Anti-inflammatory and DNA Repair Effects of Astragaloside IV on PC12 Cells Damaged by Lipopolysaccharide

Objective This study aimed to establish a neural cell injury model in vitro by stimulating PC12 cells with lipopolysaccharide(LPS)and to examine the effects of astragaloside IV on key targets using high-throughput sequence technology and bioinformatics analyses.Methods PC12 cells in the logarithmic growth phase were treated with LPS at final concentrations of 0.25,0.5,0.75,1,and 1.25 mg/mL for 24 h.Cell morphology was evaluated,and cell survival rates were calculated.A neurocyte inflammatory model was established with LPS treatment,which reached a 50%cell survival rate.PC12 cells were treated with 0.01,0.1,1,10,or 100µmol/L astragaloside IV for 24 h.The concentration of astragaloside IV that did not affect the cell survival rate was selected as the treatment group for subsequent experiments.NOS activity was detected by colorimetry;the expression levels of ERCC2,XRCC4,XRCC2,TNF-α,IL-1β,TLR4,NOS and COX-2 mRNA and protein were detected by RT-qPCR and Western blotting.The differentially expressed genes(DEGs)between the groups were screened using a second-generation sequence(fold change>2,P<0.05)with the following KEGG enrichment analysis,RT-qPCR and Western blotting were used to detect the mRNA and protein expression of DEGs related to the IL-17 pathway in different groups of PC12 cells.Results The viability of PC12 cells was not altered by treatment with 0.01,0.1,or 1µmol/L astragaloside IV for 24 h(P>0.05).However,after treatment with 0.5,0.75,1,or 1.25 mg/mL LPS for 24 h,the viability steadily decreased(P<0.01).The mRNA and protein expression levels of ERCC2,XRCC4,XRCC2,TNF-α,IL-1β,TLR4,NOS,and COX-2 were significantly increased after PC12 cells were treated with 1 mg/mL LPS for 24 h(P<0.01);however,these changes were reversed when PC12 cells were pretreated with 0.01,0.1,or 1µmol/L astragaloside IV in PC12 cells and then treated with 1 mg/mL LPS for 24 h(P<0.05).Second-generation sequencing revealed that 1026 genes were upregulated,while 1287 genes were downregulated.The DEGs were associated with autophagy,TNF-α,interleukin-17,MAPK,P53,Toll-like receptor,and NOD-like receptor signaling pathways.Furthermore,PC12 cells treated with a 1 mg/mL LPS for 24 h exhibited increased mRNA and protein expression of CCL2,CCL11,CCL7,MMP3,and MMP10,which are associated with the IL-17 pathway.RT-qPCR and Western blotting analyses confirmed that the DEGs listed above corresponded to the sequence assay results.Conclusion LPS can damage PC12 cells and cause inflammatory reactions in nerve cells and DNA damage.astragaloside IV plays an anti-inflammatory and DNA damage protective role and inhibits the IL-17 signaling pathway to exert a neuroprotective effect in vitro.

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 Bushen Decoction Against Glutamate-Induced Neurotoxicity in PC12 Cells

Aim The enhanced effect of Bushen (Kidney-tonifying) decoction (BS) oncultured PC12 cell proliferation and its antagonistic action on neurotoxicity induced by glutamatewere investigated by serum pharmacological method of the Chinese material medica (CMM) in vitro.Methods The effect of BS on cultured PC12 cell activity and its antagonistic action on neurotoxicityinduced by glutamate was observed by MTT method. Flow cytometry and fluorescence microscopetechniques were employed to observe the antagonistic effect of BS on early period apoptosis of PC12cells induced by glutamate. Results The serum with BS was able to enhance activity of PC12 cells andexert antagonistic effect on glutamate-induced neurotoxicity. Meanwhile, these beneficial effectsproduced by BS were found to be the strongest in 20% concentration of in serum BS. Moreover, it caninhibit apoptosis of PC12 cells induced by glutamate , which occurs in the early period. ConclusionBS may exert a potential neuroprotective effect.

