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1.
Int J Mol Sci ; 23(21)2022 Nov 06.
Article in English | MEDLINE | ID: mdl-36362394

ABSTRACT

Ca2+ signaling is implicated in the transition between microglial surveillance and activation. Several L-type Ca2+ channel blockers (CCBs) have been shown to ameliorate neuroinflammation by modulating microglial activity. In this study, we examined the effects of the L-type CCB felodipine on LPS-mediated proinflammatory responses. We found that felodipine treatment significantly diminished LPS-evoked proinflammatory cytokine levels in BV2 microglial cells in an L-type Ca2+ channel-dependent manner. In addition, felodipine leads to the inhibition of TLR4/AKT/STAT3 signaling in BV2 microglial cells. We further examined the effects of felodipine on LPS-stimulated neuroinflammation in vivo and found that daily administration (3 or 7 days, i.p.) significantly reduced LPS-mediated gliosis and COX-2 and IL-1ß levels in C57BL/6 (wild-type) mice. Moreover, felodipine administration significantly reduced chronic neuroinflammation-induced spatial memory impairment, dendritic spine number, and microgliosis in C57BL/6 mice. Taken together, our results suggest that the L-type CCB felodipine could be repurposed for the treatment of neuroinflammation/cognitive function-associated diseases.


Subject(s)
Lipopolysaccharides , Spatial Memory , Mice , Animals , Lipopolysaccharides/toxicity , Mice, Inbred C57BL , Felodipine/adverse effects , Dendritic Spines , Inflammation/drug therapy , Inflammation/chemically induced , Microglia
2.
Biomedicines ; 10(4)2022 Apr 04.
Article in English | MEDLINE | ID: mdl-35453595

ABSTRACT

Alzheimer's disease (AD) is a neurodegenerative disease accompanied by cognitive and behavioral symptoms. These AD-related manifestations result from the alteration of neural circuitry by aggregated forms of amyloid-ß (Aß) and hyperphosphorylated tau, which are neurotoxic. From a neuroscience perspective, identifying neural circuits that integrate various inputs and outputs to determine behaviors can provide insight into the principles of behavior. Therefore, it is crucial to understand the alterations in the neural circuits associated with AD-related behavioral and psychological symptoms. Interestingly, it is well known that the alteration of neural circuitry is prominent in the brains of patients with AD. Here, we selected specific regions in the AD brain that are associated with AD-related behavioral and psychological symptoms, and reviewed studies of healthy and altered efferent pathways to the target regions. Moreover, we propose that specific neural circuits that are altered in the AD brain can be potential targets for AD treatment. Furthermore, we provide therapeutic implications for targeting neuronal circuits through various therapeutic approaches and the appropriate timing of treatment for AD.

3.
Aging Cell ; 20(3): e13332, 2021 03.
Article in English | MEDLINE | ID: mdl-33709472

ABSTRACT

We previously demonstrated that ibrutinib modulates LPS-induced neuroinflammation in vitro and in vivo, but its effects on the pathology of Alzheimer's disease (AD) and cognitive function have not been investigated. Here, we investigated the effects of ibrutinib in two mouse models of AD. In 5xFAD mice, ibrutinib injection significantly reduced Aß plaque levels by promoting the non-amyloidogenic pathway of APP cleavage, decreased Aß-induced neuroinflammatory responses, and significantly downregulated phosphorylation of tau by reducing levels of phosphorylated cyclin-dependent kinase-5 (p-CDK5). Importantly, tau-mediated neuroinflammation and tau phosphorylation were also alleviated by ibrutinib injection in PS19 mice. In 5xFAD mice, ibrutinib improved long-term memory and dendritic spine number, whereas in PS19 mice, ibrutinib did not alter short- and long-term memory but promoted dendritic spinogenesis. Interestingly, the induction of dendritic spinogenesis by ibrutinib was dependent on the phosphorylation of phosphoinositide 3-kinase (PI3K). Overall, our results suggest that ibrutinib modulates AD-associated pathology and cognitive function and may be a potential therapy for AD.


