H2O2预处理通过ERK1／2和p38 MAPK信号通路上调14-3-3蛋白在PC12细胞中的表达

目的探讨H2O2预处理对1-甲基-4-苯基吡啶离子（1-methyl-4-phenylpyridinium，MPP^＋）诱导PC12细胞毒性损伤的保护作用及其可能的机制。方法分别用3-（4，5-二甲基噻唑-2）-2，5-二苯基四氮唑嗅盐[3-（4，5-dimethylthiazol-2-yl）-2，5-diphenyltetrazolium bromide，MTT]和4，6-二氨基-2-苯基吲哚（4′，6′．diamidino-2-phenylindole，DAPI）染色技术检测PC12细胞的活力及细胞凋亡核形态改变；Westem blot检测PC12细胞中14-3-3蛋白、磷酸化p38 MAPK的水平。酶联免疫吸附实验（Enzyme—linked immunosorbent assay，ELISA）试剂盒检测ERK1／2磷酸化水平。结果MPP^＋处理PC12细胞24h使细胞活力显著下降（51．6％），DAPI染色显示（51．3±6．6）％的PC12细胞呈现核固缩等细胞凋亡形态改变；H2O2预处理能显著增加PC12细胞活力（83．4％），减少凋亡细胞数[（24．9±4．3）％]，说明H2O2预处理能对抗MPP^＋毒性，对PC12细胞具有保护作用。Western blot结果显示，H2O2预处理在减少PC12细胞凋亡的同时伴随有14-3-3蛋白及磷酸化p38 MAPK表达上调；ELISA实验显示ERK1／2磷酸化水平显著增加。相关分析显示14-3-3蛋白表达的上调与ERK1／2磷酸化水平呈正相关（r=0．923，P〈0．01），而且PD98059抑制ERK1／2磷酸化后，H2O2预处理诱导14-3-3蛋白表达上调的作用消失。结论H2O2预处理能对抗MPP^＋对PC12细胞的毒性作用，这种保护作用与细胞内14-3-3蛋白表达上调有关；而14-3-3蛋白表达上调与ERK1／2和p38MAPK信号通路的激活有关。     

H2O2预处理通过上调14-3-3蛋白表达减轻MPP+对PC12细胞的毒性作用

目的 探讨H2O2预处理(HPP)1-甲基4-苯基吡啶离子(MPP )诱导PC12细胞损伤的保护作用和可能的机制.方法 采用4甲基偶氮唑盐法(MTT法)、自动生化分析仪、4,6-二氨基-2-苯基吲哚(DAPI)染色法及免疫印迹(western blot)技术分别检测细胞活力、乳酸脱氢酶(LDH)活性、细胞凋亡及14-3-3蛋白的表达.结果 H2O2预处理能够上调14-3-3蛋白表达,增加PC12细胞活力(MPP 组52.46%±6.15%,HPP MPP 组83.78%±5.84%),抑制LDH的活性[MPP 组(37.31±3.99)U/L,HPP MPP 组(12.49±2.26)U/L];抑制细胞凋亡(MPP 48.72%±6.68%,HPP MPP 组17.56%±5.21%).结论 H202预处理能减轻MPP 对PCI2细胞的毒性损伤作用,这种保护作用是通过上调14-3-3蛋白的表达实现的.     

14-3-3蛋白过表达减轻1-甲基-4-苯基吡啶离子对PC12细胞的毒性

目的 研究14—3—3蛋白过表达对1-甲基-4苯基吡啶离子（MPP^＋诱导的PC12细胞死亡的影响作用及其可能的机制。方法 构建pcDNA3．1（＋）-14—3—3真核表达质粒,用脂质体2000转染PCI2细胞;Westernn blot技术检测PC12细胞中14—3—3蛋白、Bcl-2蛋白,和BAD蛋白的表达;然后分别用MTT法、酶标仪及流式细胞仪检测PC12细胞的活力、caspase的活性及PC12细胞的凋亡率。结果 （1）将pcDNA3．1（＋）-14—3—3质粒转染PCI2细胞3周后,14—3—3蛋白的表达显著增加;（2）MPP^＋诱导PC12细胞存活率的下降是剂量依赖性的,当MPP^＋的浓度达100μmol／L时,PC12细胞的存活率丧失约50％;（3）caspase的活性随着MPP^＋浓度的增加而增高,当MPP^＋浓度到达100μmol／L时caspase的活性也到达最大值,而当MPP^＋浓度超过100μmol／L时,caspase的活性急剧下降;（4）用100μmol／L的MPP^＋处理PC12细胞24h后,PC12细胞的凋亡率为26．5％,14—3—3蛋白的过表达使PC12细胞的凋亡率下降到8．6％;（5）用100μmol／LMPP^＋处理PC12细胞后,Bcl-2蛋白的表达趋于下调而BAD蛋白的表达上调,14—3-3蛋白的过表达能显著的增加Bcl-2蛋白的表达而使BAD蛋白的表达下调。结论 14—3—3蛋白过表达通过上调Bcl-2蛋白的表达并下调BAD蛋白的表达,减少了MPP^＋诱导的PC12细胞的凋亡,从而发挥对PC12细胞的保护作用。这些结果可能为PD的治疗提供新的药物靶点。     

