Protocatechuic acid suppresses MPP+ -induced mitochondrial dysfunction and apoptotic cell death in PC12 cells.

Protocatechuic acid (PCA), a phenolic compound isolated from the kernels of Alpinia (A.) oxyphylla, showed antioxidant neuroprotective effect in our previous study. Here, we investigated the effect of PCA on the MPP(+)-induced mitochondrial dysfunction and apoptotic cell death in PC12 cells. The apoptosis in MPP(+)-induced PC12 cells was associated with loss of mitochondrial membrane potential, the formation of reactive oxygen species (ROS), GSH depletion, activation of caspase-3 and down-regulation of Bcl-2. In contrast, treatment of PC12 cells with PCA significantly prevented the above-mentioned mitochondrial dysfunction. Our data pointed to the potential clinical application/use of PCA to overcome neurodegenerative diseases such as Parkinson's disease.     

毛蕊花苷对MPP~+诱导的SHSY5Y细胞凋亡的保护作用

目的观察肉苁蓉提取物毛蕊花苷对MPP+诱导的SHSY5Y细胞损伤的影响。方法用MTT法检测细胞存活率,以流式细胞仪检测细胞内活性氧的产生和线粒体膜电位的变化,以及细胞凋亡的发生,并用荧光酶标仪测定caspase-3的活性,蛋白印迹测定Bcl-2的表达水平。结果200μmol·L-1MPP+处理细胞24h降低细胞的存活率;诱导细胞发生凋亡,凋亡率达38.9%;细胞内活性氧水平及caspase-3的活性升高;而线粒体膜电位却明显降低。而预先给予0.1、1或者10mg·L-1浓度的毛蕊花苷处理细胞12h,可提高细胞存活率;流式细胞仪检测凋亡率分别降低到29.5%,15.3%和8.6%,而且细胞内活性氧的水平明显降低,并可逐渐恢复线粒体的高能量状态;caspase-3的活性不断降低,Bcl-2的表达水平增高,并呈现一定的剂量依赖性。结论毛蕊花苷能抑制MPP+诱导的SHSY5Y细胞凋亡,其神经细胞保护作用可能与其降低细胞内活性氧水平,维持线粒体膜电位的高能状态和抑制caspase-3的活性有关。     

Protocatechuic acid inhibits apoptosis by mitochondrial dysfunction in rotenone-induced PC12 cells.

Protocatechuic acid (PCA), a phenolic compound isolated from the kernels of Alpinia (A.) oxyphylla, showed the significant neuroprotective effects on hydrogen peroxide (H2O2) or MPP+-induced apoptosis in cultured PC12 cells. However, the mechanism how PCA suppresses rotenone-induced neurotoxicity in cultured PC12 cells remains unclear. In this study, we investigated the protective effects of PCA in PC12 cells exposed to rotenone as an in vitro model of mitochondrial dysfunction and apoptotic cell death. The apoptosis in rotenone-induced PC12 cells was accompanied by the loss of mitochondrial membrane potential, the formation of reactive oxygen species (ROS), the total glutathione depletion, activation of caspase-3 and down-regulation of Bcl-2. In contrast, PCA markedly attenuated the above-mentioned mitochondrial dysfunction in a dose-dependent manner. Taken together, these results suggest that treatment of PC12 cells with PCA can block rotenone-induced apoptosis via ameliorating the mitochondrial dysfunction.     

Antioxidant effect of erythropoietin on 1-methyl-4-phenylpyridinium-induced neurotoxicity in PC12 cells

The neuroprotective effects of erythropoietin on 1-methyl-4-phenylpyridinium (MPP(+))-induced oxidative stress and apoptosis in cultured PC12 cells as well as the underlying mechanism were investigated. Treatment of PC12 cells with MPP(+) caused the loss of cell viability, which was associated with the elevation in apoptotic rate, the formation of reactive oxygen species and the disruption of mitochondrial transmembrane potential. It was also shown that MPP(+) significantly induced upregulation of Bax/Bcl-2 ratio and activation of caspase-3. In contrast, erythropoietin reversed these phenotypes and had its maximum protective effect at 1 U/ml. The effect of erythropoietin was mediated by the phosphatidylinositol 3-kinase (PI3K) signaling pathway since erythropoietin failed to rescue cells from MPP(+) insult in the presence of the PI3K inhibitor, LY 294002. In addition, the downstream effector of PI3K, Akt, was activated by erythropoietin, and Akt activation was inhibited by LY 294002. Furthermore, the effect of erythropoietin on reactive oxygen species levels was also blocked by LY 294002. These results show that erythropoietin may provide a useful therapeutic strategy for the treatment of oxidative stress-induced neurodegenerative diseases such as Parkinson disease.     