Subject(s)
Adenine/analogs & derivatives , Alzheimer Disease/physiopathology , Amyloid beta-Peptides/metabolism , Brain/pathology , Cognition , Inflammation/pathology , Piperidines/pharmacology , tau Proteins/metabolism , Adenine/pharmacology , Animals , Brain/drug effects , Brain/physiopathology , Cognition/drug effects , Cyclin-Dependent Kinase 5/metabolism , Cytokines/metabolism , Dendritic Spines/drug effects , Dendritic Spines/metabolism , Disease Models, Animal , Down-Regulation/drug effects , Gliosis/complications , Inflammation Mediators/metabolism , Memory, Long-Term/drug effects , Mice, Transgenic , Neurogenesis/drug effects , Neuroglia/drug effects , Neuroglia/metabolism , Neuroglia/pathology , Phosphorylation/drug effects , Plaque, Amyloid/pathology
4.
Antioxidants (Basel) ; 10(2)2021 Feb 01.
Article in English | MEDLINE | ID: mdl-33535469

ABSTRACT

Alzheimer's disease (AD) is a devastating neurodegenerative disease characterized by irreversible cognitive dysfunction. Amyloid beta (Aß) peptide is an important pathological factor that triggers the progression of AD through accumulation and aggregation, which leads to AD-related pathologies that consequently affect cognitive functions. Interestingly, several studies have reported that Platycodon grandiflorum root extract (PGE), besides exhibiting other bioactive effects, displays neuroprotective, anti-neuroinflammatory, and cognitive-enhancing effects. However, to date, it is not clear whether PGE can affect AD-related cognitive dysfunction and pathogenesis. Therefore, to investigate whether PGE influences cognitive impairment in an animal model of AD, we conducted a Y-maze test using a 5XFAD mouse model. Oral administration of PGE for 3 weeks at a daily dose of 100 mg/kg significantly ameliorated cognitive impairment in 5XFAD mice. Moreover, to elucidate the neurohistological mechanisms underlying the PGE-mediated alleviative effect on cognitive dysfunction, we performed histological analysis of hippocampal formation in these mice. Histopathological analysis showed that PGE significantly alleviated AD-related pathologies such as Aß accumulation, neurodegeneration, oxidative stress, and neuroinflammation. In addition, we observed a neuroprotective and antioxidant effect of PGE in mouse hippocampal neurons. Our findings suggest that administration of PGE might act as one of the therapeutic agents for AD by decreasing Aß related pathology and ameliorating Aß induced cognitive impairment.

5.
Free Radic Biol Med ; 164: 233-248, 2021 02 20.
Article in English | MEDLINE | ID: mdl-33422674

ABSTRACT

Biological aging provokes morbidity and several functional declines, causing older adults more susceptible to a variety of diseases than younger adults. In particular, aging is a major risk factor contributing to non-communicable diseases, such as neurodegenerative disorders. Alzheimer's disease (AD) is an aging-related neurodegenerative disease that is characterized by cognitive deficits and the formation of amyloid plaques formed by the accumulation of amyloid-ß (Aß) peptides. Non-saponin fraction with rich polysaccharide (NFP) from red ginseng, the largest fraction of the components of red ginseng, perform many biological activities. However, it has not been clarified whether the NFP from Korean red ginseng (KRG) has beneficial effects in the aging and AD. First, proteomics analysis was performed in aged brain to identify the effect of NFP on protein changes, and we confirmed that NFP induced changes in proteins related to the neuroprotective- and neurogenic-effects. Next, we investigated (1) the effects of NFP on AD pathologies, such as Aß deposition, neuroinflammation, neurodegeneration, mitochondrial dysfunction, and impaired adult hippocampal neurogenesis (AHN), in 5XFAD transgenic mouse model of AD using immunostaining; (2) the effect of NFP on Aß-mediated mitochondrial respiration deficiency in HT22 mouse hippocampal neuronal cells (HT22) using Seahorse XFp analysis; (3) the effect of NFP on cell proliferation using WST-1 analysis; and (4) the effect of NFP on Aß-induced cognitive dysfunction in 5XFAD mouse model of AD using Y-maze test. Histological analysis indicated that NFP significantly alleviated the accumulation of Aß, neuroinflammation, neuronal loss, and mitochondrial dysfunction in the subiculum of 5XFAD mouse model of AD. In addition, NFP treatment ameliorated mitochondrial deficits in Aß-treated HT22 cells. Moreover, NFP treatment significantly increased the AHN and neuritogenesis of neural stem cells in both healthy and AD brains. Furthermore, NFP significantly increased cell proliferation in the HT22 cells. Finally, NFP administration significantly enhanced and restored the cognitive function of healthy and AD mice, respectively. Taken together, NFP treatment demonstrated changes in proteins involved in central nervous system organization/maintenance in aged brain and ameliorates AD pathology. Collectively, our findings suggest that NFP from KRG could be a potential therapeutic candidate for aging and AD treatments.


