Hydrogen Sulfide Inhibits Chronic Restraint Stress-induced Endoplasmic Reticulum Stress In The Mice Hippocampus

Objective Chronic stress has been implicated in the pathogenesis of psychiatric disorders, such as depression. In our previous work, we demonstrated that hydrogen sulfide(H2S) played an neuroprotective role in chronic unpredictable mild stress animal model and corticosterone stress insults PC12 cells. It has been shown that endoplasmic reticulum(ER) stress is a crucial process in pathogenesis of the chronic stress related learning and memory defects and that H2 S exerts its neuroprotection via suppressing ER stress. the neuroprotective effect of Silent mating type information regulator 2 homolog 1(SIRT1) and Brain-derived neurotrophic factor(BDNF) in both acute and chronic neurological diseases has been widely reported. Therefore, we established the model of chronic restraint stress(CRS) to explore the effect of CRS on the expression of ER stress, the endogenous H2 S, the Silent mating type information regulator 2 homolog 1(SIRT1), Brain-derived neurotrophic factor(BDNF)-tyrosineprotein kinase B(Trk B) pathway in the hippocampus of rats and to investigate the role of exogenous application of H2 S on the CRS-induced neuronal damages.Methods 1. The mice were randomly divided into 6 groups(15 mice per group), including the control group, CRS group, CRS+ low concentration of sodium hydrosulfide(Na HS)(30u M/Kg) group, CRS+ middle concentration of Na HS(60u M/Kg) group, CRS+ high concentration of Na HS(100u M/Kg) group, and CRS+imipramine(Imip)(30mg/Kg) group. Except for the control group, the remaining mice were restraint into a 50 ml syringe for 4 weeks, 3 hours a day to establish the model of CRS. Na HS and imipramine were given by intraperitoneal injection 30 min before CRS. 2. The expression of CBS, 3-MST, CHOP, GRP-78, SIRT1, BDNF, Trk B in hippocampus of mice were determined by western blot.Results 1. CRS induces ER stress responses in the hippocampus of mice. After 4 weeks exposed to the CRS, the expression of C/EBP homologous protein(CHOP) and 78-k Da glucose-regulated protein(GRP78) in the hippocampus of mice were significantly increased contrast to the control group. These data suggest that CRS could induce ER stress responses in the hippocampus of mice.2. CRS reduces the endogenous H2 S production. The protein expression levels of cystathionine beta synthase(CBS) and 3- mercaptopyruvate sulfurtransferase(3-MST) in hippocampus of mice exposed in 4 weeks of CRS were prominently attenuated. It suggests that CRS could reduce the endogenous H2 S production. 3. The H2 S treatment markedly inhibits mice hippocampal ER stress responses induced by CRS. The administration of Na HS or Imip of each group was gave 30 minute before CRS treatment. After treated with different doses of Na HS(30,60,100μM/Kg), the expression of CHOP and GRP-78 were obviously decreased in hippocampus of CRS mice in dose depend manner. Just as the effect of Imip(30mg/Kg), the expression of CHOP and GRP-78 in the hippocampus of high concentration of Na HS(100 μM/Kg) group almost return to the level of non-treated control group. These data suggest the neuroprotection of H2 S is closely related to the suppression of CRS induced ER stress in the mice hippocampus. 4. H2 S could up-regulate the suppression of SIRT1 induced by CRS in the mice hippocampus. The administration of Na HS or Imip of each group was given 30 minute before CRS treatment. After treated with different doses of Na HS(30,60,100μM/Kg), the expression of Silent mating type information regulator 2 homolog 1(SIRT1) was obviously increased inthe hippocampus of CRS mice in dose depend manner. Just as the effect of Imip(30mg/Kg), the expression of SIRT1 in the hippocampus of high concentration of Na HS(100μM/Kg) group increased almost 30% compared to the CRS group. These data elucidate that H2 S could up-regulate the suppression of SIRT1 induced by CRS in the mice hippocampus. Moreover, it suggests that H2 S treatment could reverse the down-regulation of SIRT1 caused by CRS in hippocampus of mice, which of great possibility mediate the suppression of CRS-induced ER stress. 5. H2 S could up-regulate the suppression of BDNF-Trk B pathway induced by CRS in the mice hippocampus. The administration of Na HS or Imip of each group was given 30 minute before CRS treatment. After treated with different doses of Na HS(30,60,100 u M/Kg), the expression of Brain-derived neurotrophic factor(BDNF)-tyrosine protein kinase B(Trk B) pathway was obviously augmented in hippocampus of CRS mice in dose depend manner. Just as the effect of Imip(30mg/Kg), the expression of SIRT1 and BDNF-Trk B pathway in the hippocampus of high concentration of Na HS(100 μM/Kg) group almost return to the level of non-treated control group. These data clarify that H2 S could up-regulate the suppression of BDNF-Trk B pathway induced by CRS in the mice hippocampus. Meanwhile, it suggests that H2 S protects the hippocampus of mice against theCRS-induced ER stress may of great possibility mediated by up-regulating BDNF-Trk B pathway.Conclusion H2 S could suppress the CRS-induced ER stress in the mice hippocampus and the mechanism of it probably by up-regulating SIRT1 and BDNF-Trk B expression.