瓜子金皂苷己对MPP~+诱导PC12细胞凋亡的保护作用

目的观察瓜子金皂苷己(polygalasaponin F,PS-F)对1-甲基-4-苯基-吡啶离子(1-methyl-4-phenylpyridinium,MPP+)诱导的PC12细胞损伤的影响,并且探讨其作用机制。方法 MTT法检测细胞存活率,Annexin V/PI染色流式细胞术检测PC12细胞凋亡,JC-1染色倒置显微镜检测细胞线粒体膜电位(mitochondrial membrane potential,MMP),Western blot检测Caspase-3蛋白的水平。结果 500μmol.L-1MPP+作用PC12细胞48 h,能明显抑制细胞生长(P<0.01),诱导细胞发生凋亡,同时降低MMP,增加活性Caspase-3的蛋白水平。同时给予不同浓度PS-F处理,PC12细胞存活率增加(P<0.01);凋亡细胞量减少;MMP增高;活性Caspase-3蛋白水平降低(P<0.01)。结论 PS-F能抑制MPP+诱导的PC12细胞的凋亡,其作用机制可能与维持线粒体正常膜电位,稳定线粒体功能,降低活性Caspase-3蛋白水平有关。     

Piperine inhibition of 1-methyl-4-phenylpyridinium-induced mitochondrial dysfunction and cell death in PC12 cells

The effect of alkaloid piperine against the toxicity of 1-methyl-4-phenylpyridinium (MPP(+)) in differentiated PC12 cells was assessed. Piperine treatment revealed a differential effect on the cytotoxicity of MPP(+) and had its maximum inhibitory effect at 1 microM. The addition of piperine (0.5-10 microM) significantly reduced the MPP(+)-induced nuclear damage, mitochondrial membrane permeability changes, formation of reactive oxygen species and depletion of GSH. In contrast, piperine at 50-100 microM showed cytotoxicity and exhibited an additive effect against the MPP(+) toxicity. The results indicate that piperine had a differential effect on the cytotoxicity of MPP(+) depending on concentration. Piperine at low concentrations may reduce the MPP(+)-induced viability loss in PC12 cells by suppressing the changes in the mitochondrial membrane permeability, leading to the release of cytochrome c and subsequent activation of caspase-3. The effects may be ascribed to its inhibitory action on the formation of reactive oxygen species and depletion of GSH.     

Vitamin E renders protection to PC12 cells against oxidative damage and apoptosis induced by single-walled carbon nanotubes

Single-walled carbon nanotubes (SWCNTs) are potential candidates in many biomedical applications. However, many reports demonstrated its potential toxicity to human and other biological systems. Our study has demonstrated that SWCNTs can induce apoptosis and oxidative damage on PC12 cells, an in vitro model of neuronal cells. In the present study, we for the first time investigated the neuroprotective effects of vitamin E (VE) on SWCNT-induced neurotoxicity in cultured PC12 cells. Vitamin E (0.01-2mM) increased PC12 cells viability and significantly attenuated SWCNTs-induced apoptotic cell death in a time and dose-dependent manner, as demonstrated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) release and morphological observation. The presence of VE inhibited the formation of reactive oxygen species (ROS), decreased the level of lipid peroxide, elevated the level of glutathione (GSH) and activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT). Additionally, VE blocked the reduction in the mitochondrial membrane potential and the activation of caspase-3. VE prevented the down-regulation of Bcl-2 expression and up-regulation of Bax expression induced by SWCNTs in PC12 cells. In summary, VE might protect PC12 cells from the injury induced by SWCNTs through the down-regulation of oxidative stress and prevention of mitochondrial-mediated apoptosis.     

Protocatechuic acid from Alpinia oxyphylla against MPP+-induced neurotoxicity in PC12 cells.

