Dl-3-n-butylphthalide promotes microglial phagocytosis and inhibits microglial inflammation via regulating AGE-RAGE pathway in APP/PS1 mice.

Alzheimer's disease (AD) stands as the most prevalent neurodegenerative condition worldwide, and its correlation with microglial function is notably significant. Dl-3-n-butylphthalide (NBP), derived from the seeds of Apium graveolens L. (Chinese celery), has demonstrated the capacity to diminish Aß levels in the brain tissue of Alzheimer's transgenic mice. Despite this, its connection to neuroinflammation and microglial phagocytosis, along with the specific molecular mechanism involved, remains undefined. In this study, NBP treatment exhibited a substantial improvement in learning deficits observed in AD transgenic mice (APP/PS1 transgenic mice). Furthermore, NBP treatment significantly mitigated the total cerebral Aß plaque deposition. This effect was attributed to the heightened presence of activated microglia surrounding Aß plaques and an increase in microglial phagocytosis of Aß plaques. Transcriptome sequencing analysis unveiled the potential involvement of the AGE (advanced glycation end products) -RAGE (receptor for AGE) signaling pathway in NBP's impact on APP/PS1 mice. Subsequent investigation disclosed a reduction in the secretion of AGEs, RAGE, and proinflammatory factors within the hippocampus and cortex of NBP-treated APP/PS1 mice. In summary, NBP alleviates cognitive impairment by augmenting the number of activated microglia around Aß plaques and ameliorating AGE-RAGE-mediated neuroinflammation. These findings underscore the related mechanism of the crucial neuroprotective roles of microglial phagocytosis and anti-inflammation in NBP treatment for AD, offering a potential therapeutic target for the disease.

ChemR23 activation attenuates cognitive impairment in chronic cerebral hypoperfusion by inhibiting NLRP3 inflammasome-induced neuronal pyroptosis.

Neuroinflammation plays critical roles in vascular dementia (VaD), the second leading cause of dementia, which can be induced by chronic cerebral hypoperfusion (CCH). NLRP3 inflammasome-induced pyroptosis, the inflammatory programmed cell death, has been reported to contribute to the development of VaD. ChemR23 is a G protein-coupled receptor that has emerging roles in regulating inflammation. However, the role of ChemR23 signalling in NLRP3 inflammasome-induced pyroptosis in CCH remains elusive. In this study, a CCH rat model was established by permanent bilateral common carotid artery occlusion (BCCAO) surgery. Eight weeks after the surgery, the rats were intraperitoneally injected with the ChemR23 agonist Resolvin E1 (RvE1) or chemerin-9 (C-9). Additionally, primary rat hippocampal neurons and SH-SY5Y cells were adopted to mimic CCH injury in vitro. Our results showed that the levels of ChemR23 expression were decreased from the 8th week after BCCAO, accompanied by significant cognitive impairment. Further analysis revealed that CCH induced neuronal damage, synaptic injury and NLRP3-related pyroptosis activation in hippocampal neurons. However, pharmacologic activation of ChemR23 with RvE1 or C-9 counteracted these changes. In vitro experiments also showed that ChemR23 activation prevented primary neuron pyroptosis induced by chronic hypoxia. In addition, manipulating ChemR23 expression markedly regulated NLRP3 inflammasome-induced neuronal pyroptosis through PI3K/AKT/Nrf2 signalling in SH-SY5Y cells under hypoglycaemic and hypoxic conditions. Collectively, our data demonstrated that ChemR23 activation inhibits NLRP3 inflammasome-induced neuronal pyroptosis and improves cognitive function via the PI3K/AKT/Nrf2 signalling pathway in CCH models. ChemR23 may serve as a potential novel therapeutic target to treat CCH-induced cognitive impairment.

Astragaloside IV supplementation attenuates cognitive impairment by inhibiting neuroinflammation and oxidative stress in type 2 diabetic mice.