Subject(s)
Alzheimer Disease , Neurodegenerative Diseases , Panax , Aging , Alzheimer Disease/drug therapy , Amyloid beta-Peptides , Animals , Disease Models, Animal , Mice , Mice, Transgenic , Polysaccharides/pharmacology
6.
Front Neurosci ; 14: 583097, 2020.
Article in English | MEDLINE | ID: mdl-33071750

ABSTRACT

Although the major causative factors of Alzheimer's disease (AD) are the accumulation of amyloid ß and hyperphosphorylated tau, AD can also be caused by metabolic dysfunction. The major clinical symptom of AD is cognitive dysfunction. However, AD is also accompanied by various secondary symptoms such as depression, sleep-wake disturbances, and abnormal eating behaviors. Interestingly, the orexigenic hormone ghrelin has been suggested to have beneficial effects on AD-related metabolic syndrome and secondary symptoms. Ghrelin improves lipid distribution and alters insulin sensitivity, effects that are hypothesized to delay the progression of AD. Furthermore, ghrelin can relieve depression by enhancing the secretion of hormones such as serotonin, noradrenaline, and orexin. Moreover, ghrelin can upregulate the expression of neurotrophic factors such as brain-derived neurotrophic factor and modulate the release of proinflammatory cytokines such as tumor necrosis factor α and interleukin 1ß. Ghrelin alleviates sleep-wake disturbances by increasing the levels of melatonin, melanin-concentrating hormone. Ghrelin reduces the risk of abnormal eating behaviors by increasing neuropeptide Y and γ-aminobutyric acid. In addition, ghrelin increases food intake by inhibiting fatty acid biosynthesis. However, despite the numerous studies on the role of ghrelin in the AD-related pathology and metabolic disorders, there are only a few studies that investigate the effects of ghrelin on secondary symptoms associated with AD. In this mini review, our purpose is to provide the insights of future study by organizing the previous studies for the role of ghrelin in AD-related pathology and metabolic disorders.

7.
Cells ; 9(9)2020 08 28.
Article in English | MEDLINE | ID: mdl-32872335

ABSTRACT

Monoamine oxidase (MAO) has been implicated in neuroinflammation, and therapies targeting MAO are of interest for neurodegenerative diseases. The small-molecule drug tranylcypromine, an inhibitor of MAO, is currently used as an antidepressant and in the treatment of cancer. However, whether tranylcypromine can regulate LPS- and/or Aß-induced neuroinflammation in the brain has not been well-studied. In the present study, we found that tranylcypromine selectively altered LPS-induced proinflammatory cytokine levels in BV2 microglial cells but not primary astrocytes. In addition, tranylcypromine modulated LPS-mediated TLR4/ERK/STAT3 signaling to alter neuroinflammatory responses in BV2 microglial cells. Importantly, tranylcypromine significantly reduced microglial activation as well as proinflammatory cytokine levels in LPS-injected wild-type mice. Moreover, injection of tranylcypromine in 5xFAD mice (a mouse model of AD) significantly decreased microglial activation but had smaller effects on astrocyte activation. Taken together, our results suggest that tranylcypromine can suppress LPS- and Aß-induced neuroinflammatory responses in vitro and in vivo.


Subject(s)
Alzheimer Disease/drug therapy , Inflammation/drug therapy , Lipopolysaccharides/metabolism , Monoamine Oxidase Inhibitors/therapeutic use , Tranylcypromine/therapeutic use , Alzheimer Disease/pathology , Animals , Disease Models, Animal , Humans , Mice , Monoamine Oxidase Inhibitors/pharmacology , Tranylcypromine/pharmacology
8.
Free Radic Biol Med ; 160: 575-595, 2020 11 20.
Article in English | MEDLINE | ID: mdl-32896600

