Endoplasmic Reticulum Stress Induces the Early Appearance of Pro-apoptotic and Anti-apoptotic Proteins in Neurons of Five Familial Alzheimer's Disease Mice / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Amyloid β (Aβ) deposits and the endoplasmic reticulum stress (ERS) are both well established in the development and progression of Alzheimer's disease (AD). However, the mechanism and role of Aβ-induced ERS in AD-associated pathological progression remain to be elucidated.</p><p><b>METHODS</b>The five familial AD (5×FAD) mice and wild-type (WT) mice aged 2, 7, and 12 months were used in the present study. Morris water maze test was used to evaluate their cognitive performance. Immunofluorescence and Western blot analyses were used to examine the dynamic changes of pro-apoptotic (CCAAT/enhancer-binding protein homologous protein [CHOP] and cleaved caspase-12) and anti-apoptotic factors (chaperone glucose-regulated protein [GRP] 78 and endoplasmic reticulum-associated protein degradation-associated ubiquitin ligase synovial apoptosis inhibitor 1 [SYVN1]) in the ERS-associated unfolded protein response (UPR) pathway.</p><p><b>RESULTS</b>Compared with age-matched WT mice, 5×FAD mice showed higher cleaved caspase-3, lower neuron-positive staining at the age of 12 months, but earlier cognitive deficit at the age of 7 months (all P < 0.05). Interestingly, for 2-month-old 5×FAD mice, the related proteins involved in the ERS-associated UPR pathway, including CHOP, cleaved caspase-12, GRP 78, and SYVN1, were significantly increased when compared with those in age-matched WT mice (all P < 0.05). Moreover, ERS occurred mainly in neurons, not in astrocytes.</p><p><b>CONCLUSIONS</b>These findings suggest that compared with those of age-matched WT mice, ERS-associated pro-apoptotic and anti-apoptotic proteins are upregulated in 2-month-old 5×FAD mice, consistent with intracellular Aβ aggregation in neurons.</p>

JNK/p38 MAPK involves in ginsenoside Rb1 attenuating beta-amyloid peptide (25-35) -induced tau protein hyperphosphorylation in embryo rat cortical neurons / 药学学报

To explore the effect of ginsenoside Rb1 on JNK/p38 MAPK in the process of beta-amyloid peptide (25-35) -induced tau protein hyperphosphorylation, Western blotting and immunocytochemical stain were performed to observe the tau protein phosphorylation and the expression of JNK/p38 MAPK. The level of tau protein phosphorylation in the sites of Ser396 , Ser199/202 and Thr205 increased after rat cortical neurons exposed to 20 micromol x L(-1) Abeta25-35, meanwhile the level of JNK/p38 MAPK also increased after Abeta25-35 treatment for 12 h. Pretreatment with several doses of ginsenoside Rbl markedly attenuated tau protein hyperphosphorylation and the expression of JNK/p38 MAPK. Ginsenoside Rbl markedly attenuated tau protein hyperphosphorylation through JNK/p38 MAPK pathway.

Inhibitory action of propyl gallate on the activation of SAPK/JNK and p38MAPK induced by cerebral ischemia-reperfusion in rats / 药学学报

<p><b>AIM</b>To explore the protective effect of propyl gallate against neuronal injury in the boundary zone of the infarction area in the rat cerebral ischemia-reperfusion model and its possible mechanism.</p><p><b>METHODS</b>Transient focal ischemia induced by middle cerebral artery occlusion in the rats was established by ligation of the left internal carotid artery for 2 h. Rats were treated by propyl gallate with different doses (23.5, 47 and 94 micromol x kg(-1)) for three days before operation. Coronal brain sections were collected after 1 , 2, 4, 6, 12 and 24 h of reperfusion, neuronal injury in the boundary zone of the infarction area was evaluated by TUNEL and Nissl staining. The expression of activated Caspase-3, total SAPK/JNK, p38MAPK and their phosphorylation (Thr183/Tyr185, Thr180/Tyr182) was investigated by immunohistochemistry and Western blotting with corresponding antibodies.</p><p><b>RESULTS</b>Although SAPK/JNK immunoreactivity did not increase at each time point in the boundary zone of the infarction area after reperfusion, p-SAPK/JNK immunoreactivity increased significantly at 1 h and then decreased gradually, and p38MAPK immunoreactivity was enhanced at each time point, peaked at 6 h. Expression of p-p38MAPK peaked at 6 h. Activated Caspase-3 immunoreactivity appeared at 6 h in the boundary zone of the infarction area and peaked at 12 h. TUNEL positive neurons were observed at 12 h and became more abundant at 24 h. The number of Nissl positive neurons decreased gradually and apoptosis ratio of neurons peaked at 24 h. Propyl gallate reduced the immunoreactivity of SAPK/JNK, p-SAPK/JNK, p38MAPK and p-p38MAPK markedly at 1 and 6 h. Propyl gallate with doses of 47 and 94 micromol x kg(-1) were more effective.</p><p><b>CONCLUSION</b>Inhibition on the activation of SAPK/JNK and p38MAPK is the possible protective mechanism of propyl gallate against neuronal injury induced by cerebral ischemia-reperfusion.</p>