Although diabetic cognitive impairment is one of the most common complications of type 2 diabetes mellitus (T2DM), optimized therapeutic strategies are not available yet. Astragalosides IV (AS-IV) is a traditional Chinese medicine possessing diverse pharmacological properties including anti-inflammatory and antioxidant effects. However, the effects of AS-IV on diabetes-related cognitive impairment and its precise mechanisms remain largely unknown. T2DM mice, induced by a high-fat diet (HFD) and an intraperitoneal injection of low-dose streptozotocin (STZ) were administrated with AS-IV every other day for eight consecutive weeks. Learning and memory abilities were assessed subsequently using the Ymaze test and the anxious behavior was evaluated using an open field test. Then, the morphology and number of neurons and microglia were observed by HE staining or immunohistochemistry. Oxidative stress biomarkers and pro-inflammatory cytokines were determined using relevant kits. In addition, the expression levels of Nrf2, Keap1, HO-1, and NQO1 were determined by Western blot analyses. The results indicated that AS-IV administration significantly improved neuronal damage and cognitive deficit in T2DM mice. Meanwhile, oxidative stress and neuroinflammation were also ameliorated in T2DM mice, which might be attributed to the regulation of Nrf2/Keap1/HO-1/NQO1 pathway in T2DM mice. Taken together, these data suggested that AS-IV ameliorates cognitive impairment in T2DM mice by attenuating oxidative stress and neuroinflammation, possibly through modulating the Nrf2/Keap1/HO1/NQO1 pathway.

Network pharmacology-based strategy to investigate pharmacological mechanisms of Andrographolide for treatment of vascular cognitive impairment.

Vascular cognitive impairment (VCI) is the second most common form of dementia. Andrographolide (Andro) shows potential effects in anti-inflammation, anti-oxidative stress, and anti-apoptosis. We have obtained 48 potential genes related to the effect of Andro on VCI through network pharmacology analysis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were used to reveal significant enriched pathway of potential genes, and the mitogen-activated protein kinase (MAPK) pathway was screened out. To verify the results of network pharmacology, we tested the effects of Andro in VCI model induced by bilateral common carotid artery occlusion (BCCAO) surgery. The results showed that Andro treatment ameliorated the cognitive impairment induced by BCCAO. Immunohistochemistry study revealed that Andro could reduce neuronal damage and activation of microglia in the cortex and hippocampus in BCCAO rats. To test the MAPK pathway changes, we analyzed the expression of JNK, p38 and ERK and found that Andro reduced the levels of phosphorylated-ERK (p-ERK) and phosphorylated-p38 (p-p38) in BCCAO rats. In conclusion, Andro could improve neuronal survival, reduce neuroinflammation and ameliorate cognitive impairment in VCI. The underlying mechanisms of Andro treatment may be through the inhibition of MAPK pathway.

NAD+ improves cognitive function and reduces neuroinflammation by ameliorating mitochondrial damage and decreasing ROS production in chronic cerebral hypoperfusion models through Sirt1/PGC-1α pathway.

BACKGROUND: Microglial-mediated neuroinflammation plays an important role in vascular dementia, and modulating neuroinflammation has emerged as a promising treatment target. Nicotinamide adenine dinucleotide (NAD+) shows anti-inflammatory and anti-oxidant effects in many neurodegenerative disease models, but its role in the chronic cerebral hypoperfusion (CCH) is still unclear. METHODS: The bilateral common carotid artery occlusion (BCCAO) was performed to establish CCH models in Sprague-Dawley rats. The rats were given daily intraperitoneal injection of NAD+ for 8 weeks. The behavioral test and markers for neuronal death and neuroinflammation were analyzed. Mitochondrial damage and ROS production in microglia were also assessed. RNA-seq was performed to investigate the mechanistic pathway changes. For in vitro studies, Sirt1 was overexpressed in BV2 microglial cells to compare with NAD+ treatment effects on mitochondrial injury and neuroinflammation. RESULTS: NAD+ administration rescued cognitive deficits and inhibited neuroinflammation by protecting mitochondria and decreasing ROS production in CCH rats. Results of mechanistic pathway analysis indicated that the detrimental effects of CCH might be associated with decreased gene expression of PPAR-γ co-activator1α (PGC-1α) and its upstream transcription factor Sirt1, while NAD+ treatment markedly reversed their decrease. In vitro study confirmed that NAD+ administration had protective effects on hypoxia-induced neuroinflammation and mitochondrial damage, as well as ROS production in BV2 microglia via Sirt1/PGC-1α pathway. Sirt1 overexpression mimicked the protective effects of NAD+ treatment in BV2 microglia. CONCLUSIONS: NAD+ ameliorated cognitive impairment and dampened neuroinflammation in CCH models in vivo and in vitro, and these beneficial effects were associated with mitochondrial protection and ROS inhibition via activating Sirt1/PGC-1α pathway.

