| [Backgroud and Objective]1-Methy-4-Phenylpyridinium Ion (MPP+) target-orientedly lead tothe toxicity of dopaminergic neurons. Hydrogen sulfide (H2S) plays arole in protecting nervous as a neuromodulator. Our laboratory hasconfirmed that H2S prevents MPP+-induced neuroxicity to PC12cells;howerver, the underlying mechanisms are unclear.Brain derived neurophic factor (BDNF), an important endogenousnenuroprotectant, play an important role in repairing of the injury andfunctional reconstruction of neurons. Recently, it has been confirmedthat aldehyde stress and endoplasmic reticulum (ER) stress playimportant roles in the neurotoxicity of MPP+. Therefore, this work is tofurther elucidate the mechanisms underlying the protective role of H2Sagainst MPP+-induced neurotoxicity by investigated whether H2Santagonize MPP+-induced aldehyde stress and ER stress by modulatingBDNF-TrkB pathway.In this experimentwe used MPP+-treated PC12cell as the model ofMPP+neurotoxicity to confirm this hypothesis by exploring whether H2Sprotects PC12cells against MPP+-induced aldehyde stress and ER stress,and upregulates of the expression of BDNF in MPP+-treated PC12cellsand whether inhibited BDNF-TrkB pathway by k252a reverses theprotection of H2S against MPP+-induced aldehyde stress, ER stress, andneurotoxicity.[Methods]The cell viability was detected by Cell Counting Kit-8; the cell apoptosis was measured by flow cytometry (FCM) after PI staining; theexpression of BDNF and ER stress related marker proteins glucose-regulated protein78(GRP78) and Cleaved-caspase-12were detectedby Western Blot; the intracellular level of reactive aldehydicmalondialdehyde (MDA) and4-Hydroxy-2-nonenal (4-HNE) weredetermined by Elisa assay.[Results]1. MPP+induced aldehyde stress and ER stress in PC12cells.Treatments of PC12cells with MPP+(0.5,1, or2mmol/L) for24hpromote the accumulation of MDA and4-HNE and up-regulate theexpression of GRP78and Cleaved-caspase-12(the ER stress relatedmarker protein) in a dose-dependent manner. The results show thatMPP+induces aldehyde stress and ER stress in PC12cells.2. H2S inhibited MPP+-induced aldehyde stress and ER stress in PC12cells.Pre-treatment of PC12cells with400μM NaHS (the donor of H2S)for30min before24-h exposure to MPP+(2mmol/L) attenuated MPP+-induced the accumulations of MDA and4-HNE and the upregulationsof GRP78and Cleaved-caspase-12expression. These resultsdemonstrated that H2S can inhibit MPP+-induced aldehyde stress andER stress and indicated that the involvment of supression in aldehydestress and ER stress in H2S–exerted protection against MPP+-inducedneurotoxicity.3. BDNF-TrkB pathway mediates the protective effects of H2S againstMPP+-induced aldehyde stress, ER stress, and neurotoxicity.3.1H2S up-regulated the expression of BDNF in PC12cells.Pretreatment of PC12cells with400μM NaHS for30min cansignificantly inhibit the down-regulation of BDNF expression induced by MPP+(2mM,24h), indicated that H2S-inhibited the neurotoxicity ofMPP+may be associated with the upregulation of BDNF.3.2Blocked BDNF-TrkB pathway by k252a reverses the protective effectof H2S on MPP+-induced aldehyde stress, ER stress, and neurotoxicity inPC12cells.After pretreatment with K252a (10nM, the blocker of BDNF-TrkBpathway) for30min,400μ M NaHS was added for30min, and thenPC12cells were co-exposed to MPP+(2mM) for24h. The resultsshowed that K252a not only significantly reduces the protection of H2Sagainst MPP+-induced cytotoxicity and apoptosis, but also significantlysuppresses the protection of H2S against MPP+-induced accumulationof cellular reaction aldehydes (MDA and4-HNE), and down-regulationsof GRP78and Cleaved-caspase-12expression. These results suggestedthat K252a, blocking BDNF-TrkB pathway, not only reverse theprotective effect of H2S on MPP+-induced neurotoxicity, but alsoreverse the protective effect of H2S on MPP+-induced aldehyde stressand ER stress.[Conclusions]H2S antagonizes MPP+-induced neurotoxicity by supression of aldehydestress and ER stress via upregulating BDNF-TrkB pathway. |
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