Pengwen Wang

Mechanisms and effects of curcumin on spatial learning and memory improvement in APPswe/PS1dE9 mice

Evidence suggests that curcumin, the phytochemical agent in the spice turmeric, might be a potential therapy for Alzheimers disease (AD). Its antioxidant, anti‐inflammatory properties have been investigated extensively. Studies have also shown that curcumin can reduce amyloid pathology in AD. The underlying mechanism, however, is complex and is still being explored. In this study, we used the APPswe/PS1dE9 double transgenic mice, an AD model, to investigate the effects and mechanisms of curcumin in the prevention and treatment of AD. The water maze test indicated that curcumin can improve spatial learning and memory ability in mice. Immunohistochemical staining and Western blot analysis were used to test major proteins in β‐amyloid aggregation, β‐amyloid production, and β‐amyloid clearance. Data showed that, 3 months after administration, curcumin treatment reduced Aβ40, Aβ42, and aggregation of Aβ‐derived diffusible ligands in the mouse hippocampal CA1 area; reduced the expression of the γ‐secretase component presenilin‐2; and increased the expression of β‐amyloid‐degrading enzymes, including insulin‐degrading enzymes and neprilysin. This evidence suggests that curcumin, as a potential AD therapeutic method, can reduce β‐amyloid pathological aggregation, possibly through mechanisms that prevent its production by inhibiting presenilin‐2 and/or by accelerating its clearance by increasing degrading enzymes such as insulin‐degrading enzyme and neprilysin.

GEPT Extract Reduces Aβ Deposition by Regulating the Balance Between Production and Degradation of Aβ in APPV717I Transgenic Mice

BACKGROUND Accumulation of beta-amyloid peptide (Abeta) in the brain is a primary influence driving Alzheimers disease (AD) pathogenesis. The disease process, including formation of neurofibrillary tangles containing tau protein, is proposed to result from an imbalance between production and clearance of Abeta. A major therapeutic strategy for AD should be to decrease deposition of Abeta by the inhibition of its production and the facilitation of its degradation. Hence, the primary aim of this study was to investigate effects of GEPT, a combination of herbal extracts, on Abeta levels, beta- and gamma-secretases substrate (BACE1 and PS1, respectively) associated with production of Abeta, and insulin-degrading enzyme (IDE) and neprilysin (NEP) related to degradation of Abeta in the brain. METHODS Three-month-old-male APPV717I mice were randomly divided into five groups (n=6 per group): (i) APP mice alone were given distilled water, (ii) APP donepezil mice were treated with donepezil (0.92 mg/kg/d), and (iii-v) APP mice treated with GEPT low dose (0.75 g/kg/d), middle dose (1.5 g/kg/d), and large dose (3.0 g/kg/d) for 8 months. Three-month-old-male C57BL/6J mice (n=6) for vehicle were given distilled water for 8 months. Immunohistochemistry and Western blot analysis were used in determining amyloid precursor protein (APP), Abeta1-42, BACE1, PS1, IDE and NEP in hippocampal CA1 region and hippocampal tissue homogenates. RESULTS Expression level of Abeta1-42 in the large GEPT dose was significantly lower than those in APP alone or APP treated with donepezil, and decreased to the level of vehicle mice. Similarly, a ratio calculated from the densitometric measures of Abeta1-42 protein/beta-actin in the large dose also was significantly lower than those in APP mice alone or APP mice treated with donepezil, and even reduced to the level of vehicle mice. Expression of PS1 in the large GEPT dose was significantly lower than that of APP mice alone and decreased to those in vehicle mice as well. A decreased level of BACE1 appeared, respectively, in APP mice treated with the large GEPT dose or donepezil but was still much greater than the level of vehicle mice. In contrast, NEP and IDE showed a significantly higher expression in APP mice treated with either the large dose or the middle dose of GEPT compared to APP mice alone or donepezil, and were even increased in level compared to vehicle mice. CONCLUSION The combination of GEPT extracts can reduce levels of endogenous Abeta peptide in APPV717I transgenic mice through the inhibition of PS1 activity rather than BACE1 and the promotion of IDE and NEP activity. Lower-expression of PS1 and over-expression of IDE or NEP may be helpful in potentially lowering brain Abeta levels in subjects with AD, and hence GEPT appears to offer potential that should be explored in AD.

