Preventive Effect of Caffeine on Alzheimer's Disease / 现代生物医学进展

Objective:To explore the effects of caffeine on the prevention of Alzheimer's disease (AD).Methods:Use Ethanol as a solvent to extract the caffeine in tea and then injecting 5％ D-galactose saline solution 1ml/d/kg to establish aging model mice.Divide mice randomly into experimental group (high-dose/low-dosecaffeine),positive control group,negative control group,and normal con-trol group (NS) and injecting appropriate drugs for consecutive four weeks.Test superoxyde dismutase (SOD) and malondialdehvde (MDA) periodically.Take mice's hippocampus and use Western blotting to detect the expression of brain derived neurotrophic factor (BDNF) and extracellular signal-regulated kinasesl/2 (p-ERK1/2).Results:The expression of BDNF and p-ERK1/2,negative control group is less than low-dose experimental group and positive control group (P＜0.01);The p-ERK1/2 expression of injecting D-galactose mice was significantly lower than normal group,negative control group compared weth the normal group,the differencd was significant (P＜0.05).The level of SOD in model group was significantly lower than that in normal control group,high,low dose caffeine group and positive control group (P＜0.01),but the level of MDA is opposite.Conclusions:Caffeine can delay aging process by increasing the level of SOD in aging mice,and enhancing the expression of BDNF and P-ERK1/2.Caffeine does a lot to prevent AD.

Sustained Intracellular Acidosis Triggers the Na⁺/H⁺ Exchager-1 Activation in Glutamate Excitotoxicity

The Na⁺/H⁺ exchanger-1 (NHE-1) is a ubiquitously expressed pH-regulatory membrane protein that functions in the brain, heart, and other organs. It is increased by intracellular acidosis through the interaction of intracellular H⁺ with an allosteric modifier site in the transport domain. In the previous study, we reported that glutamate-induced NHE-1 phosphorylation mediated by activation of protein kinase C-β (PKC-β) in cultured neuron cells via extracellular signal-regulated kinases (ERK)/p90 ribosomal s6 kinases (p90RSK) pathway results in NHE-1 activation. However, whether glutamate stimulates NHE-1 activity solely by the allosteric mechanism remains elusive. Cultured primary cortical neuronal cells were subjected to intracellular acidosis by exposure to 100 μM glutamate or 20 mM NH₄Cl. After the desired duration of intracellular acidosis, the phosphorylation and activation of PKC-β, ERK1/2 and p90RSK were determined by Western blotting. We investigated whether the duration of intracellular acidosis is controlled by glutamate exposure time. The NHE-1 activation increased while intracellular acidosis sustained for >3 min. To determine if sustained intracellular acidosis induced NHE-1 phosphorylation, we examined phosphorylation of NHE-1 induced by intracellular acidosis by transient exposure to NH₄Cl. Sustained intracellular acidosis led to activation and phosphorylation of NHE-1. In addition, sustained intracellular acidosis also activated the PKC-β, ERK1/2, and p90RSK in neuronal cells. We conclude that glutamate stimulates NHE-1 activity through sustained intracellular acidosis, which mediates NHE-1 phosphorylation regulated by PKC-β/ERK1/2/p90RSK pathway in neuronal cells.

Platelet Rich Plasma (PRP) Produces an Atherofibrotic Histophenotype During Craniofacial Bone Repair Due to Changes of Immunohistochemical Expression of Erk1/2, p38α /β, Adiponectin and Elevated Presence of Cells Exhibiting B-scavenger Receptor (CD36+)

Abstract The platelet-extracellular matrix interaction in platelet rich plasma (PRP) through thrombospondin receptor-CD36 induces the secretion of growth factors responsible for cellular proliferation and differentiation during the repair process. Since CD36 also acts as a class B-scavenger-receptor for development of foam-like cells and mitogen-activated kinases, such as Erk1/2 and p38α/β, are important proteins activated by platelet growth factor, the aim of this study was to evaluate the immunohistochemical presence of CD36, Erk1/2, p38α/β during the bone repair treated and non-treated with PRP and to compare these results with the histomorphometry of repair. Simultaneously, the immunopresence of adiponectin was analyzed, which may contribute to osteogenesis at the same time it inhibits fibrosis and impairs adipogenesis and foam cell formation in the medullary area. An artificial bone defect measuring 5×1 mm was produced in the calvaria of 56 Wistar rats. The defects were randomly treated with autograft, autograft+PRP, PRP alone and sham. The animals were euthanized at 2 and 6 weeks post-surgery. Data were analyzed by ANOVA followed by non-parametric test Student Newman-Keuls (p<0.05) for histomorphometric and immunohistochemical interpretation. The results revealed that in specimens that received PRP the immunopositivity for Erk1/2, p38α/β and CD36 proteins increased significantly while the immunohistochemical expression of adiponectin decreased simultaneously. There was also an accentuated reduction of bone matrix deposition and increase of the medullary area represented by fibrosis and/or presence of foam-like cells, which exhibited immunophenotype CD36+adiponectin. The findings of this study suggest that PRP acted as an inhibitor of osteogenesis during the craniofacial bone repair and induced a pathological condition that mimics an atherofibrotic condition.