ABSTRACT

Regulating amyloid beta (Aß) pathology and neuroinflammatory responses holds promise for the treatment of Alzheimer's disease (AD) and other neurodegenerative and/or neuroinflammation-related diseases. In this study, the effects of KVN93, an inhibitor of dual-specificity tyrosine phosphorylation-regulated kinase-1A (DYRK1A), on cognitive function and Aß plaque levels and the underlying mechanism of action were evaluated in 5x FAD mice (a mouse model of AD). KVN93 treatment significantly improved long-term memory by enhancing dendritic synaptic function. In addition, KVN93 significantly reduced Aß plaque levels in 5x FAD mice by regulating levels of the Aß degradation enzymes neprilysin (NEP) and insulin-degrading enzyme (IDE). Moreover, Aß-induced microglial and astrocyte activation were significantly suppressed in the KVN-treated 5xFAD mice. KVN93 altered neuroinflammation induced by LPS in microglial cells but not primary astrocytes by regulating TLR4/AKT/STAT3 signaling, and in wild-type mice injected with LPS, KVN93 treatment reduced microglial and astrocyte activation. Overall, these results suggest that the novel DYRK1A inhibitor KVN93 is a potential therapeutic drug for regulating cognitive/synaptic function, Aß plaque load, and neuroinflammatory responses in the brain.


Subject(s)
Alzheimer Disease , Amyloid beta-Peptides , Protein Serine-Threonine Kinases/antagonists & inhibitors , Protein-Tyrosine Kinases/antagonists & inhibitors , Alzheimer Disease/drug therapy , Alzheimer Disease/genetics , Animals , Cognition , Disease Models, Animal , Mice , Mice, Transgenic , Microglia , Plaque, Amyloid/drug therapy , Dyrk Kinases
9.
Mol Brain ; 13(1): 131, 2020 09 25.
Article in English | MEDLINE | ID: mdl-32977842

ABSTRACT

Alzheimer's disease (AD) is a highly prevalent neurodegenerative disease characterized by Aß accumulation and tau hyperphosphorylation. Epidemiological evidence for a negative correlation between cancer and AD has led to the proposed use of tyrosine kinase inhibitors (TKIs) such as dasatinib and masitinib for AD, with reported beneficial effects in the AD brain. The TKI vatalanib inhibits angiogenesis by inhibiting vascular endothelial growth factor receptor (VEGFR). Although changes in VEGF and VEGFR have been documented in AD, the effect of vatalanib on AD pathology has not been investigated. In this study, the effects of vatalanib on tau phosphorylation and Aß accumulation in 5xFAD mice, a model of AD, were evaluated by immunohistochemistry. Vatalanib administration significantly reduced tau phosphorylation at AT8 and AT100 by increasing p-GSK-3ß (Ser9) in 5xFAD mice. In addition, vatalanib reduced the number and area of Aß plaques in the cortex in 5xFAD mice. Our results suggest that vatalanib has potential as a regulator of AD pathology.


Subject(s)
Alzheimer Disease/pathology , Phthalazines/pharmacology , Pyridines/pharmacology , Vascular Endothelial Growth Factor A/antagonists & inhibitors , Animals , Humans , Male , Mice, Transgenic , Phosphorylation/drug effects , Phthalazines/chemistry , Pyridines/chemistry , Vascular Endothelial Growth Factor A/metabolism , tau Proteins/metabolism
10.
Oxid Med Cell Longev ; 2020: 7829842, 2020.
Article in English | MEDLINE | ID: mdl-32685100

ABSTRACT

Tau, a microtubule-associated protein expressed in mature neurons, interacts with tubulin to promote the assembly and stabilization of microtubules. However, abnormally hyperphosphorylated tau dissociates from microtubules and self-aggregates. Tau aggregates, including paired helical filaments and neurofibrillary tangles, promote neuronal dysfunction and death and are the defining neuropathological feature of tauopathies. Therefore, suppressing tau aggregation or stimulating the dissociation of tau aggregates has been proposed as an effective strategy for treating neurodegenerative diseases associated with tau pathology such as Alzheimer's disease (AD) and frontotemporal dementia. Interestingly, ginsenosides extracted from Panax ginseng reduced the hippocampal and cortical expression of phosphorylated tau in a rat model of AD. However, no studies have been conducted into the effect of red ginseng (RG) and its components on tau pathology. Here, we evaluated the effect of Korean red ginseng extract (KRGE) and its components on the aggregation and disassociation of tau. Using the thioflavin T assay, we monitored the change in fluorescence produced by the aggregation or disassociation of tau K18, an aggregation-prone fragment of tau441 containing the microtubule-binding domain. Our analysis revealed that KRGE not only inhibited tau aggregation but also promoted the dissociation of tau aggregates. In addition, the KRGE fractions, such as saponin, nonsaponin, and nonsaponin fraction with rich polysaccharide, also inhibited tau aggregation and promoted the dissociation of tau aggregates. Our observations suggest that RG could be a potential therapeutic agent for the treatment of neurodegenerative diseases associated with tauopathy.


