BACKGROUND: Parkinson's disease is a neurodegenerative disorder, and recent studies suggested that oxidative stress contributes to the degeneration of dopamine cell in Parkinson's disease. Glutamine also has a positive role in reducing oxidative stress damage. In this study, we hypothesized that glutamine offers protection against oxidative stress injury in 1-methyl-4-phenylpyridinium (MPP)-induced Parkinson's disease cell model. METHODS: MPP was used to induce PD models in PC12 cells and classified into control, M0 (MPP), G0 (glutamine), and M0+G0 groups. CCK-8 and AO/EB staining assays were used to examine cell proliferation and apoptosis, respectively. Western blotting was applied to examine the protein expression of PI3K, P-Akt, Akt, P-mTOR, and mTOR. RESULTS: We showed that glutamine suppressed cytotoxicity induced by MPP in PC12 cells. MPP decreased the superoxide dismutase and glutathione peroxidase activity and increased the malondialdehyde content, which were restored by glutamine. Moreover, MPP increased the expression of PI3K, P-Akt, Akt, P-mTOR, and mTOR, which were inhibited by glutamine. And the antioxidant capacity of glutamine on PC12 cells could be improved by LY294002 and inhibited by IGF-1. CONCLUSION These results suggest that glutamine strengthens the antioxidant capacity in PC12 cells induced by MPP through inhibiting the activation of the PI3K/Akt signaling pathway. The effects of glutamine should be investigated and the protective mechanism of glutamine in PD must be explored in future studies.
1-Methyl-4-phenylpyridinium ; administration & dosage ; Analysis of Variance ; Animals ; Cell Culture Techniques ; Disease Models, Animal ; Glutamine ; pharmacology ; Oxidative Stress ; drug effects ; Parkinson Disease ; Phosphatidylinositol 3-Kinases ; metabolism ; Protective Agents ; pharmacology ; Proto-Oncogene Proteins c-akt ; metabolism ; Rats

PURPOSE: Parkinson's disease (PD) is a common age-dependent neurodegenerative disease. MiR-212 has been demonstrated to exert protective effects in several neurological disorders. The present study aimed to investigate the role and underlying molecular mechanism of miR-212 in PD. MATERIALS AND METHODS: 1-methyl-4-phenylpyridinium (MPP+)-induced SH-SY5Y cells were applied as a PD model in vitro. RTqPCR was used to measure the expression of miR-212 and Kruppel-like factor 4 (KLF4) mRNA. Western blot analysis was performed to detect the protein levels of KLF4, Notch1 and Jagged1. Cell viability and apoptosis were determined by the Cell Counting Kit-8 and flow cytometry, respectively. Quantitative analysis of caspase-3 activity, lactate dehydrogenase (LDH), reactive oxygen species (ROS), superoxide dismutase (SOD), tumor necrosis factor-α (TNF-α), and interleukin-1 beta (IL-1β) was conducted with corresponding ELISA kits. Dual-luciferase reporter assay was employed to evaluate the relationship between miR-212 and KLF4. RESULTS: MiR-212 was downregulated in MPP+-induced SH-SY5Y cells. Also, miR-212 alleviated MPP+-induced SH-SY5Y cell damage, embodied by increased cell viability, decreased caspase-3 activity, LDH release, ROS production, TNF-α, and IL-1β expression, as well as elevated SOD levels. KLF4 was a direct target of miR-212, and miR-212 repressed KLF4 expression in a post-transcriptional manner. Moreover, miR-212-mediated protection effects were abated following KLF4 expression restoration in MPP+-induced SH-SY5Y cells, represented as lowered cell viability and enhanced apoptotic rate. Furthermore, Notch signaling was involved in the regulation of miR-212/KLF4 axis in MPP+-induced SH-SY5Y cells. CONCLUSION: miR-212 might attenuate MPP+-induced neuronal damage by regulating KLF4/Notch signaling pathway in SH-SY5Y cells, a promising target for PD therapy.
1-Methyl-4-phenylpyridinium ; Apoptosis ; Blotting, Western ; Caspase 3 ; Cell Count ; Cell Survival ; Enzyme-Linked Immunosorbent Assay ; Flow Cytometry ; In Vitro Techniques ; Interleukin-1beta ; L-Lactate Dehydrogenase ; Necrosis ; Nervous System Diseases ; Neurodegenerative Diseases ; Neurons* ; Parkinson Disease ; Reactive Oxygen Species ; RNA, Messenger ; Superoxide Dismutase

