人参皂苷Rg1对PC12细胞凋亡保护作用的可能机制

目的探讨人参皂苷Rg1对多巴胺诱导PC12细胞凋亡的保护作用及其机制.方法用流式细胞仪检测PC12细胞的凋亡率及Bcl-2和Bax蛋白表达率,RT-PCR分析bcl-2和baxmRNA表达水平,荧光分光光度计法检测CPP32活力.结果经10μmol·L^-1Rg1预处理后,由多巴胺诱导的PC12细胞凋亡受到明显的抑制.同时,Bcl-2蛋白和mRNA表达增加,Bax蛋白和mRNA表达减少,CPP32活力明显下降.结论Rg1可抑制多巴胺诱导的PC12细胞凋亡,其作用机制可能通过调节Bcl-2与Bax蛋白的比值和抑制CPP32的激活而起作用.     

The roles of cyclic AMP–ERK–Bad signaling pathways on 6-hydroxydopamine-induced cell survival and death in PC12 cells

The roles of cyclic AMP (cAMP)–ERK1/2–Bad signaling pathways in 6-hydroxydopamine (6-OHDA)-induced cell survival and death were investigated. In PC12 cells, 6-OHDA (10–100 μM) concentration-dependently increased the intracellular levels of cAMP mediated by the Ca²⁺-CaMKII-adenylyl cyclase system. 6-OHDA at the non-toxic level (10 μM) induced transient ERK1/2 phosphorylation and BadSer112 phosphorylation, which maintained cell survival. In contrast, the high levels of cAMP induced by toxic levels (50 and 100 μM) of 6-OHDA induced sustained ERK1/2 phosphorylaton and BadSer155 phosphorylation. The cells then moved to cell death process through Bcl2 phosphorylation and caspase-3 activation. BadSer155 phosphorylation by 6-OHDA was inhibited by PKA (H89) and MEK (U0126) inhibitors, indicating that it was mediated via the cAMP–PKA-sustained ERK1/2 system. In SK-N-BE(2)C cells, the non-toxic level of 6-OHDA also showed transient ERK1/2 phosphorylation and BadSer112 phosphorylation, and toxic levels of 6-OHDA exhibited sustained ERK1/2 phosphorylation and BadSer155 phosphorylation. These results suggest that ERK1/2 phosphorylation by 6-OHDA shows biphasic functions on cell survival and death in PC12 cells. It is, therefore, proposed that the cAMP–ERK1/2–Bad signaling pathways incurred by toxic levels of 6-OHDA play a role in dopamine neuron death of animal models of Parkinson’s disease.     

IGF-1对6-OHDA诱导神经元氧化损伤的保护作用

目的 探讨胰岛素样生长因子-1（IGF-1）对6-羟基多巴胺（6-OHDA）诱导的PC12细胞氧化损伤的保护作用。方法 以25、50、100、150、200 μmol/L 的6-OHDA 处理PC12细胞,在12、24、48 h用MTT 法检测6-OHDA 对PC12细胞活性的影响,筛选最佳的实验浓度和观察时间。实验分为3组：对照组、6-OHDA组（150 μmol/L处理24 h）和IGF-1+6-OHDA组（IGF-1 100 nmol/L预处理2 h,后加入150 μmol/L 6-OHDA处理24 h）,MTT法检测各组细胞活性;免疫荧光染色法检测细胞活性氧（ROS）水平;Hoechst33342/PI双染法检测细胞凋亡。结果 随6-OHDA浓度的增加和作用时间的延长,PC12细胞的活性呈梯度降低,150 μmol/L 6-OHDA浓度和处理后24 h作为本研究的最佳的实验浓度和观察时间。与6-OHDA组比较,IGF-1+6-OHDA组PC12细胞活力增强、ROS水平下降、细胞凋亡减少。结论 IGF-1预处理能减少6-OHDA引起的PC12细胞氧化损伤及凋亡,增加细胞活性,为防治帕金森病提供了潜在的治疗策略。     

