Objective To observe the effect of Puerarin on the level of tau phosphorylation in the olfactory bulb of Alzheimer's disease rat brain, and explore the underlying molecular mechanism. Methods ① Twenty-two male SD rats were randomly divided into the normal control group, model control group and Puerain-treated group.The levels of tau-1, PS396 and tau-5 in the olfactory bulb were detected by Western blotting.② Twenty male SD rats were randomly divided into model control group, low-dose Puerarin (40 mg·kg-1·d-1), medium-dose puerarin (80 mg·kg-1·d-1) and high-dose puerarin (160 mg·kg-1·d-1) groups.The levels of tau-1 and PS396 phosphorylation in the olfactory bulb were detected by Western blotting.③ The level of GSK-3β phosphorylation in the olfactory bulb of the normal control group, model control group A and puerain-treated group was detected by Western blotting. Results ① It was shown by Western blotting that the relative expression of tau-1 was significantly decreased in the olfactory bulb of the model group A(0.49±0.07)rat brain compared with the normal control group(0.85±0.03)(P<0.01), and the level of tau-1 was obviously higher in the puerarin-treated group(0.58±0.03)compared with that of the model group A(P<0.05).The differences of the levels of tau-5 and PS396 in the olfactory bulb were insignificant among the 3 groups.②Compared with the model group B, the expression of tau-1 in the olfactory bulb was significantly enhanced in the low-, medium- and high-dose of puerarin group: (0.39±0.09)vs(0.69±0.11),(0.55±0.11),(0.70±0.04); and the level of PS396 was significantly decreased in the olfactory bulb of low-dose puerarin group(0.36±0.07) compared with the model group B(0.55±0.05)(P<0.01).③Compared with the normal control group(0.96±0.07), the ratio of pS9-GSK-3β/tGSK-3β was obviously decreased in the olfactory bulb of the model group A(0.51±0.12),while that was significantly increased in the puerarin group(0.62±0.03) compared with the model group A(P<0.01). Conclusion Puerarin can attenuate AD-like tau hyperphosphorylation in the olfactory bulb of Alzheimer's disease rat brains, and decreased activity of GSK-3β might be involved in the effects of puerarin on tau hyperphosphorylation.
Fig.1
Expression of PS396,tau-1 and tau-5 protein in olfactory bulb of three groups of rats A.normal control group;B.model control group A;C.puerarin group
表1
Tab.1
表1
表1
3组大鼠嗅球内PS396、tau-1、tau-5表达比较
Tab.1
Comparison of the expression of PS396,tau-1 and tau-5 protein in olfactory bulb among three groups of rats x¯±s
组别
大鼠数
PS396/ Tau-5
tau-1/ tau-5
tau-5/ β-actin
正常对照组
6
0.92±0.10
0.85±0.03
0.45±0.01
模型对照组A
8
0.93±0.06
0.49±0.07*1
0.44±0.02
葛根素治疗组
8
0.91±0.11
0.58±0.03*2
0.44±0.02
Compared with normal control group,*1P<0.01;Compared with model control group A,*2P<0.05
与正常对照组比较,*1P<0.01;与模型对照组A比较,*2P<0.05
表1
3组大鼠嗅球内PS396、tau-1、tau-5表达比较
Tab.1
Comparison of the expression of PS396,tau-1 and tau-5 protein in olfactory bulb among three groups of rats x¯±s
Fig.2
Expression of PS396 and tau-1 protein in olfactory bulb of four groups of rats A.model control group B; B.low-dose puerarin group; C.medium-dose puerarin group; D.high-dose puerarin group
