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OBJECTIVE@#To observe the effect of electroacupuncture (EA) on the expression of insulin phosphatidylinositol-3 kinase/glycogen synthetase kinase-3α (PI3K/GSK3α) signal pathway related proteins in the hippocampus in mice with Alzheimer's disease (AD), and to explore the regulatory mechanism of EA on improving the pathological characteristics of AD.@*METHODS@#Twelve male APP/PS1 double transgenic mice were randomly divided a model group and a treatment group, 6 mice in each group; another 6 wild-type male mice were taken as the control group. The mice in the treatment group were treated with EA (continuous wave, 2 Hz of frequency) at "Baihui" (GV 20) and bilateral "Shenshu" (BL 23), once a day; 7-day treatment was taken as a course of treatment, and 2 courses of treatment were given. The immunohistochemistry method and Western blot method were used to detect the distribution and expression level of hippocampal PI3K/GSK3α signal pathway related proteins P85α, P110α, GSK3α and pSGSK3α, and the number of hippocampal senile plaques (SP) was observed.@*RESULTS@#The proteins of P85α, P110α, GSK3α and pSGSK3α were mainly distributed in the cytoplasm of hippocampal neurons, and the GSK3α was also distributed in the axons of neurons in the model group and the treatment group. The immunohistochemistry results showed that the distribution level of GSK3α in the hippocampus in the model group was significantly higher than that in the control group (<0.001), and the distribution level of pSGSK3α, P85α and P110α was significantly decreased (<0.01, <0.001); compared with the model group, the distribution level of GSK3α in the hippocampus in the treatment group was significantly decreased (<0.001), and the distribution level of pSGSK3α, P85α and P110α in hippocampus was significantly increased (<0.05, <0.001). The Western blot results showed compared with the control group, the expression of pSGSK3α, P85α and P110α as well as the ratio of pSGSK3α/GSK3α in the hippocampus in the model group were significantly decreased (<0.001), and the expression of GSK3α was increased (<0.05); compared with the model group, the expression of pSGSK3α, P85α, P110α and the ratio of pSGSK3α/GSK3α in the hippocampus in the treatment group were significantly increased (<0.01, <0.001), and the expression of GSK3α was decreased (<0.05). Compared with the control group, the number of hippocampal SP in the model group was significantly increased (<0.001); compared with the model group, the number of hippocampal SP in the treatment group was significantly decreased (<0.01).@*CONCLUSION@#EA could effectively regulate the expression of PI3K/GSK3α signal pathway related proteins in the hippocampus in mice with AD, so as to reduce the formation and deposition of SP.
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Animals , Male , Mice , Alzheimer Disease , Therapeutics , Electroacupuncture , Hippocampus , Physiology , Insulin , Physiology , Mice, Transgenic , Random Allocation , Signal TransductionABSTRACT
Amyloid deposits are one of the hallmark pathological lesions of Alzheimer's disease (AD). They can be visualized by thioflavin-S, silver impregnation, Congo red staining, and immunohistochemical reactions. However, that amyloid deposits generate blue autofluorescence (auto-F) has been ignored. Here, we report that visible light-induced auto-F of senile plaques (SPs) was detected and validated with conventional methods. Brain slices from APP/PS1 (amyloid precursor protein/presenilin 1) transgenic mice were mounted on slides, rinsed, coverslipped and observed for details of the imaging and spectral characteristics of the auto-F of SPs. Then the slices were treated with the above classic methods for comparative validation. We found that the SP auto-F was greatest under blue-violet excitation with a specific emission spectrum, and was much easier, more sensitive, and reliable than the classic methods. Because it does not damage slices, observation of auto-F can be combined with all post-staining techniques in slices and for brain-wide imaging in AD.
