Alpha-asarone improves cognitive function of aged rats by alleviating neuronal excitotoxicity via GABAA receptors

Efficacy and safety of acupuncture for cognitive impairment in Alzheimer's disease: a systematic review and meta-analysis

Objective

To systematically evaluate the efficacy of acupuncture in the treatment of cognitive impairment in Alzheimer's disease (AD) by meta-analysis, in order to provide evidence-based evidence for the application of acupuncture therapy in the clinical process of AD.

Methods

From the establishment of the database to December 31, 2022, China Biomedical Literature Database (CBM), China National Knowledge Network (CNKI), VIP database, WanFang Database, Pubmed, Embase and Cochrane Library Database were systematically searched. To collect published randomized controlled clinical trials (RCTS) of acupuncture in the treatment of cognitive impairment in AD. The subjects in the intervention group were given acupuncture alone or combined with other treatments the same as the control group; the control group received conventional Western medicine treatment. The main outcome indicators of the study were cognitive function assessment of subjects, including: Simple Mental State Examination Scale (MMSE), Assessment of daily Living Ability Scale (ADL), Alzheimer's Disease Cognitive Function Assessment Scale (ADAS-Cog), TCM syndrome score (SDSD), Montreal Cognitive Test (MoCA), Secondary outcome indicators were the occurrence of adverse reactions. Literature screening, data extraction, and quality evaluation of the included literature were performed independently by two researchers, according to bias risk assessment tools recommended in the Cochrane manual. Data were analyzed by RevMan5.3 software. Dichotomous variables were represented by risk ratio (OR) and 95% CI, and continuity variables were represented by mean difference (MD) and 95% CI. For heterogeneity analysis, when P > 0.1 and I 2 ≤ 50%, fixed effect model was applied. When P ≤ 0.1 and I 2 > 50%, the random effects model is applied.

Results

A total of 1,172 eligible subjects were included in 18 RCTS, including 595 in the intervention group and 577 in the control group. The results of meta-analysis are as follows: acupuncture intervention group improved MMSE [MD = 1.67, 95% CI (0.94, 2.41), P < 0.00001], ADL [MD = -1.18, 95% CI (-3.09, 0.72), P = 0.22], ADAS-Cog [MD = 3.31, 95% CI (5.84, 0.78), P = 0.01], SDSD [MD = 2.40, 95% CI (3.53, 1.26), P < 0.0001], MoCA [MD = 4.80, 95% CI (3.74, 5.86), P = 0.04] were better than the control group. No serious adverse reactions related to acupuncture were observed in the intervention group, and the incidence and severity of adverse reactions were lower than those in the control group, with statistical significance [OR = 0.17, 95% CI (0.04, 0.67), P = 0.01].

Conclusion

Existing data show that acupuncture therapy has certain advantages in improving cognitive dysfunction and improving self-care ability of patients with Alzheimer's disease. However, due to the small number of RCTS and cases evaluating the efficacy of acupuncture, and the possibility of measurement bias and selectivity bias in included studies, it is still unable to conduct high-intensity demonstration on its effectiveness. Further large-scale, high-quality randomized, double-blind controlled trials are needed to evaluate its efficacy.

Systematic Review Registration

https://inplasy.com/inplasy-2021-12-0125/, identifier: INPLASY2021120125.

Alpha-Asarone Ameliorates Neurological Dysfunction of Subarachnoid Hemorrhagic Rats in Both Acute and Recovery Phases via Regulating the CaMKII-Dependent Pathways

