Neuroprotective effects of neural stem cells pretreated with neuregulin1β on PC12 cells exposed to oxygen-glucose deprivation/reoxygenation

Studies on ischemia/reperfusion(I/R)injury suggest that exogenous neural stem cells(NSCs)are ideal candidates for stem cell therapy reperfusion injury.However,NSCs are difficult to obtain owing to ethical limitations.In addition,the survival,differentiation,and proliferation rates of transplanted exogenous NSCs are low,which limit their clinical application.Our previous study showed that neuregulin1β(NRG1β)alleviated cerebral I/R injury in rats.In this study,we aimed to induce human umbilical cord mesenchymal stem cells into NSCs and investigate the improvement effect and mechanism of NSCs pretreated with 10 nM NRG1βon PC12 cells injured by oxygen-glucose deprivation/reoxygenation(OGD/R).Our results found that 5 and 10 nM NRG1βpromoted the generation and proliferation of NSCs.Co-culture of NSCs and PC12 cells under condition of OGD/R showed that pretreatment of NSCs with NRG1βimproved the level of reactive oxygen species,malondialdehyde,glutathione,superoxide dismutase,nicotinamide adenine dinucleotide phosphate,and nuclear factor erythroid 2-related factor 2(Nrf2)and mitochondrial damage in injured PC12 cells;these indexes are related to ferroptosis.Research has reported that p53 and solute carrier family 7 member 11(SLC7A11)play vital roles in ferroptosis caused by cerebral I/R injury.Our data show that the expression of p53 was increased and the level of glutathione peroxidase 4(GPX4)was decreased after RNA interference-mediated knockdown of SLC7A11 in PC12 cells,but this change was alleviated after co-culturing NSCs with damaged PC12 cells.These findings suggest that NSCs pretreated with NRG1βexhibited neuroprotective effects on PC12 cells subjected to OGD/R through influencing the level of ferroptosis regulated by p53/SLC7A11/GPX4 pathway.

Neuroprotective Effects of Dexmedetomidine Preconditioning on Oxygen-glucose Deprivation-reoxygenation Injury in PC12 Cells via Regulation of Ca^2+-STIM1/Orail Signaling

Summary:Dexmedetomidine(DEX),a potent and highly selective agonist for a2-adrenergic receptors(a2AR),exerts neuroprotective effects by reducing apoptosis through decreased neuronal Ca^2+influx.However,the exact action mechanism of DEX and its effects on oxygen-glucose deprivation-reoxygenation(OGD/R)injury in vitro are unknown.We demonstrate that DEX pretreatment reduced OGD/R injury in PC12 cells,as evidenced by decreased oxidative stress,autophagy,and neuronal apoptosis.Specifically,DEX pretreatment decreased the expression levels of stromal interaction molecule 1(STIM1)and calcium release-activated calcium channel protein 1(Orail),and reduced the concentration of intracellular calcium pools.In addition,variations in cytosolic calcium concentration altered apoptosis rate of PC12 cells after exposure to hypoxic conditions,which were modulated through STIM 1/Orail signaling.Moreover,DEX pretreatment decreased the expression levels of Beclin-1 and microtubule-associated protein 1A/1B-light chain 3(LC3),hallmark markers of autophagy,and the formation of autophagosomes.In conclusion,these results suggested that DEX exerts neuroprotective effects against oxidative stress,autophagy,and neuronal apoptosis afier OGD/R injury via modulation of Caf-STIM1/Orai1 signaling.Our results offer insights into the molecular mechanisms of DEX in protecting against neuronal ischemia-reperfusion injury.

Enzyme-digested Colla Corii Asini(E’jiao) prevents hydrogen peroxide-induced cell death and accelerates amyloid beta clearance in neuronal-like PC12 cells

As an aging-associated degenerative disease,Alzheimer’s disease is characterized by the deposition of amyloid beta(Aβ),oxidative stress,inflammation,dysfunction and loss of cholinergic neurons.Colla Corii Asini(CCA)is a traditional Chinese medicine which has been used for feebleness-related diseases and anti-aging.CCA might delay aging-induced degenerative changes in neurons.In the present study,we evaluated antioxidant activity,cytoprotective effects,and Aβremovability of enzyme-digested Colla Corii Asini(CCAD).Oxygen radical absorbance capacity(ORAC)activity assay showed that,as compared to gelatins from the skin of porcine,bovine and cold water fish,CCA exhibited the highest ORAC activity.The ORAC activity of CCA and CCAD was increased gradually by the length of time in storage.Ultrastructure analysis by scanning electron microscopy showed that among CCA manufactured in 2008,2013,2017 and gelatin from cold water fish skin,CCA manufactured in 2008 presented the smoothest surface structure.We further tested the protective effects of CCAD(manufactured in 2008)and enzyme-digested gelatin from cold water fish skin(FGD)on hydrogen peroxide(H2O2)-induced cell death in nerve growth factor-differentiated neuronal-like PC12 cells.Presto blue assay showed that both FGD and CCAD at 0.5 mg/m L increased cell viability in H2O2-treated neuronal-like PC12 cells.The protection of CCAD was significantly superior to that of FGD.Acetylcholinesterase(Ach E)assay showed that both FGD and CCAD inhibited Ach E activity in nerve growth factor-differentiated neuronal-like PC12 cells to 89.1%and 74.5%of that in non-treated cells,respectively.The data suggest that CCAD might be able to increase the neurotransmitter acetylcholine.Although CCAD inhibited Ach E activity in neuronal-like PC12 cells,CCAD prevented H2O2-induced abnormal deterioration of Ach E.ELISA and neprilysin activity assay results indicated that CCAD reduced amyloid beta accumulation and increased neprilysin activity in Aβ1–42-treated neuronal-like PC12 cells,suggesting that CCAD can enhance Aβclearance.Our results suggest that CCA might be useful for preventing and treating Alzheimer’s disease.

