Folate and vitamin B-12 deficiencies additively impaire memory function and disturb the gut microbiota in amyloid-ß infused rats.

Folate and vitamin B12(V-B12) deficiencies are associated with metabolic diseases that may impair memory function. We hypothesized that folate and V-B12 may differently alter mild cognitive impairment, glucose metabolism, and inflammation by modulating the gut microbiome in rats with Alzheimer's disease (AD)-like dementia. The hypothesis was examined in hippocampal amyloid-ß infused rats, and its mechanism was explored. Rats that received an amyloid-ß(25-35) infusion into the CA1 region of the hippocampus were fed either control(2.5 mg folate plus 25 µg V-B12/kg diet; AD-CON, n = 10), no folate(0 folate plus 25 µg V-B12/kg diet; AD-FA, n = 10), no V-B12(2.5 mg folate plus 0 µg V-B12/kg diet; AD-V-B12, n = 10), or no folate plus no V-B12(0 mg folate plus 0 µg V-B12/kg diet; AD-FAB12, n = 10) in high-fat diets for 8 weeks. AD-FA and AD-VB12 exacerbated bone mineral loss in the lumbar spine and femur whereas AD-FA lowered lean body mass in the hip compared to AD-CON(P < 0.05). Only AD-FAB12 exacerbated memory impairment by 1.3 and 1.4 folds, respectively, as measured by passive avoidance and water maze tests, compared to AD-CON(P < 0.01). Hippocampal insulin signaling and neuroinflammation were attenuated in AD-CON compared to Non-AD-CON. AD-FAB12 impaired the signaling (pAkt→pGSK-3ß) and serum TNF-α and IL-1ß levels the most among all groups. AD-CON decreased glucose tolerance by increasing insulin resistance compared to Non-AD-CON. AD-VB12 and AD-FAB12 increased insulin resistance by 1.2 and 1.3 folds, respectively, compared to the AD-CON. AD-CON and Non-AD-CON had a separate communities of gut microbiota. The relative counts of Bacteroidia were lower and those of Clostridia were higher in AD-CON than Non-AD-CON. AD-FA, but not V-B12, separated the gut microbiome community compared to AD-CON and AD-VB12(P = 0.009). In conclusion, folate and B-12 deficiencies impaired memory function by impairing hippocampal insulin signaling and gut microbiota in AD rats.

The effect of 4-Week rehabilitation by aerobic exercise on hippocampus BDNF and TGF-ß1 gene expressions inAß 1-42-induced rat model of Alzheimer's disease.

Alzheimer's disease (AD) is a type of brain dysfunction featuring a gradual loss in memory. This study aimed to determine the effect of 4 weeks of aerobic rehabilitation exercise (RhExe) on the genes expression of BDNF and TGF-ß1 in the hippocampus tissue of rats with the AD induced by injection of amyloid-beta (Aß1-42). Twenty-one male Wistar rats were randomly divided into 3 groups: Aß injection (n = 7), Aß + exercise (n = 7) and control (n = 7). AD was induced by a single dose of Aß injection into the hippocampus of rats. Three days after surgery, the Aß + exercise group experienced four weeks of the RhExe (5 days/week). Forty-eight hours after the last training session, the animals underwent the Morris water maze test. The animals were sacrificed 24 h after the test, and hippocampal tissue was split. The mRNA expression of BDNF, TGF-ß1, and TGF-ß1 II receptors was measured. The TGF-ß1 and TGF-ß1 II receptor genes expression of Aß + exercise group were significantly higher than the Aß injection group (P ≤ 0.001). BDNF gene expression in the hippocampus of the Aß + exercise group was significantly higher than the Aß injection group (P ≤ 0.001). Spatial memory was significantly higher in the Aß + exercise group than in the Aß injection group (p ≤ 0.01). It seems that aerobic exercise can counteract the harmful effects of Aß through the BDNF and TGF-ß1molecular signaling pathways.

Novel brain-targeted nanomicelles for anti-glioma therapy mediated by the ApoE-enriched protein corona in vivo.