Ⅱ、Ⅲ组亲代型谷氨酸受体激动剂对6-羟基多巴诱导的PC12细胞毒性无保护作用

阐明Ⅱ、Ⅲ组亲代谢型谷氨酸受体(metabotropic glutamate receptors,mGluRs)激动剂对6—羟基多巴(6-hydroxydopamine,6-OHDA)诱导的PC12细胞毒性是否具有保护作用。方法：应用高效液相色谱仪联用荧光检测技术测定谷氨酸浓度，应用四甲基偶氮唑盐(MTT)比色法测定PC12细胞活性。结果：6—OHDA剂量依赖性地诱导PC12细胞释放谷氨酸、减低细胞活性，Ⅱ组mGluRs激动剂DCG—IV和Ⅲ组mGluRs激动剂L-AP4对6—0HDA诱导的PC12细胞释放谷氨酸和细胞活性的降低均无显影响。结论：6—OHDA对多巴胺神经元的损伤作用与其诱导谷氨酸过度释放及其继发的兴奋性神经毒性有关，Ⅱ、Ⅲ组亲代谢型谷氨酸受体激动剂对6—OHDA诱导的PC12细胞毒性无保护作用。     

The intracellular mechanism of NF-kappa B activation involved in iNOS and chemokine induction in C6 glioma cells

To elucidate the intracellular mechanism of NF-kappa B activation, we performed the involvement of I kappa B alpha of NF-kappa B in the expression of inducible NO synthase (iNOS) and chemokine (CINC) following pretreatment with bacterial endotoxin (LPS) or IL-1 beta, respectively, using rat C6 glioma cells. We found that herbimycin A, a tyrosine protein kinase inhibitor, blocked: 1) LPS/IFN gamma-induced iNOS expression, 2) LPS-induced intranuclear translocation of activated NF-kappa B (p50. p65) and 3) IFN gamma-induced autophosphorylation and activation of Jak 2 and Stat 1 as well as intranuclear translocation of phosphorylated Stat 1. Furthermore, transfection of a dominant negative form of I kappa B alpha (SS-->AA) suppressed LPS/IFN gamma-induced iNOS expression, suggesting that NF-kappa B, in particular, I kappa B alpha molecules could play important roles in the iNOS expression. We also found in IL-1 beta-induced CINC expression using cultured C6 glioma cells, the transient translocation of NF-kappa B in response to IL-1 beta is partly dependent on transient proteasome activation. Thus we suggest that the formation of heterodimer p50.p65 from inactive trimer p50.p65.I kappa B alpha, particularly, proteolytic degradation and dissociation of I kappa B alpha from p50.p65 are a critical phase in NF-kappa B activation during LPS-induced iNOS and IL-1 beta-induced CINC expression in astroglial cells.     

6-羟基多巴胺诱导PC12细胞释放谷氨酸及死亡不受Ⅰ组亲代谢型谷氨酸受体配基的影响(英文)

目的:探讨Ⅰ组亲代谢型谷氨酸受体(mGluR)配基对6-羟基多巴胺(6-OHDA)诱导的PC12细胞死亡及谷氨酸(Glu)释放的影响。方法:培养PC12细胞,以100μmol/LⅠ组mGluR激动剂(RS)-3,5-dihydroxyphenylglycine(DHPG)和拮抗剂DL-2-amino-3-phosphonopropionic acid(DL-AP3)预先剌激细胞1h,再加入6-OHDA100μmol/L共孵育24h,显微镜下观察细胞形态变化,用TUNEL法检测凋亡细胞,用噻唑蓝(MTT)法检测细胞存活率,并用高效液相色谱检测Glu的释放量。结果:6-OHDA 降低PC12细胞存活率(P<0.01),其诱导的Glu释放呈浓度和时间依赖性。Ⅰ组mGluR配基不能减少6-OHDA引起的PC12细胞死亡,也不影响6OHDA引起的Glu释放量。结论:Ⅰ组mGluR配基对6-OHDA引起死亡的PC12细胞无保护作用。     

