and dapagliflozin (10 μM) + MGO (100 μM). Several assays were conducted to explore the effect of the treatment groups on the SH-SY5Y cells. These included: MTT assay; LDH assay, peroxynitrite fluorescence assay, and laser scanning confocal microscopy. MGO (100 μM) led to significant cell injury and damage and significantly reduced the survival of the cells by approximately 50-75 %, associated with significant increase in peroxynitrite. The addition of metformin (100 μM) or dapagliflozin (10 μM) represented significant protective effects on the cells and prevented the cell damage caused by the high MGO concentration. As a result, the findings of this research reveal that MGO-induced cell damage may partly be mediated by the generation of peroxynitrite, while the antidiabetic agents such as metformin and dapagliflozin prevent brain cell death, which potentially may play prophylactic roles against the risk of dementia in diabetic patients.