Subject(s)
Panax/chemistry , tau Proteins/antagonists & inhibitors , Animals , Disease Models, Animal , Humans , Rats
11.
Int J Mol Sci ; 21(11)2020 May 29.
Article in English | MEDLINE | ID: mdl-32486013

ABSTRACT

It has been reported that damage to the mitochondria affects the progression of Alzheimer's disease (AD), and that mitochondrial dysfunction is improved by omega-3. However, no animal or cell model studies have confirmed whether omega-3 inhibits AD pathology related to mitochondria deficits. In this study, we aimed to (1) identify mitigating effects of endogenous omega-3 on mitochondrial deficits and AD pathology induced by amyloid beta (Aß) in fat-1 mice, a transgenic omega-3 polyunsaturated fatty acids (PUFAs)-producing animal; (2) identify if docosahexaenoic acid (DHA) improves mitochondrial deficits induced by Aß in HT22 cells; and (3) verify improvement effects of DHA administration on mitochondrial deficits and AD pathology in B6SJL-Tg(APPSwFlLon,PSEN1*M146L*L286V)6799Vas/Mmjax (5XFAD), a transgenic Aß-overexpressing model. We found that omega-3 PUFAs significantly improved Aß-induced mitochondrial pathology in fat-1 mice. In addition, our in vitro and in vivo findings demonstrate that DHA attenuated AD-associated pathologies, such as mitochondrial impairment, Aß accumulation, neuroinflammation, neuronal loss, and impairment of adult hippocampal neurogenesis.


Subject(s)
Alzheimer Disease/pathology , Amyloid beta-Peptides/metabolism , Disease Models, Animal , Docosahexaenoic Acids/metabolism , Mitochondria/pathology , Alzheimer Disease/metabolism , Animals , Cell Line , Cell Survival , Female , Genotype , Hippocampus/metabolism , Hippocampus/pathology , Image Processing, Computer-Assisted , Inflammation , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Mitochondria/metabolism , Neurogenesis , Neurons/metabolism
12.
Aging Dis ; 11(3): 705-724, 2020 May.
Article in English | MEDLINE | ID: mdl-32489714

ABSTRACT

Several studies have revealed that the transcription factor nuclear receptor related 1 (Nurr1) plays several roles not only in the regulation of gene expression related to dopamine synthesis, but also in alternative splicing, and miRNA targeting. Moreover, it regulates cognitive functions and protects against inflammation-induced neuronal death. In particular, the role of Nurr1 in the pathogenesis of Parkinson's disease (PD) has been well investigated; for example, it has been shown that it restores behavioral and histological impairments in PD models. Although many studies have evaluated the connection between Nurr1 and PD pathogenesis, the role of Nurr1 in Alzheimer's disease (AD) remain to be studied. There have been several studies describing Nurr1 protein expression in the AD brain. However, only a few studies have examined the role of Nurr1 in the context of AD. Therefore, in this review, we highlight the overall effects of Nurr1 under the neuropathologic conditions related to AD. Furthermore, we suggest the possibility of using Nurr1 as a therapeutic target for AD or other neurodegenerative disorders.

13.
Int J Mol Sci ; 21(1)2019 Dec 18.
Article in English | MEDLINE | ID: mdl-31861329

ABSTRACT

Nuclear receptor related-1 (Nurr1) protein performs a crucial role in hippocampal neural stem cell (hNSC) development as well as cognitive functions. We previously demonstrated that the pharmacological stimulation of Nurr1 by amodiaquine (AQ) promotes spatial memory by enhancing adult hippocampal neurogenesis. However, the role of Nurr1 in the cell cycle regulation of the adult hippocampus has not been investigated. This study aimed to examine changes in the cell cycle-related molecules involved in adult hippocampal neurogenesis induced by Nurr1 pharmacological stimulation. Fluorescence-activated cell sorting (FACS) analysis showed that AQ improved the progression of cell cycle from G0/G1 to S phase in a dose-dependent manner, and MEK1 or PI3K inhibitors attenuated this progression. In addition, AQ treatment increased the expression of cell proliferation markers MCM5 and PCNA, and transcription factor E2F1. Furthermore, pharmacological stimulation of Nurr1 by AQ increased the expression levels of positive cell cycle regulators such as cyclin A and cyclin-dependent kinases (CDK) 2. In contrast, levels of CDK inhibitors p27KIP1 and p57KIP2 were reduced upon treatment with AQ. Similar to the in vitro results, RT-qPCR analysis of AQ-administered mice brains revealed an increase in the levels of markers of cell cycle progression, PCNA, MCM5, and Cdc25a. Finally, AQ administration resulted in decreased p27KIP1 and increased CDK2 levels in the dentate gyrus of the mouse hippocampus, as quantified immunohistochemically. Our results demonstrate that the pharmacological stimulation of Nurr1 in adult hNSCs by AQ promotes the cell cycle by modulating cell cycle-related molecules.