Effect of insulin on 1-methyl-4-phenylpyridinium ion-induced apoptosis of PC12 cells

BACKGROUND: Insulin receptor (IR) expression in the substantia nigra of patients with Parkinson disease (PD) is not only significantly lower than that in the substantia nigra of normal persons of the same age, but also significantly lower than that in other regions in brain of himself/herself. It suggests that the abnormal effect of insulin receptor-mediated insulin, as a neurotrophic factor, is very possibly related to the loss of dopaminergic neurons in the substantia nigra and striatum in patients with Parkinson disease.OBJECTIVE: To observe the interventional effect of insulin on 1-methyl-4-phenylpyridinium ion (MPP+)-induced apoptosis of PC12.DESIGN: Controlled observation.SETTINGS: Department of Neurology, Beijing China-Japan Friendship Hospital; Department of Neurology, Huashan Hospital Affiliated to Fudan University.MATERIALS: PC12 cells were provided by the Cell Bank, Shanghai Institute of Cell Biology, Chinese Academy of Science. MPP+, MTT, HOECHST 33258 (Invitrogen Life Technologies), reverse transcription-polymerase chain reaction (RT-PCR) reagent (Takara Shuzo Co., Ltd.), flow cytometer (Bacton Dickionson, San Jose, CA), enzyme labelling instrument (Bio-Tek, Winooski, VT) and PCR circulation instrument (Takara Shuzo Co., Ltd) were used in this study.METHODS: This study was carried out in the Department of Neurology, Huashan Hospital Affiliated to Fudan University during June 2003 to August 2004. ① Cell culture and experimental grouping: PC12 cells were cultured according to the method from Peng et al, then were randomized into 3 groups; blank control group, MPP+ group and insulin group.② Detection of relative survival rate of cells: The relative survival rate of cells at different MPP+ final concentrations (0, 50, 100, 200, 300, 1 000 μmol/L) and at different culture time (0, 4, 8, 12, 18, 24 hours) in the 300 μmol/L MPP+ group and different concentrations of insulin (0, 15, 50, 100 nmol/L) in the insulin group was detected with MTT method according to the method from Hansen et al. ③ Observation of cell apoptosis: After stained by HOECHST 33258, the apoptotic cells were observed under the fluorescence miscroscope with the method from Chen et al. ④ Dection of apoptotic rate of cells: Apoptotic rate of cells was detected with flow cytometry according to the method from Zhang et al. ⑤ The expression of tyrosine hydroxylase (TH) mRNA in PC12 cells was detected with RT-PCR methods according to the modified method from Peng et al.MAIN OUTCOME MEASURES: Comparison of relative survival rate, apoptosis rate, the expression of IR mRNA and TH mRNA and cell apoptosis.RESULTS: ① After 12-hour incubation of 100, 200, 300 and 1 000 μmol/L MPP+, the relative survival rate of PC12 cells was (72.88±2.91)%, (60.64±0.81)%, (54.56±0.76)% and (16.89±2.83)%, respectively, which was significantly lower than that of blank control group (100%, P < 0.05); After 12, 18 and 24-hour incubation, the relative survival rate of PC12 cells was (54.56±0.76)%, (42.43±0.16)% and (23.56±0.17)% respectively, which was significantly lower than that of blank control group (100%, P < 0.05); When 15, 50 and 100 nmol/L insulin was pre-added to cells, the relative survival rate was (70.10±0.16)%, (78.01±2.43)% and (83.55±1.43)%, respectively, which was significantly higher than MPP+ alone [(54.56±0.76)%, P < 0.05]. ② Appototic bodies were rarely seen in the blank control group, but densely gathered in the MPP+ group and were significantly decreased in the insulin group. ③ Apoptosis rate of PC12 cells in the MPP+ group was significantly higher than that in the blank control group [(36.56±0.89)% vs. (2.34±0.23)%, P < 0.05], and that in the 15, 50, 100 nmol/L insulin group [(30.01±0.04)%, (24.23±0.37)%, (20.01±1.01)%, respectively] was significantly lower than that in MPP+ group (P < 0.05). ④ The TH mRNA expression in PC12 cells in MPP+ group was significantly lower than that in blank control group; The expression of TH mRNA in insulin group was gradually increased in an insulin dose-dependent manner. There were no significant changes in the expression of IR mRNA under different experimental conditions.CONCLUSION: Insulin can resist MPP+-induced apoptosis of PC12 cells, lessen the damage of PC12 cells, but does not change the gene expression of target cell insulin receptor.