Protective effect of erythropoietin against 1-methyl-4-phenylpyridinium-induced neurodegenaration in PC12 cells

Objective The neuroprotective effect of erythropoietin （EPO） against 1-methyl-4-phenylpyridinium （MPP^＋）- induced oxidative stress in cultured PC12 cells, as well as the underlying mechanism, were investigated. Methods PC12 ceils impaired by MPP^＋ were used as the cell model of Parkinson＇s disease. Methyl thiazolyl tetrazolium （MTT） was used to assay the viability of the PC12 cells exposed to gradient concentrations of EPO, and the terminal deoxynucleotidyl transferase dUTP nick end labelling （TUNEL） assay was used to analyze the apoptosis ratio of PC 12 cells. The expression of Bcl-2 and Bax in PC 12 cells were examined by Western blot, and the reactive oxygen species （ROS）, the mitochondrial transmembrane potential and the activity of caspase-3 in each group were detected by spectrofluorometer. Results Treatment of PC12 cells with MPP^＋ caused the loss of cell viability, which may be associated with the elevation in apoptotic rate, the formation of ROS and the disruption of mitochondrial transmembrane potential. It was also shown that MPP＋ significantly induced the upregulation of Bax/Bcl-2 ratio and the activation of caspase-3. In contrast, EPO significantly reversed these responses and had the maximum protective effect at 1 U/mL. Conclusion The inhibitive effect of EPO on the MPP^＋ -induced cytotoxicity may be ascribed to its anti-oxidative property and anti-apoptotic activity, and EPO may provide a useful therapeutic strategy for treatment of neurodegenerative diseases such as Parkinson＇s disease.

Protection of PC12 Cells against Superoxide-induced Damage by Isoflavonoids from Astragalus mongholicus

Objective To further investigate the neuroprotective effects of five isoflavonoids from Astragalus mongholicus on xanthine （XA）/xanthine oxidase （XO）-induced injury to PC12 cells. Methods PC12 cells were damaged by XA/XO. The activities of antioxidant enzymes, MTT, LDH, and GSH assays were used to evaluate the protection of these five isofavonoids. Contents of Bcl-2 family proteins were determined with flow cytometry. Results Among the five isoflavonoids including formononetin, ononin, 9, 10-dimethoxypterocarpan-3-O-β-D-glucoside, calycosin and calycosin-7-O-glucoside, calycosin and calycosin-7-O-glucoside were found to inhibit XA/XO-induced injury to PC12 cells. Their ECs0values of formononetin and calycosin were 0.05 μg/mL. Moreover, treatment with these three isoflavonoids prevented a decrease in the activities of antioxidant enzymes, superoxide dismutase （SOD） and glutathione peroxidase （GSH-Px）, while formononetin and calycosin could prevent a significant deletion of GSH. In addition, only calycosin and calycosin-7-O-glucoside were shown to inhibit XO activity in cell-free system, with an approximate IC50 value of 10 μg/mL and 50 μg/mL. Formononetin and calycosin had no significant infuence on Bcl-2 or Bax protein contents. Conclusion Neuroprotection of formononetin, calycosin and calycosin-7-O-glucoside may be mediated by increasing endogenous antioxidants, rather by inhibiting XO activities or by scavenging free radicals.

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.

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.

Baicalin inhibits colistin sulfate-induced apoptosis of PC12 cells

Baicalin, a type of flavonoid extracted from the dried root of Scutellaria baicalensis georgi, has been shown to effectively inhibit cell apoptosis. Therefore, we assumed that baicalin would suppress colistin sulfate-induced neuronal apoptosis. PC12 cells exposed to colistin sulfate （62.5-500 μg/mL） for 24 hours resulted in PCl2 cell apoptosis. In addition, caspase-3 activity, lactate dehydrogenase level and free radical content increased in a dose-dependent manner. Subsequently, PC12 cells were pretreated with baicalin （25, 50 and 100 pg/mL）, and exposed to 125 pg/mL colistin sulfate. Cell morphology markedly changed, and cell viability increased. Moreover, caspase-3 activity, lac- tate dehydrogenase level and free radical content decreased. Results indicated that baicalin inhib- ited colistin sulfate-induced PC12 cell apoptosis by suppressing free radical injury, and reducing caspase-3 activity and lactate dehydrogenase activity.

