Danshensu attenuates scopolamine and amyloid-β-induced cognitive impairments through the activation of PKA-CREB signaling in mice

Buyang huanwu decoction improves synaptic plasticity of ischemic stroke by regulating the cAMP/PKA/CREB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Ischemic stroke is an acute central nervous system disease that poses a threat to human health. It induces a series of severe pathological mechanisms, ultimately leading to neuronal cell death in the brain due to local ischemia and hypoxia. Buyang Huanwu decoction (BYHWD), as a representative formula for treating ischemic stroke, has shown good therapeutic effects in stroke patients.

AIM OF THE STUDY

This study aimed to explore the mechanism of BYHWD in promoting neural remodeling after ischemic stroke from the perspective of neuronal synaptic plasticity, based on the cAMP/PKA/CREB signaling pathway.

MATERIALS AND METHODS

A modified suture technique was employed to establish a rat model of MCAO. The rats were divided into sham, model, and BYHWD (20 g/kg) groups. After the corresponding intervention, rat brains from each group were collected. TMT quantitative proteomics technology was employed for the research. Following proteomics studies, we investigated the mechanism of BYHWD in the intervention of ischemic stroke through animal experiments and cell experiments. The experimental animals were divided into sham, model, and BYHWD (5 g/kg, 10 g/kg, and 20 g/kg) groups. Infarct volume and severity of brain injury were measured by TTC staining. HE staining was utilized to evaluate alterations in tissue morphology. The Golgi staining was used to observe changes in cell body, dendrites, and dendritic spines. Transmission electron microscopy was used to observe the ultrastructure of synapses in the cortex and hippocampus. TUNEL staining was conducted to identify apoptotic neurons. Meanwhile, a stable and reliable (OGD/R) SH-SY5Y cell model was established. The effect of BYHWD-containing serum on SH-SY5Y cell viability was measured by CCK-8 kit. The apoptosis situation of SH-SY5Y cells was determined by Annexin V-FITC/PI. Immunofluorescence was employed to measure the fluorescence intensity of synaptic-related factors Syt1, Psd95, and Syn1. Synaptic plasticity pathways were assessed by using RT-qPCR and Western blot to determine the expression levels of cAMP, Psd95, Prkacb, Creb1/p-Creb1, BDNF, Shank2, Syn1, Syt1, Bcl-2, Bcl-2/Bax mRNA and proteins.

RESULTS

After treatment with BYHWD, notable alterations were detected in the signaling pathways linked to synaptic plasticity and the cAMP signaling pathway-related targets among the intervention targets. This trend of change was also reflected in other bioinformatics analyses, indicating the important role of synaptic plasticity changes before and after modeling and drug intervention. The results of vivo and vitro experiments showed that BYHWD improved local pathological changes, and reduced cerebral infarct volume, and neurological function scores in MCAO rats. It increased dendritic spine density, improved synaptic structural plasticity, and had a certain neuroprotective effect. BYHWD increased the postsynaptic membrane thickness, synaptic interface curvature, and synaptic quantity. 10% BYHWD-containing serum was determined as the optimal concentration for treatment. 10% BYHWD-containing serum significantly reduced the overall apoptotic rate of (OGD/R) SH-SY5Y cells. Immunofluorescence experiments demonstrated that 10% BYHWD-containing serum could improve synaptic plasticity and increase the relative expression levels of synaptic-related proteins Syt1, Psd95, and Syn1. BYHWD and decoction-containing serum upregulated the mRNA and protein expression levels in (OGD/R) SH-SY5Y cells and MCAO rats, suggesting its ability to improve damaged neuronal synaptic plasticity and enhance transmission efficiency, which might be achieved through the regulation of the cAMP/PKA/CREB pathway.

CONCLUSIONS

This study may provide a basis for clinical medication by elucidating the underlying experimental evidence for the promotion of neural plasticity after ischemic stroke by BYHWD.

