SummaryParkinson's disease (PD) is a neurodegenerative disorder characterized by a progressive loss of dopaminergic neurons in the substantia nigra (SN). The present study was designed to examine the therapeutic effect of hydrogen sulfide (H 2 S, a novel biological gas) on PD. The endogenous H 2 S level was markedly reduced in the SN in a 6-hydroxydopamine (6-OHDA)-induced PD rat model. Systemic administration of NaHS (an H 2 S donor) dramatically reversed the progression of movement dysfunction, loss of tyrosine-hydroxylase positive neurons in the SN and the elevated malondialdehyde level in injured striatum in the 6-OHDA-induced PD model. H 2 S specifically inhibited 6-OHDA evoked NADPH oxidase activation and oxygen consumption. Similarly, administration of NaHS also prevented the development of PD induced by rotenone. NaHS treatment inhibited microglial activation in the SN and accumulation of pro-inflammatory factors (e.g. TNF-a and nitric oxide) in the striatum via NF-jB pathway. Moreover, significantly less neurotoxicity was found in neurons treated with the conditioned medium from microglia incubated with both NaHS and rotenone compared to that with rotenone only, suggesting that the therapeutic effect of NaHS was, at least partially, secondary to its suppression of microglial activation. In summary, we demonstrate for the first time that H 2 S may serve as a neuroprotectant to treat and prevent neurotoxin-induced neurodegeneration via multiple mechanisms including anti-oxidative stress, anti-inflammation and metabolic inhibition and therefore has potential therapeutic value for treatment of PD.

BACKGROUND AND PURPOSE Hydrogen sulphide (H2S) is a novel neuromodulator. The present study aimed to investigate the protective effect of H2S against cell injury induced by 6‐hydroxydopamine (6‐OHDA), a selective dopaminergic neurotoxin often used to establish a model of Parkinson's disease for studying the underlying mechanisms of this condition. EXPERIMENTAL APPROACH Cell viability in SH‐SY5Y cells was measured using MTT assay. Western blot analysis and pharmacological manipulation were employed to study the signalling mechanisms. KEY RESULTS Treatment of SH‐SY5Y cells with 6‐OHDA (50–200 µM) for 12 h decreased cell viability. Exogenous application of NaHS (an H2S donor, 100–1000 µM) or overexpression of cystathionine β‐synthase (a predominant enzyme to produce endogenous H2S in SH‐SY5Y cells) protected cells against 6‐OHDA‐induced cell apoptosis and death. Furthermore, NaHS reversed 6‐OHDA‐induced loss of tyrosine hydroxylase. Western blot analysis showed that NaHS reversed the down‐regulation of PKCα, ε and Akt and the up‐regulation of PKCδ in 6‐OHDA‐treated cells. Blockade of PKCα with Gö6976 (2 µM), PKCε with EAVSLKPT (200 µM) or PI3K with LY294002 (20 µM) reduced the protective effects of H2S. However, inhibition of PKCδ with rottlerin (5 µM) failed to affect 6‐OHDA‐induced cell injury. These data suggest that the protective effects of NaHS mainly resulted from activation of PKCα, ε and PI3K/Akt pathway. In addition, NaHS‐induced Akt phosphorylation was significantly attenuated by Gö6976 and EAVSLKPT, suggesting that the activation of Akt by NaHS is PKCα, ε‐dependent. CONCLUSIONS AND IMPLICATIONS H2S protects SH‐SY5Y cells against 6‐OHDA‐induced cell injury by activating the PKCα, ε/PI3K/Akt pathway.

Parkinson’s disease (PD), characterized by loss of dopaminergic neurons in the substantia nigra, is a neurodegenerative disorder of central nervous system. The present study was designed to investigate the therapeutic effect of ACS84, a hydrogen sulfide-releasing-L-Dopa derivative compound, in a 6-hydroxydopamine (6-OHDA)-induced PD model. ACS84 protected the SH-SY5Y cells against 6-OHDA-induced cell injury and oxidative stress. The protective effect resulted from stimulation of Nrf-2 nuclear translocation and promotion of anti-oxidant enzymes expression. In the 6-OHDA-induced PD rat model, intragastric administration of ACS84 relieved the movement dysfunction of the model animals. Immunofluorescence staining and High-performance liquid chromatography analysis showed that ACS84 alleviated the loss of tyrosine-hydroxylase positive neurons in the substantia nigra and the declined dopamine concentration in the injured striatums of the 6-OHDA-induced PD model. Moreover, ACS84 reversed the elevated malondialdehyde level and the decreased glutathione level in vivo. In conclusion, ACS84 may prevent neurodegeneration via the anti-oxidative mechanism and has potential therapeutic values for Parkinson’s disease.

Endoplasmic reticulum (ER) stress has been implicated in several neurodegenerative diseases, including Parkinson's disease. The present study attempted to investigate the effect of hydrogen sulfide (H(2)S) on 6-hydroxydopamine (6-OHDA)-induced ER stress in SH-SY5Y cells. We found in the present study that exogenous application of sodium hydrosulfide (NaHS; an H(2)S donor, 100 μM) significantly attenuated 6-OHDA (50 μM)-induced cell death. NaHS also reversed the upregulation of cleaved poly(ADP-ribose) polymerase and caspase 9 in 6-OHDA-treated cells. Consistent with its cytoprotective effects, NaHS markedly reduced 6-OHDA induced-ER stress responses, including the upregulated levels of eukaryotic initiation factor-2α phosphorylation, glucose-regulated protein 78, and C/EBP homologous protein expression. The protective effect of H(2)S on ER stress was attenuated by blockade of Akt activity with an Akt inhibitor or inhibition of heat shock protein (Hsp)90 with geldanamycin but not by suppression of ERK1/2 with PD-98059. Blockade of Akt also significantly decreased the protein abundance of Hsp90 in SH-SY5Y cells. Moreover, overexpression of cystathionine β-synthase (a main H(2)S-synthesizing enzyme in the brain) elevated the Hsp90 protein level and suppressed 6-OHDA-induced ER stress. In conclusion, the protective effect of H(2)S against 6-OHDA-induced ER stress injury in SH-SY5Y cells involves the Akt-Hsp90 pathway.

Lu M, Liu YH, Ho CY, Tiong CX, Bian JS. Hydrogen sulfide regulates cAMP homeostasis and renin degranulation in As4.1 and rat renin-rich kidney cells.