Postsynaptic GluR2 Involved in Amelioration of Aβ-Induced Memory Dysfunction by KAIXIN-San Through Rescuing Hippocampal LTP in Mice

Classic Famous Prescription Kai-Xin-San Ameliorates Alzheimer's Disease via the Wnt/β-Catenin Signaling Pathway

Kai-Xin-San (KXS) is a classic famous prescription composed of Polygalae Radix, Ginseng Radix et Rhizoma, Acori Tatarinowii Rhizoma, and Poria. Clinically, KXS is effective in treating amnesia and regulating cognitive dysfunction of Alzheimer's disease (AD), whereas its mechanism of action is still unclear. In this study, the AD model rats were established by combining intraperitoneal injection of D-galactose (150 mg/kg/day) and intracerebral injection of Aβ25-35 (10 μL) to investigate the meliorative effect of KXS on AD and explore its mechanism. After 1-month KXS treatment, Morris water maze test showed that different doses of KXS all improved the cognitive impairment of AD rats. The results of hematoxylin and eosin staining, Nissl staining, and Tunnel staining showed that the neuron injury in the hippocampal CA1 region of the AD rats was markedly improved after KXS treatment. Concurrently, KXS reversed the levels of biochemical indexes of AD rats. Furthermore, the protein expressions of Wnt1 and β-catenin in KXS groups were remarkably increased, while the expressions of Bax and caspase-3 were significantly decreased. Besides, KXS-medicated serum reduced the levels of tumor necrosis factor-α, interleukin-1β, and reactive oxygen species and regulated the protein expressions of β-catenin, glycogen synthase kinase-3β (GSK-3β), p-GSK-3β, Bax, and caspase-3 in Aβ25-35-induced pheochromocytoma cells. Most importantly, this effect was attenuated by the Wnt inhibitor IWR-1. Our results suggest that KXS improves cognitive and memory function of AD rats, and its neuroprotective mechanism may be mediated through the Wnt/β-catenin signaling pathway.

Rivastigmine nasal spray for the treatment of Alzheimer's Disease: Olfactory deposition and brain delivery

Alzheimer's disease (AD) is characterized by a gradual decline in cognitive function and memory impairment, significantly impacting the daily lives of patients. Rivastigmine (RHT), a cholinesterase inhibitor, is used to treat mild to moderate AD via oral administration. However, oral administration is associated with slow absorption rate and severe systemic side effects. RHT nasal spray (RHT-ns), as a nose-to-brain delivery system, is more promising for AD management due to its efficient brain delivery and reduced peripheral exposure. This study constructed RHT-ns for enhancing AD treatment efficacy, and meanwhile the correlation between drug olfactory deposition and drug entering into the brain was explored. A 3D-printed nasal cast was employed to quantify the drug olfactory deposition. Brain delivery of RHT-ns was quantified using fluorescence tracking and Desorption Electrospray Ionization Mass Spectrometry (DESI-MS) analysis, which showed a good correlation to the olfactory deposition. F2 (containing 1% (w/v) viscosity modifier Avicel® RC-591) with high olfactory deposition and drug brain delivery was further investigated for pharmacodynamics study. F2 exhibited superiority in AD treatment over the commercially available oral formulation. In summary, the present study showed the successful development of RHT-ns with improved olfactory deposition and enhanced brain delivery. It might provide new insight into the design and development of nose-to-brain systems for the treatment of AD.

Constituents, pharmacological activities, pharmacokinetic studies, clinical applications, and safety profile on the classical prescription Kaixinsan

Kaixinsan (KXS) is a noteworthy classical prescription, which consists of four Chinese medicinal herbs, namely Polygalae Radix, Ginseng Radix et Rhizoma, Poria, and Acori Tatarinowii Rhizoma. KXS was initially documented in the Chinese ancient book Beiji Qianjin Yaofang written by Sun Simiao of the Tang Dynasty in 652 A.D. As a traditional Chinese medicine (TCM) prescription, it functions to nourish the heart and replenish Qi, calm the heart tranquilize the mind, and excrete dampness. Originally used to treat amnesia, it is now also effective in memory decline and applied to depression. Although there remains an abundance of literature investigating KXS from multiple aspects, few reviews summarize the features and research, which impedes better exploration and exploitation of KXS. This article intends to comprehensively analyze and summarize up-to-date information concerning the chemical constituents, pharmacology, pharmacokinetics, clinical applications, and safety of KXS based on the scientific literature, as well as to examine possible scientific gaps in current research and tackle issues in the next step. The chemical constituents of KXS primarily consist of saponins, xanthones, oligosaccharide esters, triterpenoids, volatile oils, and flavonoids. Of these, saponins are the predominant active ingredients, and increasing evidence has indicated that they exert therapeutic properties against mental disease. Pharmacokinetic research has illustrated that the crucial exposed substances in rat plasma after KXS administration are ginsenoside Re (GRe), ginsenoside Rb1 (GRb1), and polygalaxanthone III (POL). This article provides additional descriptions of the safety. In this review, current issues are highlighted to guide further comprehensive research of KXS and other classical prescriptions.