Danshensu reduces neuronal excitability by enhancing potassium currents in bushy cells in the mouse cochlear nucleus

Danshensu, also known as salvianic acid A, is a primary active compound extracted from a traditional Chinese herb Danshen (Salvia miltiorrhiza). While its antioxidative and neuroprotective effects are well-documented, the underlying mechanisms are poorly understood. In this study, we sought out to investigate if and how Danshensu modulates neuronal excitability and voltage-gated ionic currents in the central nervous system. We prepared brain slices of the mouse brainstem and performed patch-clamp recording in bushy cells in the anteroventral cochlear nucleus, with or without Danshensu incubation for 1 h. QX-314 was used internally to block Na+ current, while tetraethylammonium and 4-aminopyridine were used to isolate different subtypes of K+ current. We found that Danshensu of 100 μm decreased the input resistance of bushy cells by approximately 60% and shifted the voltage threshold of spiking positively by approximately 7 mV, resulting in significantly reduced excitability. Furthermore, we found this reduced excitability by Danshensu was caused by enhanced voltage-gated K+ currents in these neurons, including both low voltage-activated IK,A, by approximately 100%, and high voltage-activated IK,dr, by approximately 30%. Lastly, we found that the effect of Danshensu on K+ currents was dose-dependent in that no enhancement was found for Danshensu of 50 μm and Danshensu of 200 μm failed to cause significantly more enhancement on K+ currents when compared to that of 100 μm. We found that Danshensu reduced neuronal excitability in the central nervous system by enhancing voltage-gated K+ currents, providing mechanistic support for its neuroprotective effect widely seen in vivo.

Heat-Killed Lactococcus Lactis KC24 Ameliorates Scopolamine-Induced Memory Impairment in ICR Mice

Heat-killed Lactococcus lactis KC24 (H-KC24) has been examined for its neuroprotective effects in SH-SY5Y cells. We hypothesized that H-KC24 could alleviate memory impairment through the gut-brain axis. Scopolamine (1 mg/kg/day) was administered to ICR mice to induce memory impairment. Low- and high-dose H-KC24 cells (1 × 109 and 2 × 109 CFU/day, respectively) or donepezil (DO, 2 mg/kg) were administered for 14 days. H-KC24 treatment alleviated the deleterious scopolamine-induced memory effects on the recognition index and object recognition ability in the novel object recognition test and the Y-maze test. Changes in neurotransmitters and synaptic plasticity were confirmed by measuring acetylcholine, acetylcholinesterase, choline acetyltransferase, brain-derived neurotrophic factor, cyclic AMP response element-binding protein, and phosphorylated cyclic AMP response element-binding protein expression in brain tissues. In the H-KC24 and DO groups, β-secretase levels increased, whereas amyloid β levels decreased, demonstrating that H-KC24 can improve memory impairment caused by oxidative stress. This study demonstrated the positive effects of H-KC24 in a scopolamine-induced memory impairment mouse model.

Natural polyphenol: Their pathogenesis-targeting therapeutic potential in Alzheimer's disease

Alzheimer's disease (AD) is a detrimental neurodegenerative disease affecting the elderly. Clinically, it is characterized by progressive memory decline and subsequent loss of broader cognitive functions. Current drugs provide only symptomatic relief but do not have profound disease-modifying effects. There is an unmet need to identify novel pharmacological agents for AD therapy. Neuropathologically, the characteristic hallmarks of the disease are extracellular senile plaques containing amyloid β-peptides and intracellular neurofibrillary tangles containing hyperphosphorylated microtubule-associated protein tau. Simultaneously, oxidative stress, neuroinflammation and mitochondrial dysfunction in specific brain regions are early events during the process of AD pathologic changes and are associated with Aβ/tau toxicity. Here, we first summarized probable pathogenic mechanisms leading to neurodegeneration and hopefully identify pathways that serve as specific targets to improve therapy for AD. We then reviewed the mechanisms that underlie disease-modifying effects of natural polyphenols, with a focus on nuclear factor erythroid 2-related factor 2 activators for AD treatment. Lastly, we discussed challenges in the preclinical to clinical translation of natural polyphenols. In conclusion, there is evidence that natural polyphenols can be therapeutically useful in AD through their multifaceted mechanism of action. However, more clinical studies are needed to confirm these effects.