An ethyl acetate extract of Alpinia oxyphylla was found to possess neuroprotective activity against 1-methyl-4-phenylpyridinium ion (MPP(+)) induced apotosis and oxidative stress in cultured PC12 cells. From the extract, a phenolic compound was isolated through bioassay-guided fractionation and identified as protocatechuic acid (PCA) by IR, MS, and (1)H and (13)C NMR spectroscopy. It was the first time which was isolated from the kernels of A. oxyphylla. Exposure of PC12 cells to 1mM MPP(+) may cause significant viability loss and apoptotic cell death. PCA stimulated PC12 cellular proliferation and markedly attenuated MPP(+)-induced apoptotic cell death in a dose-dependent manner. By observing the nuclear morphological changes and flow cytometric analysis, PCA showed its significant effect on protecting PC12 cells against MPP(+)-induced apoptosis. Meanwhile, PCA enhanced the activities of superoxide dismutase (SOD) and catalase (CAT) in PC12 cells. In addition, PCA also dose-dependently reduced the hydrogen peroxide (H(2)O(2))- or sodium nitroprusside (SNP)-induced cell death in PC12 cells. The results suggest that PCA may be one of the primary active components in the kernels of A. oxyphylla and provide a useful therapeutic strategy for the treatment of oxidative stress-induced neurodegenerative disease such as Parkinson's disease.     

利福平抑制MPP^＋所致PC12细胞凋亡的研究

目的探讨利福平对MPP＋（1-甲基4-苯基吡啶离子）诱导的分化大鼠嗜铬细胞瘤细胞株（ratphaeochmmocytoma,PC12）细胞活性、细胞形态、调亡率的影响及其影响的机制。方法（1）利用MPP^＋诱导分化PCI2细胞建立帕金森病细胞模型;（2）MTT法检测细胞活性,（3）Tunel原位末端标记法检测细胞形态及半定量细胞凋亡率,（4）流式细胞术检测caspase－3激活率。结果（1）MPP＋作用后,细胞生长活性明显受到抑制,凋亡细胞数量增多,调亡率增加,caspase－3激活率明显增高;（2）而经100、200和300μmol／L各浓度利福平预处理后,利福平各浓度组内细胞活性增高,细胞凋亡程度、凋亡率及caspase－3激活率降低,且与利福平作用浓度存在剂量一效应关系。结论利福平可抑制MPP＋所致PCI2细胞的凋亡,这一作用是通过caspase-3途径起作用的,且存在剂量一效应关系。     

Neuroprotective effects of the stable nitroxide compound Tempol on 1-methyl-4-phenylpyridinium ion-induced neurotoxicity in the Nerve Growth Factor-differentiated model of pheochromocytoma PC12 cells

Nerve growth factor (NGF) differentiated pheochromocytoma PC12 cells exposed to 1-methyl-4-phenylpyridinium (MPP+) toxin were used as an in vitro pharmacological model of Parkinson's disease to examine the neuroprotective effects of 4-hydroxy-2,2,6,6-tetramethyl piperidine-n-oxyl (Tempol), a free radical scavenger and a superoxide dismutase-mimetic compound. MPP+-induced PC12 cell death was measured 72 h after exposure to 1.5 mM MPP+ by the release of lactate dehydrogenease, caspase-3 activation and stimulation of survival and stress mitogen-activated protein kinases. Exposure of PC12 cells to MPP+ activated ERK1 and ERK2 (forty-fold over control after 72 h), JNK1 and JNK2 (fourfold after 48 h) and p-38alpha (tenfold after 24 h). Pretreatment of PC12 cells with 500 microM Tempol, 1 h before induction of the MPP+ insult, reduced by 70% the release of LDH into the medium, inhibited caspase-3 activity by 30% and improved by 33% mitochondrial function, effects correlated with a 70% reduction in ERK1 and ERK2 phosphorylation activity. These findings support the neuroprotective effect of Tempol in the MPP+-induced PC12 cell death model and its use as a potential drug for treatment of Parkinson's disease.     