Rifampicin inhibits apoptosis in rotenone-induced differentiated PC12 cells by ameliorating mitochondrial oxidative stress

BACKGROUND:Previous studies have shown that rifampicin exhibits neuroprotective effects,but the precise mechanisms remain unclear.Rifampicin is thought to exert the neuroprotective effect as a hydroxyl free radical scavenger.OBJECTIVE:To investigate the protective effects of rifampicin pretreatment on rotenone-induced mitochondrial oxidative stress in differentiated PC12 cells.DESIGN,TIME AND SETTING:A repeated measure,cell-based study was performed at the Department of Neurology,Second Affiliated Hospital,Sun Yat-sen University,China between December 2007 and November 2008.MATERIALS:PC12 cells were a kind gift from the Physiology Laboratory of Zhongshan Medical School,Sun Yat-sen University,China.Rotenone and rifampicin were purchased from Sigma,USA.METHODS:PC12 cells were differentiated by culturing with 100 ng/mL 7S nerve growth factor for 9 days in Dulbecco's modified Eagle's medium/Nutrient Mix F12(DMEM/F12) supplemented with 10% fetal bovine serum.The cells were assigned to six groups according to various treatment conditions:control,cultured with normal media;rifampicin group,treated with 300 μmol/L rotenone for 26 hours;rotenone group,treated with 2.5 μmol/L rotenone for 24 hours;rifampicin pretreatment groups,pretreated with 100,200,and 300 μmol/L rifampicin for 2 hours,respectively,followed by 2.5 μmol/L rotenone for 24 hours.MAIN OUTCOME MEASURES:Mitochondrial membrane potential was measured by fluorescence microscopy and flow cytometry,respectively,using rhodamine123 staining.Intracellular reactive oxygen species formation was analyzed by flow cytometry using 2',7'-dichlorofluorescin-diacetate staining,and intracellular reduced glutathione was measured with a microplate reader.Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.Cell apoptosis was detected by Hoechst 33342 staining and flow cytometry.RESULTS:Increased apoptosis in rotenone-induced,differentiated,PC12 cells was accompanied by the loss of mitochondrial transmembrane potential,the formation of reactive oxygen species,and reduced glutathione depletion(P<0.01).Rotenone-induced mitochondrial dysfunction was blocked in a dose-dependent manner by rifampicin(P<0.05 or P<0.01).CONCLUSION:Pretreatment of differentiated PC12 cells with rifampicin blocked rotenone-induced apoptosis by ameliorating mitochondrial dysfunction and oxidative stress.

Humulus japonicus extract alleviates oxidative stress and apoptosis in 6-hydroxydopamine-induced PC12 cells

Objective:To explore the possible neuroprotective activities of Humulus japonicus extract against Parkinson's disease(PD)in a cellular model.Methods:PD was modeled in PC12 cells using 6-hydroxydopamine(6-OHDA).The cell activity,intracellular levels of reactive oxygen species(ROS),anti-oxidative and anti-apoptotic effects,and other related indicators and related signaling pathways were evaluated to elucidate the neuroprotective effects of Humulus japonicus extract.Results:Humulus japonicus extract exhibited anti-oxidative and anti-apoptotic effects in 6-OHDA-stimulated PC12 cells.It also reduced oxidative stress-induced ROS accumulation;upregulated antioxidant enzymes,such as glutathione,catalase,heme oxidase-1,and 8-oxguanine glycosylase 1;promoted cell survival by decreasing BAX and increasing Bcl-2 and sirtuin 1 expression via the MAPK and/or Nrf2 signaling pathways.Conclusions:Humulus japonicus extract has antioxidative and anti-apoptotic effects and could be developed as a promising candidate for preventing and treating oxidative stress-related neurodegenerative diseases.

Interventional effect of phycocyanin on mitochondrial membrane potential and activity of PC12 cells after hypoxia/reoxygenation