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@#Objective To observe the effects of 2,3,5,4'-tetrahydroxy-stilbene-2-O-β-D-glycoside (TSG) on formation of senile plaques and beta amyloid (Aβ), as well as activation of microglia and astrocytes, in cortex and hippocampus of APP/PS1 double transgenic mice. Methods A total of 64 five-month-old APP/PS1 mice were randomly divided into model group (n=16), low-dose TSG (0.05 g/kg) group (n=16), high-dose TSG (0.1 g/kg) group (n=16), and donepezil group (n=16); other 32 same age wild type (WT) mice were randomly divided into normal control group (n=16) and high-dose TSG (0.1 g/kg) WT group (n=16). The normal control group and model group were given distilled water, and the other groups were given the corresponding drugs intragastrically. The mice were tested with object recognition test, the deposi-tion of plaques in brain was detected with Congo red staining, and the expression of Aβ40/42, ionized calcium bind-ing adapter molecule 1 (Iba1) and glial fibrillary acidic protein (GFAP) with immunohistochemistry after seven months of treatment (twelve-month-old). Results Compared with the model group, the discrimination index significantly increased (P<0.01), the deposition of plaques decreased in brain (P<0.05), and the expression of Aβ40/42, Iba1 and GFAP all significantly decreased in each treatment group (P<0.05). Conclusion TSG can improve learning and memory of APP/PS1 transgenic mice, reduce Aβ deposition and senile plaques, and reduce the inflammatory response, even in low-dose, which is similar to that of donepezil.
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OBJECTIVE: To observe the effect of electroacupuncture (EA) intervention on learning-memory ability and the expression of senile plaques (SP), amyloid precursor protein (APP), β-secretase 1(BACE 1) and insulin degrading enzyme (IDE) in the hippocampus in APP/presenilin 1 (PS 1) double transgenic Alzheimer's disease (AD) mice, so as to reveal its mechanisms underlying improvement of AD. METHODS: A total of 18 male APP/PS 1 double transgenic AD mice were randomly divided into model, EA-2-week and EA-3-week groups (n=6 in each). The control group was consisted of 6 male wild mice. EA (2 Hz, 2 mA) was applied to "Baihui" (GV 20) and bilateral "Shenshu" (BL 23) for 15 min, once a day, with 7 days being a therapeutic course, 2 or 3 courses altogether and with an one day's interval between every two courses. The spatial learning-memory ability was assessed using Morris water maze test during 5 days' training. The immunoactivity of SP in the hippocampus tissue was detected by immunohistochemistry, and the expression levels of APP, BACE 1 and IDE in the hippocampus were analyzed by Western blot. RESULTS: Following modeling, the escape latency and path length of hidden platform tests were significantly increased (P<0.01, P<0.05), and the platform crossing time of spatial probing test significantly decreased (P<0.01) in the model group compared with the control group. After EA intervention, the escape latency on the 5th day of training, and the path length on the 4th and 5th day of training in both EA-2-week and EA-3-week groups were significantly shorter relevant to the model group (P<0.01), and those of the EA-3-week group were considerably shorter than those of the EA-2-week group in the escape latency and path length (P<0.05, P<0.01). The platform crossing times of spatial probing test were significanthy increased in both EA-2-week and EA-3-week groups in comparison with the model group (P<0.01), and that of the EA-3-week group was considerably increased compared with the EA-2-week group (P<0.05). Immunohistochemical staining showed that the number of SP in the hippocampus was markedly increased in the model group compared with the control group (P<0.01), and was markedly reduced in both EA-2-week and EA-3-week groups (P<0.01), and that of the EA-3-week group was significantly decreased compared with the EA-2-week group (P<0.01). The expression levels of hippocampal APP and BACE 1 proteins were significantly higher in the model group than in the control group (P<0.01), and that of hippocampal IDE was markedly lower in the model group than in the control group (P<0.01). After EA, the increased expression levels of APP and BACE 1 proteins and the decreased expression level of IDE in the EA-2-week and EA-3-week groups were significantly inhibited (P<0.01). The effects of EA-3-week were significantly stronger than those of EA-2-week in down-regulating the expression of APP and BACE 1 proteins and up-regulating the expression of IDE (P<0.01, P<0.05). CONCLUSION: EA stimulation of GV 20 and BL 23 can improve the learning-memory ability in APP/PS 1 double transgenic AD mice, which may be related to its effects in down-regulating the expression of SP, APP and BACE 1 proteins and up-regulating the expression of IDE protein in the hippocampus.