A combination extract of ginseng, epimedium, polygala, and tuber curcumae increases synaptophysin expression in APPV717I transgenic mice

BackgroundThe density of presynaptic markers of synaptic communication and plasticity, especially synaptophysin (SYP), is significantly correlated with cognitive decline and the progression of Alzheimer’s disease (AD), indicating that synaptic protection is an important therapeutic strategy for AD. This study aims to investigate the synaptic protective effects of a combination of several active components extracted from the Chinese herbs ginseng, epimedium, polygala and tuber curcumae (GEPT), in the brains of APPV717I transgenic mice.MethodsThree-month-old APPV717I mice were arbitrarily divided into 10 groups (n = 12 per group): APP groups receiving vehicle treatment for four or eight months (model groups), three dose groups of GEPT-treated mice for each treatment period, and donepezil-treated mice for each treatment period. Three-month-old C57BL/6 J mice (n = 12) were also given vehicle for four or eight months (control groups). Vehicle, donepezil or GEPT were intragastrically administered. Immunohistochemistry (IHC) and Western blot analysis were used to assess protein expression in the hippocampal CA1 region and ratios of SYP to β-actin levels in hippocampal tissue homogenate, respectively.ResultsBoth IHC and Western blot revealed a decrease in SYP levels in the CA1 region of 7- and 11-month-old APPV717I transgenic mice compared with the control groups, whereas SYP levels were increased in donepezil- and GEPT-treated transgenic mice compared with the APP group. There was a significant difference in the levels of SYP detected by IHC between the GEPT high-dose group and the APP group after 4 months of treatment, and there were significant differences between all three GEPT groups and the APP group after 8 months of treatment. Western blotting showed that the SYP protein–β-actin ratio was decreased in APP mice, while donepezil- and GEPT-treated transgenic mice showed increased trends in the SYP protein–β-actin ratios.ConclusionGEPT increases SYP expression and protects synapses before and after the formation of amyloid plaques in the brains of APPV717I transgenic mice.

Effects of curcumin on synapses in APPswe/PS1dE9 mice.

Significant losses of synapses have been demonstrated in studies of Alzheimer’s disease (AD), but structural and functional changes in synapses that depend on alterations of the postsynaptic density (PSD) area occur prior to synaptic loss and play a crucial role in the pathology of AD. Evidence suggests that curcumin can ameliorate the learning and memory deficits of AD. To investigate the effects of curcumin on synapses, APPswe/PS1dE9 double transgenic mice (an AD model) were used, and the ultra-structures of synapses and synapse-associated proteins were observed. Six months after administration, few abnormal synapses were observed upon electron microscopy in the hippocampal CA1 areas of the APPswe/PS1dE9 double transgenic mice. The treatment of the mice with curcumin resulted in improvements in the quantity and structure of the synapses. Immunohistochemistry and western blot analyses revealed that the expressions of PSD95 and Shank1 were reduced in the hippocampal CA1 areas of the APPswe/PS1dE9 double transgenic mice, but curcumin treatment increased the expressions of these proteins. Our findings suggest that curcumin improved the structure and function of the synapses by regulating the synapse-related proteins PSD95 and Shank1.

Curcumin regulates insulin pathways and glucose metabolism in the brains of APPswe/PS1dE9 mice.

Recent studies have shown the therapeutic potential of curcumin in Alzheimer’s disease (AD). In 2014, our lab found that curcumin reduced Aβ40, Aβ42 and Aβ-derived diffusible ligands in the mouse hippocampus, and improved learning and memory. However, the mechanisms underlying this biological effect are only partially known. There is considerable evidence in brain metabolism studies indicating that AD might be a brain-specific type of diabetes with progressive impairment of glucose utilisation and insulin signalling. We hypothesised that curcumin might target both the glucose metabolism and insulin signalling pathways. In this study, we monitored brain glucose metabolism in living APPswe/PS1dE9 double transgenic mice using a micro-positron emission tomography (PET) technique. The study showed an improvement in cerebral glucose uptake in AD mice. For a more in-depth study, we used immunohistochemical (IHC) staining and western blot techniques to examine key factors in both glucose metabolism and brain insulin signalling pathways. The results showed that curcumin ameliorated the defective insulin signalling pathway by upregulating insulin-like growth factor (IGF)-1R, IRS-2, PI3K, p-PI3K, Akt and p-Akt protein expression while downregulating IR and IRS-1. Our study found that curcumin improved spatial learning and memory, at least in part, by increasing glucose metabolism and ameliorating the impaired insulin signalling pathways in the brain.

Curcumin ameliorates insulin signalling pathway in brain of Alzheimer's disease transgenic mice.