Early brain injury (EBI) is the leading cause of poor prognosis for patients suffering from subarachnoid hemorrhage (SAH), particularly learning and memory deficits in the repair phase. A recent report has involved calcium/calmodulin-dependent protein kinase II (CaMKII) in the pathophysiological process underlying SAH-induced EBI. Alpha-asarone (ASA), a major compound isolated from the Chinese medicinal herb Acorus tatarinowii Schott, was proven to reduce secondary brain injury by decreasing CaMKII over-phosphorylation in rats' model of intracerebral hemorrhage in our previous report. However, the effect of ASA on SAH remains unclear, and the role of CaMKII in both acute and recovery stages of SAH needs further investigation. In this work, we first established a classic SAH rat model by endovascular perforation and intraperitoneally administrated different ASA doses (10, 20, and 40 mg/kg) 2 h after successful modeling. Then, the short- and long-term neurobehavioral performances were blindly evaluated to confirm ASA's efficacy against SAH. Subsequently, we explored ASA's therapeutic mechanism in both acute and recovery stages using histopathological examination, TUNEL staining, flow cytometry, Western-blot, double-immunofluorescence staining, and transmission electron microscopy (TEM) observation. Finally, KN93, a selective CaMKII inhibitor, was applied in oxyhemoglobin-damaged HT22 cells to explore the role of CaMKII in ASA's neuroprotective effect. The results demonstrated that ASA alleviated short- and long-term neurological dysfunction, reduced mortality and seizure rate within 24 h, and prolonged 14-day survival in SAH rats. Histopathological examination showed a reduction of neuronal damage and a restoration of the hippocampal structure after ASA treatment in both acute and recovery phases of SAH. In the acute stage, the Western-blot and flow cytometer analyses showed that ASA restored E/I balance, reduced calcium overload and CaMKII phosphorylation, and inhibited mitochondrion-involved apoptosis, thus preventing neuronal damage and apoptosis underlying EBI post-SAH. In the recovery stage, the TEM observation, double-immunofluorescence staining, and Western-blot analyses indicated that ASA increased the numbers of synapses and enhanced synaptic plasticity in the ipsilateral hippocampi, probably by promoting NR2B/CaMKII interaction and activating subsequent CREB/BDNF/TrkB signaling pathways. Furthermore, KN93 notably reversed ASA's neuroprotective effect on oxyhemoglobin-damaged HT22 cells, confirming CaMKII a potential target for ASA's efficacy against SAH. Our study confirmed for the first time that ASA ameliorated the SAH rats' neurobehavioral deterioration, possibly via modulating CaMKII-involved pathways. These findings provided a promising candidate for the clinical treatment of SAH and shed light on future drug discovery against SAH.

Therapeutic potential of natural products against Alzheimer's disease via autophagic removal of Aβ

The pathological features of Alzheimer's disease (AD), a progressive neurodegenerative disorder, include the deposition of extracellular amyloid beta (Aβ) plaques and intracellular tau neurofibrillary tangles. A decline in cognitive ability is related to the accumulation of Aβ in patients with AD. Autophagy, which is a primary intracellular mechanism for degrading aggregated proteins and damaged organelles, plays a crucial role in AD. In this review, we summarize the most recent research progress regarding the process of autophagy and the effect of autophagy on Aβ. We further discuss some typical monomers of natural products that contribute to the clearance of Aβ by autophagy, which can alleviate AD. This provides a new perspective for the application of autophagy modulation in natural product therapy for AD.

Ethnic, Botanic, Phytochemistry and Pharmacology of the Acorus L. Genus: A Review

The genus Acorus, a perennial monocotyledonous-class herb and part of the Acoraceae family, is widely distributed in the temperate and subtropical zones of the Northern and Southern Hemispheres. Acorus is rich in biological activities and can be used to treat various diseases of the nervous system, cardiovascular system, and digestive system, including Alzheimer's disease, depression, epilepsy, hyperlipidemia, and indigestion. Recently, it has been widely used to improve eutrophic water and control heavy-metal-polluted water. Thus far, only three species of Acorus have been reported in terms of chemical components and pharmacological activities. Previously published reviews have not further distinguished or comprehensively expounded the chemical components and pharmacological activities of Acorus plants. By carrying out a literature search, we collected documents closely related to Acorus published from 1956 to 2022. We then performed a comprehensive and systematic review of the genus Acorus from different perspectives, including botanical aspects, ethnic applications, phytochemistry aspects, and pharmacological aspects. Our aim was to provide a basis for further research and the development of new concepts.

Benzene, 1,2,4-trimethoxy-5-(2-methyl-1-propen-1-yl) Attenuates D-galactose /AlCl3-induced Cognitive Impairment by Inhibiting Inflammation, Apoptosis, and Improving ExpressionofMemory-Related Proteins

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by decreased learning ability and memory deficits. Our previous findings suggested that benzene, 1,2,4-trimethoxy-5-(2-methyl-1-propen-1-yl) (BTY) can ameliorate the dysfunction of GABAergic inhibitory neurons associated with neurological diseases. On this basis, we investigated the neuroprotective effect of BTY on AD and explored the underlying mechanism. This study included in vitro and in vivo experiments. BTY could maintain cell morphology, improve cell survival rate, reduce cell damage, and inhibit cell apoptosis in vitro experiments. Further, BTY has good pharmacological activity in vivo experiments, of which behavioral experiments showed that BTY could improve AD-like mice's learning and memory abilities. Besides, histopathological experiments indicated that BTY could maintain the morphology and function of neurons, reduce amyloid β-protein 42 (Aβ₄₂) and phosphorylated tau (p-tau) accumulation, and decrease the levels of inflammatory cytokines. Finally, western blot experiments showed that BTY could inhibit the expression of apoptosis-related proteins and promote the expression of memory-related proteins. In conclusion, this study indicated that BTY may be a promising drug candidate for AD.