Molecular mechanism of panaxydol on promoting axonal growth in PC12 cells

Nerve growth factor（NGF） promotes axonal growth in PC12 cells primarily by regulating the RTK-RAS-MEK-ERK pathway. Panaxydol, a polyacetylene isolated from Panax notoginseng, can mimic the effects of NGF. Panaxydol promotes neurite outgrowth in PC12 cells, but its molecular mechanism remains unclear. Indeed, although alkynol compounds such as panaxydol can increase intracellular cyclic adenosine 3′,5′-monophosphate（cAMP） levels and the ERK inhibitor U0126 inhibits alkynol-induced axonal growth, how pathways downstream of cAMP activate ERK have not been investigated. This study observed the molecular mechanism of panaxydol-, NGF-and forskolin-induced PC12 cell axon growth using specific signaling pathway inhibitors. The results demonstrated that although the RTK inhibitor SU5416 obviously inhibited the growth-promoting effect of NGF, it could not inhibit the promoting effect of panaxydol on axonal growth of PC12 cells. The adenylate cyclase inhibitor SQ22536 and cAMP-dependent protein kinase inhibitor RpcAMPS could suppress the promoting effect of forskolin and panaxydol on axonal growth. The ERK inhibitor U0126 inhibited axonal growth induced by all three factors. However, the PKA inhibitor H89 inhibited the promoting effect of forskolin on axonal growth but could not suppress the promoting effect of panaxydol. A western blot assay was used to determine the effects of stimulating factors and inhibitors on ERK phosphorylation levels. The results revealed that NGF activates the ERK pathway through tyrosine receptors to induce axonal growth of PC12 cells. In contrast, panaxydol and forskolin increased cellular cAMP levels and were inhibited by adenylyl cyclase inhibitors. The protein kinase A inhibitor H89 completely inhibited forskolin-induced axonal outgrowth and ERK phosphorylation, but could not inhibit panaxydol-induced axonal growth and ERK phosphorylation. These results indicated that panaxydol promoted axonal growth of PC12 cells through different pathways downstream of cAMP. Considering that exchange protein directly activated by cAMP 1（Epac1） plays an important role in mediating cAMP signaling pathways, RNA interference experiments targeting the Epac1 gene were employed. The results verified that Epac1 could mediate the axonal growth signaling pathway induced by panaxydol. These findings suggest that compared with NGF and forskolin, panaxydol elicits axonal growth through the cAMP-Epac1-Rap1-MEK-ERK-CREB pathway, which is independent of PKA.

Cell viability and dopamine secretion of 6-hydroxydopamine-treated PC12 cells co-cultured with bone marrow-derived mesenchymal stem cells

In the present study, PC12 cells induced by 6-hydroxydopamine as a model of Parkinson＇s Disease, were used to investigate the protective effects of bone marrow-derived mesenchymal stem cells bone marrow-derived mesenchymal stem cells against 6-hydroxydopamine-induced neurotoxicity and to verify whether the mechanism of action relates to abnormal a-synuclein accumulation in cells Results showed that co-culture with bone marrow-derived mesenchymal stem cells enhanced PC12 cell viability and dopamine secretion in a cell dose-dependent manner. MitoLight staining was used to confirm that PC12 cells co-cultured with bone marrow-derived mesenchymal stem cells demonstrate reduced levels of cell apoptosis. Immunocytochemistry and western blot analysis found the quantity of α-synuclein accumulation was significantly reduced in PC12 cell and bone marrow-derived mesenchymal stem cell co-cultures. These results indicate that bone marrow-derived mesenchymal stem cells can attenuate 6-hydroxydopamine-induced cytotoxicity by reducing abnormal α-synuclein accumulation in PC12 cells.