14-3-3蛋白过表达减轻MPP+对PC12细胞的毒性损伤

目的 探讨14-3-3蛋白过表达对1-甲基-4-苯基吡啶离子(MPP+)诱导PC12细胞损伤的保护作用和可能的机制.方法 构建pcDNA3.1(+)-14-3-3真核表达质粒,转染PC12细胞,建立稳定过表达14-3-3蛋白细胞株;通过四甲基偶氮唑盐法(MTT法)、流式细胞术和酶标仪分别检测14-3-3蛋白过表达对MPP+诱导的PC12细胞存活力、凋亡率和SOD及谷胱甘肽过氧化物酶(GSH-Px)活性的影响.结果 14-3-3蛋白过表达显著增加PC12细胞SOD活性[质粒转染组(9.13±0.41)U/mg,MPP+组(6.45±0.52)U/mg]和GSH-Px活性[质粒转染组(89.66±3.42)μmol/mg,MPP+组(82.73±4.15)μmol/mg]、增强细胞活力[吸光度(A570):质粒转染组0.78±0.06,MPP+组0.54±0.07]、抑制细胞的凋亡(质粒转染组11.87%±3.26%,MPP+组36.30%±2.39%).结论 14-3-3蛋白过表达对MPP+的毒性有保护作用,这是通过增加SOD和GSH-Px的活性,减少氧化应激实现的.     

14-3-3蛋白在PC12细胞的分布及MPP+对其表达的影响

目的探讨14-3-3蛋白在PC12细胞中的分布及其与MPP 诱导PC12细胞死亡的关系。方法用免疫荧光染色检测14-3-3蛋白的分布,并分别用免疫印迹技术与MTT法检测MPP ,对14-3-3蛋白表达及细胞活力的影响。结果PC12细胞中β、γ、ε、ζ、η和θ亚型免疫反应阳性。14-3-3蛋白表达随着MPP 处理的时间延长呈下降趋势,在6h变化不明显,12h显著下降(P<0.05),到48h后14-3-3蛋白的减少极其显著(P<0.01)。PC12细胞的存活率也呈现同样的变化趋势。结论MPP 引起PC12细胞的死亡可能与细胞内14-3-3蛋白含量的下降有关。     

14-3-3蛋白过表达减轻1-甲基-4-苯基吡啶离子对PC12细胞的毒性(英文)

目的研究14-3-3蛋白过表达对1-甲基-4苯基吡啶离子(MPP )诱导的PC12细胞死亡的影响作用及其可能的机制。方法构建pcDNA3.1( )-14-3-3 真核表达质粒,用脂质体2000转染PC12细胞;Western blot技术检测PC12细胞中14-3-3蛋白、Bcl-2 蛋白, 和BAD蛋白的表达;然后分别用MTT法、酶标仪及流式细胞仪检测PC12细胞的活力、caspase的活性及PC12细胞的凋亡率。结果(1)将pcDNA3.1( )-14-3-3质粒转染PC12细胞3周后,14-3-3蛋白的表达显著增加;(2)MPP 诱导PC12细胞存活率的下降是剂量依赖性的,当MPP 的浓度达100 μmol/L时,PC12细胞的存活率丧失约50%;(3)caspase 的活性随着MPP 浓度的增加而增高,当MPP 浓度到达100 μmol/L时caspase的活性也到达最大值,而当MPP 浓度超过100 μmol/L时,caspase的活性急剧下降;(4)用100 μmol/L 的MPP 处理PC12细胞24 h后,PC12细胞的凋亡率为26.5%,14-3-3蛋白的过表达使PC12细胞的凋亡率下降到8.6%;(5)用100 μmol/L MPP 处理PC12细胞后,Bcl-2蛋白的表达趋于下调而BAD蛋白的表达上调,14-3-3蛋白的过表达能显著的增加Bcl-2蛋白的表达而使BAD蛋白的表达下调。结论14-3-3蛋白过表达通过上调Bcl-2蛋白的表达并下调BAD蛋白的表达,减少了MPP 诱导的PC12细胞的凋亡,从而发挥对PC12细胞的保护作用。这些结果可能为PD的治疗提供新的药物靶点。     