Ginsenoside Rb1 attenuates okadaic acid-induced Tau protein hyperphosphorylation in rat hippocampal neurons / 生理学报

The present study was aimed to investigate the effects of ginsenoside Rb1 on okadaic acid (OA)-induced Tau hyperphosphorylation in hippocampal neurons of Sparague-Dawley rat and to explore its possible mechanism. Animals were randomly divided into four groups. Group 1 received dimethysulphoxide (DMSO) injection (vehicle group), group 2 only received OA injection (OA group), group 3 was pretreated with Rb1 and then received OA injection (Rb1 pretreatment group), and the group 4 was an intact control group. The animals in group 3 were injected intraperitoneally with various doses of Rb1 at 5, 10, and 20 mg/kg (once a day for 14 d). On the thirteen day of pretreatment, animals in Rb1 pretreatment group as well as animals in OA group received a bolus injection of 0.483 microg of OA (1.5 microl of solution in DMSO) at right dorsal aspect of hippocampus to induce Tau hyperphosphrylation. The brains were harvested one day after the last treatment. In all groups, the morphology of neurofibrils, phosphorylation of Tau protein, and the activity of phosphatase 2A (PP2A) were investigated. In OA group, the Bielschowski's assay revealed darkened and uneven neurofibrils staining in the hippocampus. The immunohistochemistry results showed a significant increase in Thr(231) phosphorylation of Tau protein in OA group relative to the control group (P<0.01). OA injection also markedly decreased PP2A activity (P<0.01). Western blot confirmed Thr(231) phosphorylation of Tau protein and it also detected phosphorylation of Ser(396) of Tau protein. The animals with Rb1 pretreatment displayed even staining of neurofibrils and normal pattern of fiber organization. Rb1 pretreatment also attenuated Thr(231) and Ser(396) hyperphosphorylations of Tau protein, and restored PP2A activity compared to the OA group (P<0.01). These results indicate that OA-induced hyperphosphorylation of Tau protein in rat hippocampal neurons can be attenuated by the pretreatment of ginsenoside Rb1. These data also implicate that Rb1 has potential neuroprotective effects on Tau-related neuropathology.

Ginsenoside Rbl attenuates beta-amyloid peptide25-35 -induced tau hyperphosphorylation in cortical neurons / 药学学报

<p><b>AIM</b>To explore the effect and the possible mechanism of ginsenoside Rb1 on beta-amyloid peptide (beta-AP)(25-35) -induced tau protein hyperphosphorylation in cortical neurons.</p><p><b>METHODS</b>Western blotting and immunocytochemical staining were used to detect tau phosphorylation level, total tau and glycogen synthase kinase-3beta (GSK-3beta) in cortical neurons.</p><p><b>RESULTS</b>After exposure to beta-AP(25-35) (20 micromol x L(-1)) for 12 h, the levels of tau protein phosphorylation in the sites of Ser 396, Ser 199/202, Thr 231 and total tau were raised. Meanwhile, the expression of GSK-3beta also increased. Pretreatment with ginsenoside Rbl or lithium chloride, a specific inhibitor of GSK-3beta, markedly reduced beta-AP(25-35)-induced tau hyperphosphorylation and the expression of GSK-3beta.</p><p><b>CONCLUSION</b>Ginsenoside Rb1 can attenuate beta AP(25-35)-induced tau protein hyperphosphorylation in cortical neurons by inhibiting the expression of GSK-3beta.</p>

Effect of ginsenoside Rg1 on expression of p21, cyclin E and CDK2 in the process of cell senescence / 药学学报

<p><b>AIM</b>To explore the possible role of p21, cyclin E and cyclin-dependent kinase 2 (CDK2) in the protection of ginsenoside Rg1 against tert-butylhydroperoxide (t-BHP)-induced senescence in WI-38 cells.</p><p><b>METHODS</b>The cellular ultrastructure, cytometric assay and beta-galactosidase (beta-gal) cytochemistry staining were used to evaluate cell senescence. The levels of of p21, cyclin E and CDK2 protein were detected by Western blot.</p><p><b>RESULTS</b>Pretreatment with Rg1 significantly attenuated t-BHP-induced senescence in WI-38 cells. Simultaneously, compared with cells treated with t-BHP alone, Rg1 pretreatment markedly decreased the level of p21 protein and increased the levels of CDK2 and cyclin E.</p><p><b>CONCLUSION</b>p21, cyclin E and CDK2 may be involved in the process of ginsenoside Rg1 protection against t-BHP-induced senescence in WI-38 cells.</p>