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 Fmol/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）%, respectivelyl 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 SETrlNG： 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 pmol/L rotenone for 26 hours; rotenone group, treated with 2.5 pmol/L rotenone for 24 hours; rifampicin pretreatment groups, pretreated with 100, 200, and 300 pmol/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 × 10^5 L 1, and cells were inoculated at 96-well culture plate. The final volume was 100μL. 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. MAEN OUTCOME MEASURES： Comparisons between quantity and activity of PC12 cells and mitochondria 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）. ~ 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.

Dried Rehmannia root protects against glutamate-induced cytotoxity to PC12 cells through energy metabolism-related pathways

Rehmannia has been shown to be clinically effective in treating neurodegenerative diseases; however, the neuroprotective mechanisms remain unclear. In this study, we established a model of neurodegenerative disease using PC12 cytotoxic injury induced by glutamate. The cells were treated with 20 mM glutamate in the absence or presence of water extracts of dried Rehmannia root of varying concentrations（70%, 50% and 30%）. The different concentrations of Rehmannia water extract significantly increased the activity of glutamate-injured cells, reduced the release of lactate dehydrogenase, inhibited apoptosis, increased the concentrations of NADH, NAD and ATP in cells, ameliorated mitochondrial membrane potential, and reduced the levels of light chain 3. Taken together, our findings demonstrate that Rehmannia water extracts exert a cytoprotective effect against glutamate-induced PC12 cell injury via energy metabolism-related pathways.

Acanthopanax senticosus aqueous extract protects PC12 cells against hypoxic injury

Acanthopanax senticosus aqueous extract, at 10, 5 and 2.5 μg/mL, lessened hypoxia-induced PC12 cell injury. Pretreatment with the extract upregulated Bcl-2 expression, downregulated Bax expression, elevated superoxide dismutase activity, diminished malondialdehyde content, relieved Ca2＋ overloading, and suppressed apoptosis of PC12 cells. These effects were most pronounced at 10 μg/mL. These results suggest that Acanthopanax senticosus aqueous extract protects PC12 cells from hypoxia-induced injury in a dose-dependent manner.

Protective effects of Ginkgo biloba extract on 6-hydroxydopamine-induced apoptosis in PC12 cells

The present study analyzed the protective effects of Ginkgo biloba extract against 6-hydroxydopamine-induced PC12 cell apoptosis in a model of Parkinson＇s disease. The results showed that Ginkgo biloba extract had a potent cytoprotective action and inhibited apoptosis of PC12 cells induced by 6-hydroxydopamine. Ginkgo biloba extract decreased the ratio of Bax to Bcl-2 and markedly inhibited the activation of p53 and caspase-3. These experimental findings indicate that Ginkgo biloba extract may significantly reduce the effects of oxidative stress induced by 6-hydroxydopamine in PC12 cells and suppress cell apoptosis. The potential effects of Ginkgo biloba extract might be greater than those of levodopa in the treatment of Parkinson＇s disease.

Adenosine triphosphate-sensitive potassium channel opener protects PC12 cells against hypoxia-induced apoptosis through PI3K/Akt and Bcl-2 signaling pathways

Although previous studies have shown the neuroprotective effects of the adenosine triphosphate （ATP）-sensitive potassium （KATP） channel opener against ischemic neuronal damage, little is known about the mechanisms involved. Phosphatidylinositol-3 kinase （PI3K）/v-akt murine thy-moma viral oncogene homolog （Akt） and Bcl-2 are thought to be important factors that mediate neuroprotection. The present study investigated the effects of KATP openers on hypoxia-induced PC12 cell apoptosis, as well as mRNA and protein expression of Akt and Bcl-2. Results demon-strated that pretreatment of PC12 cells with pinacidil, a KATP opener, resulted in decreased PC12 cell apoptosis following hypoxia, as detected by Annexin-V fluorescein isothiocyanate/ propidium iodide double staining flow cytometry. In addition, mRNA and protein expression of phosphorylated Akt （p-Akt） and Bcl-2 increased, as detected by immunofluorescence, Western blot analysis, and reverse-transcription polymerase chain reaction. The protective effect of this preconditioning was attenuated by glipizide, a selective KATP blocker. These results demonstrate for the first time that the protective mechanisms of KATP openers on PC12 cell apoptosis following hypoxia could result from activation of the PI3K/Akt signaling pathway, which further activates expression of the downstream Bcl-2 gene.