Therapeutic implications of phosphorylation- and dephosphorylation-dependent factors of cAMP-response element-binding protein (CREB) in neurodegeneration

Neurodegeneration is a condition of the central nervous system (CNS) characterized by loss of neural structures and function. The most common neurodegenerative disorders (NDDs) include Alzheimer's disease (AD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), multiple sclerosis (MS), motor neuron disorders, psychological disorders, dementia with vascular dementia (VaD), Lewy body dementia (DLB), epilepsy, cerebral ischemia, mental illness, and behavioral disorders. CREB (cAMP-response element-binding protein) represent a nuclear protein that regulates gene transcriptional activity. The primary focus of the review pertains to the exploration of CREB expression and activation within the context of neurodegenerative diseases, specifically in relation to the phosphorylation and dephosphorylation events that occur within the CREB signaling pathway under normal physiological conditions. The findings mentioned have contributed to the elucidation of the regulatory mechanisms governing CREB activity. Additionally, they have provided valuable insights into the potential mediation of diverse biological processes, such as memory consolidation and neuroprotective effects, by various related studies. The promotion of synaptic plasticity and neurodevelopment in the central nervous system through the targeting of CREB proteins has the potential to contribute to the prevention or delay of the onset of neurodegenerative disorders. Multiple drugs have been found to initiate downstream signaling pathways, leading to neuroprotective advantages in both animal model studies and clinical trials. The clinical importance of the cAMP-response element-binding protein (CREB) is examined in this article, encompassing its utility as both a predictive/prognostic marker and a target for therapeutic interventions.

Ranuncoside's attenuation of scopolamine-induced memory impairment in mice via Nrf2 and NF-ĸB signaling

Scopolamine is a well-known pharmacological agent responsible for causing memory impairment in animals, as well as oxidative stress and neuroinflammation inducer which lead to the development of Alzheimer disease. Although a cure for Alzheimer's disease is unavailable. Ranuncoside, a metabolite obtained from a medicinal plant has demonstrated antioxidant and anti-inflammatory properties in vitro, making it a promising treatment with potential anti-Alzheimer disease properties. However, as ranuncoside has not been evaluated for its antioxidant and anti-neuroinflammatory properties in any in vivo model, our study aimed to evaluate its neurotherapeutic efficacy against scopolamine-induced memory impairment in adult male albino mice. Mice were randomly divided into four experimental groups. Mice of group I was injected with saline, group II was injected with scopolamine (1 mg/kg/day) for 3 weeks. After receiving a daily injection of scopolamine for 1 week, the mice of group III were injected with ranuncoside (10 mg/kg) every other day for 2 weeks along with scopolamine daily and group IV were injected with ranuncoside on 5th alternate days. Behavioral tests (i.e., Morris water maze and Y-maze) were performed to determine the memory-enhancing effect of ranuncoside against scopolamine's memory deleterious effect. Western blot analysis was also performed to further elucidate the anti-neuroinflammatory and antioxidant effects of ranuncoside against scopolamine-induced neuroinflammation and oxidative stress. Our results showed memory-enhancing, anti-neuroinflammatory effect, and antioxidant effects of ranuncoside against scopolamine by increasing the expression of the endogenous antioxidant system (i.e., Nrf2 and HO-1), followed by blocking neuroinflammatory markers such as NF-κB, COX-2, and TNF-α. The results also revealed that ranuncoside possesses hypoglycemic and hypolipidemic effects against scopolamine-induced hyperglycemia and hyperlipidemia in mice as well as scopolamine's hyperglycemic effect. In conclusion, our findings suggest that ranuncoside could be a potential agent for the management of Alzheimer's disease, hyperglycemia, and hyperlipidemia.