Acorus calamus var. angustatus Besser: Insight into current research on ethnopharmacological use, phytochemistry, pharmacology, toxicology, and pharmacokinetics

A. calamus var. angustatus Besser is an important traditional medicinal herb commonly used in China and other Asian countries. This study is the first systematic review of the literature to thoroughly analyze the ethnopharmacological application, phytochemistry, pharmacology, toxicology and pharmacokinetic properties of A. calamus var. angustatus Besser and provides a rationale for future research and prospects for application in clinical treatment. Information on relevant studies investigating A. calamus var. angustatus Besser was collected from SciFinder, the Web of Science, PubMed, CNKI, Elsevier, ResearchGate, ACS, Flora of China, and Baidu Scholar, etc. up to December 2022. In addition, information was also obtained from Pharmacopeias, books on Chinese herbal classics, local books, as well as PhD and MS dissertations. A. calamus var. angustatus Besser has played an important role in the herbal treatment of coma, convulsion, amnesia, and dementia for thousands of years. Studies investigating the chemical constituents of A. calamus var. angustatus Besser have isolated and identified 234 small-molecule compounds and a few polysaccharides. Among them, simple phenylpropanoids represented by asarone analogues and lignans are the two main active ingredients, which can be considered characteristic chemotaxonomic markers of this herb. In vitro and in vivo pharmacological studies indicated that crude extracts and active compounds from A. calamus var. angustatus Besser display a wide range of pharmacological activities, especially as treatment for Alzheimer's disease (AD), and anticonvulsant, antidepressant-like, anxiolytic-like, anti-fatigue, anti-Parkinson, neuroprotection, and brain protection properties, providing more evidence to explain the traditional medicinal uses and ethnopharmacology. The clinical therapeutic dose of A. calamus var. angustatus Besser does not present any toxic effects, but its main active ingredients α-asarone and β-asarone at excessive dose may lead to toxicity, and in particular, their respective epoxide metabolites may exert potential toxicity to the liver. This review provides a reference and further information for the future development and clinical application of A. calamus var. angustatus Besser.

Alpha-asaronol promoted oligodendrocyte precursor cell differentiation and improved myelination as an activator PPARγ

Preterm white matter injury (PWMI), characterized by oligodendrocyte precursor cell (OPC) differentiation disorder and dysmyelination, is a prevalent demyelinating disease of the central nervous system in premature infants, necessitating the development of mitigating strategies. Convincing evidence suggests that peroxisome proliferator-activated receptor γ (PPARγ) activation is a stimulative factor against the hindered process of oligodendrocyte (OL) differentiation. However, much remains unknown about its promotive mechanism. Our previous study indicated that alpha-asaronol (α-asaronol) could alleviate myelination disorder in a neonatal PWMI rat model, but the mechanism remained unclear. In this study, we demonstrated that α-asaronol attenuated cognitive deficits, repaired myelin damage, and stimulated OL differentiation in the corpus callosum of PWMI rats. Co-immunoprecipitation analysis confirmed that α-asaronol induced the binding of PPARγ with its coactivator peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), which in turn activated oligodendroglial PPARγ. This activation subsequently upregulated the expression of phosphatase and tensin homolog (PTEN) and pro-differentiation-associated genes of Cnp1 and Klk6 and downregulated the expression of Clk1. However, the benefits of α-asaronol were blocked by GW9662, an antagonist of PPARγ. Moreover, α-asaronol also promoted OPC differentiation under oxygen-glucose deprivation conditions. In conclusion, α-asaronol can promote OL differentiation and myelination and alleviate cognitive deficits in neonatal PWMI rats by activating PPARγ and modulating OL differentiation-associated gene expression. This study suggests that α-asaronol may be a potential therapeutic drug for myelination failure in PWMI.

Network pharmacology-based prediction and validation of the active ingredients and potential mechanisms of the Huangxiong formula for treating ischemic stroke

ETHNOPHARMACOLOGICAL RELEVANCE

Huangxiong Formula (HXF) is composed of four herbs: Rheum palmatum L., Ligusticum striatum DC., Curcuma aromatica Salisb., and Acorus gramineus Aiton. HXF is clinically used for the treatment of ischemic stroke (IS). However, its molecular mechanism remains unclear.