Resumo A interação da matriz extracelular-plaquetas no plasma rico em plaquetas (PRP) através de receptor trombospondina CD36 induz a secreção de fatores de crescimento responsáveis pela proliferação e diferenciação celular durante o processo de reparo. Uma vez que o CD36 também age como receptor scavenger de classe B para o desenvolvimento de células do tipo espuma, e as quinases ativadas por mitógenos, tais como ERK1/2 e p38α/β, são importantes proteínas ativadas por fator de crescimento das plaquetas, o objetivo deste estudo foi avaliar a presença imunoistoquímica de CD36, ERK1/2, p38α/β durante o reparo ósseo tratado e não-tratado com PRP e comparar estes resultados com a histomorfometria do reparo. Simultaneamente, analisou-se a imunopresença da adiponectina, que pode contribuir para osteogênese ao mesmo tempo que inibe a fibrose e prejudica a formação de células tipo espuma/xantomatosas na área medular. Um defeito artificial de osso medindo 5×1 mm foi produzido na calvária de 56 ratos Wistar. Os defeitos foram tratados aleatoriamente com auto-enxerto, enxerto autógeno+PRP, PRP apenas e sham. Os animais foram sacrificados 2 e 6 semanas pós-cirurgia. Os dados foram examinados por meio de ANOVA, seguido pelo teste não-paramétrico Student Newman-Keuls (p<0,05) para a interpretação histomorfométrica e imunoistoquímica. Os resultados revelaram que as amostras que receberam PRP aumentaram significativamente a imunopositividade para as proteínas ERK1/2, p38α/β e CD36, simultaneamente à diminuição de expressão imunoistoquímica da adiponectina. Houve também expressiva redução de deposição de matriz óssea e aumento da área medular representada por fibrose e/ou presença de células do tipo espuma que apresentaram imunofenótipo CD36 + adiponectina. Estes resultados sugerem que o PRP atuou como um inibidor da osteogênese durante o reparo ósseo craniofacial e induziu uma condição patológica que mimetiza uma condição aterofibrótica.

Mechanisms of ERK1/2 signaling pathway participate in inflammatory reaction caused by coronary heart disease / 天津医药

Objective To investigate the effects of ERK1/2 signaling pathway on coronary atherosclerosis-associated inflammatory reaction in autopsy cases. Methods Forty-five autopsy cases were divided into three groups:coronary arterydisease (CHD)-associated death group, CHD group and control group (n=15 for each group). The inflammatory cell infiltration in myocardial tissues was observed through staining leucocyte common antigen (CD45) by HE and immunohistochemistry method. The protein expression level and distribution in extracellular signal-regulated kinase 1/2 (t-ERK1/2) and phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2) of myocardial tissues were detected by immunohistochemistry and Western-blot assay. The expression level of tumor necrosis factor α (TNF-α) was determined using semiquantitative RT-PCR analysis. The activity of nuclear factor (NF)-κB was assessed using electrophoretic mobility shift assay (EMSA). Results Compared with CHD and control groups, myocardial inflammatory cell counts, phosphorylation of ERK1/2, TNF-α mRNA expression and NF-κB activation were significantly increased in CHD-associated death group (P < 0.05). Western blot analysis showed that the phosphorylation of ERK1/2 was positively correlated with expression of TNF-αmRNA and the number of inflammatory cells in CHD-associated death group (r=0.675, P<0.01;r=0.893, P<0.01). Conclusion Results reveal that the activation of ERK1/2 signaling pathway is considered as an important mechanism for coronary atherosclerosis caused myocardial inflammatory reaction, which indicates that the inhibition of ERK1/2 signal transduction pathway may become a potential new target for prevention and treatment of atherosclerotic coronary infarction.

Downregulation of Aquaporin 4 Expression through Extracellular Signal-regulated Kinases1/2 Activation in Cultured Astrocytes Following Scratch-injury / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To investigate the role of extracellular signal-regulated kinase1/2 (ERK1/2) pathway in the regulation of aquaporin 4 (AQP4) expression in cultured astrocytes after scratch-injury.</p><p><b>METHODS</b>The scratch-injury model was produced in cultured astrocytes of rat by a 10-μL plastic pipette tip. The morphological changes of astrocytes and lactate dehydrogenase (LDH) leakages were observed to assess the degree of scratch-injury. AQP4 expression was detected by immunofluorescence staining and Western blot, and phosphorylated-ERK1/2 (p-ERK1/2) expression was determined by Western blot. To explore the effect of ERK1/2 pathway on AQP4 expression in scratch-injured astrocytes, 10 µmol/L U0126 (ERK1/2 inhibitor) was incubated in the medium at 30 min before the scratch-injury in some groups.</p><p><b>RESULTS</b>Increases in LDH leakage were observed at 1, 12, and 24 h after scratch-injury, and AQP4 expression was reduced simultaneously. Decrease in AQP4 expression was associated with a significant increase in ERK1/2 activation. Furthermore, pretreatment with U0126 blocked both ERK1/2 activation and decrease in AQP4 expression induced by scratch-injury.</p><p><b>CONCLUSION</b>These results indicate that ERK1/2 pathway down-regulates AQP4 expression in scratch-injured astrocytes, and ERK1/2 pathway might be a novel therapeutic target in reversing the effects of astrocytes that contribute to traumatic brain edema.</p>

Staurosporine aglycone at high concentration causes ERK1/2 phosphorylation in rat pulmonary artery smooth muscle cells / 中国药理学通报

Aim To investigate the effect of SA on induction of ERK1/2 activity in rat pulmonary smooth muscle cells(PASMCs).Methods Western blot analysis was employed to identify the activation of ERK1/2 stimulated by SA at different time points and concentrations in cultured rat PASMCs.Results An unexpected observation showed that ERK1/2 phosphorylation was seen after treatment of SA for 2h at a high concentration(30 ?mol?L-1) but not at lower concentration(from 1 nmol?L-1 to 1 ?mol?L-1).Activation of ERK1/2 pathway could be inhibited by an ERK1/2 inhibitor PD98059 or a protein kinase A(PKA) activator isoproterenol.Conclusion Together,these results suggest that SA has a strong dual regulating effect upon ERK1/2 through PKC and/or PKA pathways in rat PASMCs.