表2
Tab.2
表2
表2
4组大鼠嗅球内PS396与tau-1蛋白相对表达比较
Tab.2
Comparison of the expression of PS396 and tau-1 protein in olfactory bulb among four groups of rats x¯±s,n=5
组别
剂量/ (mg·kg-1·d-1)
PS396/ β-actin
tau-1/ β-actin
模型对照组B
…
0.55±0.05
0.39±0.09
葛根素
小剂量组
40
0.36±0.07*1
0.69±0.11*1
中剂量组
80
0.53±0.06
0.55±0.11*1
大剂量组
160
0.46±0.07
0.70±0.04*1
Compared with model control group B,*1P<0.01
与模型对照组B比较,*1P<0.01
表2
4组大鼠嗅球内PS396与tau-1蛋白相对表达比较
Tab.2
Comparison of the expression of PS396 and tau-1 protein in olfactory bulb among four groups of rats x¯±s,n=5
Fig.3
Expression of tGSK-3β and pS9-GSK-3β protein in olfactory bulb of three groups of rats A.normal control group; B.model control group A;C.Puerarin group
表3
Tab.3
表3
表3
3组大鼠嗅球内tGSK-3β、pS9-GSK-3β蛋白相对比较
Tab.3
Comparison of the expression of tGSK-3β and pS9-GSK-3β in olfactory bulb among three groups of rats x¯±s
组别
大鼠/ 只
tGSK-3β/ β-actin
pS9-GSK-3β/ tGSK-3β
正常对照组
6
0.69±0.00
0.96±0.07
模型对照组A
8
0.65±0.03
0.51±0.12*1
葛根素治疗组
8
0.65±0.01
0.62±0.03*2
Compared with normal control group,*1P<0.01;Compared with model control group A,*2P<0.05
与正常对照组比较,*1P<0.01;与模型对照组A比较,*2P<0.05
表3
3组大鼠嗅球内tGSK-3β、pS9-GSK-3β蛋白相对比较
Tab.3
Comparison of the expression of tGSK-3β and pS9-GSK-3β in olfactory bulb among three groups of rats x¯±s
tau蛋白磷酸化受多种蛋白激酶及磷酸酯酶的调控,其中GSK-3β被普遍认为在AD患者脑内tau蛋白磷酸化水平异常增高中发挥极为关键的作用,可对tau蛋白丝氨酸199/202/396及苏氨酸205/212/231等多个氨基酸位点进行磷酸化修饰[16]。大量证据显示,GSK-3β与AD病变的发生、发展有着密不可分的联系。研究表明,AD患者脑内神经原纤维缠结与活性GSK-3β存在明显的共定位[17]。在细胞或动物脑内过度表达GSK-3β可明显导致tau蛋白磷酸化水平异常增高。此外 ,在培养细胞内上调GSK-3β的水平可引起长时程增强(long time potentiation,LTP)抑制及突触功能受损[18];而在GSK-3β转基因小鼠脑内则可观察到明显的神经退行性改变[19]。目前已有不少研究针对GSK-3β作为靶点展开对AD的防治。笔者研究发现,葛根素可明显缓解D-半乳糖所致的大鼠海马内GSK-3β活性水平增高[6]。本研究结果也显示,葛根素可明显减轻D-半乳糖注射引起的大鼠嗅球内GSK-3β活性水平增高,提示葛根素可能通过GSK-3β途径改善D-半乳糖所致的大鼠嗅球内tau蛋白磷酸化水平增高。
OLIVEIRA FH,RODRIGUES-NETOE,FONSECA MK,et al.Neurodegenerative changes in the brainstem and olfactory bulb in people older than 50 years old:a descriptive study[J].Arq Neuropsiquiatr,2015,73(7):569-577.
ABSTRACT With the increase in life expectancy in Brazil, concerns have grown about the most prevalent diseases in elderly people. Among these diseases are neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. Protein deposits related to the development of these diseases can pre-date the symptomatic phases by years. The tau protein is particularly interesting: it might be found in the brainstem and olfactory bulb long before it reaches the limbic cortex, at which point symptoms occur. Of the 14 brains collected in this study, the tau protein was found in the brainstems of 10 (71.42%) and in olfactory bulbs of 3 out 11. Of the 7 individuals who had a final diagnosis of Alzheimer's disease (AD), 6 presented tau deposits in some region of the brainstem. Our data support the idea of the presence of tau protein in the brainstem and olfactory bulb in the earliest stages of AD.
ZELAYA MV,PEREZ-VALDERRAMAE,DE-MORENTIN X M.et al.Olfactory bulb proteome dynamics during the progression of sporadic Alzheimer's disease:identification of common and distinct olfactory targets across Alzheimer-related co-pathologies[J].Oncotarget,2015,6(37):39437-39456.
