Exogenous Hydrogen Sulfide Offers Neuroprotection on Intracerebral Hemorrhage Injury Through Modulating Endogenous H(2)S Metabolism in Mice

Hydrogen sulfide (H(2)S), an important endogenous signaling molecule, has a significant neuroprotective role in the central nervous system. In this study, we examined the protective effects of exogenous H(2)S against intracerebral hemorrhage (ICH), as well as its underlying mechanisms. We investigated the effects of exogenous H(2)S on ICH using Western blotting, injury volume, measurement of brain edema, propidium iodide (PI) staining, and behavior assessment, respectively. We found that endogenous H(2)S production was downregulated in the brain after ICH, which is caused by the decrease in cystathionine β-synthase (CBS) as the predominant cerebral H(2)S-generating enzyme in the brain. Treatment with sodium hydrosulfide (NaHS; an H(2)S producer) could restore the H(2)S production and the expression of CBS. NaHS could also attenuate brain edema, injury volume, and neurological deficits in the Morris water maze test after ICH. Western blotting results indicated that H(2)S pretreatment reversed the increase in caspase 3 cleavage and the decrease in Bcl-2, suppressed the activation of autophagy marker (LC3II and Beclin-1), and maintained the p62 level in injured striatum post-ICH. However, H(2)S could not restore brain CBS expression and H(2)S content, reduce brain edema, and improve motor performance and memory function after ICH through modulating autophagy and apoptosis when pretreated with the CBS inhibitor aminooxyacetic acid (AOAA). We also found that AOAA reduced the endogenous H(2)S production through inhibiting the enzyme activity of CBS rather than modulating the expression of CBS protein level. These present results indicate that H(2)S may possess potential therapeutic value in the treatment of brain injury after ICH, and the protective effect of exogenous H(2)S against ICH may be not a direct action but an indirect effect through inducing endogenous H(2)S metabolism responses.