BACKGROUND: Phycocyanin can relieve decrease of mitochondrial membrane potential through reducing production of active oxygen so as to protect neurons after hypoxia/reoxygenation. OBJECTIVE: To observe the effect of phycocyanin on activity of PC12 cells and mitochondrial membrane potential after hypoxia/reoxygenation. DESIGN: Randomized controlled study. SETTING: Cerebrovascular Disease Institute of Affiliated Hospital, Medical College of Qingdao University. MATERIALS: The experiment was carried out at the Key Laboratory of Prevention and Cure for cerebropathia in Shandong Province from October to December 2005. PC12 cells, rat chromaffin tumor cells, were provided by Storage Center of Wuhan University; phycocyanin was provided by Ocean Institute of Academia Sinica; Thiazoyl blue tetrazolium bromide (MTT) and rhodamine 123 were purchased from Sigma Company, USA; RPMI-1640 medium, fetal bovine serum and equine serum were purchased from Gibco Company, USA. METHODS: ① Culture of PC12 cells: PC12 cells were put into RPMI-1640 medium which contained 100 g/L heat inactivation equine serum and 0.05 volume fraction of fetal bovine serum and incubated in CO2 incubator at 37 ℃. Number of cells was regulated to 4 × 105 L-1, and cells were inoculated at 96-well culture plate. The final volume was 100 μL. ② Model establishing and grouping: Cultured PC12 cells were randomly divided into three groups: phycocyanin group, model control group and non-hypoxia group. At 24 hours before hypoxia, culture solution in phycocyanin group was added with phycocyanin so as to make sure the final concentration of 3 g/L , but cells in model control group did not add with phycocyanin. Cells in non-hypoxia group were also randomly divided into adding phycocyanin group (the final concentration of 3 g/L) and non-adding phycocyanin group. Cells in model control group and phycocyanin group were cultured with hypoxia for 1 hour and reoxygenation for 1, 2 and 3 hours; meanwhile, cells in non-hypoxia group were cultured with oxygen and were measured at 1 hour after hypoxia/reoxygenation. ③ Detecting items: At 1, 2 and 3 hours after reoxygenation, absorbance (A value) of PC12 cells was measured with MTT technique so as to observe activity and quantity of cells. Fluorescence intensity of PC12 cells marked by rhodamine 123 was measured with confocal microscope in order to observe changes of mitochondrial membrane potential. MAIN OUTCOME MEASURES: Comparisons between quantity and activity of PC12 cells and mitochondrial membrane potential at 1, 2 and 3 hours after reoxygenation. RESULTS: ① Effect of phycocyanin on quantity and activity of PC12 cells: A value was 0.924±0.027 in adding phycocyanin group and 0.924±0.033 in non-adding phycocyanin group. A value was lower in model control group and phycocyanin group than that in non-hypoxia group at 1, 2 and 3 hours after reoxygenation (0.817±0.053, 0.838±0.037, 0.875±0.029; 0.842±0.029, 0.872±0.025, 0.906±0.023, P < 0.05). A value was higher in phycocyanin group than that in model control group at 1, 2 and 3 after culture (P < 0.05). With culture time being longer, A value was increased gradually in phycocyanin group and model control group after reoxygenation (P < 0.05). ② Effect of phycocyanin on mitochondrial membrane potential of PC12 cells: Fluorescence intensity was 2.967±0.253 in adding phycocyanin group and 2.962±0.294 in non-adding phycocyanin group. Fluorescence intensity was lower in model control group and phycocyanin group than that in non-hypoxia group at 1, 2 and 3 hours after hypoxia/reoxygenation (1.899±0.397, 2.119±0.414, 2.287±0.402; 2.191±0.377, 2.264±0.359, 2.436±0.471, P < 0.05); but it was higher in phycocyanin group than that in model control group at 1, 2 and 3 after reoxygenation (P < 0.05). With culture time being longer, fluorescence intensity was increased gradually in phycocyanin group and model control group after reoxygenation (P < 0.05). CONCLUSION: Phycocyanin and reoxygenation can protect PC12 cells after hypoxia injury through increasing mitochondrial membrane potential and cellular activity, and the effect is improved gradually with prolonging time of reoxygenation.

The neuroprotective effect of walnut-derived peptides against glutamate-induced damage in PC12 cells: mechanism and bioavailability

In our previous study, defatted walnut meal hydrolysate(DWMH) could attenuate D-galactose-induced acute memory deficits in vivo, and six potent active peptides including WSREEQ, WSREEQE, WSREEQEREE, ADIYTE, ADIYTEEAG and ADIYTEEAGR were identified. The aim of this study was to investigate the possible mechanism underlying their neuroprotective effects on glutamate-induced apoptosis in PC12 cells and their digestive stability. Results showed that all these peptides could attenuate the reduction of cell viability caused by glutamate in PC12 cells, especially WSREEQEREE and ADIYTEEAGR. The addition of Arg residue in WSREEQEREE and ADIYTEEAGR might be the potential reason for their stronger protective effects. Additionally, these two peptides possibly protected PC12 cells against glutamate-induced apoptosis via activating intracellular antioxidant defence(superoxide dismutase(SOD) and glutathione peroxidase(GSH-Px)) through Kelch-like ECH-associated protein 1(Keap1) inhibition, inhibiting ROS production, Ca;influx and mitochondrial membrane potential(MMP) collapse as well as regulating the expression of apoptosis-related proteins(Bax and Bcl-2). This might be due to the presence of Trp, Tyr and Arg in these two peptides. However, encapsulation of WSREEQEREE and ADIYTEEAGR should be considered based on their digestive sensibility during in vitro gastrointestinal digestion.

