Cell death in rat cerebellar granule neurons induced by hydrogen peroxide in vitro: Mechanisms and protection by adenosine receptor ligands

Oxidative stress, resulting from excessive production of reactive oxygen species (ROS), is a pathological state that causes profound cellular damage and eventual death resulting from the overactivation of glutamate receptors, and the generation of nitric oxide, superoxide and hydrogen peroxide (H2O2). As such, H2O2 represents an important model for studying the neuropathology of oxidative stress in a variety of CNS disorders. The effects of H2O2 on the viability of post-natal cerebellar granule neurons (CGNs), the nature of the cell death involved and the potential protection by adenosine receptors against the damage were examined in the current study. Hydrogen peroxide (10–400 μM) reduced CGN viability in a concentration- and time-dependent manner. The addition of catalase (100 U/ml) prevented this effect, and the non-specific COX inhibitor aspirin (1 mM) also alleviated the damage. A combination of H2O2 (5 μM) and Cu2+ (0.5 mM) resulted in a significant damage that was not prevented by the hydroxyl radical scavenger mannitol (50 mM). The permeability transition pore blocker cyclosporin A, the caspase-3 inhibitor Z-DEVD-fmk (40 μM) and the PARP-1 inhibitor DPQ (10 μM) each significantly protected against peroxide damage. While the A1 adenosine receptor agonist CPA and the A2A receptor antagonist ZM241385 (each at 100 nM) elicited protection, the A1 adenosine receptor blocker DPCPX and the A2A receptor agonist CGS21680 (each at 100 nM) showed no effect. The data demonstrate that H2O2 induced oxidative stress in CGNs, involving both apoptotic and necrotic death, and this can be ameliorated by A1 receptor activation or A2A receptor blockade.