Andrographolide ameliorates neuroinflammation in APP/PS1 transgenic mice.

Alzheimer's disease is a devastating neurodegenerative disorder, with no disease-modifying treatment available yet. There is increasing evidence that neuroinflammation plays a critical role in the pathogenesis of AD. Andrographolide (Andro), a labdane diterpene extracted from the herb Andrographis paniculata, has been reported to exhibit neuroprotective property in central nervous system diseases. However, its effects on Aß and Aß-induced neuroinflammation have not yet been studied. In the present study, we found that Andro administration significantly alleviated cognitive impairments, reduced amyloid-ß deposition, inhibited microglial activation, and decreased the secretion of proinflammatory factors in APP/PS1 mice. Furthermore, transcriptome sequencing analysis revealed that Andro could significantly decrease the expression of Itgax, TLR2, CD14, CCL3, CCL4, TLR1, and C3ar1 in APP/PS1 mice, which was further validated by qRT-PCR. Our results suggest that Andro might be a potential therapeutic drug for AD by regulating neuroinflammation.

Curcumin protects against cognitive impairments in a rat model of chronic cerebral hypoperfusion combined with diabetes mellitus by suppressing neuroinflammation, apoptosis, and pyroptosis.

BACKGROUND: Chronic cerebral hypoperfusion (CCH) is regarded as a high-risk factor for cognitive decline in vascular dementia (VaD). We have previously shown that diabetes mellitus (DM) synergistically promotes CCH-induced cognitive dysfunction via exacerbating neuroinflammation. Furthermore, curcumin has been shown to exhibit anti-inflammatory and neuroprotective activities. However, the effects of curcumin on CCH-induced cognitive impairments in DM have remained unknown. METHODS: Rats were fed with a high-fat diet (HFD) and injected with low-dose streptozotocin (STZ), followed by bilateral common carotid artery occlusion (BCCAO), to model DM and CCH in vivo. After BCCAO, curcumin (50 mg/kg) was administered intraperitoneally every two days for eight weeks to evaluate its therapeutic effects. Additionally, mouse BV2 microglial cells were exposed to hypoxia and high glucose to model CCH and DM pathologies in vitro. RESULTS: Curcumin treatment significantly improved DM/CCH-induced cognitive deficits and attenuated neuronal cell death. Molecular analysis revealed that curcumin exerted protective effects via suppressing neuroinflammation induced by microglial activation, regulating the triggering receptor expressed on myeloid cells 2 (TREM2)/toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) pathway, alleviating apoptosis, and reducing nod-like receptor protein 3 (NLRP3)-dependent pyroptosis. CONCLUSIONS: Taken together, our findings suggest that curcumin represents a promising therapy for DM/CCH-induced cognitive impairments.

Leptin Receptor Deficiency Protects Mice against Chronic Cerebral Hypoperfusion-Induced Neuroinflammation and White Matter Lesions.

Leptin participates in the inflammatory responses in multiple cell types and animal models. Chronic cerebral hypoperfusion (CCH) induces inflammation in the central nervous system (CNS), which acts as one of the main reasons for CCH-induced white matter lesions (WMLs). But whether leptin participates in the pathogenesis of CCH-induced WMLs remains unknown. Therefore, we performed bilateral common carotid artery stenosis (BCAS) to induce CCH on the leptin receptor- (LepR-) deficient db/db mice, aiming to evaluate the possible involvement of leptin in CCH-induced cognitive impairment, WMLs, and neuroinflammation, and further explore the effect of leptin on chronic hypoxia-induced inflammation using the BV2 microglial cell line. After four weeks of BCAS, wild-type mice showed significant working memory deficits, WMLs, activation of microglia and astrocytes, decrease in the number of oligodendrocytes, downregulation of myelin basic protein expression, and increase in the expression of TNF-α and IL-1ß; however, four weeks of BCAS failed to induce significant changes in the LepR-deficient db/db mice but elevated the production of anti-inflammatory cytokines and activated the M2 microglia. We further confirmed that leptin would aggravate the hypoxia-induced proinflammatory cytokine expression in the BV2 microglia cell line. These results suggested that LepR deficiency would protect mice against the CCH-induced cognitive impairment and WMLs by inhibiting glial activation and suppressing proinflammatory responses as well as promoting anti-inflammatory cytokine expression and M2 microglia activation in the white matter.