α-Linolenic acid alleviates aluminium chloride-induced toxicity in PC12 cells by activation of PKA-CREB-BDNF signaling pathway

Aluminum has been associated with neurodegenerative diseases.ALA(α-linolenic acid),an essential dietary component for human health,possesses prominent biological activities.Herein,we aim to explore the neuroprotective effects of ALA on aluminum toxicity and reveal the underlying mechanism.Results show that aluminum chloride(denoted as Al)enabled cell viability decline and apoptosis with oxidative stress and mitochondrial damage in differentiated rat pheochromocytoma cells(PC12)for 24 h incubation.Compared with Al(10 mmol/L)treatment alone,ALA(50μmol/L)pretreatment for 24 h significantly enhanced cell viability by 28.40%,and hindered cell apoptosis by 12.35%,together with recovering redox state balance and alleviating mitochondrial damage.It was measured that ALA treatment upregulated Bcl-2 expression and down-regulated Bax level,accompanied with an expression decline of caspase-3 and caspase-9.Meanwhile,ALA pretreatment was proved to increase protein kinase A(PKA)expression and to promote phosphorylation of cAMP response element-binding protein(p-CREB),resulting in elevation on the level of brain-derived neurotrophic factor(BDNF).The above results showed that ALA attenuated Al toxicity in PC12 cells by mediating the PKA-CREBBDNF signaling pathway.

Treatment time influences the effects of a low-frequency pulsed electric field on synthesis of tyrosine hydroxylase and dopamine in PC12 cells

BACKGROUND:Electromagnetic radiation can influence dopamine(DA) synthesis in brain tissues or cells,but electromagnetic frequencies,intensities,and radiation time can produce different effects.In addition,the signal pathway by which electromagnetic radiation influences DA synthesis remains controversial.OBJECTIVE:To determine tyrosine hydroxylase(TH) expression in PC12 cells and DA levels in cell culture media after different periods of low-frequency pulsed electric field(LF-PEF) stimulation,and to determine how LF-PEF signaling stimulates TH synthesis using inhibitors.DESIGN,TIME AND SETTING:A parallel,controlled,cell experiment was performed at the Laboratory of Cell Biology,School of Life Science,East China Normal University,between January and October 2006.MATERIALS:PC12 cells were purchased from the Shanghai Institute of Biochemistry and Cell Biology,Chinese Academy of Sciences,China.Nerve growth factor was purchased from PeproTech,USA.The protein kinase A inhibitor,H-89,and mitogen-activated protein kinase kinase inhibitor,U0126,were purchased from Sigma,USA.METHODS:(1) Following routine culture in Dulbecco's modified eagle medium,primary PC12 cells were stimulated under LF-PEF(pulse frequency 50 Hz,pulse width 20 μs,peak field strength 1 V/m) for 5,10,15,20,and 30 minutes.(2) Inhibitors(H-89 or U0126,1 μmol/L) were added 30 minutes before LF-PEF stimulation for 10 minutes.MAIN OUTCOME MEASURES:(1) TH expression was determined by Western blot in PC12 cells at 0.5,1,2,3,and 4 days after LF-PEF stimulation.Similarly,DA was measured by high-performance liquid chromatography in media at 2,3,4,or 5 days after LF-PEF.(2) TH expression was detected 1 day after H-89 or U0126 treatment and LF-PEF.RESULTS:(1) Short-term LF-PEF stimulation(5 and 10 minutes) increased TH expression and media DA levels after short-term culture(2 days)(P<0.01),but both parameters decreased with longer culture(3-4 days)(P<0.01).Long-term LF-PEF stimulation(15,20,or 30 minutes) decreased TH and DA synthesis,followed by a rapid increase(P<0.01).(2) H89 could completely inhibit TH expression in PC12 cells stimulated by LF-PEF for 10 minutes,while the inhibition rate of U0126 was 53.2%.CONCLUSION:Short-term LF-PEF first promotes then inhibits,while long-term LF-PEF first inhibits then promotes,TH and DA synthesis.LF-PEF stimulation regulates TH expression primarily by activating protein kinase A to regulate DA synthesis.

Mu-Xiang-You-Fang protects PC12 cells against OGD/R-induced autophagy via AMPK/mTOR signaling pathway

OBJECTIVE Mu-Xiang-You-Fang(MXYF)is a classic prescription of Hui medicine,composed of five herbs,which has been used to treat ischemic stroke for many years.However,the potential pharmacological mecha⁃nisms of MXYF remain unclear.The present research is to investigate the neuroprotective effect of MXYF and its role in modulating autophagy via AMPK/mTOR signaling pathway in the PC12 oxygen-glucose deprivation and reperfusion(OGD/R)injury model.METHODS MXYF was extracted by supercritical CO2 fluid extraction apparatus.PC12 OGD/R injury model was established by oxygen-glucose deprivation for 2 h and reperfusion for 24 h.The effects of MXYF on the viability and cytotoxicity of PC12 cells were determined through cell counting kit(CCK-8)assay.Colorimetric method was performed to determine the LDH leakage rate.The calcium concentration was determined by chemical fluorescence method and the mitochondrial membrane potential was determined through flow cytometry.Monodansylcadaverine(MDC)staining was conducted to detect autophagosome formation.The expression of LC3,Beclin1,p62,p-AMPK,ULK1,p-mTOR and p-p70s6k proteins were determined by immunofluorescence and Western blotting analyses.RESULTS MXYF(1,2 and 4 mg·L^-1)could significantly increase the cell viability and mitochondrial membrane potential,while decreased the release of lactate dehydrogenase(LDH)and calcium concentration in PC12 cells.Mechanistic studies showed that MXYF reduced the LC3-II/LC3-I ratio and inhibited the expression of beclin1,p-AMPK and ULK1.In comparison,the expres⁃sion of p-mTOR,p-p70s6k and p62 were significantly enhanced.CONCLUSION MXYF inhibits autophagy after OGD/Rinduced PC12 cell injury through AMPK-mTOR pathway,thus MXYF might have therapeutic potential for treating the ischemic stroke.