AIM OF THE STUDY

A network pharmacology-based strategy combined with experimental study in vivo and in vitro to were used to investigate the bioactive components, potential targets, and molecular mechanisms of HXF in the treatment of IS.

MATERIALS AND METHODS

The components of HXF were detected by ultra-performance liquid chromatography (UPLC). The potential active ingredients of HXF were acquired from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) and literature, and corresponding targets were discerned through the Swiss TargetPrediction database. IS-related targets were obtained from Genecards, Online Mendelian Inheritance in Man (OMIM), Therapeutic Target Database (TTD), and DisGeNET. The intersection of ingredient and disease targets was screened, and a herbal-compound-target network was constructed. A protein-protein interaction (PPI) network was created, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed. Based on these analyses, we established a compound-target-pathway (C-T-P) network. A cerebral ischemia-reperfusion (I/R) animal model was established, and the cerebral protective effect of HXF was assessed. The accuracy of the predicted targets was verified by real-time quantitative polymerase chain reaction (RT-qPCR). Hippocampal neuronal injury cell model induced by oxygen-glucose deprivation and reperfusion (OGD/R) was used to evaluate the protective effect of α-Asarone. Furthermore, molecular docking, drug affinity responsive target stability (DARTS) assay, and cellular thermal shift assay (CETSA) were performed to verify whether α-Asarone can bind to PI3K.

RESULTS

A total of 44 active ingredients and 795 gene targets were identified through network pharmacology. Network analysis showed that naringenin, eupatin, kaempferol, and α-Asarone were possible drug candidates. SRC, AKT1, TP53, MAPK3, STAT3, HRAS, CTNNB1, EGFR, VEGFA, PIK3R1 could serve as potential drug targets. KEGG analysis implied that the PI3K/AKT signaling pathway might play an important role in treating IS by HXF. Moreover, HXF significantly reduced neurological impairment, cerebral infarct volume, brain index, and brain histopathological damage in I/R rats. The mRNA expression of the top 10 potential targets was verified in the brain tissue. The C-T-P network and UPLC analysis suggested that α-Asarone might be an important component of HXF and can inhibit oxidative stress and apoptosis in HT22 cells by activating the PI3K/AKT signaling pathway. Molecular docking, DARTS, and CETSA assay analysis confirmed that there were direct interactions between α-Asarone and PI3K.

CONCLUSION

HXF had a therapeutic effect in IS with multi-component, multi-target, and multi-approach features. α-Asarone, identified as one of the major active components of HXF, could alleviate oxidative stress and apoptosis by targeting PI3K/AKT pathway.

Alpha-Asarone modulates kynurenine disposal in muscle and mediates resilience to stress-induced depression via PGC-1α induction

INTRODUCTION

Kynurenine (KYN) accumulation in periphery induces brain injury, responsible for depression. α-Asarone is a simple phenylpropanoids that exerts beneficial effects on central nervous system. However, the effect of α-asarone on periphery is unexplored.

AIMS

Here, we investigated its protective role against depression from the aspect of KYN metabolism in skeletal muscle.

METHODS

The antidepressant effects of α-asarone were evaluated in chronic mild stress (CMS) and muscle-specific PGC-1α-deficient mice. The effects of KYN metabolism were determined in mice and C2C12 myoblasts.

RESULTS

α-Asarone exerted antidepressant effects in CMS and KYN-challenged mice via modulating KYN metabolism. In myoblasts, α-asarone regulated PGC-1α induction via cAMP/CREB signaling and upregulated KYN aminotransferases (KATs) to increase KYN clearance in a manner dependent on PGC-1α. KAT function is coupled with malate-aspartate shuttle (MAS), while α-asarone combated oxidative stress to protect MAS and mitochondrial integrity by raising the NAD⁺ /NADH ratio, ensuring effective KYN disposal. In support, the antidepressant effect of α-asarone was diminished by muscle-specific PGC-1α deficient mice subjected to KYN challenge.

CONCLUSION

KATs coupled with MAS to clear KYN in muscle. α-Asarone increased PGC-1α induction and promoted KYN disposal in muscle, suggesting that protection of mitochondria is a way for pharmacological intervention to depression.

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.

Bidirectional effects and mechanisms of traditional Chinese medicine

ETHNOPHARMACOLOGICAL RELEVANCE

The bidirectional property of traditional Chinese medicines (TCMs) was recorded in the classic work Medicine Origin (Yi Xue Qi Yuan) as early as the Jin and Yuan dynasties of ancient China. Since then, this imperative theory has been applied to guide the clinical application of TCMs. Studies have been performed to investigate this phenomenon only over the last three decades. A limited number of reviews on the bidirectional role of TCMs have been published, and almost all current studies are published in the Chinese language.