Gene Polymorphisms Affecting the Pharmacokinetics and Pharmacodynamics of Donepezil Efficacy.

Donepezil (DNP) is the first-line drug used for Alzheimer's disease (AD). However, the therapeutic response rate of patients to DNP varies from 20 to 60%. The main reason for the large differences in the clinical efficacy of DNP therapy is genetic factors, some of which affect pharmacokinetics (PK), while others affect pharmacodynamics (PD). Thus, much emphasis has been placed on the investigation of an association between PK- and PD-related gene polymorphisms and therapeutic response to DNP, but a consistent view does not yet exist. In this review, we summarize recent findings regarding genetic factors influencing the clinical efficacy of DNP, including substantial differences in individual responses as a consequence of polymorphisms in Cytochrome P450 (CYP) 2D6, CY3A4, CY3A5, APOE, ABCA1, ABCB1, ESR1, BCHE, PON-1, CHRNA7, and CHAT. We also discuss possible strategies for the evaluation of the clinical efficacy of DNP, with a specific focus on possible biomarkers of PK/PD parameters, and provide perspectives and limitations within the field, which will also be beneficial for understanding the multiple mechanisms of DNP therapy in AD.

TREM-2-p38 MAPK signaling regulates neuroinflammation during chronic cerebral hypoperfusion combined with diabetes mellitus.

BACKGROUND: Diabetes mellitus (DM) and chronic cerebral hypoperfusion(CCH)are both risk factors for cognitive impairment. However, whether DM and CCH can synergistically promote cognitive impairment and the related pathological mechanisms remain unknown. METHODS: To investigate the effect of DM and CCH on cognitive function, rats fed with high-fat diet (HFD) and injected with low-dose streptozotocin (STZ) followed by bilateral common carotid artery occlusion (BCCAO) were induced to mimic DM and CCH in vivo and mouse BV2 microglial cells were exposed to hypoxia and/or high glucose to mimic CCH complicated with DM pathologies in vitro. To further explore the underlying mechanism, TREM-2-specific small interfering RNA and TREM-2 overexpression lentivirus were used to knock out and overexpress TREM-2, respectively. RESULTS: Cognitive deficits, neuronal cell death, neuroinflammation with microglial activation, and TREM-2-MAPK signaling were enhanced when DM was superimposed on CCH both in vivo and in vitro. Manipulating TREM-2 expression levels markedly regulated the p38 MAPK signaling and the inflammatory response in vitro. TREM-2 knockout intensified while TREM-2 overexpression suppressed the p38 MAPK signaling and subsequent pro-inflammatory mediator production under high glucose and hypoxia condition. CONCLUSIONS: These results suggest that TREM-2 negatively regulates p38 MAPK-mediated inflammatory response when DM was synergistically superimposed on CCH and highlight the importance of TREM-2 as a potential target of immune regulation in DM and CCH.

Parkin overexpression attenuates Aß-induced mitochondrial dysfunction in HEK293 cells by restoring impaired mitophagy.

AIMS: Mitochondrial dysfunction is an early prominent feature of Alzheimer's disease (AD). In the present study, we sought to investigate whether defective mitophagy is tightly related to amyloid-ß (Aß)-induced mitochondrial dysfunction. MAIN METHODS: Immunofluorescence, western blot and transmission electron microscopy were used to examine mitophagy. Mitochondrial membrane potential was assessed using the JC-1 dye. Mitochondrial ROS was detected using MitoSOX™ Red staining. KEY FINDINGS: Aß induced mitochondrial dysfunction in HEK293 cells. Moreover, Aß induced an increase in parkin translocation to mitochondria and led to a drastic reduction in cytosolic parkin. Furthermore, Aß-treated cells displayed a microtubule-associated protein 1 light chain 3 (LC3) punctate pattern and elevated mitochondrial LC3-II levels, suggesting the upregulation of mitophagy. Notably, Aß induced the accumulation of mitochondrial p62, which was associated with impaired mitophagy. In addition, Aß-treated cells exhibited fragmented or swollen mitochondria with severely decreased cristae. We then investigated whether overexpression of parkin could protect cells against Aß-induced mitochondrial dysfunction. Interestingly, parkin overexpression inhibited Aß-induced mitochondrial dysfunction. Besides, parkin overexpression increased cytosolic and mitochondrial parkin levels as well as mitochondrial LC3-II levels in Aß-treated cells. Additionally, parkin overexpression reversed the accumulation of p62 in mitochondria, indicating that parkin overexpression restored impaired mitophagy in Aß-treated cells. Importantly, parkin overexpression remarkably reversed Aß-induced mitochondrial fragmentation. SIGNIFICANCE: Our data demonstrate that overexpression of parkin ameliorates impaired mitophagy and promotes the removal of damaged mitochondria in Aß-treated cells, indicating that upregulation of parkin-mediated mitophagy may be a potential strategy for the therapy of AD.