脑脊液14-3-3蛋白定量检测对散发性Creutzfeldt-Jakob病的诊断价值

目的探讨脑脊液14-3-3蛋白定量检测对散发性Creutzfeldt-Jakob病(sCJD)的诊断价值。方法采用Capture Assay方法定量检测14例sCJD患者(sCJD组)、10例痴呆患者(OD组)、12例非痴呆患者(ND组)脑脊液14-3-3蛋白的含量。结果脑脊液中14-3-3蛋白含量中位数(MD)sCJD组为40.00ng/mg,OD组为2.65ng/mg,ND组为3.10ng/mg;sCJD组脑脊液中14-3-3蛋白含量明显高于OD组及ND组(均P<0.01)。以脑脊液14-3-3蛋白含量≥9ng/ml为分界值时,其对sCJD诊断的敏感性为86.7%,特异性为86.4%,阳性预测值为81.3%,阴性预测值为90.5%。结论应用Capture Assay方法定量检测脑脊液中14-3-3蛋白含量对于临床可疑sCJD的患者有较高的敏感性和特异性。     

p38 MAPK、Caspase-s介导PTH诱导PC12细胞凋亡机制的研究

目的甲状旁腺激素(PTH1-34)对PC12细胞作用和p38MAPK、Caspase-s在PTH1-34对PC12细胞凋亡中作用机制。方法应用CCK-8法测定PTH对PC12细胞生长抑制率,通过细胞形态学、乳酸脱氢酶(LDH)和流式细胞仪方法检测细胞损伤,RT-PCR测定p38 mRNA的表达,通过Western blot检测细胞中p38磷酸化丝裂原活化蛋白激酶(MAPK)及caspase-3蛋白的变化。结果 CCK-8法测定PTH抑制PC12细胞生长;透射电镜可见细胞核呈固缩状、凋亡小体出现等典型的凋亡形态学改变;流式细胞仪可见细胞凋亡率增多;LDH渗出量增多等。PTH1-34可明显上调p38 mRNA的表达,并可明显地促进PC12细胞磷酸化p38MAPK与Caspase-3的蛋白表达。结论 PTH可诱导PC12细胞凋亡,p38MAPK和Caspase-s共同介导参与PTH致PC12细胞凋亡。     

14-3-3蛋白与吉兰-巴雷综合征早期诊断关系的研究

目的 观察吉兰-巴雷综合征(GBS)急性期脑脊液中是否存在14-3-3蛋白,探讨其与GBS早期诊断是否具有相关性. 方法 采用ELISA KiT方法检测40例GBS患者起病后3 d内、第7天、第14天脑脊液14-3-3蛋白浓度,对照组为10例同期骨科手术患者及25例同期住院的其它神经系统疾病患者;并同时用罗氏P.800全自动生化分析仪检测脑脊液蛋白;观察早期GBS患者脑脊液中14-3-3蛋白含量变化及其与脑脊液蛋白是否具有相关性.结果 GBS组在起病后3 d内、第7天、第14天脑脊液中测得的14-3-3蛋白含量分别为(6.237±2.627)ng/mL、(8.369±3.003)ng/mL、(13.431±6.461)ng/mL;脑脊液蛋白含量分别为(0.308±0.1 13)g/L、(0.378±0.135)g/L、(0.587±0.273)g/L;GBS组脑脊液14-3-3蛋白最早可于起病后20～48 h出现,其含量在起病后第7天、第14天明显高于对照组,差异有统计学意义(P<0.05);GBS组脑脊液蛋白含量在起病后第14天明显高于对照组,差异有统计学意义(P<0.05);脑脊液14-3-3蛋白含量与脑脊液蛋白含量存在正相关关系(P<0.05).结论 GBS早期脑脊液中存在14-3-3蛋白,其含量增高可使脑脊液蛋白量随之增高:用ELISA KiT方法检测脑脊液中14-3-3蛋白浓度可用于GBS的早期诊断.     