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Objective To examine the changes of Aβ expression and its related metabolic enzymes in the brains of AD and T2DM mice, so as to explore the possible mechanism of type 2 diabetes mellitus combined with AD.Methods Five-month-old APP/PS1 double transgenic mice, ob/ob mice and the wild-type control mice were employed in this study.Immunohistochemical (IHC) staining, Elisa and Western blot were used to detect SP, Aβ and its related metabolic enzymes.Results A certain number of SPs were observed in the cerebral cortex and hip-pocampus of APP/PS1 mice;SPs were occasionally observed in the cortex of ob/ob mice, while no SP appeared in wild-type mice.Aβ40 and Aβ42 levels were significantly increased in APP/PS1 and ob/ob mice brains as compared with controls (P<0.05), thought both Aβ40 and Aβ42 levels in AD mice were significantly higher than those of ob/ob mice (P<0.05).APP expression level was highest in APP/PS1 mice among 3 groups, and its expressed higher in ob/ob mice than that of control mice (P<0.05).BACE1 expression was notably increased in APP/PS1 and ob/ob mice as compared with control(P<0.05), however, it expressed higher in APP/PS1 mice than ob/ob mice (P<0.05).The expression of Aβ degradation enzyme IDE was reduced in APP/PS1 and ob/ob mice(P<0.05), while lowest in ob/ob mice.Conclusions Overexpression of Aβ may be one of main reasons for T2DM combined AD.
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Objective To investigate the effect of ovarian estrogen on autophagy and senile plaques (SP) in the brain of adult APP/PS1 double transgenic mice, and inquire into the mechanism of Alzheimer disease (AD) neuropathogenesis due to estrogen deficiency. Methods APP/PS1 AD mice (3-month old) were divided into ovariectomy group (OVX-AD) and sham group (sham-AD). Two months after operation, transmission electron microscopy (TEM) was employed to observe the morphological structures of the brains of AD model mice, and immunohistochemical staining was performed to examine the changes in SP and autophagy-related proteins LC3 and Beclin-1 in the brain of AD model mice. Results Immunohistochemical staining showed that the number of SP in the brain of OVX-AD mice incrcased significantly compared with that in sham-AD mice, and distribution of SP was observed more extensively, including the cortex and hippocampus. The autophagy related proteins LC3 and Beclin-1 positive neurons were decreased greatly in the OVX-AD mice brain compared with that of sham-AD mice. TEM revealed a larger number of swollen and dark neurons in hippocampus of OVX-AD mice, while more autophagosome was observed around the neuronal processes in OVX-AD mice brain compared with sham-AD mice. Conclusion Estrogen deficiency may lead to delayed maturation of autophagy, decrease the activity and weaken the function of autophagy, which in turn may result in aggravation of pathological features of AD.
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Objective To investigate whether catalpol affects senile plaque formation and spatial learning and memory ability in the amyloid-β protein precursor/presenilin 1 (APP/PSI) double transgenic mice.Methods Three month-old APP/PS1 double transgenic mice were randomly divided into catalpoltreated and saline-treated groups (n =10),with C57 mice of the same age and genetic background as normal control group (n =10).The catalpol (in a dose of 5 mg · kg-1 · d-1) and the same amount of saline were peritoneally injected into Alzheimer' s disease (AD) model mice for 3 weeks.Immunohistochemical staining was performed to examine senile plaques in the brain of AD model mice,and Morris water maze was used to assess the spatial learning and memory abilities of the mice.Results Compared with the saline-treated AD model mice (6.0 ±0.6),the number of senile plaques of catalpol treated AD mice significantly decreased (2.3± 0.7; t =3.500,P =0.025); Mice in each groups had similar latency and path length to reach platform in visible platform test; In hidden platform test,catalpol-treated mice had a significant lesser latency and path length compared with saline-treated mice,furthermore,catalpol-treated mice had much more platform-crossing times (6.4 ± 0.8) than saline-treated mice (2.9 ± 0.4 ; t =5.592,P =0.001).Conclusion Catalpol can significantly decrease the senile plaque formation and improve the spatial learning and memory abilities of APP/PS1 double transgenic mice.