MiRNA-181d Is Involved in CREB1 Expression in PC12 Cells

MicroRNAs are involved in regulation of the central nervous system (CNS) development, and miR-181d highly expressed in mature neurons. CREB is many signal pathways converged point in hippocampal neurons, and it plays a crucial role in learning and memory. In this study, we detected the negative relationship between CREB1 protein and miR-181d expression in lewis rat hippocampus development. And the bioinformatic analysis showed that, CREB1 mRNA contains complementary sequence to the miR-181d seed region. Then we further demonstrated that miR-181d controls the expression level of CREB1 gene in PC12 cells by luciferase assay and western blot. Taken together, our data demonstrated that CREB1 mRNA is the target gene of miR-181d, and conformed CREB1 protein expression was regulated by miR-181d in PC12 cells.

Dental pulp stem cells stimulate neuronal differentiation of PC12 cells

Dental pulp stem cells(DPSCs) secrete neurotrophic factors which may play an important therapeutic role in neural development, maintenance and repair. To test this hypothesis, DPSCs-conditioned medium(DPSCs-CM) was collected from 72 hours serum-free DPSCs cultures. The impact of DPSCs-derived factors on PC12 survival, growth, migration and differentiation was investigated. PC12 cells were treated with nerve growth factor(NGF), DPSCs-CM or co-cultured with DPSCs using Transwell inserts for 8 days. The number of surviving cells with neurite outgrowths and the length of neurites were measured by image analysis. Immunocytochemical staining was used to evaluate the expression of neuronal markers NeuN, microtubule associated protein 2(MAP-2) and cytoskeletal marker βIII-tubulin. Gene expression levels of axonal growth-associated protein 43 and synaptic protein Synapsin-I, NeuN, MAP-2 and βIII-tubulin were analysed by quantitative polymerase chain reaction(qRT-PCR). DPSCs-CM was analysed for the neurotrophic factors(NGF, brain-derived neurotrophic factor [BDNF], neurotrophin-3, and glial cell-derived neurotrophic factor [GDNF]) by specific ELISAs. Specific neutralizing antibodies against the detected neurotrophic factors were used to study their exact role on PC12 neuronal survival and neurite outgrowth extension. DPSCs-CM significantly promoted cell survival and induced the neurite outgrowth confirmed by NeuN, MAP-2 and βIII-tubulin immunostaining. Furthermore, DPSCsCM was significantly more effective in stimulating PC12 neurite outgrowths than live DPSCs/PC12 co-cultures over the time studied. The morphology of induced PC12 cells in DPSCs-CM was similar to NGF positive controls;however, DPSCs-CM stimulation of cell survival was significantly higher than what was seen in NGF-treated cultures. The number of surviving PC12 cells treated with DPSCs-CM was markedly reduced by the addition of anti-GDNF, whilst PC12 neurite outgrowth was significantly attenuated by anti-NGF, anti-GDNF and anti-BDNF antibodies. These findings demonstrated that DPSCs were able to promote PC12 survival and differentiation. DPSCs-derived NGF, BDNF and GDNF were involved in the stimulatory action on neurite outgrowth, whereas GDNF also had a significant role in promoting PC12 survival. DPSCs-derived factors may be harnessed as a cell-free therapy for peripheral nerve repair. All experiments were conducted on dead animals that were not sacrificed for the purpose of the study. All the methods were carried out in accordance with Birmingham University guidelines and regulations and the ethical approval is not needed.

ADENO-ASSOCIATED VIRUS INTRODUCED INTEGRATION AND EXPRESSION OF FOREIGN GENES IN PC12 CELLS

Objective To investigate integration and expression of adeno-associated virus (AAV) vectors in neuronal PC12 cells,the result of which can be applied in further gene therapy of diseases of the central nervous sys- tem. Methods Human neurotrophin-3(hNT3)genes were inserted into AAV vectors. Then the recombinat AAV plas- mids were encapsidated as recombinant virions. PCl2 cells were transfected with the virions and the positive cells were selected by G418. The transfection positive (hNT3 modified)PC12 cells were cultured for several generations and the cellular genomic DNA and total RNA were extracted. We investigated the integration locus or AAV vectors by South- ern blot and transcript situation or foreign genes by dot blot. Results The hybridization tests showed that AAV in- troduced foreign genes were stably integrated, but at random locus, and robustly transcribed in hNT3 modified PCl2 cells. Conclusion AAV vectors can serve as high efficiency vectors or target genes in neuronal PC12 cells.

