Hexarelin reduces H2O2-induced oxidative stress in Neuro2A cell line

Hexarelin is a well-known Growth Hormone Secretagogues (GHS) that possesses growth hormone-releasing effects and neuroprotective activities, such as prevention of status epilepticus and promotion of neurogenesis. Moreover, hexarelin reduces the activation of caspase 3 and 7 caused by brain hypoxia-ischemia in neonatal and adult rats and exerts protective effects against β-amyloid cytotoxicity. Several neurodegenerative diseases (NDDs), such as amyotrophic lateral sclerosis (ALS), Alzheimer’s disease (AD), Huntington’s disease (HD), are characterized by an increased production of reactive oxygen species (ROS), which lead to a dysregulation of mitochondrial dynamics, neuronal plasticity and apoptosis. In particular, ROS cause the downregulation of the anti-apoptotic protein Bcl-2 and the phosphorylation of the pro-apoptotic molecule Bax, with the subsequent activation of caspases 3 and 7. In this study, we explored the protective effects of hexarelin against oxidative stress and its anti-apoptotic mechanisms to attenuate H2O2-induced neurotoxicity using mouse neuroblastoma Neuro2A cells. MTT assay was used to measure changes in the viability of Neuro2A cells at different concentrations of H2O2 for 24 hours, and 100 μM H2O2 was selected as the lower concentration that significantly induced oxidative stress and a reduction of cells survival. Further assays showed that 24 hours treatment with 100 μM H2O2 induced significant changes in caspase 3 and caspase 7 mRNA levels and induced apoptosis. Treatment of Neuro2A cells with hexarelin blunted 100 μM H2O2 effects in MTT assay and cytotoxicity assay (CCK8). The apoptosis mechanism induced by H2O2 was reduced by hexarelin, which was confirmed by real-time PCR analysis of caspase 3, caspase 7, Bcl-2 and Bax mRNA expression. In conclusion, our results suggest that hexarelin exerts neuroprotective activities against H2O2-induced toxicity in Neuro2A cells. Further experiments are needed to identify the molecular mechanisms underlying the neuroprotective effects.