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Objective To develop specific targeted magnetic biomarkers which can selectively mark the senile plaques in Alzheimer' s disease (AD) and verify its feasibility and validity.Methods Aβ1-40 peptide and Tat-PTD ( Tat-protein transduction domain) was binded with dextran-coated ultrasmall superparamagnetic iron oxide ( USPIO) particles.Visualization of plaques in vivo in Alzheimer transgenic mice was investigated at 7.0 Tesla using T2 sequences after intravenous administration of the targeted nanoiron contrast agent and verified by histological staining.Results The targeted nano-iron contrast agent could enter the cultured neural stem cells,and was able to accelerate T2 relaxation rates of water protons in the cells and negatively reinforce the T2 signal intensity in the labeled cells.Plaques were specifically detected in vivo by magnetic resonance imaging ( MRI) and correlated well with histological staining after injection of nano-iron contrast agent into the APP/PS1 mice.Conclusion The targeted nano-iron contrast agent has the ability of selectively labeling the senile plaques in AD brain tissues in vivo,which might enable the early detection of plaques by MRI and can be further applied in the studies of early diagnosis of AD.
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Objective To investigate whether valproic acid (VPA) affect spatial learning memory and senile plaques in the APP/PS1 double transgenic AD mouse model of different gender. MethodsTwenty 3-month old APP/PS1 double transgenic AD mice,male and female mouse evenly,were randomly divided into VPA-treated and saline-treated groups ( 10 for each group). 30 mg· kg-1 · d-1 of VPA and the same amount of saline were peritoneally injected into mice for 4 weeks. Morris water maze was conducted to check the effect of VPA on the capability of spatial learning and memory of AD mouse model. Immunohistochemical staining was used to examine the effect of VPA on the morphological changes in the brains of mice. ResultsVisible platform test showed that VPA-treated and saline-treated mice had similar escape latency (P＞0.05) and path length (P＞0.05) ,the swimming speed between male and female mice had no difference (P＞0.05). Hidden platform test showed that VPA treated mice had a significantly shorter latency (P＜0.01) and path length (P＜0.01) to reach the platform compared with saline-treated mice. Meanwhile, both in VPA-treated and control groups, the male mice had a shorter correlation escape latency and path-length than female mice had(P＜0.05 ). Immuohistochemical staining showed that the number (11.23±3.78) of senile plaques (SP) in the cerebral cortex and hippocampus of VPA-treated male mice were notably decreased than that(28.17 ±3.46) in the control group ( t= 14.67, P＜0.01 ),furthermore,the number of SP in the cerebral cortex and hippocampus of VPA-treated male mice was significantly reduced,as compared with which (20.36 ±4.21)in the VPA-treated female mice(P＜0.05). ConclusionVPA can significantly lower formation of SP, and remarkably improve the capability of spatial learning and memory of APP/PS1 transgenic mice,which have gender difference.