As an environmental risk factor, psychological stress may trigger the onset or accelerate the progression of Parkinson's disease (PD). Here, we evaluated the effects of acute restraint stress on striatal dopaminergic terminals and the brain metabolism of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which has been widely used for creating a mouse model of PD. Exposure to 2 h of restraint stress immediately after injection of a low dose of MPTP caused a severe loss of striatal dopaminergic terminals as indicated by decreases in the dopamine transporter protein and dopamine levels compared with MPTP administration alone. Both striatal 1-methyl-4-phenylpyridinium ion (MPP) and MPTP concentrations were significantly increased by the application of restraint stress. Striatal monoamine oxidase-B, which catalyzes the oxidation of MPTP to MPP, was not changed by the restraint stress. Our results indicate that the enhanced striatal dopaminergic terminal loss in the stressed mice is associated with an increase in the transport of neurotoxin into the brain.
1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine ; metabolism ; 1-Methyl-4-phenylpyridinium ; metabolism ; Animals ; Corpus Striatum ; drug effects ; metabolism ; Disease Models, Animal ; Dopaminergic Neurons ; drug effects ; MPTP Poisoning ; chemically induced ; metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Neurotoxins ; metabolism ; Restraint, Physical ; Stress, Psychological ; metabolism

BACKGROUND: The extract and hemiterpene glycosides of Ilex Rotunda Thunb exert antioxidant and anti-inflammatory effects. The effect of rotundarpene on apoptosis in neuronal cells caused by the 1-methyl-4-phenylpyridinium (MPP⁺) has not been reported previously. METHODS: Using differentiated PC12 cells and human neuroblastoma SH-SY5Y cells, we investigated the effect of rotundarpene on MPP⁺-caused apoptosis in relation to the cell death process. RESULTS: MPP⁺-induced cell death was identified using the MTT and neutral red uptake tests. Apoptosis was induced by eliciting decreases in the cytosolic levels of Bid and Bcl-2 proteins, increases in the cytosolic levels of Bax and p53, disruption of the mitochondrial transmembrane potential, and the release of cytochrome c and the activation of caspase-8, -9, and -3 in differentiated PC12 cells and SH-SY5Y cells. Treatment with rotundarpene reduced the MPP⁺-induced changes in the levels of apoptosis-regulated proteins, formation of reactive oxygen species, depletion and oxidation of glutathione, and cell death in both PC12 and SH-SY5Y cells. CONCLUSIONS: Rotundarpene may reduce MPP⁺-induced apoptosis in neuronal cells by suppressing the activation of the mitochondria-mediated pathway and the caspase-8 and Bid pathways. Rotundarpene appears to act by inhibiting the production of reactive oxygen species and by the depletion and oxidation of glutathione.
1-Methyl-4-phenylpyridinium ; Animals ; Apoptosis ; Caspase 8 ; Cell Death* ; Cytochromes c ; Cytosol ; Glutathione ; Glycosides ; Humans ; Ilex ; Membrane Potentials ; Neuroblastoma ; Neurons ; Neutral Red ; PC12 Cells ; Reactive Oxygen Species

Icariin is the major bioactive component of Epimedium and has been demonstrated to be a potential drug for age-related diseases. The present study was aimed to investigate the neuroprotective properties of icariin against 1-methyl-4-phenylpyridinium ion (MPP)-induced neurotoxicity in MES23.5 cells and the possible mechanisms. MTT assay showed that treatment with MPPattenuated the cell viability in a dose-dependent manner in MES23.5 cells. Icariin pretreatment resulted in an enhancement of survival. Immunocytochemistry analysis revealed that icariin treatment attenuated MPP-induced loss of tyrosine hydroxylase (TH) positive cells. Meanwhile, Western blot confirmed MPPsignificantly decreased the TH protein expression, and icariin pretreatment could reverse the toxic effect of MPP. Moreover, flow cytometry showed that MPP-induced decrease of the mitochondrial membrane potential could be partly restored by icariin. Furthermore, real-time RT-PCR and Western blot analysis demonstrated that icariin treatment restored the MPP-induced up-regulation of Bax and down-regulation of Bcl-2 mRNA and protein expressions. Western blot data also revealed the inhibitory effect of icariin on MPP-induced up-regulation of cleaved caspase-3. These findings provide the evidence that icariin has neuroprotective properties against MPP-induced neurotoxicity in MES23.5 cells and the mechanism might be related to the anti-apoptotic action of icariin.
1-Methyl-4-phenylpyridinium ; Animals ; Apoptosis ; Caspase 3 ; Cell Line ; Cell Survival ; Down-Regulation ; Flavonoids ; pharmacology ; Membrane Potential, Mitochondrial ; Mitochondria ; Neuroprotective Agents ; pharmacology ; Neurotoxicity Syndromes ; RNA, Messenger ; Up-Regulation