A sesquiterpene lactone, costunolide, from Magnolia grandiflora inhibits NF-kappa B by targeting I kappa B phosphorylation

A sesquiterpene lactone, costunolide (CTN), was identified from Magnolia grandiflora together with parthenolide (PTN) by its strong inhibition of LPS-induced NF-kappa B activation. CTN, which showed more potent inhibition than PTN in the NF-kappa B activation, strongly suppressed nitric oxide (NO) production in LPS-stimulated RAW 264.7 cells. RT-PCR and Western blot analyses demonstrated that CTN suppressed the expression of iNOS mRNA and protein in a dose-dependent manner. CTN also significantly inhibited LPS-induced DNA-binding activity of NF-kappa B as well as the LPS-induced degradation of I kappa B-alpha and -beta. Furthermore, CTN inhibited LPS-induced phosphorylation of I kappa B-alpha. These findings support that CTN inhibits NO production by down-regulating iNOS expression, at least, in part through the inhibition of I kappa Bs' phosphorylation and degradation, which are essential for the activation of NF-kappa B.     

芍药苷对6羟基多巴胺致PC12细胞损伤的保护作用

目的:探讨芍药苷对6羟基多巴胺(6-OHDA)致大鼠肾上腺嗜铬细胞瘤细胞(PC12)的细胞损伤保护作用及其可能机制.方法:体外培养PC12细胞,用6-OHDA建立细胞损伤模型.MTT和乳酸脱氢酶(LDH)活性测定存活率;RT-PCR检测Bcl-2、Bax的mRNA表达,Hochest33342/PI双染检测细胞凋亡率.结果:25、50、100 μmol·L-1芍药苷可显著减少6-OHDA诱导的PC12细胞凋亡,降低LDH漏出率,增加Bcl-2 mRNA和减少Bax mRNA表达.结论:芍药苷可显著减少6-OHDA诱导的PC12细胞凋亡,其作用机制可能与调节Bax、Bcl-2表达有关.     

Carnosic Acid Prevents 6-Hydroxydopamine-Induced Cell Death in SH-SY5Y Cells via Mediation of Glutathione Synthesis

Understanding the neuroprotective effects of the rosemary phenolic diterpene carnosic acid (CA) has attracted increasing attention. We explored the mechanism by which CA modulates the neurotoxic effects of 6-hydroxydopamine (6-OHDA) in SH-SY5Y cells. Cells were pretreated with CA for 12 h followed by treatment with 100 μM 6-OHDA for 12 or 24 h. Cell viability determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolim bromide (MTT) assay indicated that 0.1 to 1 μM CA dose-dependently attenuated the cell death induced by 6-OHDA, whereas the effect of 3-5 μM CA was weaker. CA at 1 μM suppressed the 6-OHDA-induced nuclear condensation, reactive oxygen species generation, and cleavage of caspase 3 and PARP. Immunoblots showed that the phosphorylation of c-Jun NH(2)-terminal kinase (JNK) and p38 by 6-OHDA was reduced in the presence of CA. Incubation of cells with CA resulted in significant increases in the total glutathione (GSH) level and the protein expression of the γ-glutamylcysteine ligase catalytic subunit and modifier subunit. l-Buthionine-sulfoximine, an inhibitor of GSH synthesis, attenuated the effect of CA on cell death and apoptosis. Treatment with CA also led to an increase in nuclear factor erythroid-2 related factor 2 (Nrf2) activation, antioxidant response element (ARE)-luciferase reporter activity, and DNA binding to the ARE. Silencing of Nrf2 expression alleviated the reversal of p38 and JNK1/2 activation by CA. These results suggest that the attenuation of 6-OHDA-induced apoptosis by CA is associated with the Nrf2-driven synthesis of GSH, which in turn down-regulates the JNK and p38 signaling pathways. The CA compound may be a promising candidate for neuroprotection in Parkinson's disease.