Protective effect of paeonol on beta-amyloid 25-35- induced toxicity in PC12 cells

BACKGROUND：Paeonol is a primary phenolic component of the Chinese medicinal herb Cortex moutan. Recent studies have shown that paeonol has anti-inflammatory, analgesic, and antioxidative effects as well as a significant cardioprotective effect against myocardial ischemia. OBJECTIVE： To investigate the protective effect of paeonol on β-amyloid 25-35-induced toxicity in PC12 cells and analyze its mechanism of action. DESIGN, TIME AND SETTING： A controlled repeated-measures cell-based study was performed in the Department of Pharmacology of Guangdong Medical College between September 2006 and December 2007. MATERIALS： Paeonol was supplied by Xuancheng Baicao Plant Industry and Trade Company, China. PC12 cells were a kind gift from Dr. Haitao Zhang at Guangdong Medical College. β-amyloid 25-35 was purchased from Sigma Company, USA. Lactate dehydrogenase （LDH） and malondialdehyde （MDA） kits were purchased from Nanjing Jiancheng Bioengineering Research Institute, China. METHODS： PC12 cells were maintained in Dulbecco＇s modified eagle＇s medium （DMEM） supplemented with 100 mL/L heat-inactivated horse serum and 50 mL/L fetal bovine serum at 37 ℃ and cultured in an incubator with 5% CO2. The medium was renewed every other day. Batches of cells were assigned into three groups. （1） Paeonol group： cells were preincubated with different concentrations of paeonol （12, 25 or 50 μmol/L） for one hour and β-amyloid 25-35 was added to the medium; （2） control group： cells were cultured in DMEM supplemented with 100 mL/L heat-inactivated horse serum and 50 mL/L fetal bovine serum; and （3） β-amyloid 25-35 group： β-amyloid 25-35 was added to the medium. MAIN OUTCOME MEASURES： When PC12 cells in each group were cultured for 24 hours, the cell viability was determined using the MTT reduction assay, LDH release into the culture media was measured by 2,4-dinitrophenylhydrazine chromatometry and MDA content was measured using a thiobarbituric acid assay. RESULTS： When PC12 cells were treated withβ-amyloid 25-35 （50 μmol/L） for 24 hours, their viability was significantly lower compared with the control group （P 〈 0.01）. When the cells were treated with paeonol for one hour prior to incubation withβ-amyloid 25-35, their viability was significantly increased compared with theβ-amyloid 25-35 group （P 〈 0.05–0.01）. LDH activity and MDA level in the β-amyloid 25-35 group were significantly increased compared with the control group （P 〈 0.01）. When the cells were treated with different concentrations of paeonol, LDH activity and MDA level in PC12 cells were significantly decreased compared with theβ-amyloid 25-35 group （P 〈 0.01）. CONCLUSION： Paeonol protects PC12 cells againstβ-amyloid 25-35-induced toxicity and the protective effect of paeonol is probably achieved through its antioxidative effects.

Mutated recombinant human glucagon-like peptide-1 induces differentiation of PC12 cells

Glucagon-like peptide-1 （GLP-1） and its long-acting analogues have neuroprotective and neurotrophic properties and are emerging as potential treatments for neurodegenerative diseases. Its short half-life has limited the application of GLP-1 in the clinic. We generated a mutated form of human GLP-1 （mGLP-1） using site-directed mutagenesis and gene recombination techniques, and found that these modifications significantly prolonged the biological half-life of GLP-1 compared with native GLP-1 （nGLP-1）. This study investigated the role of mGLP-1 on inducing PC12 cell differentiation, mGLP-1 induced PC12 cell differentiation with neurite outgrowth and increased the expression of growth-associated protein-43 and neuronal class III I^-tubulin, and significantly increased cyclic adenosine monophosphate level. No significant difference was found between mGLP-1 and nGLP-I. The results indicate that mGLP-1 activates the GLP-1 receptor, induces PC12 cell differentiation, and has neurotrophic effects.