Curcumin inhibits LPS-induced neuroinflammation by promoting microglial M2 polarization via TREM2/ TLR4/ NF-κB pathways in BV2 cells.

Microglia mediate multiple facets of neuroinflammation, which plays a double-edged role in various brain diseases via distinct microglial phenotypes (deleterious M1 and neuroprotective M2). Therefore, the inhibition of overactivated inflammatory M1 microglia by switching to the protective M2 phenotype appears to be a potential therapeutic strategy in neuroinflammatory disorders. Curcumin has been shown to exhibit anti-inflammatory and neuroprotective activities. The present study investigated the potential effects of curcumin on microglial M1/M2 polarization and elucidated the possible molecular mechanisms of action in vitro. In this study, the BV2 microglial cell line was pretreated with different curcumin concentrations in the presence or absence of lipopolysaccharide (LPS) to assess the anti-inflammatory efficacy of curcumin based on the morphological and inflammatory changes. The cytotoxicity of curcumin for BV2 cells was evaluated using the CCK-8 assay. Further, the effect of curcumin concentrations on LPS-induced BV2 cells was studied. The morphological changes were observed using an optical microscope and immunofluorescent staining. Nitric oxide (NO) expression was determined using the Griess reagent. The expression of cytokines and inflammatory mediators was also measured by ELISA, qRT-PCR, flow cytometry, and immunofluorescence. Western blot analysis was used to determine the levels of triggering receptor expressed on myeloid cells 2 (TREM2), toll-like receptor 4 (TLR4), nuclear factor-kappa B (NF-κB) p65, p-NF-κB p65, IκB, and p-IκB expression. Results showed that curcumin concentrations less than 10 µM did not induce any detectable cytotoxicity but decreased BV2 cell viability up to 20 µM. Curcumin inhibited LPS-induced microglial activation. Curcumin treatment switched the M1 pro-inflammatory phenotype to the M2 anti-inflammatory phenotype by decreasing the expression of M1 markers (i.e., iNOS, IL-1ß, IL-6, and CD16/32) and elevating the expression of M2 markers (i.e., arginase 1, IL-4, IL-10, and CD206). Interestingly, curcumin attenuated the activation of TLR4/NF-κB pathways and the downregulation of TREM2 expression in LPS-activated BV2 cells. Collectively, these results suggest that curcumin significantly alleviates LPS-induced inflammation by regulating microglial (M1/M2) polarization by reducing the imbalance of TREM2 and TLR4 and balancing the downstream NF-κB activation.

USP18 Overexpression Protects against Focal Cerebral Ischemia Injury in Mice by Suppressing Microglial Activation.