Kaixin-San improves Aβ-induced synaptic plasticity inhibition by affecting the expression of regulation proteins associated with postsynaptic AMPAR expression

Objective: To explore the mechanism underlying Kaixin-San (KXS) regulation of postsynaptic AMPA receptor (AMPAR) expression to mitigate toxic effects of the amyloid-β protein (Aβ). Methods: An animal model was established via intracerebroventricular injection of Aβ1-42. The Morris water maze test was conducted to evaluate learning and memory, while electrophysiological recording was conducted to assess the hippocampal long-term potentiation (LTP). Western blotting was used to detect expression levels of the hippocampal postsynaptic AMPAR and its accessory proteins. Results: The time spent to find the platform was significantly prolonged, the number of mice crossing the target site was significantly reduced, and the maintenance of LTP was inhibited in the Aβ group than in the control group. In the Aβ/KXS group, the time taken to find the platform was significantly shortened and the number of mice crossing the target site was significantly increased than in the Aβ group; furthermore, the inhibition of LTP induced by Aβ was reversed. The expression of GluR1, GluR2, ABP, GRIP1, NSF, and pGluR1-Ser845 was upregulated, while that of pGluR2-Ser880 and PKC δ was downregulated in the Aβ/KXS group. Conclusion: The increased expression of ABP, GRIP1, NSF, and pGluR1-Ser845 and the decreased expression of pGluR2-Ser880 and PKC δ under the influence of KXS, followed by the upregulation of postsynaptic GluR1 and GluR2, alleviated the inhibition of LTP induced by Aβ. Ultimately, the memory function of model animals was improved by KXS. Our study provides novel insights into the mechanism underlying KXS mitigation of Aβ-induced synaptic plasticity inhibition and memory impairment by altering the levels of accessory proteins associated with AMPAR expression.

Therapeutic Potential of Active Components from Acorus gramineus and Acorus tatarinowii in Neurological Disorders and Their Application in Korean Medicine

Neurological disorders represent a substantial healthcare burden worldwide due to population aging. Acorus gramineus Solander (AG) and Acorus tatarinowii Schott (AT), whose major component is asarone, have been shown to be effective in neurological disorders. This review summarized current information from preclinical and clinical studies regarding the effects of extracts and active components of AG and AT (e.g., α-asarone and β-asarone) on neurological disorders and biomedical targets, as well as the mechanisms involved. Databases, including PubMed, Embase, and RISS, were searched using the following keywords: asarone, AG, AT, and neurological disorders, including Alzheimer's disease, Parkinson's disease, depression and anxiety, epilepsy, and stroke. Meta-analyses and reviews were excluded. A total of 873 studies were collected. A total of 89 studies were selected after eliminating studies that did not meet the inclusion criteria. Research on neurological disorders widely reported that extracts or active components of AG and AT showed therapeutic efficacy in treating neurological disorders. These components also possessed a wide array of neuroprotective effects, including reduction of pathogenic protein aggregates, antiapoptotic activity, modulation of autophagy, anti-inflammatory and antioxidant activities, regulation of neurotransmitters, activation of neurogenesis, and stimulation of neurotrophic factors. Most of the included studies were preclinical studies that used in vitro and in vivo models, and only a few clinical studies have been performed. Therefore, this review summarizes the current knowledge on AG and AT therapeutic effects as a basis for further clinical studies, and clinical trials are required before these findings can be applied to human neurological disorders.

Mitochondrial Protection and Against Glutamate Neurotoxicity via Shh/Ptch1 Signaling Pathway to Ameliorate Cognitive Dysfunction by Kaixin San in Multi-Infarct Dementia Rats