Naringin ameliorates H_(2)O_(2)-induced oxidative damage in cells and prolongs the lifespan of female Drosophila melanogaster via the insulin signaling pathway

Naringin exists in a wide range of Chinese herbal medicine and has proven to possess several pharmacological properties.In this study,PC12,HepG2 cells,and female Drosophila melanogaster were used to investigate the antioxidative and anti-aging effects of naringin and explore the underlying mechanisms.The results showed that naringin inhibited H_(2)O_(2)-induced decline in cell viability and decreased,the content of reactive oxygen species in cells.Meanwhile,naringin prolonged the lifespan of flies,enhanced the abilities of climbing and the resistance to stress,improved the activities of antioxidant enzymes,and decreased malondialdehyde content.Naringin also improved intestinal barrier dysfunction and reduced abnormal proliferation of intestinal stem cells.Moreover,naringin down-regulated the mRNA expressions of inr,chico,pi 3k,and akt-1,and up-regulated the mRNA expressions of dilp2,dilp3,dilp5,and foxo,thereby activating autophagy-related genes and increasing the number of lysosomes.Furthermore,the mutant stocks assays and computer molecular simulation results further indicated that naringin delayed aging by inhibiting the insulin signaling(IIS)pathway and activating the autophagy pathway,which was consistent with the result of network pharmacological predictions.

Inhibition of Corydalis decumbens Alkaloids on Hydrogen Peroxide-induced Apoptosis of PC12 Cells through Down-regulating Caspase-3 Expression

Objective To extract alkaloids from Corydalis decumbens(AsCD) by supercritical CO2 fluid extraction(SFE) and to evaluate protective effects of AsCD against hydrogen peroxide(H2O2)-induced apoptosis in rat PC12 cells. Methods AsCD were extracted by SFE and oxidative damage PC12 cells model was induced by H2O2.The survival rate of the cells was determined by MTT assay;Lactate dehydrogenase release was determined by ultraviolet spectrophotometry;Flow cytometry was used to detect apoptosis;Caspase-3 mRNA and protein were determined by real-time PCR and Western blotting assay,respectively.Results AsCD remarkably reduced the cytotoxicity, prevented membrane damage,and inhibited cell apoptosis.AsCD inhibited Caspase-3 mRNA and protein expression induced by H2O2 in PC12 cells.Conclusion AsCD possess protective effects against H2O2-induced apoptosis in PC12 cells,and the mechanism of AsCD responsible to the inhibition of apoptosis is possibly attributed to the down-regulating Caspase-3 expression.AsCD might be useful in the treatment of oxidative stress-related neurodegenerative diseases.

Protective effects of proanthocyanidins on beta-amyloid peptide (25-35)-induced PC12 cell apoptosis by blocking S-phase and increasing p53 gene expression

BACKGROUND: Current studies related to the effects of proanthocyanidins on Alzheimer’s disease have focused primarily on the signal transduction pathway of cellular apoptosis.However,the influence of p53 gene expression on cell cycle regulation,with regard to the protective mechanisms of proanthocyanidins,has not been reported.OBJECTIVE: To observe the effect of proanthocyanidins on cell cycle distribution,cellular apoptosis,and p53 gene expression in β-amyloid peptide (25-35) (Aβ25-35)-induced PC12 cells cultured in serum-free media,and to investigate the molecular neuroprotective mechanisms of proanthocyanidins with regard to cell cycle regulation.DESIGN,TIME AND SETTING: A parallel,controlled,cellular,and molecular study was performed at the Institute of Biochemistry and Molecular Biology,Guangdong Medical College from July 2006 to July 2008.MATERIALS: Proanthocyanidins were provided by Nanjing Xuezi Medical and Chemical Research Center,China;Aβ25-35 was provided by Sigma,USA;PC12 cells were provided by the Institute of Basic Medical Science,Academy of Military Medical Sciences;and rabbit anti-p53 polyclonal antibody was provided by Santa Cruz Biotechnology,USA.METHODS: PC12 cells were cultured in serum-free media for 24 hours.Cells from the model group were treated with 25 μmol/L Aβ25-35 for 24 hours.Cells in the drug protection group were pre-treated with 30 mg/L proanthocyanidins for 1 hour and then treated with 25 μmol/L Aβ25-35 for 24 hours.The control group was not treated.MAIN OUTCOME MEASURES: Flow cytometry was used to detect cell cycle distribution and rate of apoptosis;reverse-transcriptase polymerase chain reaction was used to detect p53 mRNA expression;and Western blot was used to detect p53 protein expression.RESULTS: After treating with 25 μmol/L Aβ25-35 for 24 hours,the rate of apoptosis and the percentage of cells in S phase were significantly increased (P < 0.01),and p53 mRNA and protein expressions were decreased.Pretreatment with proanthocyanidins for 1 hour blocked the increase in apoptosis and the percentage of cells in S phase in Aβ25-35-induced PC12 cells (P < 0.01) and increased p53 mRNA and protein expressions.CONCLUSION: Proanthocyanidins blocked apoptosis and S-phase arrest in Aβ25-35-induced PC12 cells cultured in serum-free media.The protective mechanism could be related to increased p53 mRNA and protein expressions.

