The key mechanisms for H2S physiology [41?45]. Tao et al proposed that cysteine residues may serve as H2S “receptors” in cells and H2S may attack disulfide bonds in proteins to regulate protein functions [46]. A recently published reportindicated that H2S S-sulfhydrated Keap1 at cysteine-151, which enhanced the release of Nrf-2 from Keap-1 and upregulated Nrf-2 activity [47]. This report was on a par with our results and suggested that S-sulfhydration may be a 
Epigenetic Reader Domain potential mechanism of ACS84 in cells. We used unilateral 6-OHDA PD rat model to evaluate the protective effect of ACS84 in vivo. This model 22948146 is mainly designed to study the oxidative injury in PD pathogenesis process [29]. Our group has demonstrated that the protective effects of H2S involved suppression of NADPH oxidase in this model [21]. In the present study, we also found that post-treatment of ACS84 preserved TH+ neurons in SN, and maintained the dopamine levels and relieved the movement dysfunction. These data suggest that ACS84 is of potential therapeutic value for Parkinson’s disease. We believe that the suppression of oxidative stress was the main mechanism in the protective effect of ACS84. We have proven that ACS84 was efficient in reducing ROS formation and was able to stimulate the expression of anti-oxidant enzymes in vitro. Along with these results obtained from SH-SY5Y cells, we also found that ACS84 treatment reversed the effect of 6-OHDA on MDA levels. Having such an effect on the two oxidative stress indicators, these data proved that ACS84 plays a role as an anti-oxidant in the dopaminergic neurons. Although we found that ACS84 produced significant anti-oxidant effect, unfortunately, we failed to find ACS84 produced better effect against movement dysfunction in 6OHDA-induced PD model when compared with L-dopa (data not shown). This result implies that ACS84 is not more efficacious to treat PD symptoms than L-Dopa alone in our observation period (7 weeks). Longer period observation and other animal models may be needed in future to determine which one, ACS84 or Ldopa, produces longer and better effects. It was reported that ACS84 intravenous injection increased the dopamine level in the rat brain [25]. Our results also indicated that ACS84 elevated dopamine levels in the 6-OHDA-injured striatum. ACS84 may increase dopamine in two aspects: firstly, ACS84 may release L-Dopa which would be further catalysed into dopamine by DOPA decarboxylase; secondly, ACS84 protected dopaminergic neuron degeneration, thus alleviated dopamine deficient. It was reported that ACS84 and other similar H2S-releasing compounds would inhibit the monoamine oxidase B activity in neonatal rat striatal astroglial cell primary cultures and SH-SY5Y cells. [25,48] We also got similar results from primary Autophagy cultured astroglial cells (data not shown). However, from our HPLC results, we did not 15755315 observe the significant decline of DOPAC/dopamine ratio in the striatum homogenates from ACS84-treated rats. These data may suggest that the inhibitory effects of ACS84 on monoamine oxidase B activity were not as efficient under physiological conditions as in cell cultures. In contrast, ACS84 significantly decreased the dopamine/HVA ratios, suggesting that ACS84 might suppress COMT activity, which was responsible for the dopamine-HVA and DOPAC-HVA turnover in dopaminergic neurons. As we found ACS84 efficacy requires a chronic administration regimen in this study, there might be some transcriptional and tra.The key mechanisms for H2S physiology [41?45]. Tao et al proposed that cysteine residues may serve as H2S “receptors” in cells and H2S may attack disulfide bonds in proteins to regulate protein functions [46]. A recently published reportindicated that H2S S-sulfhydrated Keap1 at cysteine-151, which enhanced the release of Nrf-2 from Keap-1 and upregulated Nrf-2 activity [47]. This report was on a par with our results and suggested that S-sulfhydration may be a potential mechanism of ACS84 in cells. We used unilateral 6-OHDA PD rat model to evaluate the protective effect of ACS84 in vivo. This model 22948146 is mainly designed to study the oxidative injury in PD pathogenesis process [29]. Our group has demonstrated that the protective effects of H2S involved suppression of NADPH oxidase in this model [21]. In the present study, we also found that post-treatment of ACS84 preserved TH+ neurons in SN, and maintained the dopamine levels and relieved the movement dysfunction. These data suggest that ACS84 is of potential therapeutic value for Parkinson’s disease. We believe that the suppression of oxidative stress was the main mechanism in the protective effect of ACS84. We have proven that ACS84 was efficient in reducing ROS formation and was able to stimulate the expression of anti-oxidant enzymes in vitro. Along with these results obtained from SH-SY5Y cells, we also found that ACS84 treatment reversed the effect of 6-OHDA on MDA levels. Having such an effect on the two oxidative stress indicators, these data proved that ACS84 plays a role as an anti-oxidant in the dopaminergic neurons. Although we found that ACS84 produced significant anti-oxidant effect, unfortunately, we failed to find ACS84 produced better effect against movement dysfunction in 6OHDA-induced PD model when compared with L-dopa (data not shown). This result implies that ACS84 is not more efficacious to treat PD symptoms than L-Dopa alone in our observation period (7 weeks). Longer period observation and other animal models may be needed in future to determine which one, ACS84 or Ldopa, produces longer and better effects. It was reported that ACS84 intravenous injection increased the dopamine level in the rat brain [25]. Our results also indicated that ACS84 elevated dopamine levels in the 6-OHDA-injured striatum. ACS84 may increase dopamine in two aspects: firstly, ACS84 may release L-Dopa which would be further catalysed into dopamine by DOPA decarboxylase; secondly, ACS84 protected dopaminergic neuron degeneration, thus alleviated dopamine deficient. It was reported that ACS84 and other similar H2S-releasing compounds would inhibit the monoamine oxidase B activity in neonatal rat striatal astroglial cell primary cultures and SH-SY5Y cells. [25,48] We also got similar results from primary cultured astroglial cells (data not shown). However, from our HPLC results, we did not 15755315 observe the significant decline of DOPAC/dopamine ratio in the striatum homogenates from ACS84-treated rats. These data may suggest that the inhibitory effects of ACS84 on monoamine oxidase B activity were not as efficient under physiological conditions as in cell cultures. In contrast, ACS84 significantly decreased the dopamine/HVA ratios, suggesting that ACS84 might suppress COMT activity, which was responsible for the dopamine-HVA and DOPAC-HVA turnover in dopaminergic neurons. As we found ACS84 efficacy requires a chronic administration regimen in this study, there might be some transcriptional and tra.