Deficits in glucose, impaired insulin signalling and brain insulin resistance are common in the pathogenesis of Alzheimer’s disease (AD); therefore, some scholars even called AD type 3 diabetes mellitus. Curcumin can reduce the amyloid pathology in AD. Moreover, it is a well-known fact that curcumin has anti-oxidant and anti-inflammatory properties. However, whether or not curcumin could regulate the insulin signal transduction pathway in AD remains unclear. In this study, we used APPswe/PS1dE9 double transgenic mice as the AD model to investigate the mechanisms and the effects of curcumin on AD. Immunohistochemical (IHC) staining and a western blot analysis were used to test the major proteins in the insulin signal transduction pathway. After the administration of curcumin for 6 months, the results showed that the expression of an insulin receptor (InR) and insulin receptor substrate (IRS)-1 decreased in the hippocampal CA1 area of the APPswe/PS1dE9 double transgenic mice, while the expression of phosphatidylinositol-3 kinase (PI3K), phosphorylated PI3K (p-PI3K), serine-threonine kinase (AKT) and phosphorylated AKT (p-AKT) increased. Among the curcumin groups, the medium-dose group was the most effective one. Thus, we believe that curcumin may be a potential therapeutic agent that can regulate the critical molecules in brain insulin signalling pathways. Furthermore, curcumin could be adopted as one of the AD treatments to improve a patient’s learning and memory ability.

A combination extract of Renshen (Panax Ginseng), Yinyanghuo (Herba Epimedii Brevicornus), Yuanzhi (Radix Palygalae) and Jianghuang (Rhizoma Curcumae Longae) decreases glycogen synthase kinase 3β expression in brain cortex of APPV717I transgenic mice

OBJECTIVE To investigate the neuroprotective mechanism of combination extract of Renshen (Panax Ginseng), Yinyanghuo (Herba Epimedii Brevicornus), Yuanzhi (Radix Palygalae) and Jianghuang (Rhizoma Curcumae Longae) (GEPT) in treating Alzheimers disease on the target of glycogen synthase kinase 3beta (GSK-3beta). METHODS Three-month-old APPV7171 transgenic mice were randomly divided into ten groups (n = 12 per group) and intragastrically administrated vehicle or medicines: APP group was given 0.5% CMC, donepezil group was given donepezil (APP + D group) (0.92 mg/kg(-1) x day(-1)), and GEPT groups were given small dose of GEPT (APP+Gs group) (0.075 g/ kg(-1) x day(-1)), medium dose (APP+Gm group) (0.15 g/ kg(-1) day(-1)), and large dose (APP+GI group) (0.30 g/ kg(-1) x day(-1)) for 4 or 8 months, respectively. Three-month-old C57BL/6J mice as vehicle controls (n=12) were given 0.5% CMC for 4 or 8 months as well. The GSK-3beta expression in the cortex of 7- and 11-month-old APPV7171 transgenic mice with and without GEPT or donepezil treatment and normal C57BL/6J mice were measured via Western blotting and Immunohistochemistry. RESULTS Immunohistochemistry analysis showed significant increase of GSK-3beta in the cerebral cortex of 7-month-old APP group (compare to control group P = 0.003), while the GSK-3beta expression of donepezil or GEPT group were all significantly decreased (Donepezil vs APP: P = 0.041; GI vs APP: P = 0.049; Gm vs APP: P = 0.029; Gh vs APP: P = 0.036). Western blot analysis showed similar results. The densitometric measures of GSK-3beta in APP mice increased significantly as compared with the control group (P = 0.008). And the GSK-3beta expression in donepezil and GEPT groups were all decreased. There was significant difference between Gh group or donepezil group and the control group (P = 0.05). Similar findings were shown in the 11-month-old mice in each group, except for greater decrease of GSK-3beta in the GEPT group. CONCLUSION GEPT can effectively decrease the level of GSK-3beta expression in the brain cortex of APPV7171 transgenic mice, and such effect is more significant in 11-month-old mice. This partially explains the neuroprotecting mechanism of GEPT in preventing and treating of AD.

Banxia Xiexin decoction ameliorated cognition via the regulation of insulin pathways and glucose transporters in the hippocampus of APPswe/PS1dE9 mice