Danshensu inhibits Aβ aggregation and neurotoxicity as one of the main prominent features of Alzheimer's disease

It has been found that the main cause of neurodegenerative proteinopathies, especially Alzheimer's disease (AD) is the formation of Aβ amyloid plaques, which can be regulated by application of potential small molecules. In the present study, we aimed to investigate the inhibitory effect of danshensu on Aβ(1-42) aggregation and relevant apoptotic pathway in neurons. A broad range of spectroscopic, theoretical, and cellular assays were done to investigate the anti-amyloidogenic characteristics of danshensu. It was found that danshensu triggers its inhibitory effect against Aβ(1-42) aggregation through modulation of hydrophobic patches as well as structural and morphological changes through a stacking interaction. Furthermore, it was observed that incubation of Aβ(1-42) samples with danshensu during aggregation process recovered the cell viability and mitigated the expression of caspase-3 mRNA and protein as well caspase-3 activity deregulated by Aβ(1-42) amyloid fibrils alone. In general, obtained data showed that danshensu potentially inhibits Aβ(1-42) aggregation and associated proteinopathies through regulation of apoptotic pathway in a concentration-dependent manner. Therefore, danshensu may be used as a promising biomolecule against the Aβ aggregation and associated proteinopathies, which can be further analyzed in the future studies for the treatment of AD.

Research progress in traditional Chinese medicine in the treatment of Alzheimer's disease and related dementias

Alzheimer's disease (AD) is the world's leading cause of dementia and has become a huge economic burden on nations and families. However, the exact etiology of AD is still unknown, and there are no efficient medicines or methods to prevent the deterioration of cognition. Traditional Chinese medicine (TCM) has made important contributions in the battle against AD based on the characteristics of multiple targets of TCM. This study reviewed the treatment strategies and new discoveries of traditional Chinese medicine in current research, which may be beneficial to new drug researchers.

Protective Effect of Ginsenosides from Stems and Leaves of Panax ginseng against Scopolamine-Induced Memory Damage via Multiple Molecular Mechanisms

Although growing evidence has shown that ginsenosides from stems and leaves of Panax ginseng (GSLS) exercise a protective impact on the central nervous system, in the model of memory damage induced by scopolamine, it is still rarely reported. Thus, the mechanism of action needs to be further explored. This study was to investigate the effect of GSLS on scopolamine (SCOP)-induced memory damage and the underlying mechanism. Male ICR mice were treated with SCOP (3 mg/kg) for 7 days, with or without GSLS (75 and 150 mg/kg) treatment for 14 days. After GSLS treatment, the memory damage induced by SCOP was significantly ameliorated as shown by the improvement of cholinergic function (AChE and ChAT), brain tissue hippocampus morphology (H&E staining), and oxidative stress (MDA, GSH, and NO). Meanwhile, immunohistochemical assay suggested that GSLS increased the expression of brain-derived neurotrophic factor (BDNF) and Tyrosine Kinase receptor B (TrkB). Further mechanism research indicated that GSLS inhibited the Tau hyperphosphorylation and cell apoptosis by regulating the PI3K/AKT pathway and inhibited neuroinflammation by regulating the NF-κB pathway, thereby exerting a cognitive impairment improvement effect. This work suggested that GSLS could protect against SCOP-induced memory defects possibly through inhibiting oxidative stress, inhibiting neuroinflammation and cell apoptosis.

Monoamine Oxidase-B Inhibitors for the Treatment of Parkinson's Disease: Past, Present, and Future

Monoamine oxidase-B (MAO-B) inhibitors are commonly used for the symptomatic treatment of Parkinson's disease (PD). MAO-B inhibitor monotherapy has been shown to be effective and safe for the treatment of early-stage PD, while MAO-B inhibitors as adjuvant drugs have been widely applied for the treatment of the advanced stages of the illness. MAO-B inhibitors can effectively improve patients' motor and non-motor symptoms, reduce "OFF" time, and may potentially prevent/delay disease progression. In this review, we discuss the effects of MAO-B inhibitors on motor and non-motor symptoms in PD patients, their mechanism of action, and the future development of MAO-B inhibitor therapy.

Activation of TAF9 via Danshensu-Induced Upregulation of HDAC1 Expression Alleviates Non-alcoholic Fatty Liver Disease