The activation of inflammatory cytokines following stroke leads to neuron apoptosis and microglial activation, both of which are involved in ischemic brain damages. The ubiquitin-specific protease 18 (USP18) negatively regulated the expression of inflammatory cytokines and suppresses microglial activation. This study aims to determine whether USP18 expression protects against brain damage in ischemic models of stroke. We investigated USP18 expression, overexpression, and knockout under ischemic conditions in vitro and in vivo. Using BV2 microglial cells under oxygen and glucose deprivation (OGD) and 60 min transient middle cerebral artery occlusion (MCAO) in mice as models of ischemia, we assessed the infarct volume, the extent of neurogenesis, the expression of proinflammatory cytokines and Janus Kinases(JAKs)/Signal Transducer and Activator of Transcription (STAT) pathway members. BV2 cells under OGD for 0, 6, 12, or 24 h exhibited decreased USP18 expression and increased expression of the proinflammatory cytokines including interleukin (IL)-1ß, IL-6, IL-8, tumor necrosis factor (TNF)-α, and interferon (INF)-γ. Lentiviral overexpression of USP18 in MCAO mice significantly decreased the infarct volume and significantly increased the number of new neurons that coexpressed bromodeoxyuridine (BrdU)/neuronal nuclei (NeuN). Additionally, microglial activation was inhibited, including the suppression of the JAK/STAT pathway and the proinflammatory cytokines expression. In vitro experiments demonstrated that USP18 inhibited BV2 microglial activity and reduced the mRNA and protein levels of NF-κB, JAK1, p-JAK1, STAT1, and p-STAT1 in BV2 microglial cells. USP18 overexpression decreased ischemic brain injury through the suppression of microglial activation by negatively regulating the release of proinflammatory cytokines.

MALAT1 Activates the P53 Signaling Pathway by Regulating MDM2 to Promote Ischemic Stroke.

BACKGROUND/AIMS: This study focused on evaluating the effect of MALAT1 and MDM2 on ischemic stroke through regulation of the p53 signaling pathway. MATERIALS: Bioinformatics analysis was performed to identify abnormally expressed lncRNAs, mRNAs and their associated pathways. Oxygen-glucose deprivation/reoxygenation (OGD/R) in cells and middle cerebral artery occlusion/reperfusion (MCAO/R) in mice were performed to simulate an ischemic stroke environment. Western blot and qRT-PCR were used to examine lncRNA expression and mRNA levels. Fluorescence in situ hybridization (FISH) LncRNA was used to locate mRNA. MTT and flow cytometry were performed to examine cell proliferation and apoptosis. Finally, immunohistochemistry was used to observe the expression of genes in vivo. RESULTS: MALAT1 and MDM2, which exhibit strong expression in stroke tissues, were subjected to bioinformatics analysis, and the p53 pathway was chosen for further study. MALAT1, MDM2 and p53 signaling pathway-related proteins were all up regulated in OGD/R cells. Furthermore, Malat1, Mdm2 and p53 pathway related-proteins were also up regulated in MCAO/R mice. Both MALAT1 and MDM2 were localized in the nuclei. Down regulation of MALAT1 and MDM2 enhanced cell proliferation ability and reduced apoptosis, resulting in decreased infarct size in MCAO/R brains. CONCLUSION: These results indicate that MALAT1/MDM2/p53 signaling pathway axis may provide more effective clinical therapeutic strategy for patients with ischemic stroke.

PTEN inhibition enhances angiogenesis in an in vitro model of ischemic injury by promoting Akt phosphorylation and subsequent hypoxia inducible factor-1α upregulation.

Angiogenesis is an important pathophysiological response to cerebral ischemia. PTEN is a lipid phosphatase whose loss activates PI3K/Akt signaling, which is related to HIF-1α upregulation and enhanced angiogenesis in human cancer cells. However, the specific roles of PTEN in endothelial cell functions and angiogenesis after cerebral ischemia remain unknown. Therefore, we sought to examine the potential effects of PTEN inhibition on post-ischemic angiogenesis in human blood vessel cells and to determine the underlying mechanism. In this present study, human umbilical vein endothelial cells (HUVECs) were exposed to oxygen-glucose deprivation (OGD), cell proliferation, migration and apoptosis, in vitro tube formation and expression of PTEN/Akt pathway and angiogenic factors were examined in HUVECs after treatment with PTEN inhibitor bisperoxovanadium (bpV) at different doses. The results showed that bpV significantly increased the cell proliferation and reduced cell apoptosis indicating that the drug exerts a cytoprotective effect on HUVECs with OGD exposure. bpV also enhanced cell migration and tube formation in HUVECs following OGD, and upregulated HIF-1α and VEGF expressions, but attenuated endostatin expression. Additionally, western blotting analysis demonstrated that Akt phosphorylation in HUVECs was significantly increased after bpV treatment. These findings suggest that PTEN inhibition promotes post-ischemic angiogenesis in HUVECs after exposure to OGD and this enhancing effect might be achieved through activation of the Akt signal cascade.