AIM OF THE REVIEW

The aim of this review is to provide the first comprehensive evidence regarding the bidirectional effects and the underlying mechanisms of TCMs and their active compounds.

MATERIALS AND METHODS

Information relevant to opposing pharmacological activities or opposing properties exerted by TCM prescriptions, herbal medicines, and their active compound, as well as their mechanisms was summarized by searching Chinese and English databases, including the Chinese National Knowledge Infrastructure (CNKI), Wan Fang Data, Chinese Scientific Journal Database (VIP), Google Scholar, PubMed, Web of Science, Science Direct, and Wiley Online Library.

RESULTS

Although the bidirectional regulation of TCMs has been applied in the clinic since ancient times in China, only limited reviews have been published in Chinese. The existing data showed that bidirectional effects can be found in TCM prescriptions, herbal medicines, and pure active compounds. Additionally, the bidirectional role of TCMs was primarily reported in the modulation of immune function, blood circulation and hemostasis, gastrointestinal motility, the central nervous system and blood pressure. This may because the therapeutic outcomes of these disorders are more obvious than those of other complicated diseases. Intriguingly, some herbal medicines have multiple bidirectional activities; for instance, Panax ginseng C. A. Meyer showed bidirectional regulation of immune function and the central nervous system; Astragalus membranaceus can bidirectionally regulate blood pressure and immune function; and Rheum officinale Baill exerts bidirectional effects on blood circulation and hemostasis, gastrointestinal motility and immune function. The mechanisms underlying the bidirectional effects of TCMs are largely attributed to the complexity of herbal constituents, dosage differences, the processing of herbal medicine, and compatibility of medicines, the physiological conditions of patients and adaptogenic effects.

CONCLUSION

Uncovering the bidirectional effects and mechanisms of TCMs is of great importance for both scientific research and clinical applications. This review may help to facilitate the recognition of the bidirectional role of TCMs, to explain some seemingly-opposite phenomena in the pharmacological study of herbal medicines and to provide guidance for TCM practitioners.

Alpha-asarone ameliorates neurological deterioration of intracerebral hemorrhagic rats by alleviating secondary brain injury via anti-excitotoxicity pathways

BACKGROUND

Secondary brain injury (SBI) has been confirmed as a leading cause for the poor prognosis of patients suffering from intracerebral hemorrhage (ICH). SBI co-exists in ischemia and hemorrhagic stroke. Neuro-excitotoxicity is considered the initiating factor of ICH-induced SBI. Our previous research has revealed alpha-asarone (ASA)'s efficacy against cerebral ischemia-reperfusion stroke by mitigating neuro-excitotoxicity. It is not yet known if ASA exhibit neuroprotection against ICH.

PURPOSE

This work aimed to investigate ASA's therapeutic effects and potential mechanisms of action against ICH in a classic rat model induced by collagenase Ⅶ injection.

METHODS

An in vivo ICH model of Sprague-Dawley rats was established by collagenase Ⅶ injection. We administrated different ASA doses (10, 20, or 40 mg/kg, i.p.) at 2 h post-ICH. Then, rats' short- and long-term neurobehavioral function, bodyweight change, and learning and memory ability were blindly evaluated. Histological, Nissl, and flow cytometry were applied to assess the neuronal damage post-ICH. The wet/dry method and Evans blue extravasation estimated brain edema and blood-brain barrier function. Pathway-related proteins were investigated by immunofluorescence staining, enzyme-linked immunosorbent assay, and Western-blot analysis.

RESULTS

The results demonstrated that ASA ameliorated neurological deterioration, bodyweight loss, and learning and memory ability of ICH rats. Histological, Nissl, and flow cytometry analyses showed that ASA reduced neuronal damage and apoptosis post-ICH. Besides, ASA probably mitigated brain edema and blood-brain barrier dysfunction via inhibiting astrocyte activation and consequent pro-inflammatory response. The mechanism investigation attributed ASA's efficacy to the following aspects: 1) promoting sodium ion excretion, thus blocking excitatory signal transduction along the axon; 2) preventing glutamate-involved pathways, i.e., decrease of N-methyl-d-aspartic acid receptor subunit 2B, increase of glutamate transporter-1, and alleviation of calcium-related cascades, mitochondrion-associated apoptosis, and neuronal autophagy; 3) enhancing the expression of GABA_ARs, thus abating neuronal excitotoxicity.