Fatty acid β-oxidation is an essential pathogenic mechanism in nonalcoholic fatty liver disease (NAFLD), and TATA-box binding protein associated factor 9 (TAF9) has been reported to be involved in the regulation of fatty acid β-oxidation. However, the function of TAF9 in NAFLD, as well as the mechanism by which TAF9 is regulated, remains unclear. In this study, we aimed to investigate the signaling mechanism underlying the involvement of TAF9 in NAFLD and the protective effect of the natural phenolic compound Danshensu (DSS) against NAFLD via the HDAC1/TAF9 pathway. An in vivo model of high-fat diet (HFD)-induced NAFLD and a palmitic acid (PA)-treated AML-12 cell model were developed. Pharmacological treatment with DSS significantly increased fatty acid β-oxidation and reduced lipid droplet (LD) accumulation in NAFLD. TAF9 overexpression had the same effects on these processes both in vivo and in vitro. Interestingly, the protective effect of DSS was markedly blocked by TAF9 knockdown. Mechanistically, TAF9 was shown to be deacetylated by HDAC1, which regulates the capacity of TAF9 to mediate fatty acid β-oxidation and LD accumulation during NAFLD. In conclusion, TAF9 is a key regulator in the treatment of NAFLD that acts by increasing fatty acid β-oxidation and reducing LD accumulation, and DSS confers protection against NAFLD through the HDAC1/TAF9 pathway.

Traditional Herbal Medicine Discovery for the Treatment and Prevention of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is characterized by pulmonary artery remodeling that may subsequently culminate in right heart failure and premature death. Although there are currently both non-pharmacological (lung transplantation, etc.) and pharmacological (Sildenafil, Bosentan, and new oral drugs on trial) therapies available, PAH remains a serious and fatal pulmonary disease. As a unique medical treatment, traditional herbal medicine (THM) treatment has gradually exerted its advantages in treating PAH worldwide through a multi-level and multi-target approach. Additionally, the potential mechanisms of THM were deciphered, including suppression of proliferation and apoptosis of pulmonary artery smooth muscle cells, controlling the processes of inflammation and oxidative stress, and regulating vasoconstriction and ion channels. In this review, the effects and mechanisms of the frequently studied compound THM, single herbal preparations, and multiple active components from THM are comprehensively summarized, as well as their related mechanisms on several classical preclinical PAH models. It is worth mentioning that sodium tanshinone IIA sulfonate sodium and tetramethylpyrazine are under clinical trials and are considered the most promoting medicines for PAH treatment. Last, reverse pharmacology, a strategy to discover THM or THM-derived components, has also been proposed here for PAH. This review discusses the current state of THM, their working mechanisms against PAH, and prospects of reverse pharmacology, which are expected to facilitate the natural anti-PAH medicine discovery and development and its bench-to-bedside transformation.

Magnolol upregulates CHRM1 to attenuate Amyloid-β-triggered neuronal injury through regulating the cAMP/PKA/CREB pathway

Alzheimer's disease (AD) is a common neurodegenerative disease characterized by neuronal degeneration and hyperphosphorylated Tau. Magnolol is an active component isolated from Magnolia officinalis with potential neuroprotection activity. However, the function and mechanism of magnolol in AD progression is largely uncertain. In present study, the biomarkers related to AD and magnolol were predicted by bioinformatics analyses. The key biomarker levels were predicted by GSE5281 and GSE36980 using AlzData. Cell viability was detected by CCK-8 assay. mRNA and protein levels were examined by qRT-PCR and western blotting assays. Cell apoptosis was investigated by caspase-3 activity and flow cytometry analyses. The cAMP/PKA/CREB signaling was evaluated by ELISA and western blotting analyses. The results showed that CHRM1 was a key biomarker for magnolol against AD progression. Magnolol attenuated Aβ-induced viability inhibition, Tau hyperphosphorylation and apoptosis in SH-SY5Y cells by upregulating CHRM1. In addition, the cAMP signaling might be a potential pathway of CHRM1 in AD. Magnolol contributed to activation of the cAMP/PKA/CREB pathway through enhancing CHRM1 level. Inactivation of the cAMP/PKA/CREB signaling reversed the suppressive effect of magnolol on Tau hyperphosphorylation and apoptosis in Aβ-treated SH-SY5Y cells. As a conclusion, magnolol mitigated Aβ-induced Tau hyperphosphorylation and neuron apoptosis by upregulating CHRM1 and activating the cAMP/PKA/CREB pathway.