Subject(s)
Adult Stem Cells/metabolism , Cell Cycle/genetics , Hippocampus/cytology , Neural Stem Cells/metabolism , Nuclear Receptor Subfamily 4, Group A, Member 2/genetics , Adult Stem Cells/drug effects , Amodiaquine/pharmacology , Animals , Biomarkers , Cell Cycle/drug effects , Cell Proliferation , Dentate Gyrus/metabolism , E2F1 Transcription Factor/genetics , E2F1 Transcription Factor/metabolism , Gene Expression Regulation , Humans , Immunohistochemistry , Male , Mice , Neural Stem Cells/drug effects , Neurogenesis/drug effects , Neurogenesis/genetics , Nuclear Receptor Subfamily 4, Group A, Member 2/metabolism , Rats
14.
Front Neurosci ; 13: 1224, 2019.
Article in English | MEDLINE | ID: mdl-31798405

ABSTRACT

As the number of older adults increases, the prevalence of dementias, such as Alzheimer's dementia (AD), vascular dementia, dementia with Lewy bodies, and frontotemporal dementias, also increases. Despite research into pharmacological approaches for treating diverse diseases, there is still no cure. Recently, novel non-pharmacological interventions are attracting attention. Non-pharmacological approaches include cognitive stimulation, alterations in diet, physical activity, and social engagement. Cognitive stimulating activities protect against the negative effects of cognitive decline caused by age-related neurogenerative diseases. Bilingualism is one form of cognitive stimulation that requires multiple aspects of brain activity and has been shown to delay the onset of dementia symptoms in patients by approximately 4-5 years as compared with monolingual patients through cognitive reserve. The purpose of this review was to bilingualism protects against cognitive decline associated with AD and other dementias. We discuss potential underlying neurological mechanisms, including: (1) stimulating adult neurogenesis, (2) enhancing synaptogenesis, (3) strengthening functional connectivity that bilingualism may delay clinical AD symptoms, (4) protecting white matter integrity, and (5) preserving gray matter density.

15.
Aging Dis ; 10(2): 307-328, 2019 Apr.
Article in English | MEDLINE | ID: mdl-31435482

ABSTRACT

Alzheimer's disease (AD), which is the most major cause of dementia, is a progressive neurodegenerative disease that affects cognitive functions. Even though the prevalence of AD is continuously increasing, few drugs including cholinesterase inhibitors and N-methyl D-aspartate-receptor antagonists were approved to treat AD. Because the clinical trials of AD drugs with single targets, such as ß-amyloid and tau, have failed, the development of multi-target drugs that ameliorate many of the symptoms of AD is needed. Thus, recent studies have investigated the effects and underlying mechanisms of herbal formulae consisting of various herb combinations used to treat AD. This review discusses the results of clinical and nonclinical studies of the therapeutic efficacy in AD and underlying mechanisms of the herbal formulae of traditional Oriental medicines and bioactive compounds of medicinal plants.