Synergistic effects of hydrogen peroxide and ethanol on cell viability loss in PC12 cells by increase in mitochondrial permeability transition

The promoting effect of ethanol against the cytotoxicity of hydrogen peroxide (H2O2) in differentiated PC12 cells was assessed by measuring the effect on the mitochondrial membrane permeability. Treatment of PC12 cells with H2O2 resulted in the nuclear damage, decrease in the mitochondrial transmembrane potential, cytosolic accumulation of cytochrome c, activation of caspase-3, increase in the formation of reactive oxygen species (ROS) and depletion of GSH. In PC12 cells and dopaminergic neuroblastoma SH-SY5Y cells, the promoting effect of ethanol on the H2O2-induced cell death was increased with exposure time. Ethanol promoted the nuclear damage, change in the mitochondrial membrane permeability, ROS formation and decrease in GSH contents due to H2O2 in PC12 cells. Catalase, carboxy-PTIO, Mn-TBAP, N-acetylcysteine, cyclosporin A and trifluoperazine inhibited the H2O2 and ethanol-induced mitochondrial dysfunction and cell injury. The results show that the ethanol treatment promotes the cytotoxicity of H2O2 against PC12 cells. Ethanol may enhance the H2O2-induced viability loss in PC12 cells by promoting the mitochondrial membrane permeability change, release of cytochrome c and subsequent activation of caspase-3, which is associated with the increased formation of ROS and depletion of GSH. The findings suggest that ethanol as a promoting agent for the formation of mitochondrial permeability transition may enhance the neuronal cell injury caused by oxidants.     

脂质立方液晶设计制备与表征评价研究进展

目的：研究伊拉地平（ ISR ）对1-甲基-4-苯基吡啶离子（ MPP＋）损伤的PC12细胞的保护作用及可能机制。方法MPP ＋处理PC12细胞建立帕金森病细胞模型;4-甲基偶氮唑蓝（ MTT）比色法检测细胞存活率;双氯荧光黄乙酸乙酯（ DCFH-DA）染色流式细胞术检测细胞内活性氧（ ROS）的生成;JC-1染色流式细胞术检测细胞线粒体膜电位（ MMP）。结果1 mmol · L－1MPP＋处理PC12细胞24 h后能明显抑制细胞生长（P＜0．01）;降低线粒体膜电位;ROS含量增加。2μmol· L－1伊拉地平预处理后, PC12细胞存活率显著增加（ P＜0．01）;线粒体膜电位升高;ROS生成减少。结论伊拉地平对MPP＋损伤的PC12细胞具有保护作用,其作用机制可能与维持线粒体正常膜电位,稳定线粒体功能,阻止线粒体氧化应激发生有关。     

Protective effects of Ginkgo biloba extract on paraquat-induced apoptosis of PC12 cells.

Previous studies have suggested that Ginkgo biloba extract (EGb761) has a protective potentiality against apoptosis of neurons or neuron-like cells induced by MPTP. In this study, the effects of EGb761 on PC12 cells injured by paraquat (PQ), a neurotoxin, were tested. The results showed that after incubation of PC12 cells with EGb761 prior to PQ exposure, the PQ-induced decrease of cell viability was significantly reversed, the collapse of mitochondrial membrane potential (MMP) was attenuated and the percentage of apoptotic cells was reduced. Moreover, EGb761 pretreatment evidently increased the numbers of tyrosine hydroxylase (TH) positive and bcl-2 positive cells and degraded the number of caspase-3 positive cells in PQ-injured PC12 cells, in comparison to the treatment with PQ alone. This study indicates that EGb761 has a neuroprotective effect on paraquat-induced apoptosis of PC12 cells. The mechanism underlying the protective effects of EGb761 in PQ-injured PC12 cells might be related to the increase of bcl-2 activation, maintenance of MMP stability and decrease of caspase-3 activation through mitochondria-dependent pathway. The results from this study provide an experimental basis for the potential use of EGb761 in treatment of Parkinson's disease.     