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Alzheimer disease is the most common cause of dementia among the elderly, accounting for ~60-70 percent of all cases of dementia. The neuropathological hallmarks of Alzheimer disease are senile plaques (mainly containing p-amyloid peptide derived from amyloid precursor protein) and neurofibrillary tangles (containing hyperphosphorylated Tau protein), along with neuronal loss. At present there is no effective treatment for Alzheimer disease. Given the prevalence and poor prognosis of the disease, the development of animal models has been a research priority to understand pathogenic mechanisms and to test therapeutic strategies. Most cases of Alzheimer disease occur sporadically in people over 65 years old, and are not genetically inherited. Roughly 5 percent of patients with Alzheimer disease have familial Alzheimer disease-that is, related to a genetic predisposition, including mutations in the amyloid precursor protein, presenilin 1, and presenilin 2 genes. The discovery of genes for familial Alzheimer disease has allowed transgenic models to be generated through the overexpression of the amyloid precursor protein and/or presenilins harboring one or several mutations found in familial Alzheimer disease. Although none of these models fully replicates the human disease, they have provided valuable insights into disease mechanisms as well as opportunities to test therapeutic approaches. This review describes the main transgenic mouse models of Alzheimer disease which have been adopted in Alzheimer disease research, and discusses the insights into Alzheimer disease pathogenesis from studies in such models. In summary, the Alzheimer disease mouse models have been the key to understanding the roles of soluble b-amyloid oligomers in disease pathogenesis, as well as of the relationship between p-amyloid and Tau pathologies.
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Animals , Humans , Mice , Alzheimer Disease/genetics , Amyloid beta-Protein Precursor/genetics , Disease Models, Animal , Mutation/genetics , Amyloid beta-Protein Precursor/metabolism , Mice, TransgenicABSTRACT
Objective To observe senile plaque and iron deposition in cortex and hippocampus of the Alzheimer's disease ( AD ) transgenic mice and investigate their influence on T2 relaxation time.Method All AD transgeic mice were divided into three groups: young group(2,4 months), adult group (6,8,10 months), old group (12,14,16 months), and C57BL/6J mice were as control and were scanned in order by using 4.7 T MR system.Regions of interest (ROI) corresponding to cortex, hippocampus,thalamus, striatum were manually drawn on MR images and T2 MR relaxation times of each ROI were calculated.After MR scan, these mice were decapitated and stained for iron and senile palques.The number of plaque and iron, plaque burden, iron load in cortex and hippocampus were acquired using image pro plus software.Result T2 relaxation times of each group were as following: wild type ( cortex (49.5 ± 2.1 ) ms,hippocampus (51.6 ± 1.1 ) ms ); young ( cortex ( 49.7 ± 0.5 ) ms, hippocampus ( 50.7 ± 0.7 ) ms ); adult (cortex(47.2 ±0.8) ms, hippocampus(47.7 ±0.9) ms) and old (cortex(44.6 ±0.8) ms, hippocampus (45.3 ±0.4)ms).T2 relaxation times in cortex and hippocampus of each group had statistical differences ( cortex F = 18.620, P ＜ 0.01; hippocampus F = 67.925, P ＜ 0.01 ); Compared with young group and wild type mice, T2 relaxation times in corex and hippocampus of adult group mice were decreased significantly.At the same time, T2 relaxation times in old group mice were reduced compared with adult group ( Adult vs young: cortex q =4.284, P ＜0.01, hippocampus q =7.902, P ＜0.01; adult vs wild type: cortex q =4.424, P＜0.05, hippocampus q = 11.450, P ＜0.01; old w adult: cortex q =4.812, P ＜0.01,hippocampus q = 7.034, P ＜ 0.01 ).Histochemical staining for senile plaques found that senile plaques was deposited as early as 4 month.Iron deposition in hippocampus and cortex were detected by perl-DAB as early as 6 months of age, and there was an overall increase in number and load of plaques and iron with age.A positive correlation was observed between plaque burden and iron load ( r = 0.931, P ＜ 0.01 ).At the same time, plaque burden and iron load were negatively correlated with T2 relaxation times ( plaque burden and T2 relaxation times r = - 0.884, P ＜ 0.01; iron load and T2 relaxation times r = - 0.827, P ＜ 0.01 ).Conclusion The changes of T2 relaxation time in AD transgenic mice are attributed to iron and senile plaques.MR T2 relaxation time is a sensitive marker to diagnosis for AD and screen antidementia drugs.
