Hydrocortisone and vitamin B12 protect SHSY-5Y cells against glutamate excitotoxicity by altering VIP and GAL levels

Background: Prolonged elevation of extracellular glutamate levels triggers intracellular events, increases glutamate excitotoxicity, and activates apoptotic pathways, causing Alzheimer's disease (AD). The literature has reported that vitamin B12 exhibits anti-inflammatory and anti-apoptotic activities in various diseases. Hydrocortisone (HC) therapy also substantially inhibits microglia and astrocyte hyperactivation, minimizing pro-inflammatory cytokines and reducing neuroinflammation. That is why our study aimed to evaluate the therapeutic effects of HC and B12 combination on oxidative stress and VIP and GAL levels in an in vitro Alzheimer's model. Method: To create the Alzheimer's model, the neuroblastoma cell line (SH-SY5Y) was cultured. Then, all cells except the control group were treated with different doses of HC and B12 combination for 24 hours by applying Glutamate (10-5 mM) to create excitotoxicity. The results were evaluated using MTT and ELISA tests. Results: When the results were examined, it was determined that exceptionally high-dose combination groups showed protective activity against glutamate excitotoxicity. HC+B12 25 µg/ml groups observed the most statistically significant results. According to our results, oxidative stress decreased in the HC+B12 25 µg/ml group, and cell viability increased. Significant changes were also observed in Vasoactive Peptide (VIP) and Galanin (GAL) levels in correlation with other analyses obtained. Conclusion: This study is the first to report the potential of vitamin B12 combined with hydrocortisone to prevent oxidative stress and glutamate excitotoxicity in primary neurons. It provides a basis for further investigating its clinical application in neurodegenerative diseases.