Neuroprotective effects of hydrogen sulfide on sodium azide-induced oxidative stress in PC12 cells

Alzheimer's disease (AD) is the most common neurodegenerative disorder, responsible for >50% of all dementia cases. Sodium azide (NaN3) inhibits cytochrome oxidase by irreversibly binding to the heme cofactor and selectively reducing the complex IV activity, which is present in post‑mortem AD brains. Previous data demonstrated that hydrogen sulfide (H2S), the third endogenous gaseous mediator, exerted protective effects against neuronal damage. Therefore, it was hypothesized that H2S may be able to scavenge excess reactive oxygen species (ROS), thereby protecting against oxidative stress and cell death. In the present study, it was observed that cell viability decreased in a concentration-dependent manner 12 h after NaN3 treatment (20, 30 and 50 mmol/l). A decrease in cell viability (to 51±3%) was observed 12 h after treatment with 30 mM NaN3. NaN3 treatment also led to decreased mitochondrial membrane potential, increased lipid peroxidation (excessive production of malondialdehyde), and increased the protein expression levels of caspase-3. Pretreatment with H2S (200 µmol/l) attenuated NaN3-mediated apoptosis, and the anti-apoptotic action of H2S was partially dependent on suppressing the production of ROS. The findings of the present study suggested that H2S exerted a neuroprotective effect against NaN3-induced neurotoxicity through mechanisms related to anti-oxidation and anti-apoptosis. Therefore, the findings of the present study suggest there may be a promising future for H2S-based preventions and therapies for neuronal damage following exposure to NaN3.