Olfactory dysfunction is present in up to 90% of Alzheimer's disease (AD) patients. Although deposition of hyperphosphorylated tau and -amyloid substrates are present in olfactory areas, the molecular mechanisms associated with decreased smell function are not completely understood. We have applied mass spectrometry-based quantitative proteomics to probe additional molecular disturbances in postmortem olfactory bulbs (OB) dissected from AD cases respect to neurologically intact controls (n=20, mean age 82.1 years). Relative proteome abundance measurements have revealed protein interaction networks progressively disturbed across AD stages suggesting an early imbalance in splicing factors, subsequent interrupted cycling of neurotransmitters, alteration in toxic and protective mechanisms of -amyloid, and finally, a mitochondrial dysfunction together with disturbance in neuron-neuron adhesion. We also present novel molecular findings in the OB in an autopsy cohort composed by Lewy body disease (LBD), frontotemporal lobar degeneration (FTLD), mixed dementia, and progressive supranuclear palsy (PSP) cases (n = 41, mean age 79.7 years). Olfactory mediators deregulated during the progression of AD such as Visinin-like protein 1, RUFY3 protein, and Copine 6 were also differentially modulated in the OB in LBD, FTLD, and mixed dementia. Only Dipeptidyl aminopeptidase-like protein 6 showed a specific down-regulation in AD. However, no differences were observed in the olfactory expression of this protein panel in PSP subjects. This study demonstrates an olfactory progressive proteome modulation in AD, unveiling cross-disease similarities and differences especially for specific proteins involved in dendritic and axonic distributions that occur in the OB during the neurodegenerative process.
ATTEMSJ,LINTNERF,JELLINGER K A.Olfactory involvement in aging and Alzheimer's disease:an autopsy study[J].J Alzheimers Dis,2005,7(2):149-157,173-180.
Abstract Olfactory dysfunction and tau pathology in the olfactory bulb increase with the severity of Alzheimer's disease. We report data of a postmortem study in the aged. 130 autopsy cases (81 female, 49 male, aged 61-102, mean 82.48 +/- 4.35 SD) years, underwent a standardized neuropathological assessment with immunohistochemical study of tau pathology in the olfactory bulb and nerve and of Alzheimer's disease using established criteria including Braak staging. All cases of definite Alzheimer's disease (Braak stages 5 and 6) (n = 40) showed large numbers of neuropil threads and neurofibrillary tangles, with amyloid deposits in 32.5% and neuritic plaques in one single case in the olfactory system. Braak stage 4 (n = 27) was associated with mild to moderate tau pathology in 85.2%, and amyloid plaques in 1.1%, Braak stage 3 (n = 28) with olfactory tau lesions in 37.0% and amyloid deposits in one single case, Braak stages 3 and 4 with olfactory tau lesions in 61.1%. Braak stage 2 (n = 15) showed olfactory tau pathology in 31.2%, whereas Braak stages 0 and 1 (n = 15) were all negative. The olfactory system tau score showed highly significant correlations with neuritic Braak stages in the brain, while both scores showed significant but low correlations with age. These data confirm previous studies demonstrating abundant tau pathology in the olfactory system in all definite Alzheimer's disease cases, in two-thirds of limbic Alzheimer's disease, and in almost one-third of non-demented elderly persons with Braak stage 2. There are strong correlations between tau pathology in the olfactory and limbic systems, both with similar increase in severity. Clinical dementia correlated with both Braak and olfactory system tau scores. Since the involvement of both systems is associated with a high risk of cognitive decline, future studies should validate the sensitivity of olfactory mucosa biopsies in the diagnosis of Alzheimer's disease.
HONG XP,CHENT,YIN NN,et al.Puerarin ameliorates D-Galactose induced enhanced hippocampal neurogenesis and tau hyperphosphorylation in rat brain[J].J Alzheimers Dis,2016,51(2):605-617.
Enhanced neurogenesis has been reported in the hippocampus of patients with Alzheimer's disease (AD), the most common neurodegenerative disorder characterized with amyloid- (A ) aggregation, tau hyperphosphorylation, and progressive neuronal loss. Previously we reported that tau phosphorylation played an essential role in adult hippocampal neurogenesis, and activation of glycogen synthase kinase (GSK-3), a crucial tau kinase, could induce increased hippocampal neurogenesis. In the present study, we found that treatment of D-galactose rats with Puerarin could significantly improve behavioral performance and ameliorate the enhanced neurogenesis and microtubule-associated protein tau hyperphosphorylation in the hippocampus of D-galactose rat brains. FGF-2/GSK-3 signaling pathway might be involved in the effects of Puerarin on hippocampal neurogenesis and tau hyperphosphorylation. Our finding provides primary in vivo evidence that Puerarin can attenuate AD-like enhanced hippocampal neurogenesis and tau hyperphosphorylation. Our finding also suggests Puerarin can be served as a treatment for age-related neurodegenerative disorders, such as AD.
MASURKAR AV,DEVANAND DP.Olfactory dysfunction in the elderly:basic circuitry and alterations with normal aging and Alzheimer's disease[J].Curr Geriatr Rep,2014,3(2):91-100.
