Lancao decoction in the treatment of alzheimer's disease via activating PI3K/AKT signaling to promote ERK involving in enhancing neuronal activities in the hippocampus.
Previous study has demonstrated lancao decoction (LC), a traditional Chinese medicine (TCM) fomula and recorded in "Huangdineijing", has a therapeutic effect on cognitive impairment (early clinical manifestations of alzheimer's disease (AD), which suggests that LC may have potential therapeutic advantages for AD. Whether LC has the therapeutic effect on AD and its potential mechanisms were still further indicated.
In this study, we aimed to uncover the potential advantage and neuronal mechanisms of LC in the treatment of AD in APP/PS1 mice in the hippocampus.
We chose APP/PS1 mice to combing with behavioral tests including morris water maze (MWM) or y-maze to determine the role of LC in the therapeutic actions of AD. Network pharmacology was used to screen potential targets and pathways involving in LC's treatments of AD. Western blot was used to detect the phosphorylated expressions of proteins in hippocampus in APP/PS1 mice in the hippocampus. Pharmacological interventions were used to elucidate the relationship between the role of LC in the treatment of AD and the pathway, as well as the upstream and downstream interactions with neuronal activities.
According to our previous LC effective dose (2.5 g/kg), the dose was also able to significantly reduce the latency to the platform, and significantly increase the number of crossing times and time spend in the target quadrant in APP/PS1 mice in MWM, which was consistent with donepezil (DON) after 14 days chronic treatments. Network pharmacology showed that PI3K/AKT and MAPK pathways were closely associated with LC's treatments of AD, and protein autophosphorylation played a role in this process. The phosphorylated expressions of PI3K and AKT were obviously reduced in APP/PS1 mice in the hippocampus, which were both reversed by LC or DON. The phosphorylated expressions of MAPK including P38, JNK and ERK were also significantly reduced in APP/PS1 mice hippocampus, but only the phosphorylated expression of ERK was reversed by LC or DON. Inhibiting the activities of PI3K/AKT pathway by LY294002 blocked LC's improvement of behavioral deficits in APP/PS1 mice, including reducing latency to platform and increasing the number of crossings time in MWM in APP/PS1 mice, which also blunted LC's up-regulated phosphorylated expressions of PI3K, AKT and ERK in the hippocampus. Moreover, suppressing the activities of ERK by PD98059 also blocked LC's improvement of AD-related behavioral deficits including decreasing latency to new arm and increasing time in new arm in y-maze test, which also inhibited LC's enhancement of synaptic proteins (PSD95 and synapsin1) in the hippocampus and the number of EGR1-positive cells in the hippocampal dentate gyrus (DG).
Take together, our study revealed that LC had the therapeutic effects on AD by activating the PI3K/AKT pathway to enhance ERK activity and further strengthened neuronal activities in the hippocampus.
Wu L
，Sun Y
，Yin Y
，Wu Z
，Liu R
，Liu Y
，Zhu Y
，Shao M
，Zhou H
，Lu C
，Zhang H
... -
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Rg1 improves Alzheimer's disease by regulating mitochondrial dynamics mediated by the AMPK/Drp1 signaling pathway.
Alzheimer's disease (AD) is the most prevalent form of dementia, characterized by a complex pathogenesis that includes Aβ deposition, abnormal phosphorylation of tau protein, chronic neuroinflammation, and mitochondrial dysfunction. In traditional medicine, ginseng is revered as the 'king of herbs'. Ginseng has the effects of greatly tonifying vital energy, strengthening the spleen and benefiting the lungs, generating fluids and nourishing the blood, and calming the mind while enhancing intelligence. Ginsenoside Rg1 (Rg1) is a well-defined major active component found in ginseng, known for its relatively high content. It has been demonstrated to exhibit neuroprotective effects in both in vivo and in vitro models, capable of ameliorating Aβ and tau pathology, regulating synaptic function, and reducing inflammation, oxidative stress, and apoptosis. However, the potential of Rg1 to improve AD pathology through the regulation of mitochondrial dynamics is still uncertain.