Pyranocoumarin(+/-)-4'-O-acetyl-3'-O-angeloyl-cis-khellactone induces mitochondrial-dependent apoptosis in HL-60 cells

The pyranocoumarin (+)-4'-O-acetyl-3 'O-angeloyl-cis-khellactone (PC) isolated from Radix Peucedani (root of Peucedanum praeruptorum Dunn) showed a dose-dependent effect at 10 -30 pg/mL on causing apoptotic DNA and nuclear fragmentations in HL-60 cells. After 24 h of PC treatment there were losses of mitochondrial membrane potential and cytochrome c. PC also increased total cellular and mitochondrial Bax protein, stimulated an increase in caspase-dependent Bcl-2 cleavage but showed no effect on Bcl-Xv. These observations strongly suggest activation of the mitochondria apoptotic pathway. The pan-specific caspase inhibitor, ZVAD-fmk, abolished the PC-induced apoptosis,whereas the caspase-8 inhibitor IETD-fmk showed no effect, implying the involvement of the caspase 9 pathway. PC caused a 2 to 12 hour transient increase in phospho-ERK, and a 72 h-long activation of JNK. Pre-treatment with the MEK inhibitor PD98059, which suppresses ERK activation, paradoxically promoted PC-induced mitochondrial cytochrome c release, procaspase-3 and -8 cleavage, and enhanced apoptosis. Our results show that PC triggers mitochondria-mediated apoptosis in HL-60 cells, and the involvement of ERK and JNK signal pathways in the process.     

Dopamine-induced death of PC12 cells is prevented by a substituted tetrahydronaphthalene

The ability of dopamine to induce apoptosis in a variety of cell types, including PC12 cells and neurons, has been well documented. Under non-reducing conditions, dopamine can be oxidized to semi-quinone and quinone species, which have the ability to arylate proteins and lead to the formation of covalent adducts. Potentially, it is the arylation of substrates critical to cell survival and/or the formation of toxic adducts which leads to the death observed after dopamine treatment. We have previously described the ability of a substituted monohydroxy-tetra-hydronaphthalene (DATN) to bind proteins that are susceptible to arylation by dopamine and related catecholamines. As DATN can prevent the covalent incorporation of dopamine into substrate molecules, we hypothesized that this compound could have a protective effect on cells that undergo apoptotic death in response to dopamine exposure. We report here that DATN prevents the dopamine-induced apoptotic death of PC12 cells in a dose-dependent manner. DATN did not prevent the oxidative stress associated with dopamine treatment, as lipid peroxide production was not influenced by DATN treatment. The ability of DATN to prevent dopamine-induced cell death was selective for this insult, as this compound did not influence the death of PC12 cells induced by hydrogen peroxide (H(2)O(2)). Consistent with this finding, DATN did not alter lipid peroxidation, nor oxidation of intracellular dichlorodihydrofluorescein subsequent to H(2)O(2) treatment. Consistent with a reduction in apoptotic death, the increase in caspase-3 activity associated with dopamine treatment was also prevented by DATN. These observations suggest that DATN may act to prevent one of the pathways linking dopamine and oxidative stress to caspase-3 activation. We propose that the inhibition of substrate arylation by the products of dopamine oxidation may provide a useful strategy for the prevention of dopamine-induced cell death.     

Possible role of interleukin-6 in PC12 cell death induced by MPP+ and tetrahydroisoquinoline

Interleukin (IL)-6 has been shown to protect neuronal cells from cell death induced by various stimulants. Although neuronal cells including PC12 cells were shown to produce IL-6, little is known about the effects of dopaminergic neurotoxins, 1,2,3,4-tetrahydroisoquinoline (TIQ) and 1-methyl-4-phenylpyridinium ion (MPP(+)), on IL-6 expression in PC12 cells. In the present study, we investigated the role of IL-6 in the TIQ- and MPP(+)-induced cell death in PC12 cells. Treatment with 3.2 mM TIQ for 24 h caused a delayed cell death (lactate dehydrogenase (LDH) leakage and nuclear DNA fragmentation) markedly 72 h after the addition. Addition of 0.4 mM MPP(+) caused LDH leakage and nuclear DNA fragmentation 24 h after the addition. The cell death induced by MPP(+) was inhibited by an inhibitor of caspases, z-Val-Ala-Asp(OMe)-fluoromethylketone. The cell death induced by TIQ or MPP(+) was inhibited by nerve growth factor and 10% serum and significantly enhanced by the treatment with anti-IL-6 antibody. Both neurotoxins decreased the IL-6 mRNA level in PC12 cells without changing the other tested mRNA levels (IL-1 alpha, beta-actin, etc.). These findings suggest that dopaminergic neurotoxins cause cell death in PC12 cells at least partially by changing IL-6 expression.     