Multi-infarct dementia (MID), a prominent subtype of vascular dementia (VD), is responsible for at least 15 to 20 percent of dementia in the elderly. Mitochondrial dysfunctions and glutamate neurotoxicity due to chronic hypoperfusion and oxidative stress were regarded as the major risk factors in the pathogenesis. Kaixin San (KXS), a classic prescription of Beiji Qianjin Yaofang, was applied to treatment for "amnesia" and has been demonstrated to alleviate the cognitive deficit in a variety of dementias, including MID. However, little is known whether mitochondria and glutamate are associated with the protection of KXS in MID treatment. The aim of this study was to investigate the role of KXS in improving the cognitive function of MID rats through strengthening mitochondrial functions and antagonizing glutamate neurotoxicity via the Shh/Ptch1 signaling pathway. Our data showed that KXS significantly ameliorated memory impairment and hippocampal neuron damage in MID rats. Moreover, KXS improved hippocampal mitochondrial functions by reducing the degree of mitochondrial swelling, increasing the mitochondrial membrane potential (MMP), and elevating the energy charge (EC) and ATP content in MID rats. As expected, the concentration of glutamate and the expression of p-NMDAR1 were significantly reduced by KXS in the brain tissue of MID rats. Furthermore, our results showed that KXS noticeably activated the Shh/Ptch1 signaling pathway which was demonstrated by remarkable elevations of Ptch1, Smo, and Gli1 protein levels in the brain tissue of MID rats. Intriguingly, the inhibition of the Shh signaling pathway with cyclopamine significantly inhibited the protective effects of KXS on glutamate-induced neurotoxicity in PC12 cells. To sum up, these findings suggested that KXS protected MID rats from memory loss by rescuing mitochondrial functions as well as against glutamate neurotoxicity through activating Shh/Ptch1 signaling pathway.

Integrated meta-analysis, network pharmacology, and molecular docking to investigate the efficacy and potential pharmacological mechanism of Kai-Xin-San on Alzheimer's disease

CONTEXT

Kai-Xin-San (KXS) has been used to treat Alzheimer's disease (AD) for thousands of years. However, no quantitative data regarding AD treatment using KXS are available. Moreover, its active compounds and mechanism of action for the treatment of AD remain largely unclear.

OBJECTIVES

To evaluate the efficacy and the potential pharmacological mechanisms of KXS in AD treatment.

MATERIALS AND METHODS

A systematic collection of KXS experiments was conducted from PubMed, Web of Science, Embase, CNKI, VIP, and Wanfang Data up to February, 2020. Review Manager 5 software was used for meta-analysis. In network pharmacology, components of KXS were screened, AD-related genes were then identified and the 'component-target-pathway' network constructed. Molecular docking was finally employed for in silico simulation matching between representative KXS compounds and their target genes.

RESULTS

Meta-analysis revealed that KXS improves the cognitive benefits in AD models by reducing the time of escape latency (SMD = -16.84) as well as increasing the number of cross-platform (SMD = 2.56) and proportion of time in the target quadrant (SMD = 7.52). Network pharmacology identified 25 KXS active compounds and 44 genes targets. DRD2, MAOA, ACHE, ADRA2A and CHRM2 were core target proteins. Besides, 22 potential pathways of KXS were identified, like cholinergic synapses, the cGMP/PKG pathway and calcium signalling. Molecular docking showed that stigmasterol, aposcopolamine and inermin can closely bind three targets (ACHE, ADRA2A and CHRM2).

DISCUSSION AND CONCLUSION

These findings suggest that KXS exerts effect on AD through multi-target, multi-component and multi-pathway mechanism. Future studies may explore the active components of KXS.

Acetylation of AMPA Receptors Regulates Receptor Trafficking and Rescues Memory Deficits in Alzheimer's Disease

In Alzheimer's disease (AD), decreases in the amount and synaptic localization of AMPA receptors (AMPARs) result in weakened synaptic activity and dysfunction in synaptic plasticity, leading to impairments in cognitive functions. We have previously found that AMPARs are subject to lysine acetylation, resulting in higher AMPAR stability and protein accumulation. Here we report that AMPAR acetylation was significantly reduced in AD and neurons with Aβ incubation. We identified p300 as the acetyltransferase responsible for AMPAR acetylation and found that enhancing GluA1 acetylation ameliorated Aβ-induced reductions in total and cell-surface AMPARs. Importantly, expression of acetylation mimetic GluA1 (GluA1-4KQ) in APP/PS1 mice rescued impairments in synaptic plasticity and memory. These findings indicate that Aβ-induced reduction in AMPAR acetylation and stability contributes to synaptopathy and memory deficiency in AD, suggesting that AMPAR acetylation may be an effective molecular target for AD therapeutics.

Kai-Xin-San, a Chinese Herbal Decoction, Accelerates the Degradation of β-Amyloid by Enhancing the Expression of Neprilysin in Rats