CONCLUSION

Our study first confirmed the effect of ASA on ameliorating the neurobehavioral deterioration of ICH rats, possibly via alleviation of glutamate-involved neuro-excitotoxicity, i.e., calcium cascades, mitochondrion-involved apoptosis, neuronal autophagy, and astrocyte-related inflammation. These findings not only provided a promising drug candidate for clinical treatment of ICH but also shed light on the future drug discovery against ICH.

Alpha-Asaronol Alleviates Dysmyelination by Enhancing Glutamate Transport Through the Activation of PPARγ-GLT-1 Signaling in Hypoxia-Ischemia Neonatal Rats

Preterm white matter injury (PWMI) is the most common form of brain damage in premature infants caused by hypoxia-ischemia (HI), inflammation, or excitotoxicity. It is characterized by oligodendrocyte precursor cell (OPC) differentiation disorder and dysmyelination. Our previous study confirmed that alpha-asarone (α-asaronol), a major compound isolated from the Chinese medicinal herb Acorus gramineus by our lab, could alleviate neuronal overexcitation and improve the cognitive function of aged rats. In the present study, we investigated the effect and mechanism of α-asaronol on myelination in a rat model of PWMI induced by HI. Notably, α-asaronol promoted OPC differentiation and myelination in the corpus callosum of PWMI rats. Meanwhile, the concentration of glutamate was significantly decreased, and the levels of PPARγ and glutamate transporter 1 (GLT-1) were increased by α-asaronol treatment. In vitro, it was also confirmed that α-asaronol increased GLT-1 expression and recruitment of the PPARγ coactivator PCG-1a in astrocytes under oxygen and glucose deprivation (OGD) conditions. The PPARγ inhibitor GW9662 significantly reversed the effect of α-asaronol on GLT-1 expression and PCG-1a recruitment. Interestingly, the conditioned medium from α-asaronol-treated astrocytes decreased the number of OPCs and increased the number of mature oligodendrocytes. These results suggest that α-asaronol can promote OPC differentiation and relieve dysmyelination by regulating glutamate levels via astrocyte PPARγ-GLT-1 signaling. Although whether α-asaronol binds to PPARγ directly or indirectly is not investigated here, this study still indicates that α-asaronol may be a promising small molecular drug for the treatment of myelin-related diseases.

Molecular Mechanisms and Therapeutic Potential of α- and β-Asarone in the Treatment of Neurological Disorders

Neurological disorders are important causes of morbidity and mortality around the world. The increasing prevalence of neurological disorders, associated with an aging population, has intensified the societal burden associated with these diseases, for which no effective treatment strategies currently exist. Therefore, the identification and development of novel therapeutic approaches, able to halt or reverse neuronal loss by targeting the underlying causal factors that lead to neurodegeneration and neuronal cell death, are urgently necessary. Plants and other natural products have been explored as sources of safe, naturally occurring secondary metabolites with potential neuroprotective properties. The secondary metabolites α- and β-asarone can be found in high levels in the rhizomes of the medicinal plant Acorus calamus (L.). α- and β-asarone exhibit multiple pharmacological properties including antioxidant, anti-inflammatory, antiapoptotic, anticancer, and neuroprotective effects. This paper aims to provide an overview of the current research on the therapeutic potential of α- and β-asarone in the treatment of neurological disorders, particularly neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), as well as cerebral ischemic disease, and epilepsy. Current research indicates that α- and β-asarone exert neuroprotective effects by mitigating oxidative stress, abnormal protein accumulation, neuroinflammation, neurotrophic factor deficit, and promoting neuronal cell survival, as well as activating various neuroprotective signalling pathways. Although the beneficial effects exerted by α- and β-asarone have been demonstrated through in vitro and in vivo animal studies, additional research is required to translate laboratory results into safe and effective therapies for patients with AD, PD, and other neurological and neurodegenerative diseases.