Acetylcholinesterase Inhibitor Donepezil Effects on Plasma ß-Hydroxybutyrate Levels in the Treatment of Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) is a complex neurodegenerative disorder characterized by a multi-factorial etiology that is not completely understood. Donepezil is a first-line acetylcholinesterase inhibitor used for the treatment of AD that has been found, in addition to its potent acetylcholinesterase inhibitory effect, to act through other non-cholinergic mechanisms such as affecting mitochondrial biogenesis through peroxisome proliferator-activated receptor gamma coactivator (PGC1α). Mitochondrial biogenesis and PGC-1α, at least in part, are associated with hepatic fatty acid oxidation and ketogenesis. Whether donepezil regulates ketogenesis in AD treatment remains unclear. Ketogenesis is important in the progression of AD and is a critical consideration during the therapeutic strategy selection for AD. Thus, our goals were to determine the differences in ketone bodies in patients with AD who were taking donepezil treatment and those who were not, to elucidate the potential effect of AD and donepezil therapy on ketone body metabolic parameters, and to discover the effect of donepezil therapy on ketogenesis in patients with AD. METHODS: Cross-sectional analysis was performed on plasma collected from 145 individuals, namely, elderly adults as healthy controls (n=30), newly diagnosed patients with AD (n=30), patients with AD who responded to donepezil therapy (n=48) and patients with AD who did not respond to donepezil therapy (n=37). Gas chromatography-mass spectrometry was performed to quantify the lipids in the plasma. The level of ß-hydroxybutyrate, a metabolite, was determined by liquid chromatographytandem mass spectrometry, and to gain further insight into the effect of donepezil on ketogenesis, the effects of donepezil were investigated in a mouse model. RESULTS: The level of ß-hydroxybutyrate decreased in AD patients, and donepezil elevated the plasma level of ß-hydroxybutyrate. Donepezil increased the plasma and liver levels of ß-hydroxybutyrate in mice as well as the hepatic expression of PGC-1α and the mitochondrial expression of HMG-CoA synthetase 2 (HMGCS2) in response to fasting, causing a subsequent increase in ketogenesis. CONCLUSIONS: Our study revealed that impaired ketogenesis is a metabolic feature of AD. Donepezil had effects on ketogenesis in mice and reversed the decrease in the level of ß-hydroxybutyrate found in patients with AD.

Curcumin attenuates cerebral ischemia injury in Sprague-Dawley rats and PC12 cells by suppressing overactivated autophagy.

The present study assessed whether the protective effects of curcumin against cerebral ischemia injury were due to the suppression of overactivated autophagy. Curcumin is a well-known natural polyphenolic compound that effectively counteracts oxidation, inflammation, and various types of cancer. Several studies have demonstrated the protective effects of curcumin against ischemia-reperfusion injury in tissues from the lungs, cardiomyocytes, and liver. The present study employed brain injury models induced by middle cerebral artery occlusion (MCAO) in rats and PC12 oxygen-glucose-deprived (OGD) cells. Infarct area, neurological score, lactate dehydrogenase (LDH) activity, autophagy expression, cell apoptosis, and mRNA and protein expressions of caspase-3 were determined following curcumin supplementation. Compared to MCAO rats, curcumin-treated MCAO rats exhibited substantial reductions in neurological score, infarct area, and LDH activity. MCAO also increased LC3 II/I protein expression and decreased p62 protein expression, but curcumin supplementation significantly reversed these altered protein expressions. Caspase-3 protein expression increased by 46.2% in the MCAO group, but curcumin supplementation significantly reduced this expression. Similarly, apoptosis increased by 33.1% in OGD cells, but curcumin supplementation significantly reduced apoptosis to 21.6% and 9.3% at doses of 100 and 200 mg/kg, respectively. The mRNA and protein expressions of caspase-3 exhibited substantial increases in OGD cells but these expressions were significantly decreased following curcumin supplementation. Taken together, the present results indicate that curcumin represents a natural bioactive substance that can protect against cerebral ischemia via the suppression of overactivated autophagy.

Association between ABCA1 gene polymorphisms and the therapeutic response to donepezil therapy in Han Chinese patients with Alzheimer's disease.