We previously demonstrated that 1-methyl-4-phenylpyridinium (MPP+) causes caspase-independent, non-apoptotic death of dopaminergic (DA) neuronal cells. Here, we specifically examined whether change of glucose concentration in culture medium may play a role for determining cell death modes of DA neurons following MPP+ treatment. By incubating MN9D cells in medium containing varying concentrations of glucose (5~35 mM), we found that cells underwent a distinct cell death as determined by morphological and biochemical criteria. At 5~10 mM glucose concentration (low glucose levels), MPP+ induced typical of the apoptotic dell death accompanied with caspase activation and DNA fragmentation as well as cell shrinkage. In contrast, MN9D cells cultivated in medium containing more than 17.5 mM (high glucose levels) did not demonstrate any of these changes. Subsequently, we observed that MPP+ at low glucose levels but not high glucose levels led to ROS generation and subsequent JNK activation. Therefore, MPP+-induced cell death only at low glucose levels was significantly ameliorated following co-treatment with ROS scavenger, caspase inhibitor or JNK inhibitor. We basically confirmed the quite similar pattern of cell death in primary cultures of DA neurons. Taken together, our results suggest that a biochemically distinct cell death mode is recruited by MPP+ depending on extracellular glucose levels.
1-Methyl-4-phenylpyridinium ; Cell Death* ; DNA Fragmentation ; Dopaminergic Neurons* ; Glucose* ; Neurons ; Parkinson Disease ; Reactive Oxygen Species

OBJECTIVETo investigate the effects of paeonol on neuron cell model of Parkinson disease (PD).

METHODSThe cell model of Parkinson disease was induced by treatment of 1-Methyl-4-phenylpyridinium (MPP+) in PC12 cells, the PD model cells were treated with 1 μmol/L, 3 μmol/L or 9 μmol/L paeonol for 24h, respectively. Cell viability and LDH leakage were detected by MTT and lactate dehydrogenase (LDH) assay; the apoptosis of PC12 cells was assessed by Hoechst 33258 staining and flow cytometry; reactive oxygen species (ROS) production was detected by DCFH-DA method; and the ratio of Bax/Bcl-2 and activation of caspase-3 were determined by Western blotting.

RESULTSMPP+ treatment significantly reduced cell viability, increased LDH leakage, enhanced the proportion of apoptotic cells and ROS production. In addition, MPP+ treatment dramatically increased the Bax/Bcl-2 ratio, and the activation of caspase-3. Compared to PD model group, paeonol treatment significantly enhanced cell viability, decreased LDH leakage, inhibited the proportion of apoptotic cells and ROS production, reduced the Bax/Bcl-2 ratio and the activated caspase-3 protein.

CONCLUSIONPaeonol can prevent PC12 cells from apoptosis induced by MPP+, and the mechanism may be associated with the down-regulation of ROS production, Bax/Bcl-2 ratio and Caspase-3 activation.

1-Methyl-4-phenylpyridinium ; Acetophenones ; pharmacology ; Animals ; Apoptosis ; Caspase 3 ; metabolism ; Cell Survival ; Down-Regulation ; Fluoresceins ; Neuroprotective Agents ; pharmacology ; PC12 Cells ; Parkinson Disease ; drug therapy ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Rats ; Reactive Oxygen Species ; metabolism ; bcl-2-Associated X Protein ; metabolism

Autophagy is a series of catabolic process mediating the bulk degradation of intracellular proteins and organelles through formation of a double-membrane vesicle, known as an autophagosome, and fusing with lysosome. Autophagy plays an important role of death-survival decisions in neuronal cells, which may influence to several neurodegenerative disorders including Parkinson's disease. Chebulagic acid, the major constituent of Terminalia chebula and Phyllanthus emblica, is a benzopyran tannin compound with various kinds of beneficial effects. This study was performed to investigate the autophagy enhancing effect of chebulagic acid on human neuroblastoma SH-SY5Y cell lines. We determined the effect of chebulagic acid on expression levels of autophagosome marker proteins such as, DOR/TP53INP2, Golgi-associated ATPase Enhancer of 16 kDa (GATE 16) and Light chain 3 II (LC3 II), as well as those of its upstream pathway proteins, AMP-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR) and Beclin-1. All of those proteins were modulated by chebulagic acid treatment in a way of enhancing the autophagy. Additionally in our study, chebulagic acid also showed a protective effect against 1-methyl-4-phenylpyridinium (MPP+) - induced cytotoxicity which mimics the pathological symptom of Parkinson's disease. This effect seems partially mediated by enhanced autophagy which increased the degradation of aggregated or misfolded proteins from cells. This study suggests that chebulagic acid is an attractive candidate as an autophagy-enhancing agent and therefore, it may provide a promising strategy to prevent or cure the diseases caused by accumulation of abnormal proteins including Parkinson's disease.
1-Methyl-4-phenylpyridinium ; Adenosine Triphosphatases ; AMP-Activated Protein Kinases ; Autophagy* ; Cell Line ; Humans ; Lysosomes ; Negotiating ; Neuroblastoma ; Neurodegenerative Diseases ; Neurons ; Neuroprotective Agents* ; Organelles ; Parkinson Disease ; Phyllanthus emblica ; Sirolimus ; Terminalia

