Neuroprotectiveeffectsof hexarelinin an in vitro model of ALS

Intracellular hydrogen peroxide (H2O2) generated through oxidative stress is involved in necrosis and apoptosis, ultimately resulting in aging, cancer and several neurodegenerative diseases, including Amyotrophic Lateral Sclerosis (ALS). Evidences demonstrate that neurotrophic factors, including insulin-like growth factor 1 (IGF-1), regulate survival and differentiation of nerve cells and maintain neuronal structural integrity. However, given the high tumorigenic potential of exogenous IGF-1 administration, alternative methods to increase endogenous IGF-1 expression should be develop. Growth hormone secretagogues (GHS) are a family of peptides that stimulates the secretion of growth hormone and IGF-1, and exerts neuroprotective effects against β-amyloid cytotoxicity. Among them, hexarelin has shown 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 caspase-7 involved in apoptosis pathway, caused by brain hypoxia-ischemia in neonatal rats. In this study, we explored the protective effects of hexarelin against oxidative stress and its anti-apoptotic mechanisms to attenuate H2O2-induced neurotoxicity in mouse neuroblastoma Neuro2A cells. Neuro2A cells were incubated with increasing concentration of H2O2 for 24 h. After determining the optimal concentration of H2O2, Neuro2A cells were treated with H2O2 in absence or presence of hexarelin (24 h). Cell viability was evaluated using MTT assay, and mRNA levels of Bax, Bcl-2, caspase-3 and caspase-7 were obtained by Real Time PCR. Western blot analysis was used to measure ERK1/2, Akt and NF- κB proteins 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 this neuroprotective effects.