Neuronal-like differentiated SH-SY5Y cells adaptation to a mild and transient H2 O2 -induced oxidative stress

Abstract

Preconditioning (PC) is a cell adaptive response to oxidative stress and, with regard to neurons, can be considered as a neuroprotective strategy. The aim of the present study was to verify how neuronal-like differentiated SH-SY5Y cells adapt to a mild and transient H₂ O₂ -induced oxidative stress and, hence, whether may be considered as more sensitive cell model to study PC pathways. A first screening allowed to define H₂ O₂ concentrations for PC (10μM-50μM), applied before damage(100μM H₂ O₂ ). Cell viability measured 24 hours after 100μM H₂ O₂ -induced damage was ameliorated by 24-hour pre-exposure to low-concentration H₂ O₂ (10μM-30μM) with cell size as well restored. Markers for apoptosis (Bcl-2 and Bad), inflammation (iNOS), and redox system (MnSOD) were also determined, showing that, in cells pre-exposed to 10μM H₂ O₂ and then submitted to 100μM H₂ O₂ , Bcl-2 levels were higher, Bad and iNOS levels were lower than those observed in damaged cells, and MnSOD levels were unchanged. Such findings show that (1) neuronal-like differentiated SH-SY5Y cells are a suitable model to investigate PC response and more sensitive to the effect of a mild and transient H₂ O₂ -induced oxidative stress with respect to other neuronal cells; (2) 10μM H₂ O₂ -induced PC is mediated by apoptotic and inflammatory pathways, unlike antioxidant system; (3) such neuroprotective strategy and underlying signals proven in neuronal-like differentiated SH-SY5Y cells may contribute to understand in vivo PC mechanisms and to define a window for pharmacological intervention, namely, related to ischemic brain damage.

Significance of the study: Neuronal-like differentiated SH-SY5Y cells are a suitable model to investigate PC, an endogenous neuroprotective response to a mild and transient H₂ O₂ -induced oxidative stress, elicited by 24-hour exposure to very low H₂ O₂ concentrations and mediated by both apoptotic and inflammatory pathways. This model reflects in vivo PC mechanisms occurring after brain trauma and provides novel information about pathways and time of protection useful for an appropriate pharmacological intervention.

Keywords: H2O2; apoptosis; inflammation; neuronal-like differentiated SH-SY5Y cells; oxidative stress; preconditioning.