miR-27-3p、miR-128-3p及miR-140-3p表达在急性脑梗死患者诊疗中的价值研究

目的 探讨miR-27-3p、miR-128-3p及miR-140-3p表达在急性脑梗死(ACI)患者诊疗中的应用价值。方法 选取2020年1月至2022年12月南通市第三人民医院全科医学科收治的ACI患者100例作为研究对象,定义为ACI组,根据ACI患者3个月改良Rankin评分量表(mRS评分)将其分为预后良好组(mRS评分≤2分)68例与预后不良组(mRS>2分)32例,另选同期于南通市第三人民医院全科医学科体检的健康者100例作为对照组。记录各组miR-27-3p、miR-128-3p及miR-140-3p表达水平并进行比较,采用Pearson相关分析探讨两变量的相关性,通过绘制受试者工作特征(ROC)曲线评价miR-27-3p、miR-128-3p及miR-140-3p联合检测在ACI诊断中的效能,采用多因素Logistic回归分析探讨ACI预后的危险因素。结果 ACI组平均年龄、吸烟史比例、合并高血压比例、miR-140-3p与miR-128-3p及miR-27-3p表达水平均明显高于对照组(^均P<0.05)。miR-27-3p、miR-...     

Focal Adhesion Kinase Activates NF-κB via the ERK1/2 and p38MAPK Pathways in Amyloid-β25-35-Induced Apoptosis in PC12 Cells

Increasing evidence supports that amyloid plaques, comprised of amyloid-β (Aβ), are a key feature of Alzheimer's disease (AD). But the mechanism of Aβ in AD is not yet fully understood. Previous studies have demonstrated that in Aβ-induced apoptosis of nerve cells, differentiated rat pheochromocytoma (PC12) cells, and microglia, nucleus factor kappa B (NF-κB) is activated. Meanwhile, focal adhesion kinase (FAK) is also activated. However, the relationship between NF-κB and FAK remains unclear. Using differentiated PC12 cells, we investigated this relationship in Aβ25-35-induced apoptosis. The results showed that FAK phosphorylation increased at 6-9 hours after Aβ treatment, slightly shorter than the activation of NF-κB (6-12 hours). In this process, both extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (p38MAPK) phosphorylation levels were increased. After FAK expression was inhibited by its siRNA, the activities of ERK1/2, p38MAPK, and NF-κB were all suppressed. When ERK1/2 and p38MAPK expressions were inhibited by their siRNAs respectively, NF-κB activity was also suppressed. But FAK phosphorylation was not affected. When NF-κB expression was inhibited, all of the phosphorylation levels of FAK, ERK1/2, and p38MAPK were not affected. These phenomena indicated that FAK is upstream of ERK1/2, p38MAPK, and NF-κB, and meanwhile both of ERK1/2 and p38MAPK are upstream of NF-κB. Co-immunoprecipitation results demonstrated that it is ERK1/2, but not p38MAPK, which directly interacts with IκB kinase. Taken together, our results suggest that FAK activates NF-κB via ERK1/2 and p38MAPK pathways in Aβ25-35-induced apoptosis of differentiated PC12 cells.     

Lead stimulates ERK1/2 and p38MAPK phosphorylation in the hippocampus of immature rats

Lead (Pb(2+)) is widely recognized as a neurotoxicant whose mechanisms of action are not completely established. We have previously demonstrated that Pb(2+) can activate the p38(MAPK) pathway and increase the phosphorylation of Hsp27 in bovine adrenal chromaffin cells and human SH SY5Y cells over a short incubation period (1 h). In the present work we analyzed the effects of Pb(2+) administered in vivo on the level and the phosphorylation state of ERK1/2 and p38(MAPK) in the hippocampus of immature rats. Rats were treated with lead acetate (2, 8 or 12 mg/kg, i.p.) or saline (control) over the 8th to 12th postnatal days, and hippocampal slices were prepared on the 14th day. The Pb(2+) level in the lead-treated animals increased 2.5-6-fold in the blood (3.0-6.0 microg/dl) and 2.0-3.0-fold in the forebrain (78-103 ng/g wet weight), compared to control (saline). The phosphorylation of both ERK1/2 and p38(MAPK) was significantly increased by prior exposure to Pb(2+) in vivo. In in vitro experiments, hippocampal slices from 14-day-old rats were exposed to Pb(2+) (1-10 microM) for 1 and 3 h. There were no changes in the phosphorylation state of ERK and p38(MAPK) for 1-h incubation, whereas a significant increase of ERK1/2 and p38(MAPK) phosphorylation by Pb(2+) (5 microM) was observed for the 3-h incubation. Cell viability measured using MTT was not modified in any of the conditions tested. These results indicate that the phosphorylation of hippocampal ERK1/2 and p38(MAPK) is stimulated by lead in a period of rapid brain development, an effect that may underlie, at least in part, the neurotoxicty elicited by this metal.     