The Functional Vision Protection Effect of Danshensu via Dopamine D1 Receptors: In Vivo Study

Danshensu, a traditional herb-based active component (Salvia miltiorrhiza Bunge), has garnered attention, due to its safety, nutritional value, and antioxidant effects, along with cardiovascular-protective and neuroprotective abilities; however, its effect on the retinal tissues and functional vision has not been fully studied. The objective of this study was to analyze the protective effect of danshensu on retinal tissues and functional vision in vivo in a mouse model of light-induced retinal degeneration. High energy light-evoked visual damage was confirmed by the loss in structural tissue integrity in the retina accompanied by a decline in visual acuity and visual contrast sensitivity function (VCSF), whereas the retina tissue exhibited severe Müller cell gliosis. Although danshensu treatment did not particularly reduce light-evoked damage to the photoreceptors, it significantly prevented Müller cell gliosis. Danshensu exerted protective effects against light-evoked deterioration on low spatial frequency-based VCSF as determined by the behavioral optomotor reflex method. Additionally, the protective effect of danshensu on VCSF can be reversed and blocked by the injection of a dopamine D1 receptor antagonist (SCH 23390). This study demonstrated that the major functional vision promotional effect of danshensu in vivo was through the dopamine D1 receptors enhancement pathway, rather than the structural protection of the retinas.

MicroRNA and mRNA profiling of cerebral cortex in a transgenic mouse model of Alzheimer's disease by RNA sequencing

In a previous study, we found that long non-coding genes in Alzheimer’s disease (AD) are a result of endogenous gene disorders caused by the recruitment of microRNA (miRNA) and mRNA, and that miR-200a-3p and other representative miRNAs can mediate cognitive impairment and thus serve as new biomarkers for AD. In this study, we investigated the abnormal expression of miRNA and mRNA and the pathogenesis of AD at the epigenetic level. To this aim, we performed RNA sequencing and an integrative analysis of the cerebral cortex of the widely used amyloid precursor protein and presenilin-1 double transgenic mouse model of AD. Overall, 129 mRNAs and 68 miRNAs were aberrantly expressed. Among these, eight down-regulated miRNAs and seven up-regulated miRNAs appeared as promising noninvasive biomarkers and therapeutic targets. The main enriched signaling pathways involved mitogen-activated kinase protein, phosphatidylinositol 3-kinase-protein kinase B, mechanistic target of rapamycin kinase, forkhead box O, and autophagy. An miRNA-mRNA network between dysregulated miRNAs and corresponding target genes connected with AD progression was also constructed. These miRNAs and mRNAs are potential biomarkers and therapeutic targets for new treatment strategies, early diagnosis, and prevention of AD. The present results provide a novel perspective on the role of miRNAs and mRNAs in AD. This study was approved by the Experimental Animal Care and Use Committee of Institute of Medicinal Biotechnology of Beijing, China (approval No. IMB-201909-D6) on September 6, 2019.

Up-regulation of miRNA-151-3p enhanced the neuroprotective effect of dexmedetomidine against β-amyloid by targeting DAPK-1 and TP53

Alzheimer's disease (AD) is the most common cause of dementia and is the leading lethal disease among the elderly. Dexmedetomidine (Dex) has been reported to have multiple neuroprotective effects, but its effect against beta-amyloid (Aβ) has not been completely determined and understood. Dex can activate both α2 adrenoceptor/cAMP/PKA and imidazoline I receptors/ERK1/2 signals. To determine which signal is critical for the effect of Dex on Aβ toxicity, we treated SH-SY5Y and PC12 cells with inhibitors of α2 adrenoceptor and ERK1/2. Dex suppressed the apoptosis of neuronal cells and production of reactive oxygen species induced by Aβ. These suppressive effects were attenuated by both inhibitors. As indicated by western blot, Dex stimulates both pro-apoptosis (activating death-associated protein kinase 1 [DAPK-1] and p53) and anti-apoptotic (up-regulating bcl-2 and bcl-xL) signals in Aβ-treated neuronal cells. This effect is likely associated with ERK1/2 signaling because ERK1/2 inhibitor disrupts the effect of Dex on these signals. To eliminate the pro-apoptotic effect of Dex while retaining its anti-apoptosis action, we screened miRNA-151-3p to target DAPK-1 and p53. Transfection with miRNA-151-3p mimics suppressed DAPK-1 and TP53 expression induced by Dex and increased Nrf-2 and SOD expression. More importantly, increasing miRNA-151-3p enhanced the anti-apoptotic and antioxidative effects of Dex in Aβ-treated neuronal cells. Overall, this study revealed that Dex additionally stimulated pro-apoptosis signaling, although it suppressed Aβ-induced apoptosis of neuronal cells. miRNA-151-3p enhanced the neuroprotective effect of Dex against Aβ by targeting DAPK-1 and TP53.