Activation of protein kinase C delta by proteolytic cleavage contributes to manganese-induced apoptosis in dopaminergic cells: protective role of Bcl-2

Chronic inorganic manganese exposure causes selective toxicity to the nigrostriatal dopaminergic system, resulting in a Parkinsonian-like neurological condition known as Manganism. Apoptosis has been shown to occur in manganese-induced neurotoxicity; however, the down-stream cellular target of caspase-3 that contributes to DNA fragmentation is not established. Herein, we demonstrate that proteolytic activation of protein kinase Cdelta (PKCdelta) by caspase-3 plays a critical role in manganese-induced apoptotic cell death. Treatment of PC12 cells with manganese caused a sequential activation of mitochondrial-dependent pro-apoptotic events, including mitochondrial membrane depolarization, cytochrome c release, caspase-3 activation, and DNA fragmentation. Overexpression of Bcl-2 in PC12 cells remarkably attenuated each of these events, indicating that the mitochondrial-dependent apoptotic cascade contributes to manganese-induced apoptosis. Furthermore, PKCdelta was proteolytically cleaved by caspase-3, causing a persistent activation of the kinase. The manganese-induced proteolytic cleavage of PKCdelta was significantly blocked by Bcl-2-overexpression. Administration of active recombinant PKCdelta induced DNA fragmentation in PC12 cells, suggesting a pro-apoptotic role of PKCdelta. Furthermore, expression of catalytically inactive mutant PKCdelta(K376R) via a lentiviral gene delivery system effectively attenuated manganese-induced apoptosis. Together, these results suggest that the mitochondrial-dependent caspase cascade mediates apoptosis via proteolytic activation of PKCdelta in manganese-induced neurotoxicity.     

Propofol attenuates oxidative stress-induced PC12 cell injury via p38 MAP kinase dependent pathway

Aim： To investigate the neuroprotective effect of propofol and its intracellular mechanism on neurons in vitro. Methods： Cell viability was determined with 3-（4, 5-dimethylthiazol-2-yl）-2,5-diphenyl tetrazolium bromide reduction. Apoptotic cell death was determined by Hoechst 33258 staining and a fluorescence-activated cell sorter. The caspase-3 activity was measured by fluorometric assay. Mitogenactivated protein （MAP） kinase phosphorylation was detected with Western blotting. Results： The pretreatment of rat pheochromocytoma cell line PC 12 with propofol （1-10 μmol/L） resulted in a significant recovery from hydrogen peroxide （H2O2）-induced cell death and the inhibition of H2O2 induced caspase-3 activation and PC12 cell apoptosis. Propofol inhibited the H2O2-induced p38 MAP kinase, but not c-Jun N-terminal kinase or extracellular signal-regulated kinase 1 and 2 activations. Conclusion： Propofol might attenuate H2O2-induced PC 12 cell death through the inhibition of signaling pathways mediated by the p38 MAP kinase.     

Alpha-mangostin induces Ca2+-ATPase-dependent apoptosis via mitochondrial pathway in PC12 cells

We investigated the cell death effects of eight xanthones on PC12 rat pheochromocytoma cells. Among these compounds, alpha-mangostin, from the fruit hull of Garcinia mangostana L., had the most potent effect with the EC(50) value of 4 microM. Alpha-mangostin-treated PC12 cells demonstrated typical apoptotic DNA fragmentation and caspase-3 cleavage (equivalent to activation). The flow cytometric analysis indicated that this compound induced apoptosis in time-and concentration-dependent manners. Alpha-mangostin showed the features of the mitochondrial apoptotic pathway such as mitochondrial membrane depolarization and cytochrome c release. Furthermore, alpha-mangostin inhibited the sarco(endo)plasmic reticulum Ca(2+)-ATPase markedly. There was a correlation between the Ca(2+)-ATPase inhibitory effects and the apoptotic effects of the xanthone derivatives. On the other hand, c-Jun NH(2)-terminal kinase (JNK/SAPK), one of the signaling molecules of endoplasmic reticulum (ER) stress, was activated with alpha-mangostin treatment. These results suggest that alpha-mangostin inhibits Ca(2+)-ATPase to cause apoptosis through the mitochondrial pathway.