AIM: It is reported that ABCA1, which plays a key role in cholesterol transport and apolipoprotein E (APOE) metabolism in the brain, is related to Alzheimer's disease. However, few studies have focused on the relationship between the ABCA1 gene and the therapeutic response to donepezil (DNP), which has been shown to be related to reduced sAPP production.This study evaluated the association between the ABCA1 gene polymorphism and the clinical response to donepezil therapy in Han Chinese patients with Alzheimer's disease. METHODS: We examined ABCA1 gene polymorphisms in 88 Han Chinese patients with Alzheimer's disease who were receiving DNP therapy. The Mini-Mental State Examination was conducted before and after DNP treatment, and the ABCA1 rs 2230806 and rs 2230808, APOE E3 genotypes of each patient were identified. RESULTS: We found that patients with the ABCA1 rs2230806 GG genotype responded better to DNP treatment compared to those with the AA and AG genotypes (p = 0.001). Patients who were APOE E3 non-carriers and had the ABCA1 rs2230806 GG genotype tended to have a better clinical response to DNP therapy. CONCLUSIONS: The ABCA1 rs 2230806 polymorphism and its combination with the APOE E3 allele may provide clinically relevant information for predicting the therapeutic response to DNP therapy.

Subcortical nuclei in Alzheimer's disease: a volumetric and diffusion kurtosis imaging study.

Background Previous studies revealed that subcortical nuclei were harmed in the process of Alzheimer's disease (AD). Purpose To investigate the volumetric and diffusion kurtosis imaging (DKI) parameter changes of subcortical nuclei in AD and their relationship with cognitive function. Materials and Methods A total of 17 mild AD patients, 15 moderate to severe AD patients, and 16 controls underwent neuropsychological tests and magnetic resonance imaging (MRI) scans. Volume, mean kurtosis (MK), mean diffusivity (MD), and fractional anisotropy (FA) were measured in hippocampus, thalamus, caudate, putamen, pallidum, and amygdala. MRI parameters were compared. Correlation analysis was performed between subcortical nuclei volume, DKI parameters, and MMSE score. Results Significant volume reduction was seen in the left hippocampus in mild AD, and the bilateral hippocampus, thalamus, putamen, left caudate, and right amygdala in moderate to severe AD ( P < 0.05). Increased MD values were observed in the left hippocampus, left amygdala, and right caudate in mild AD, and the bilateral hippocampus and right amygdala in moderate to severe AD ( P < 0.05). Decreased MK values were observed only in the bilateral hippocampus in moderate to severe AD ( P < 0.05). No group significances were found in FA value. MMSE score was positively correlated with the volume of the bilateral hippocampus, thalamus, and putamen, and MK value of the left hippocampus ( P < 0.05). A negative correlation was found with the MD value of the bilateral hippocampus and left amygdala ( P < 0.05). Conclusion Mild AD mainly has microscopic subcortical changes revealed by increased MD value, and moderate to severe AD mainly has macroscopic subcortical changes revealed by volume reduction. MK is more sensitive in severe AD than mild AD.

Involvement of impaired autophagy and mitophagy in Neuro-2a cell damage under hypoxic and/or high-glucose conditions.

Chronic cerebral hypoperfusion (CCH) plays an insidious role in the development of cognitive impairment. Considerable evidence suggests that Diabetes Mellitus (DM) as a vascular risk factor may exacerbate CCH and is closely related to cognitive decline. Dysregulation of autophagy is known to be associated with the pathogenesis of neurodegenerative diseases such as Alzheimer's disease. To elucidate the role of autophagy in CCH- and/or DM-related pathogenesis, mouse neuroblastoma Neuro-2a cells were exposed to hypoxia and/or high glucose for 48 h, mimicking CCH complicated with DM pathologies. Chronic hypoxia reduced cell proliferation and increased levels of cleaved caspase-3, whereas high glucose had no obvious synergistic toxic effect. Accumulation of autophagic vacuoles under hypoxia may be due to both autophagy impairment and induction, with the former accounting for Neuro-2a cell death. Additionally, aberrant accumulation of mitochondria in Neuro-2a cells may be attributed to insufficient BNIP3-mediated mitophagy due to poor interaction between BNIP3 and LC3-II. Despite the lack of a significant cytotoxic effect of high glucose under our experimental conditions, our data indicated for the first time that impaired autophagy degradation and inefficient BNIP3-mediated mitophagy may constitute mechanisms underlying neuronal cell damage during chronic hypoxia.