Potential Role of Phenolic Extracts of Mentha in Managing Oxidative Stress and Alzheimer's Disease

With an increase in the longevity and thus the proportion of the elderly, especially in developed nations, there is a rise in pathological conditions that accompany ageing, such as neurodegenerative disorders. Alzheimer’s disease (AD) is a neurodegenerative disease characterized by progressive cognitive and memory decline. The pathophysiology of the disease is poorly understood, with several factors contributing to its development, such as oxidative stress, neuroinflammation, cholinergic neuronal apoptotic death, and the accumulation of abnormal proteins in the brain. Current medications are only palliative and cannot stop or reverse the progression of the disease. Recent clinical trials of synthetic compounds for the treatment of AD have failed because of their adverse effects or lack of efficacy. Thus, there is impetus behind the search for drugs from natural origins, in addition to the discovery of novel, conventional therapeutics. Mints have been used traditionally for conditions relevant to the central nervous system. Recent studies showed that mint extracts and/or their phenolic constituents have a neuroprotective potential and can target multiple events of AD. In this review, we provide evidence of the potential role of mint extracts and their derivatives as possible sources of treatments in managing AD. Some of the molecular pathways implicated in the development of AD are reviewed, with focus on apoptosis and some redox pathways, pointing to mechanisms that may be modulated for the treatment of AD, and the need for future research invoking knowledge of these pathways is highlighted.

Therapeutic Potential of Quercetin as an Antiatherosclerotic Agent in Atherosclerotic Cardiovascular Disease: A Review

Atherosclerotic cardiovascular disease (ASCVD) is one of the diseases with the highest morbidity and mortality globally. It causes a huge burden on families and caregivers and high costs for medicine and surgical interventions. Given expensive surgeries and failures of most conventional treatments, medical community tries to find a more cost-effective cure. Thus, attentions have been primarily focused on food or herbs. Quercetin (Qu) extracted from food, a flavonoid component, develops potentials of alternative or complementary medicine in atherosclerosis. Due to the wide range of health benefits, researchers have considered to apply Qu as a natural compound in therapy. This review is aimed to identify the antiatherosclerosis functions of Qu in treating ASCVD such as anti-inflammatory, antioxidant properties, effects on endothelium-dependent vasodilation, and blood lipid-lowering.

Inhibition of acetylcholinesterase activity and β-amyloid oligomer formation by 6-bromotryptamine A, a multi-target anti-Alzheimer's molecule

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by learning and memory impairments. Recent studies have suggested that AD can be induced by multiple factors, such as cholinergic system dysfunction and β-amyloid (Aβ) neurotoxicity. It was reported that 6-bromo-N-propionyltryptamine could treat neurological diseases, including AD. In the present study, 6-bromotryptamine A, a derivative of 6-bromo-N-propionyltryptamine, was synthesized by the condensation of 2-(6-bromo-1H-indol-3-yl)ethan-1-amine and 2-(4-bromophenyl)acetic acid, and was used as a potential anti-AD molecule. Furthermore, scopolamine can induce impairments of learning and memory, and was widely used to establish AD animal models. The results demonstrated that 6-bromotryptamine A significantly prevented scopolamine-induced short-term cognitive impairments, as revealed by various behavioral tests in mice. Furthermore, an acetylcholinesterase (AChE) activity assay revealed that 6-bromotryptamine A directly inhibited AChE activity. Notably, it was observed that 6-bromotryptamine A blocked the formation of Aβ oligomer, as evaluated by the dot blot assay. All these results suggested that 6-bromotryptamine A may be used to prevent impairments in short-term learning and memory ability possibly via the inhibition of AChE and the blockade of Aβ oligomer formation.