Preclinical detection of Alzheimer’s disease is critical to determining at-risk individuals in order to improve patient and caregiver planning for their futures, and to identify individuals likely to benefit from treatment as advances in therapeutics develop over time. Identification of olfactory dysfunction at the preclinical and early stages of the disease is a potentially useful method to accomplish these goals. We first review basic olfactory circuitry. We then evaluate the evidence of pathophysiological change in the olfactory processing pathways during aging and Alzheimer’s disease in both human and animal models. We also review olfactory behavioral studies during these processes in both types of models. In doing so, we suggest hypotheses about the localization and mechanisms of olfactory dysfunction and identify important avenues for future work.
THOMANN PA,DOS-SANTOSV,SEIDLU,et al.MRI-derived atrophy of the olfactory bulb and tract in mild cognitive impairment and Alzheimer's disease[J].J Alzheimers Dis,2009 ,17(1):213-221.
There is increasing histopathological evidence that the olfactory bulb and tract (OBT) is a primary focus of neurodegenerative changes in (AD). Correspondingly, high-resolution magnetic resonance imaging revealed significant atrophy of the OBT in manifest AD. Whether these alterations are already present in mild , the assumed preclinical stage of AD, has not been investigated yet. OBT volumes were assessed by manual tracing in 29 patients with mild , 27 patients with probable AD, and 30 healthy controls. In a second step, voxel based morphometry was used to investigate the potential association between OBT atrophy and morphological changes in other brain regions. Patients had significantly lower OBT volumes when compared to controls, with atrophy being most prominent in the AD group. In addition, OBT atrophy was associated with a decreased medial temporal lobe (MTL) gray matter density bilaterally. Our findings indicate that neurodegeneration in OBT and MTL regions is linked and suggest that OBT volume might be a surrogate marker in AD.
ZHOUY,XIEN,LIL,et al.Puerarin alleviates cognitive impairment and oxidative stress in APP/PS1 transgenic mice[J].Int J Neuropsychopharmacol,2014,17(4):635-644.
Abstract Increasing evidence demonstrates that β-amyloid (Aβ) elicits oxidative stress, which contributes to the pathogenesis and disease progression of Alzheimer's disease (AD). Thus, there is interest in developing antioxidant therapies for the prevention/treatment of cognitive decline during AD. We reported previously that puerarin has antioxidative properties in vitro. Therefore, the aim of the present study was to determine whether puerarin improves cognitive function and reduces oxidative stress in amyloid precursor protein/presenilin-1 (APP/PS1) mice, a well established AD mouse model, and explore its potential mechanism. Our results show that oral administration of puerarin significantly ameliorates cognitive impairment in APP/PS1 mice assessed by the Morris water maze (MWM) test. This was accompanied by a significant decrease in the levels of lipid peroxidation (LPO) through, at least in part, induction of nuclear factor erythroid 2-related factor 2 (Nrf2) target gene heme oxygenase 1 (HO-1) in the hippocampus of APP/PS1 transgenic mice at 9 months of age, but without altering brain Aβ burden. Furthermore, puerarin significantly activated Akt, reduced activation of glycogen synthase kinase 3β (GSK-3β), and induced nuclear translocation of Nrf2 in the hippocampus of APP/PS1 mice but did not alter ERK1/2 phosphorylation. Thus, puerarin may improve cognitive performance in APP/PS1 mice through activation of the Akt/GSK-3β signaling pathway. These findings suggest that puerarin might be an attractive agent for prevention and treatment of cognitive impairment and dementia.
LINF,XIEB,CAIF,et al.Protective effect of puerarin on beta-amyloid-induced neurotoxicity in rat hippocampal neurons[J].Arzneimittelfors Chung,2012,62(4):187-193.
WANG JZ,LIUF.Microtubule-associated protein tau in development,degeneration and protection of neurons[J].Prog Neurobiol,2008,85(2):148-175.
As a principal neuronal microtubule-associated protein, tau has been recognized to play major roles in promoting microtubule assembly and stabilizing the microtubules and to maintain the normal morphology of the neurons. Recent studies suggest that tau, upon alternative mRNA splicing and multiple posttranslational modifications, may participate in the regulations of intracellular signal transduction, development and viability of the neurons. Furthermore, tau gene mutations, aberrant mRNA splicing and abnormal posttranslational modifications, such as hyperphosphorylation, have also been found in a number of neurodegenerative disorders, collectively known as tauopathies. Therefore, changes in expression of the tau gene, alternative splicing of its mRNA and its posttranslational modification can modulate the normal architecture and functions of neurons as well as in a situation of tauopathies, such as Alzheimer's disease. The primary aim of this review is to summarize the latest developments and perspectives in our understanding about the roles of tau, especially hyperphosphorylation, in the development, degeneration and protection of neurons.