The role of phospholipid methylation in 1-methyl-4-phenyl-pyridinium ion (MPP+)-induced neurotoxicity in PC12 cells

Excessive methylation has been proposed to be involved in the pathogenesis of Parkinson's disease (PD), via mechanisms that involve phospholipid methylation. Meanwhile, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was found to stimulate phospholipid methylation via the oxidized metabolite, 1-methyl-4-phenyl-pyridinium (MPP+), in the rat brain and liver tissues. In the present study, we investigated the effect of MPP+ on phosphatidylethanolamine N-methyltransferases (PENMT) and the potential role of this pathway in MPP(+)-induced neurotoxicity using PC12 cells. The results obtained indicate that MPP+ stimulated phosphatidylethanolamine (PTE) methylation to phosphatidylcholine (PTC) and correspondingly increased the formation of lysophosphatidylcholine (lyso-PTC). Moreover, the addition of S-adenosylmethionine (SAM) to the cell culture medium increases MPP(+)-induced cytotoxicity. The incubation of 1mM MPP+ and various concentrations of SAM (0-4 mM) decreased the viability of PC12 cells from 80% with MPP+ alone to 38% viability with 4 mM SAM for 4 days incubation. The data also revealed that the addition of S-adenosylhomocysteine (SAH), a methylation inhibitor, offered significant protection against MPP(+)-induced cytotoxicity, indicating that methylation plays a role in MPP(+)-induced cytotoxicity. Interestingly, lyso-PTC showed similar actions to MPP+ in causing many cytotoxic changes with at least 10 times higher potency. Lyso-PTC induced dopamine release and inhibited dopamine uptake in PC12 cells. Lyso-PTC also caused the inhibition of mitochondrial potential and increased the formation of reactive oxygen species in PC12 cells. These results indicate that phospholipid methylation pathway might be involved in MPP+ neurotoxicity and lyso-PTC might play a role in MPP(+)-induced neurotoxicity.     

Neurotoxicity of cadmium on immature hippocampus and a neuroprotective role for p38 MAPK

The developing brain is very sensitive to damage by toxic agents, many of which only manifest in adulthood. Cadmium [Cd(II)] is an environmental pollutant which is widely used in industry and is a constituent of tobacco smoke. Exposure to Cd(II) has been linked to detrimental effects on mammalian cells including neural cells. We have investigated the action of Cd(II) on immature hippocampus by assessing cell viability and modulation of AKT/PKB and mitogen-activated protein kinase (MAPK) family members including extracellular signal-regulated kinase (ERK)-1/2, p38 MAPK and c-Jun N-terminal kinases (JNK). Hippocampal slices from immature rats (postnatal day 14; PN14) were incubated with Cd(II) (5-200 microM) for 3h and the effects on protein phosphorylation were analyzed by western blotting. Phosphorylation of p38(MAPK) was enhanced by Cd(II) at all doses tested. Cd(II) also stimulated the phosphorylation of ERK1/2 in a concentration-dependent manner. However, the phosphorylation of JNK and AKT was not altered by the metal. Moreover, Cd(II) reduced cell viability, as measured by MTT reduction. Inhibition of p38 MAPK by SB203580 aggravated the acute Cd(II)-induced impairment of cell viability, whereas inhibition of MEK by PD98059 did not alter the effects of Cd(II). The present data suggest that in immature hippocampal cells p38 MAPK may be a part of signaling pathway that counteracts acute Cd(II) neurotoxicity. In conclusion, our results showed that Cd(II) impairs cell viability and disturbs MAPKs pathways in an important developmental stage for synaptic organization.     