This study aimed to investigate the mechanisms of Kai-Xin-San (KXS, a famous Chinese herbal decoction used to treat amnesia) on the degradation of Aβ and further elucidate the mechanism of KXS on Aβ-induced memory dysfunction. After pretreatment with KXS (1.08 g/kg/day) for two weeks, Aβ₄₂ (2 μL, 200 μM) was injected into rat hippocampus to induce cognitive dysfunction. Morris water maze (MWM) test was developed to evaluate cognitive performance in rats. Hippocampal neurons were observed by histological staining using Hematoxylin-Eosin (HE) methods. Levels of exogenous Aβ₄₂, which was injected into the hippocampus, were continually measured through a special Enzyme-linked immunoassay (ELISA) kit to observe the catabolic process of Aβ in the brain. Similarly, Aβ degradation in PC12 cells was also investigated using the ELISA kit. The expressions of Aβ degeneration enzymes, including neprilysin (NEP), angiotensin-converting enzyme (ACE), and endothelin-converting enzyme (ECE), were detected by western blotting to elucidate Aβ reduction mechanism. Our results showed that KXS prevented Aβ₄₂-induced cognitive impairment and attenuated hippocampus neuronal damage caused by Aβ₄₂. Moreover, KXS could accelerate Aβ₄₂ degradation in Aβ₄₂ injected rats. Furthermore, NEP, an Aβ degradation enzyme, was increased in the hippocampus while ECE and ACE, other two Aβ-degrading enzymes, were not changed. KXS accelerated Aβ degradation in PC12 cells. Our findings revealed that KXS facilitated the degradation of Aβ₄₂ by increasing the expression of NEP in rat hippocampus. By reducing the Aβ burdens, KXS protected hippocampal neurons, leading to the improvement of cognitive function in rats.

The Traditional Formula Kai-Xin-San Alleviates Polyglutamine-Mediated Neurotoxicity by Modulating Proteostasis Network in Caenorhabditis elegans

The inherited polyglutamine (polyQ) expansion diseases are characterized by progressive accumulation of aggregation-prone polyQ proteins, which may provoke proteostasis imbalance and result in significant neurotoxicity. Using polyQ transgenic Caenorhabditis elegans models, we find that Kai-Xin-San (KXS), a well-known herbal formula traditionally used to treat mental disorders in China, can alleviate polyQ-mediated neuronal death and associated chemosensory deficiency. Intriguingly, KXS does not reduce polyQ aggregation in vitro as demonstrated by Thioflavin-T test, but does inhibit polyQ aggregation in C. elegans models, indicating an indirect aggregation-inhibitory mechanism. Further investigation reveals that KXS can modulate two key arms of the protein quality control system, that is, heat shock response and autophagy, to clear polyQ aggregates, but has little effect on proteasome activity. In addition, KXS is able to reduce oxidative stress, which is involved in proteostasis and neurodegeneration, but has no effect on life span or dietary restriction response. To examine potential interaction of the four component herbs of KXS, a dissection strategy was used to study the effects of differential herbal combinations in C. elegans polyQ models. While the four herbs do contribute additively to KXS function, Panax ginseng is found to be the most effective constituent. Taken together, these findings not only demonstrate the neuroprotective ability of KXS but also suggest its potential as a proteostasis regulator in protein aggregation disorders and provide an insight into the mechanism studies of traditionally used complex prescriptions and their rationality.

Kaixinsan, a Well-Known Chinese Herbal Prescription, for Alzheimer's Disease and Depression: A Preclinical Systematic Review

Alzheimer's disease (AD), the most common cause of dementia, is highly prevalent worldwide with no modifying therapy. Behavioral and psychological symptoms of dementia (BPSD) occur in most patients with AD, and depression is one of the most common AD-related BPSD. Kaixinsan (KXS) is an ancient Chinese herbal prescription widely used to treat dementia and forgetfulness. In this systematic review, we conducted a meta-analysis to assess preclinical evidence for the effects of KXS on cognitive impairment and depression. Thirty-eight articles involving 1,050 animals were included after searching from six databases from the inception up to June 2019. The primary outcome measures were behavioral outcome. Indicators of cognitive function in AD included escape latency, time spent on the target quadrant, and the number of target platform crossings in the Morris water maze (MWM) test. Indicators of depression included number of rearing events and total distance in the open-field test, duration of immobility in the forced swim test, and sucrose consumption or sucrose preference index in the sucrose preference test. The secondary outcomes were mechanisms of KXS for treatment of AD and depression. The results showed that KXS significantly reduced escape latency (P < 0.01), increased time spent in the target quadrant (P < 0.01), and increased the number of target platform crossings (P < 0.01) in the MWM test in AD models compared with control. The possible mechanisms for KXS-mediated improvements in cognitive function were antioxidant activity, anti-inflammatory activity, antiapoptotic activity, neuroprotection, and synapse protection. In addition, the results demonstrated that KXS significantly increased the number of rearing instances (P < 0.01) in the open-field test, decreased the duration of immobility (P < 0.01) in forced swim test, and increased sucrose consumption or sucrose preference index (P < 0.01) in the sucrose preference test in depression models compared with control. The mechanisms of KXS-mediated anti-depressive effects were HPA axis regulation, antioxidant activity, anti-inflammatory activity, synapse protection, and neuroprotection. The results of this study suggested that KXS can be used to effectively treat AD and depression through multiple mechanisms, extrapolating the therapeutic potential of KXS for treating AD-related BPSD.