PEI JJ,BRAAKE,BRAAKH,et al.Distribution of active glycogen synthase kinase 3beta(GSK-3beta) in brains staged for Alzheimer disease neurofibrillary changes[J].J Neuropathol Exp Neurol,1999,58(9):1010-1019.
Accumulation of paired helical filaments (PHFs) in , neuropil threads, and dystrophic neurites is one of the major neuropathological hallmarks of (AD). The principal subunit of PHFs is the abnormally hyperphosphorylated tau. () is one of the candidate kinases involved in . To play a role in , it would be expected that is active in tangle bearing neurons. In the present study, we investigated the regional and distributions of active and inactive forms of in brains staged for neurofibrillary changes. We found that neurons with tangle-like inclusions positive for active, but not inactive, appear initially in the Pre-alpha layer of the entorhinal cortex and extend to other brain regions, coincident with the sequence of the development of neurofibrillary changes. Active, but not inactive, was found to initially accumulate in the of pretangle neurons. These data provide direct in situ evidence that is consistent with the involvement of in .
ZHU LQ,WANG SH,LIUD,et al.Activation of glycogen synthase kinase-3 inhibits long-term potentiation with synapse-associated impairments[J].J Neurosci,2007,27(45):12211-12220.
Abstract Activation of glycogen synthase kinase-3 (GSK-3) can cause memory deficits as seen in Alzheimer's disease, the most common age-associated dementia, but the mechanism is not understood. Here, we found that activation of GSK-3 by wortmannin or transient overexpression of wild-type GSK-3beta could suppress the induction of long-term potentiation (LTP) in rat hippocampus, whereas simultaneous inhibition of GSK-3 by lithium or SB216763 or transient expression of a dominant-negative GSK-3beta mutant (dnGSK-3beta) preserved the LTP. After high-frequency stimulation (HFS), the presynaptic release of glutamate and the expression/clustering of synapsin I, a synaptic vesicle protein playing an important role in neurotransmitter release, decreased markedly after upregulation of GSK-3. In vitro studies further demonstrated that GSK-3 inhibited the expression of SynI independent of HFS. In postsynaptic level, the expression of PSD93 and NR2A/B proteins decreased significantly when GSK-3 was activated. The LTP-associated synapse impairments including less presynaptic active zone, thinner postsynaptic density, and broader synaptic cleft were also prominent in the hippocampal slices after HFS with activation of GSK-3. These synaptic impairments were attenuated when GSK-3 was simultaneously inhibited by LiCl or SB216763 or transient expression of dnGSK-3. We conclude that upregulation of GSK-3 impairs the synaptic plasticity both functionally and structurally, which may underlie the GSK-3-involved memory deficits.
AGHDAM SY,BARGER SW.Glycogen synthase kinase-3 in neurodegeneration and neuroprotection:lessons from lithium[J].Curr Alzheimer Res,2007,4(1):21-31.
For over fifty years lithium has been a fundamental component of therapy for patients with bipolar disorders. Lithium has been considered recently for its potential to alleviate neuronal loss and other neurodegeneration processes. For instance, lithium reduces the severity of some behavioral complications of Alzheimer's disease (AD). And there are growing indications that lithium may be of benefit to the underlying pathology of AD, as well as an array of other common CNS disorders, including stroke, Parkinson's disease, and Huntington's disease. Despite these demonstrated and prospective therapeutic benefits, lithium's mechanism of action remains elusive, and opinions differ regarding the most relevant molecular targets. Lithium inhibits several enzymes; significant among these are inositol monophosphatase (IMPase), glycogen synthase kinase-3 (GSK-3), and the proteasome. Most recent publications discussing the medical application of lithium have converged on GSK-3, so this article reviews data and discussions regarding the roles and interactions of GSK-3 with other proteins and its proposed role in the pathogenesis of Alzheimer's disease.
Olfactory bulb proteome dynamics during the progression of sporadic Alzheimer's disease:identification of common and distinct olfactory targets across Alzheimer-related co-pathologies
, 殷妮娜, 韩永明, 段妍君, 袁芳, 洪小平