细胞外信号调节激酶参与调节鱼藤酮介导的嗜铬细胞瘤细胞损伤

目的 探讨细胞外信号调节激酶(extracellular signal-regulated kinase,ERK)1/2在鱼藤酮介导的多巴胺能细胞损伤中的信号调节机制.方法 鱼藤酮处理体外培养的大鼠肾上腺嗜铬细胞瘤(PC12)细胞株,建立帕金森病细胞模型.采用二甲基噻唑二苯基四唑溴盐(MTT)比色法检测鱼藤酮对PC12细胞活力的影响,免疫组织化学方法观察鱼藤酮对磷酸化ERK1/2(p-ERK1/2)表达的影响,免疫印迹法研究p-ERK1/2蛋白表达随时间变化的趋势,并检测ERK1/2上游激酶抑制剂PD98059对鱼藤酮诱导ERK1/2磷酸化及细胞活力的影响.结果 PC12细胞随鱼藤酮(5 μmol/L)作用时间的增加,细胞吸光度(%)出现下降,1 h降至对照组的75.46±5.47,2、4、8 h分别降至70.42±1.94、65.23±0.96、59.04±2.85,24 h降至29.64±1.63,各时间点差异有统计学意义(F=143.014,P=0.000);与对照组(100.00±2.89)比较,q值分别为17.07、20.58、24.19、28.50、48.95,均P<0.01.镜下观察显示鱼藤酮处理的细胞中有明显p-ERK1/2聚集;免疫印迹实验结果显示,随鱼藤酮作用时间的增加,p-ERK1/2出现双相表达升高,30 min开始升高,1～2 h达高峰,4 h转而降低,8 h又重新升高,16 h后基本消失;PD98059明显抑制鱼藤酮导致的ERK1/2磷酸化,明显减低了细胞损伤的程度.结论 在鱼藤酮介导的多巴胺神经元损伤中呈现ERK1/2双相活化,该过程可能在调控PD多巴胺能细胞损伤中起重要作用.     

Protective effects of sesamin and sesamolin on hypoxic neuronal and PC12 cells

Reactive oxygen species (ROS) are important mediators of a variety of pathological processes, including inflammation and ischemic injury. The neuroprotective effects of sesame antioxidants, sesamin and sesamolin, against hypoxia or H2O2-induced cell injury were evaluated by cell viability or lactate dehydrogenase (LDH) activity. Sesamin and sesamolin reduced LDH release of PC12 cells under hypoxia or H2O2-stress in a dose-dependent manner. Dichlorofluorescein (DCF)-sensitive ROS production was induced in PC12 cells by hypoxia or H2O2-stress but was diminished in the presence of sesamin and sesamolin. We evaluated further the role of mitogen-activated protein kinases (MAPKs) and caspase-3 in hypoxia-induced PC12 cell death. Extracellular signal-regulated protein kinase (ERK) 1, c-jun N-terminal kinase (JNK), and p38 MAPKs of signaling pathways were activated during hypoxia. We found that the inhibition of MAPKs and caspase-3 by sesamin and sesamolin correlated well with the reduction in LDH release under hypoxia. Furthermore, the hypoxia-induced apoptotic-like cell death in cultured cortical cells as detected by a fluorescent DNA binding dye was reduced significantly by sesamin and sesamolin. Taken together, these results suggest that the protective effect of sesamin and sesamolin on hypoxic neuronal and PC12 cells might be related to suppression of ROS generation and MAPK activation.     

(-)-Epigallocatechin gallate regulates dopamine transporter internalization via protein kinase C-dependent pathway

Dopamine transporter (DAT) provides not only an integral component of dopaminergic neurotransmission but also a molecular gateway for the accumulation of some neurotoxins such as 1-methyl-4-phenylpyridinium (MPP(+)), a metabolite of 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP). Previous study reported that the neuroprotective effects of green tea polyphenols against MPP(+)-induced neurotoxicity were related to its inhibitory effect on MPP(+) uptake via DAT in dopaminergic cells. To extend the study, we investigated (-)-epigallocatechin gallate (EGCG), a monomer of green tea polyphenols, on DAT internalization in DAT-overexpressed PC12 cells. We found that EGCG (1-100 microM) can induce a dose-dependent inhibition of dopamine uptake in DAT-PC12 cells. In parallel, treatment of EGCG decreased membrane-bound DAT by 15% to 60%. Furthermore, protein kinase C (PKC) inhibitor GF109203X at 2 microM can markedly diminish the inhibitory effects of EGCG on dopamine uptake and reverse the EGCG-induced internalization of DAT. In addition, semiquantitative RT-PCR analysis indicated that EGCG did not affect DAT mRNA expression in the PC12 cells. These data suggest that EGCG exerts its inhibitory effect on DAT by modulating DAT internalization, in which PKC activation may be involved.