Despite the active research efforts on drugs for AD, the currently available anti-AD medications can only slow disease progression and manage symptoms, yet unable to provide a cure for AD. Furthermore, some anti-AD drugs failed phase III and IV clinical trials due to significant side effects. Therefore, there is an urgent need to further investigate the pathogenesis of AD, to identify new therapeutic targets, and to explore more effective therapies. The aim of this study is to evaluate the potential therapeutic effects of Rg1 on APP/PS1 double transgenic mice and Aβ42-induced HT22 cell models, and to investigate the potential mechanisms through which it provides neuroprotective effects.
This study investigates the effects of Rg1 in treating AD on APP/PS1 double transgenic mice and Aβ42-induced HT22 cells. In the in vivo experiments, APP/PS1 mice were divided into a model group, Rg1-L group, Rg1-H group, and donepezil group, with C57BL/6 mice serving as the control group (n = 12 per group). The Rg1-L and Rg1-H groups were administered Rg1 at doses of 5 mg/kg/d and 10 mg/kg/d, respectively, while the donepezil group received donepezil at a dose of 1.3 mg/kg/d. Both the control and model groups received an equal volume of physiological saline daily for 28 days. Learning and spatial memory were assessed by the Morris water maze (MWM) and novel object recognition (NOR) tests, and neuronal damage by Nissl staining. Aβ deposition was analyzed through immunohistochemistry and Western blot, while the expression levels of synaptic proteins PSD95 and SYN were evaluated via immunofluorescence staining and Western blot. The dendritic spines of neurons was observed by Golgi staining.The ultrastructure of neuronal mitochondria and synapses was examined by transmission electron microscopy (TEM). Mitochondrial function was assessed through measurements of Reactive oxygen species (ROS), Superoxide Dismutase (SOD), and Adenosine Triphosphate (ATP), and Western blot analysis was performed to detect the expression levels of AMPK, p-AMPK, Drp1, p-Drp1, OPA1, Mfn1, and Mfn2, thereby investigating the protective effects of Rg1 on mitochondrial dysfunction and cognitive impairment in APP/PS1 double transgenic mice. In vitro experiments, HT22 cells were treated with Aβ42 of 10 μM for 24 h to verify the therapeutic effects of Rg1. Flow cytometry was used to detect ROS and JC-1, biochemical methods were employed to measure SOD and ATP, immunofluorescence staining was used to detect the expression levels of PSD95 and SYN, and Western blot analysis was conducted to elucidate its potential mechanisms of action.
The findings suggest that after 28 days of Rg1 treatment, cognitive dysfunction in APP/PS1 mice was improved. Pathological and immunohistochemical analyses demonstrated that Rg1 treatment significantly reduced Aβ deposition and neuronal loss. Rg1 can improve synaptic dysfunction and mitochondrial function in APP/PS1 mice. Rg1 activated AMPK, enhanced p-AMPK expression, inhibited Drp1, and reduced p-Drp1 levels, which led to increased expression of OPA1, Mfn1, and Mfn2, thereby inhibiting mitochondrial fission and facilitating mitochondrial fusion. Additionally, Rg1 effectively reversed the decrease in mitochondrial membrane potential (MMP) and the increase in ROS production induced by Aβ42 in HT22 cells, restoring SOD and ATP levels. Furthermore, Rg1 regulated mitochondrial fission mediated by the AMPK/Drp1 signaling pathway, promoting mitochondrial fusion and improving synaptic dysfunction.
Our research provides evidence for the neuroprotective mechanisms of Rg1 in AD models. Rg1 modulates mitochondrial dynamics through the AMPK/Drp1 signaling pathway, thereby reducing synaptic and mitochondrial dysfunction in APP/PS1 mice and AD cell models.
Zhang Y
，Liu S
，Cao D
，Zhao M
，Lu H
，Wang P
... -
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Vascular dysfunction occurs prior to the onset of amyloid pathology and Aβ plaque deposits colocalize with endothelial cells in the hippocampus of female APPswe/PSEN1dE9 mice.