16.
Int J Mol Sci ; 20(16)2019 Aug 16.
Article in English | MEDLINE | ID: mdl-31426329

ABSTRACT

It is widely known that the degeneration of neural circuits is prominent in the brains of Alzheimer's disease (AD) patients. The reciprocal connectivity of the medial septum (MS) and hippocampus, which constitutes the septo-hippocampo-septal (SHS) loop, is known to be associated with learning and memory. Despite the importance of the reciprocal projections between the MS and hippocampus in AD, the alteration of bidirectional connectivity between two structures has not yet been investigated at the mesoscale level. In this study, we adopted AD animal model, five familial AD mutations (5XFAD) mice, and anterograde and retrograde tracers, BDA and DiI, respectively, to visualize the pathology-related changes in topographical connectivity of the SHS loop in the 5XFAD brain. By comparing 4.5-month-old and 14-month-old 5XFAD mice, we successfully identified key circuit components of the SHS loop altered in 5XFAD brains. Remarkably, the SHS loop began to degenerate in 4.5-month-old 5XFAD mice before the onset of neuronal loss. The impairment of connectivity between the MS and hippocampus was accelerated in 14-month-old 5XFAD mice. These results demonstrate, for the first time, topographical evidence for the degradation of the interconnection between the MS and hippocampus at the mesoscale level in a mouse model of AD. Our results provide structural and functional insights into the interconnectivity of the MS and hippocampus, which will inform the use and development of various therapeutic approaches that target neural circuits for the treatment of AD.


Subject(s)
Alzheimer Disease/pathology , Hippocampus/pathology , Septum of Brain/pathology , Alzheimer Disease/genetics , Amyloid beta-Protein Precursor/genetics , Animals , Disease Models, Animal , Female , Hippocampus/metabolism , Humans , Male , Mice, Transgenic , Mutation , Neural Pathways/metabolism , Neural Pathways/pathology , Presenilin-1/genetics , Septum of Brain/metabolism
17.
Ageing Res Rev ; 55: 100945, 2019 11.
Article in English | MEDLINE | ID: mdl-31434007

ABSTRACT

Ghrelin, which has many important physiological roles, such as stimulating food intake, regulating energy homeostasis, and releasing insulin, has recently been studied for its roles in a diverse range of neurological disorders. Despite the several functions of ghrelin in the central nervous system, whether it works as a therapeutic agent for neurological dysfunction has been unclear. Altered levels and various roles of ghrelin have been reported in Alzheimer's disease (AD), which is characterized by the accumulation of misfolded proteins resulting in synaptic loss and cognitive decline. Interestingly, treatment with ghrelin or with the agonist of ghrelin receptor showed attenuation in several cases of AD-related pathology. These findings suggest the potential therapeutic implications of ghrelin in the pathogenesis of AD. In the present review, we summarized the roles of ghrelin in AD pathogenesis, amyloid beta (Aß) homeostasis, tau hyperphosphorylation, neuroinflammation, mitochondrial deficit, synaptic dysfunction and cognitive impairment. The findings from this review suggest that ghrelin has a novel therapeutic potential for AD treatment. Thus, rigorously designed studies are needed to establish an effective AD-modifying strategy.


Subject(s)
Alzheimer Disease/metabolism , Ghrelin/metabolism , Amyloid beta-Peptides/metabolism , Animals , Humans , Mitochondria/metabolism , tau Proteins/metabolism
18.
Int J Mol Sci ; 20(12)2019 Jun 21.
Article in English | MEDLINE | ID: mdl-31234321

ABSTRACT

Alzheimer's disease (AD) is the most common neurodegenerative disease and is characterized by neurodegeneration and cognitive deficits. Amyloid beta (Aß) peptide is known to be a major cause of AD pathogenesis. However, recent studies have clarified that mitochondrial deficiency is also a mediator or trigger for AD development. Interestingly, red ginseng (RG) has been demonstrated to have beneficial effects on AD pathology. However, there is no evidence showing whether RG extract (RGE) can inhibit the mitochondrial deficit-mediated pathology in the experimental models of AD. The effects of RGE on Aß-mediated mitochondrial deficiency were investigated in both HT22 mouse hippocampal neuronal cells and the brains of 5XFAD Aß-overexpressing transgenic mice. To examine whether RGE can affect mitochondria-related pathology, we used immunohistostaining to study the effects of RGE on Aß accumulation, neuroinflammation, neurodegeneration, and impaired adult hippocampal neurogenesis in hippocampal formation of 5XFAD mice. In vitro and in vivo findings indicated that RGE significantly improves Aß-induced mitochondrial pathology. In addition, RGE significantly ameliorated AD-related pathology, such as Aß deposition, gliosis, and neuronal loss, and deficits in adult hippocampal neurogenesis in brains with AD. Our results suggest that RGE may be a mitochondria-targeting agent for the treatment of AD.