Hyperbaric oxygen protects against PC12 and H9C2 cell damage caused by oxygen-glucose deprivation/reperfusion via the inhibition of cell apoptosis and autophagy

In this study,we investigated the protective effect of hyperbaric oxygen(HBO)on PC12 and H9C2 cell damage caused by oxygen-glucose deprivation/reperfusion and its possible mechanism.PC12 and H9C2 cell oxygen-glucose deprivation/reperfusion model were established.Cells were divided into a control group,model group,hyperbaric air(HBA)group and HBO group.The cell viability was detected by the CCK8 assay.Hoechst 33342 and PI staining assays and mitochondrial membrane potential(MMP)assays were used to detect cell apoptosis.The ultrastructure of cells,including autophagosomes,lysosomes,and apoptosis,were examined using a transmission electron microscope.The expression of autophagy-related proteins was detected by cellular immunofluorescence and immunocytochemistry.Our results showed that HBO can significantly improve the vitality of damaged PC12 and H9C2 cells caused by oxygen–glucose deprivation/reperfusion.HBO can significantly inhibit apoptosis of PC12 and H9C2 cells caused by oxygenglucose deprivation/reperfusion.Importantly,we found that the protective mechanism of PC12 and H9C2 cell damage caused by oxygen-glucose deprivation/reperfusion may be related to the inhibition of the autophagy pathway.In this study,the results of cellular immunofluorescence and immunocytochemistry experiments showed that the 4E-BP1,p-AKt and mTOR levels of PC12 and H9C2 cells in the model group decreased,while the levels of LC3B,Atg5 and p53 increased.However,after HBO treatment,these autophagy-related indexes were reversed.In addition,observation of the cell ultrastructure with transmission electron microscopy found that in the model group,a significant increase in the number of autophagic vesicles was observed.In the HBO group,a decrease in autophagic vesicles was observed.The study demonstrated that hyperbaric oxygen protects against PC12 and H9C2 cell damage caused by oxygen-glucose deprivation/reperfusion via the inhibition of cell apoptosis and autophagy.

Genistein and daidzein reduced chlorpyrifos induced damage in PC12 cell

The present study preliminarily evaluated neurotoxicity injuries induced by chlorpyrifos in PC12 cell,which were used as a model for nervous cell system.In cultured PC12 cell,application of soy isoflavones(genistein,daidzein,monomer and mixture)significantly reduced chlorpyrifos induced toxicity,a widely used pesticide,and resulted in a better cell survival rate.Treatments with isoflavones reduced malondialdehyde content,reactive oxygengeneration and acetylcholine level in medium,and maintained mitochondrial membrane potential integrity.Daidzein enhanced endogenous antioxidant system in PC12 cell with an increasing in superoxide dismutase perunit activity.Genistein reduced acetylcholine content in the medium.Daidzein and genistein showed different effects,and their combined effect were greater than individual.In conclusion,soy isoflavones as an antioxidant and neuroprotectant,enhanced choline metabolism,which effectively mitigated disadvantageous influence of PC12 cell caused by chlorpyrifos.

Rapamycin reverses ferroptosis by increasing autophagy in MPTP/MPP+-induced models of Parkinson's disease

Parkinson’s disease is a neurodegenerative disorder,and fe rroptosis plays a significant role in the pathological mechanism underlying Parkinson’s disease.Rapamycin,an autophagy inducer,has been shown to have neuroprotective effects in Parkinson’s disease.However,the link between rapamycin and ferroptosis in Parkinson’s disease is not entirely clear.In this study,rapamycin was administe red to a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinson’s disease mouse model and a 1-methyl-4-phenylpyridinium-induced Parkinson’s disease PC12 cell model.The results showed that rapamycin improved the behavioral symptoms of Parkinson’s disease model mice,reduced the loss of dopamine neurons in the substantia nigra pars compacta,and reduced the expression of ferroptosis-related indicators(glutathione peroxidase 4,recombinant solute carrier family 7,member 11,glutathione,malondialdehyde,and reactive oxygen species).In the Parkinson’s disease cell model,rapamycin improved cell viability and reduced ferro ptosis.The neuroprotective effect of rapamycin was attenuated by a ferroptosis inducer(methyl(1S,3R)-2-(2-chloroacetyl)-1-(4-methoxycarbonylphenyl)-1,3,4,9-tetrahyyridoindole-3-carboxylate)and an autophagy inhibitor(3-methyladenine).Inhibiting ferro ptosis by activating autophagy may be an important mechanism by which rapamycin exerts its neuroprotective effects.Therefo re,the regulation of ferroptosis and autophagy may provide a therapeutic target for drug treatments in Parkinson’s disease.