Increasing evidence shows that cardiovascular diseases (CVDs) are associated with an increased risk of cognitive impairment and Alzheimer's diseases (AD). It is unknown whether systemic vascular dysfunction occurs prior to the development of AD, if this occurs in a sex-dependent manner, and whether endothelial cells play a role in the deposition of amyloid beta (Aβ) peptides. We hypothesized that vascular dysfunction occurs prior to the onset of amyloid pathology, thus escalating its progression. Furthermore, endothelial cells from female mice will present with an exacerbated formation of Aβ peptides due to an exacerbated pressure pulsatility. To test this hypothesis, we used a double transgenic mouse model of early-onset AD (APPswe/PSEN1dE9). We evaluated hippocampus-dependent recognition memory and the cardiovascular function by echocardiography and direct measurements of blood pressure through carotid artery catheterization. Vascular function was evaluated in resistance arteries, morphometric parameters in the aortas, and immunofluorescence in the hippocampus and aortas. We observed that endothelial dysfunction occurred prior to the onset of amyloid pathology irrespective of sex. However, during the onset of amyloid pathology, only female APP/PS1 mice had vascular stiffness in the aorta. There was elevated Aβ deposition which colocalized with endothelial cells in the hippocampus from female APP/PS1 mice. Overall, these data showed that vascular abnormalities may be an early marker, and potential mediator of AD, but exacerbated aortic stiffness and pressure pulsatility after the onset of amyloid pathology may be associated with a greater burden of Aβ formation in hippocampal endothelial cells from female but not male APP/PS1 mice.
Waigi EW
，Pernomian L
，Crockett AM
，Costa TJ
，Townsend P Jr
，Webb RC
，McQuail JA
，McCarthy CG
，Hollis F
，Wenceslau CF
... -
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Neuroprotection by chronic administration of Fluoroethylnormemantine (FENM) in mouse models of Alzheimer's disease.
Fluoroethylnormemantine (FENM), a new Memantine (MEM) derivative, prevented amyloid-β[25-35] peptide (Aβ25-35)-induced neurotoxicity in mice, a pharmacological model of Alzheimer's disease (AD) with high predictive value for drug discovery. Here, as drug infusion is likely to better reflect drug bioavailability due to the interspecies pharmacokinetics variation, we analyzed the efficacy of FENM after chronic subcutaneous (SC) infusion, in comparison with IP injections in two AD mouse models, Aβ25-35-injected mice and the transgenic APPswe/PSEN1∂E9 (APP/PS1) line.
In Aβ25-35-treated mice, FENM was infused at 0.03-0.3 mg/kg/day during one week after Aβ25-35 injection. For comparison, FENM and MEM were administered IP daily at 0.03-0.3 mg/kg. In 10-month-old APP/PS1 mice, FENM was administered during four weeks by daily IP injections at 0.3 mg/kg or chronic SC infusion at 0.1 mg/kg/day. Memory deficits, spatial working memory and recognition memory, were analysed. Markers of neuroinflammation, apoptosis, oxidative stress, and amyloid burden in APP/PS1 mice, were quantified. Markers of synaptic plasticity such as PSD-95 and GluN2A/B/D subunits expression in hippocampus homogenates or synaptosomes were quantified in Aβ25-35-treated mice and synaptic long-term potentiation (LTP) in hippocampal slices was analysed in APP/PS1 mice.
Deficits in spontaneous alternation and object recognition in Aβ25-35 mice were prevented by infused FENM at all doses tested. Similar effects were observed with the daily FENM or MEM treatments. Animals infused with 0.1 mg/kg/day FENM showed prevention of Aβ25-35-induced neuroinflammation, oxidative stress and apoptosis. FENM infusion restored Aβ25-35-induced alterations in synaptosomal PSD-95, GluN2A and P-GluN2B levels. GluN2D levels were unchanged whatever the treatment. In APP/PS1 mice, FENM infused or administered IP alleviated spontaneous alternation deficits, neuroinflammation, increases in Aβ1-40/Aβ1-42 and hippocampal LTP alteration.
These data confirmed the neuroprotective potential of FENM in the pharmacological Aβ25-35 and transgenic APP/PS1 mouse models of AD, with a superiority to MEM, and showed that the drug can be efficiently infused chronically.
Carles A
，Freyssin A
，Guehairia S
，Reguero T
，Vignes M
，Hirbec H
，Rubinstenn G
，Maurice T
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