Subject(s)
Alzheimer Disease/drug therapy , Amyloid beta-Peptides/metabolism , Mitochondria/drug effects , Panax , Plant Preparations/therapeutic use , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Animals , Brain/drug effects , Brain/metabolism , Brain/pathology , Cell Line , Disease Models, Animal , Female , Male , Mice , Mitochondria/metabolism , Mitochondria/pathology , Panax/chemistry , Plant Preparations/chemistry
19.
Nanomedicine ; 17: 297-307, 2019 04.
Article in English | MEDLINE | ID: mdl-30794963

ABSTRACT

The aggregation and accumulation of amyloid beta (Aß) peptide is believed to be the primary cause of Alzheimer's disease (AD) pathogenesis. Vitamin D-binding protein (DBP) can attenuate Aß aggregation and accumulation. A biocompatible polymer poly (D,L-lactic acid-co-glycolic acid) (PLGA) can be loaded with therapeutic agents and control the rate of their release. In the present study, a PLGA-based drug delivery system was used to examine the therapeutic effects of DBP-PLGA nanoparticles in Aß-overexpressing (5XFAD) mice. DBP was loaded into PLGA nanoparticles and the characteristics of the DBP-PLGA nanoparticles were analyzed. Using a thioflavin-T assay, we observed that DBP-PLGA nanoparticles significantly inhibited Aß aggregation in vitro. In addition, we found that intravenous injection of DBP-PLGA nanoparticles significantly attenuated the Aß accumulation, neuroinflammation, neuronal loss and cognitive dysfunction in the 5XFAD mice. Collectively, our results suggest that DBP-PLGA nanoparticles could be a promising therapeutic candidate for the treatment of AD.


Subject(s)
Alzheimer Disease/drug therapy , Drug Carriers/chemistry , Polylactic Acid-Polyglycolic Acid Copolymer/chemistry , Vitamin D-Binding Protein/administration & dosage , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Amyloid beta-Peptides/metabolism , Animals , Male , Mice , Mice, Transgenic , Nanoparticles/chemistry , Protein Aggregation, Pathological/drug therapy , Protein Aggregation, Pathological/metabolism , Protein Aggregation, Pathological/pathology , Vitamin D-Binding Protein/therapeutic use
20.
Aging Cell ; 18(1): e12866, 2019 02.
Article in English | MEDLINE | ID: mdl-30515963

ABSTRACT

The orphan nuclear receptor Nurr1 (also known as NR4A2) is critical for the development and maintenance of midbrain dopaminergic neurons, and is associated with Parkinson's disease. However, an association between Nurr1 and Alzheimer's disease (AD)-related pathology has not previously been reported. Here, we provide evidence that Nurr1 is expressed in a neuron-specific manner in AD-related brain regions; specifically, it is selectively expressed in glutamatergic neurons in the subiculum and the cortex of both normal and AD brains. Based on Nurr1's expression patterns, we investigated potential functional roles of Nurr1 in AD pathology. Nurr1 expression was examined in the hippocampus and cortex of AD mouse model and postmortem human AD subjects. In addition, we performed both gain-of-function and loss-of-function studies of Nurr1 and its pharmacological activation in 5XFAD mice. We found that knockdown of Nurr1 significantly aggravated AD pathology while its overexpression alleviated it, including effects on Aß accumulation, neuroinflammation, and neurodegeneration. Importantly, 5XFAD mice treated with amodiaquine, a highly selective synthetic Nurr1 agonist, showed robust reduction in typical AD features including deposition of Aß plaques, neuronal loss, microgliosis, and impairment of adult hippocampal neurogenesis, leading to significant improvement of cognitive impairment. These in vivo and in vitro findings suggest that Nurr1 critically regulates AD-related pathophysiology and identify Nurr1 as a novel AD therapeutic target.


Subject(s)
Alzheimer Disease/pathology , Alzheimer Disease/physiopathology , Cognition , Nuclear Receptor Subfamily 4, Group A, Member 2/metabolism , Aging/pathology , Alzheimer Disease/complications , Alzheimer Disease/metabolism , Amodiaquine/pharmacology , Animals , Brain/metabolism , Brain/pathology , Cognition/drug effects , Disease Models, Animal , Glutamic Acid/metabolism , Humans , Mice, Inbred C57BL , Mice, Transgenic , Neuroglia/drug effects , Neuroglia/metabolism , Neurons/drug effects , Neurons/metabolism , Nuclear Receptor Subfamily 4, Group A, Member 2/antagonists & inhibitors , Postmortem Changes
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