Combination of Polygoni Multiflori Radix Praeparata and Acori Tatarinowii Rhizoma Alleviates Learning and Memory Impairment in Scopolamine-Treated Mice by Regulating Synaptic-Related Proteins

Polygoni Multiflori Radix Praeparata (ZhiHeShouWu, PMRP) and Acori Tatarinowii Rhizoma (ShiChangPu, ATR) and their traditional combination (PA) are frequently used in traditional Chinese medicine to prevent and treat Alzheimer disease (AD) based on the theory that PMRP tonifies the kidney and ATR dissipates phlegm. However, the components of PA and their mechanisms of action are not known. The present study analyzed the active components of PA, and investigated the protective effect of PA against cognitive impairment induced by scopolamine in mice along with the underlying mechanism.The aqueous extract of PA was analyzed by high-performance liquid chromatography–mass spectrometry (HPLC-MS) and gas chromatography (GC)-MS in order to identify the major components. To evaluate the protective effect of PA against cognitive dysfunction, mice were orally administered PA, PMRP, or ATR for 30 days before treatment with scopolamine. Learning and memory were assessed in mice with the Morris water maze test; neurotransmitter levels in the hippocampus were analyzed by HPLC-MS; and the expression of synapse-related proteins in the hippocampus was detected by western blotting and immunohistochemistry. Eight active compounds in PA and rat plasma were identified by HPLC-MS and GC-MS. Plasma concentrations of 2,3,5,4′-tetrahydroxystilbene-2-O-β-d-glucoside, emodin, α-asarone, and asarylaldehyde were increased following PA administration; meanwhile, gallic acid, emodin-8-O-β-d-glucopyranoside, β-asarone, and cis-methyl isoeugenol concentrations were similar in rats treated with PA, PMRP, and ATR. In scopolamine-treated mice, PA increased the concentrations of neurotransmitters in the hippocampus, activated the brain-derived neurotrophic factor (BDNF)/extracellular signal-regulated kinase (ERK)/cAMP response element binding protein (CREB) signaling pathway, and increased the expression of p90 ribosomal S6 kinase (p90RSK) and postsynaptic density (PSD)95 proteins. Thus, PA alleviates cognitive deficits by enhancing synaptic-related proteins, suggesting that it has therapeutic potential for the treatment of aging-related diseases such as AD.

Traditional Chinese Medicine Intervenes in Vascular Dementia: Traditional Medicine Brings New Expectations

Vascular dementia (VD) is one of the most common forms of dementia, referring to a group of symptoms that mainly manifest as advanced neurocognitive dysfunction induced by cerebrovascular disease (CVD). A significant number of studies have shown that traditional Chinese medicine (TCM) has a clinical impact on VD and thus has promising prospects. There have been many discussions regarding the pharmacological mechanisms involved in treatment of the kidney, elimination of turbidity, and promotion of blood circulation. TCM has a prominent effect on improving patients’ cognitive function and quality of life. In this review, we summarize the pathogenesis of VD in modern medicine and TCM, traditional prescriptions, single-agent effective ingredients and their pharmacological mechanisms for treating VD, highlight TCM’s characteristics, and discuss TCM’s multi-targeted mechanism for the treatment of VD.

Comprehensive Quality Assessment of Kaixin Powder by HPLC-DAD Quantification and HPLC-QTOF-MS/MS Confirmation

Kaixin Powder (KXP) is a classic formula for treating morbid forgetfulness in ancient China. To guarantee the efficacy and safety of KXP, a simple and accurate HPLC-DAD method has been established and validated for the quantitative analysis of seven bioactive compounds in KXP. Dehydrotumulosic acid (DTU) and dehydrotrametenolic acid (DTR) were quantified in KXP for the first time. Good chromatographic separation was conducted on a Kromasil 100-5 C₁₈ column (250 mm × 4.6 mm, 5 μm) by gradient elution using mobile phases containing acetonitrile and 0.1% formic acid aqueous solution at different detection wavelengths. The calibration curves of each compound showed good linearity (r ≥ 0.9990), and the LOD and LOQ were in the ranges of 0.01-0.10 and 0.03-0.40 μg/mL, respectively. The relative standard deviations (RSDs) of intra-day and inter-day precisions were in the ranges of 0.45-1.74% and 0.56-2.32%, respectively. All recoveries were in the range of 93.6-105.5% with an RSD no more than 2.77%. These quantification results of seven compounds determined in the samples were further confirmed by HPLC-QTOF-MS/MS. This study provides a useful and simple method for analyzing the major bioactive compounds and improves the quality assessment research of KXP.

Filling the Gap in Understanding the Mechanism of GABAAR and Propofol Using Computational Approaches

γ-Aminobutyric acid type-A receptors (GABA_ARs) play a critical role in neural transmission by mediating the inhibitory neural firing and are the target of many psychiatric drugs. Among them, propofol is one of the most widely used and important general anesthetics in clinics. Recent advances in structural biology revealed the structure of a human GABA_AR in both open and closed states. Yet, the detailed mechanism of the receptor and propofol remains to be fully understood. Therefore, in this study, based on the previous successes in structural biology, a variety of computational techniques were applied to fill the gap between previous experimental studies. This study investigated the ion-conducting mechanism of GABA_AR, predicted the possible binding mechanism of propofol, and revealed a new motion mechanism of transmembrane domain (TMD) helices. We hope that this study may contribute to future studies on ion-channel receptors, general anesthetics, and drug development.