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Objective To study the neuropathological characteristics of late-onset Alzheimer' s disease (LOAD) in Chinese people, to ensure correct diagnosis of LOAD.Methods Choosing cerebral cortex of temporal layer of 8 cases of LOAD and 5 cases of age-matched normal control group by autopsy.Histopathologlc diagnosis was established in all these 13 cases.Cerebral cortex were taken from temporal layer in 13-101 hours after death and were fixed with 40 g/L paraformaldehyde, followed by paraffin-embedding and serial sectioning with 6 μm thickness.Brain tissue was analyzed neuropatholically by using immunohistochemical staining for β-amyloid (Aβ) and AT8 on these cases.Positive distribution of temporal layer was observed under light microscope.Results The results of immunohistochemical stainings of Aβ and AT8 were positive in all of LOAD.Aβ immunoreactant located in the cerebral cortex.The diffuse plaques, primitive plaques and burn-out plaques of senile plaques were displayed clearly by immunohistochcmical stainings of Aβ.AT8 immunoreactants showed neurofibrillary tangles, neuropil thread and senile plaques in nerve cell of cerebral cortex in different degree respectively.The positive rate Aβ and AT8 were both 8/8 by semiquantitative analysis in AD group.As the normal aging control group, which was 0 and 1/5 respectively.There was significant difference of the positive rate Aβ and AT8 in two groups(χ2 = 13.000,P=0.001; χ2=9.244,P=0.007).Conclusions Sensitive immunnhistochemical technique was significant to display senile plaques and neurofibrillary tangles.The findings demonstrate that immunohistochemistry staining of Aβ and AT8 can display senile plaques and neurofibrillary tangles clearly.The connection of the 2 different methods might improve diagnose accordance rate of AD.
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Objectives To detect the expression and distribution of ubiquitin in neurofibrillary tangles(NFT) and senile plaque neurites in the hippocampal formation of Alzheimer's disease brain and explore the significance of ubiquitin in pathological mechanism of Alzheimer's disease.Methods The expression of ubiquitin in the hippocampal formation of 7 patients with Alzheimer's disease and 5 non-dementia elderly was detected using immunohistochemical technique.Results Neurofibrillary tangles and senile plaque neuritis were labeled by the antibody of ubiquitin in hippocampal formation of Alzheimer's disease brain, but pretangle neurons were not stained. Containing NFT neurons stained by ubiqutin antibody immunoreactive products were distributed more in the CA1 and CA2 (42.13?0.65, 30.57?0.78 respectively)than those in CA3 and CA4 (12.43?0.24?18.34?0.81 respectively)of the hippocampal formation (P
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Two aberrant structures, extracellular senile plaques (SP) and intracellular neurofibrillary tangles (NFTs) are the characteristic neuropathological hallmarks of Alzheimers disease (AD). Amyloid ? protein (A?) and hyperphosphorylated tau protein are the major components of SP and NFTs respectively. A large body of evidence has highlighted the pivotal role of sulfated polysaccharides in the amyloidogenesis and formation of NFTs. The underlying mechanisms of the involvement of sulfated polysaccharides in the development of AD were reported to contribute to their high affinity for both A? and tau protein. Sulfated polysaccharides not only promoted the ? secretase cleavage of APP and the increased production of A? and induced the aggregation and deposition of A?, but also facilitated the phosphylation of tau and promoted tau polymerization into fibrils and tangle formation. On the other hand, the neurotrophic effects exerted by sulfated polysaccharides were also demonstrated. These notions were probably due to the inhibition of the formation of A? fibrils or to the counteraction of the abnormal phosphorylation of tau by promoting the protein phosphatase2B activity, which has been speculated to be attributed to the variation in either structural backbone or degree of sulfation or position of sulfation. Putting together, the appropriate structural modification of sulfated polysaccharides may be effective as therapeutic agents for AD.