BACKGROUND: 1-Methyl-4-phenylpyridinium (MPP+) causes a neuronal cell injury that is similar to the findings observed in Parkinson's disease. Caffeoylquinic acid derivatives have demonstrated anti-oxidant and anti-inflammatory effects. Nevertheless, the effect of 3,4,5-tricaffeoylquinic acid (3,4,5-triCQA) on the neuronal cell death due to exposure of parkinsonian toxin MPP+ remains unclear. METHODS: Using differentiated PC12 cells, the preventive effect of 3,4,5-triCQA on the MPP+-induced cell death in relation to apoptotic process was examined. RESULTS: MPP+ induced a decrease in Bid, Bcl-2 and survivin protein levels, increase in Bax levels, loss of the mitochondrial transmembrane potential, cytochrome c release, activation of caspases (-8, -9 and -3), cleavage of PARP-1, and an increase in the tumor suppressor p53 levels. 3,4,5-Tricaffeoylquinic acid attenuated the MPP+-induced changes in the apoptosis-related protein levels, formation of reactive oxygen species, depletion of GSH, nuclear damage and cell death. 3,4,5-Tricaffeoylquinic acid attenuated another parkinsonian neurotoxin rotenone-induced cell death. CONCLUSIONS: 3,4,5-Tricaffeoylquinic acid may attenuate the MPP+-induced apoptosis in PC12 cells by suppressing the activation of the mitochondrial pathway and the caspase-8- and Bid-dependent pathways. The preventive effect seems to be ascribed to its inhibitory effect on the formation of reactive oxygen species and depletion of GSH.
1-Methyl-4-phenylpyridinium ; Animals ; Apoptosis* ; Caspases ; Cell Death ; Cytochromes c ; Membrane Potentials ; Neurons ; Parkinson Disease ; PC12 Cells ; Reactive Oxygen Species

BACKGROUND: Parkinson disease (PD) is caused by selective cell death of dopaminergic neurons in the substantia nigra. An early onset form of PD, autosomal recessive juvenile parkinsonism has been associated with a mutation in the parkin gene. The function of parkin is known to remove misfolding proteins and protect cell death. We aimed to investigate the role of parkin against oxidative stress in neuronal cells. METHODS: Parkin knockout embryonic stem cells (PKO ES cells) were differentiated into neurons by adherent monolayer culture method. Oxidative stress was induced by the treatment of 1-methyl-4-phenylpyridinium (MPP+) in neurons derived from wild type and PKO ES cells, and cell viability was examined by MTT assay. After exposure to MPP+, Tuj1-positive cell population was compared between PKO and wild type cells by fluorescence activated cell sorter (FACS) analysis. The activated caspase3 protein level was also measured by Western blot analysis, FACS and immunocytochemistry. RESULTS: There was no difference in the efficiency of neuronal differentiation between wild type and PKO ES cells. After exposure to MPP+, no significant differences were found in cell viability and Tuj1-positive cell population between the two groups determined by MTT assay and FACS analysis, respectively. The activated caspase3 protein levels examined by Western blot analysis, FACS and immunocytochemistry were not changed in PKO cells compared with those of wild type cells after MPP+ treatment. CONCLUSION: These results suggest that PKO neuronal cells including dopaminergic neurons are not sensitive to caspase3-dependent cell death pathway during the response against MPP+-induced oxidative stress.
1-Methyl-4-phenylpyridinium ; Blotting, Western ; Cell Death ; Cell Survival ; Dopaminergic Neurons ; Embryonic Stem Cells ; Fluorescence ; Immunohistochemistry ; Neurons ; Oxidative Stress* ; Parkinson Disease ; Parkinsonian Disorders ; Substantia Nigra