Alpha-asarone Improves Cognitive Function of APP/PS1 Mice and Reducing Aβ42, P-tau and Neuroinflammation, and Promoting Neuron Survival in the Hippocampus

Alzheimer's disease (AD) is a progressive neurodegenerative disease most often characterized by memory impairment and cognitive decline. Alpha-asarone has been reported to have the potential to treat AD. Our previous studies have found that alpha-asarone improves aged rats' cognitive function by alleviating neuronal excitotoxicity via type A gamma-aminobutyric acid (GABA) receptors. GABA level's change, neuroinflammation, and dysfunctional autophagy are found to be associated with AD. However, the effect of alpha-asarone on cognitive function of APP/PS1 transgenic mice and its underlying mechanism in terms of aggregation of amyloid-β42 (Aβ₄₂) and phosphorylated tau (p-tau), glutamic acid decarboxylase (GAD) level, neuroinflammation, and autophagy are unclear. Accordingly, we attempted to explore whether alpha-asarone improves AD mice's cognitive function and alleviates pathological symptoms by regulating GAD level, inhibiting neuroinflammation, or restore autophagy. We found that alpha-asarone enhanced spatial learning memory and decreased Aβ₄₂ and p-tau levels without influencing the GAD level in APP/PS1 transgenic mice. Also, it decreased the GFAP expression and reduced pro-inflammatory cytokines levels, thus alleviating neuroinflammation. Furthermore, alpha-asarone decreased the excess number of autophagosomes and promoted hippocampal neurons' survival. In conclusion, the results confirmed the therapeutic effect of alpha-asarone on AD-related astrogliosis, dysfunctional autophagy, and neuronal damage, which indicates its great potential to treat AD.

GABAergic Inhibitory Interneuron Deficits in Alzheimer's Disease: Implications for Treatment

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized clinically by severe cognitive deficits and pathologically by amyloid plaques, neuronal loss, and neurofibrillary tangles. Abnormal amyloid β-protein (Aβ) deposition in the brain is often thought of as a major initiating factor in AD neuropathology. However, gamma-aminobutyric acid (GABA) inhibitory interneurons are resistant to Aβ deposition, and Aβ decreases synaptic glutamatergic transmission to decrease neural network activity. Furthermore, there is now evidence suggesting that neural network activity is aberrantly increased in AD patients and animal models due to functional deficits in and decreased activity of GABA inhibitory interneurons, contributing to cognitive deficits. Here we describe the roles played by excitatory neurons and GABA inhibitory interneurons in Aβ-induced cognitive deficits and how altered GABA interneurons regulate AD neuropathology. We also comprehensively review recent studies on how GABA interneurons and GABA receptors can be exploited for therapeutic benefit. GABA interneurons are an emerging therapeutic target in AD, with further clinical trials urgently warranted.

The PERK-Dependent Molecular Mechanisms as a Novel Therapeutic Target for Neurodegenerative Diseases

Higher prevalence of neurodegenerative diseases is strictly connected with progressive aging of the world population. Interestingly, a broad range of age-related, neurodegenerative diseases is characterized by a common pathological mechanism-accumulation of misfolded and unfolded proteins within the cells. Under certain circumstances, such protein aggregates may evoke endoplasmic reticulum (ER) stress conditions and subsequent activation of the unfolded protein response (UPR) signaling pathways via the protein kinase RNA-like endoplasmic reticulum kinase (PERK)-dependent manner. Under mild to moderate ER stress, UPR has a pro-adaptive role. However, severe or long-termed ER stress conditions directly evoke shift of the UPR toward its pro-apoptotic branch, which is considered to be a possible cause of neurodegeneration. To this day, there is no effective cure for Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), or prion disease. Currently available treatment approaches for these diseases are only symptomatic and cannot affect the disease progression. Treatment strategies, currently under detailed research, include inhibition of the PERK-dependent UPR signaling branches. The newest data have reported that the use of small-molecule inhibitors of the PERK-mediated signaling branches may contribute to the development of a novel, ground-breaking therapeutic approach for neurodegeneration. In this review, we critically describe all the aspects associated with such targeted therapy against neurodegenerative proteopathies.