Reduced glucose utilization and deficient energy metabolism that occur in the early stages of Alzheimer’s disease correlate with impaired cognition, and this information is evidence that Alzheimer’s disease is a metabolic disease that is associated with brain insulin/insulin-like growth factor resistance. This research aimed to investigate the effects of Banxia Xiexin decoction (BXD) on cognitive deficits in APPswe/PS1dE9 double transgenic mice and verify the hypothesis that BXD treatment improves cognitive function via improving insulin signalling, glucose metabolism and synaptic plasticity in the hippocampus of APPswe/PS1dE9 double transgenic mice. We used 3-month-old APPswe/PS1dE9 double transgenic mice as the case groups and wild-type littermates of the double transgenic mice from the same colony as the control group. Forty-five APPswe/PS1dE9 double transgenic mice were randomly divided into the model group, donepezil group and BXD group. The mice in the control and model groups were administered 0.5% carboxymethyl cellulose orally. The Morris water maze and step-down test were conducted to evaluate the cognitive performance of APPswe/PS1dE9 double transgenic mice after BXD treatment. Ultrastructure of synapses was observed in the hippocampal CA1 area. Proteins involved in insulin signalling pathways and glucose transports in the hippocampus were assessed through immunohistochemical staining and western blot. After 3 months intervention, we found that BXD treatment improved cognitive performance and the synaptic quantity and ultrastructure, restored insulin signalling and increased the expression of glucose transporter 1 (GLUT1) and GLUT3 levels. These findings suggest that the beneficial effect of BXD on cognition may be due to the improvement of insulin signalling, glucose metabolism and synaptic plasticity.

Effect of GAPT extract on expression of tau protein and its phosphorylation related enzymes in hippocampal neurons of APPV717I transgenic mice

ObjectiveTo investigate the effect of GAPT, an extract mixture from Radix Ginseng, Rhizoma Acor tatarinowii, Radix Polygalae and Radix Curcuma (containing ingredient of turmeric), etc. on expression of tau protein and its phosphorylation related enzyme in hippocampal neurons of APPV717I transgenic mice.MethodsSixty three-month-old APPV717I transgenic mice were randomly divided into model group, donepezil group [0.92 mg/(kg•d)], the low, medium and high dosage of GAPT groups [0.075, 0.15, 0.30 g/(kg•d), 12 in each group], and 12 three-month-old C57BL/6J mice were set as a normal control group, treatments were administered orally once a day respectively, and both the normal group and model group were given 0.5% sodium carboxymethyl cellulose solution. Immunohistochemistry (IHC) and Western blot analysis were used to detect the expression of total tau protein (Tau-5), cyclin-dependent kinase 5 (CDK5) and protein phosphatase 2A (PP2A) in hippocampal neurons of experimental mice after 8-month drug administration (11 months old).ResultsIn the model group, the expression of Tau-5 and CDK5 were increased, whereas the expression of PP2A was decreased in hippocampal neurons, which were signifificantly different compared with that in the normal group (all P<0.01). IHC test indicated the number and area of either Tau-5 or CDK5 positive cells were decreased with a dose-depended way in GAPT groups, and an increase of PP2A. Compared with the model group, the changes were signifificant in GAPT groups (P<0.05 or P<0.01). Similar results were shown by Western blot.ConclusionGAPT could attenuate abnormal hyperphosphorylation of tau protein in hippocampal neurons of APPV717I transgenic mice via inhibiting the expression of CDK5 and activating the expression of PP2A.

ADDING CHINESE HERBAL MEDICINE TO CONVENTIONAL THERAPY BRINGS COGNITIVE BENEFITS TO PATIENTS WITH ALZHEIMER’S DISEASE: A TWO-YEAR STUDY

or 10 mg/kg or a titration regimen up to 10 mg/kg [average expected dose, 5.3 mg/kg at 52 weeks]) or placebo once every 4 weeks for 52 weeks in a staggered, ascending-dose design. Randomization in fixed-dose arms was stratified by ApoE4 status (carrier/noncarrier). Baseline to week 54 change in CDR-sum of boxes (CDR-SB) score was an exploratory endpoint. This post hoc analysis assessed cognitive and functional domains of the CDR at the week 54 visit in the overall study population and a subpopulation of patients with early AD defined by CDR global score, 0.5; CDR memory domain score, 0.5; and MMSE score, 24. Results:A total of 196 patients were randomized and dosed in PRIME. In the overall study population, the baseline means for CDR-SB, cognitive domain scores, and functional domain scores were 3.17, 2.00, and 1.17, respectively. At week 54, the adjusted mean changes for the cognitive domain scores were 0.93 (placebo), 0.94 (1 mg/kg), 0.72 (3 mg/kg), 0.49 (6 mg/kg), 0.30 (10 mg/kg), and 0.64 (titration regimen). For functional domain scores, the corresponding adjusted mean changes were 0.91, 0.81, 0.67, 0.62, 0.32, and 0.10. A subanalysis of patients with early AD was consistent with findings from the overall study population. Conclusions: This interim post hoc analysis suggests an effect of aducanumab on both cognitive and functional CDR domain scores at week 54 in the overall study population and in a subset with early AD.