BACKGROUND: The interactions between nanoparticles (NPs) and plasma proteins form a protein corona around NPs after entering the biological environment, which provides new biological properties to NPs and mediates their interactions with cells and biological barriers. Given the inevitable interactions, we regard nanoparticle‒protein interactions as a tool for designing protein corona-mediated drug delivery systems. Herein, we demonstrate the successful application of protein corona-mediated brain-targeted nanomicelles in the treatment of glioma, loading them with paclitaxel (PTX), and decorating them with amyloid ß-protein (Aß)-CN peptide (PTX/Aß-CN-PMs). Aß-CN peptide, like the Aß1-42 peptide, specifically binds to the lipid-binding domain of apolipoprotein E (ApoE) in vivo to form the ApoE-enriched protein corona surrounding Aß-CN-PMs (ApoE/PTX/Aß-CN-PMs). The receptor-binding domain of the ApoE then combines with low-density lipoprotein receptor (LDLr) and LDLr-related protein 1 receptor (LRP1r) expressed in the blood-brain barrier and glioma, effectively mediating brain-targeted delivery. METHODS: PTX/Aß-CN-PMs were prepared using a film hydration method with sonication, which was simple and feasible. The specific formation of the ApoE-enriched protein corona around nanoparticles was characterized by Western blotting analysis and LC-MS/MS. The in vitro physicochemical properties and in vivo anti-glioma effects of PTX/Aß-CN-PMs were also well studied. RESULTS: The average size and zeta potential of PTX/Aß-CN-PMs and ApoE/PTX/Aß-CN-PMs were 103.1 nm, 172.3 nm, 7.23 mV, and 0.715 mV, respectively. PTX was efficiently loaded into PTX/Aß-CN-PMs, and the PTX release from rhApoE/PTX/Aß-CN-PMs exhibited a sustained-release pattern in vitro. The formation of the ApoE-enriched protein corona significantly improved the cellular uptake of Aß-CN-PMs on C6 cells and human umbilical vein endothelial cells (HUVECs) and enhanced permeability to the blood-brain tumor barrier in vitro. Meanwhile, PTX/Aß-CN-PMs with ApoE-enriched protein corona had a greater ability to inhibit cell proliferation and induce cell apoptosis than taxol. Importantly, PTX/Aß-CN-PMs exhibited better anti-glioma effects and tissue distribution profile with rapid accumulation in glioma tissues in vivo and prolonged median survival of glioma-bearing mice compared to those associated with PMs without the ApoE protein corona. CONCLUSIONS: The designed PTX/Aß-CN-PMs exhibited significantly enhanced anti-glioma efficacy. Importantly, this study provided a strategy for the rational design of a protein corona-based brain-targeted drug delivery system. More crucially, we utilized the unfavorable side of the protein corona and converted it into an advantage to achieve brain-targeted drug delivery.

Depichering the Effects of Astragaloside IV on AD-Like Phenotypes: A Systematic and Experimental Investigation.

Astragaloside IV (AS-IV) is an active component in Astragalus membranaceus with the potential to treat neurodegenerative diseases, especially Alzheimer's diseases (ADs). However, its mechanisms are still not known. Herein, we aimed to explore the systematic pharmacological mechanism of AS-IV for treating AD. Drug prediction, network pharmacology, and functional bioinformatics analyses were conducted. Molecular docking was applied to validate reliability of the interactions and binding affinities between AS-IV and related targets. Finally, experimental verification was carried out in AßO infusion produced AD-like phenotypes to investigate the molecular mechanisms. We found that AS-IV works through a multitarget synergistic mechanism, including inflammation, nervous system, cell proliferation, apoptosis, pyroptosis, calcium ion, and steroid. AS-IV highly interacted with PPARγ, caspase-1, GSK3Β, PSEN1, and TRPV1 after docking simulations. Meanwhile, PPARγ interacts with caspase-1, GSK3Β, PSEN1, and TRPV1. In vivo experiments showed that AßO infusion produced AD-like phenotypes in mice, including impairment of fear memory, neuronal loss, tau hyperphosphorylation, neuroinflammation, and synaptic deficits in the hippocampus. Especially, the expression of PPARγ, as well as BDNF, was also reduced in the hippocampus of AD-like mice. Conversely, AS-IV improved AßO infusion-induced memory impairment, inhibited neuronal loss and the phosphorylation of tau, and prevented the synaptic deficits. AS-IV prevented AßO infusion-induced reduction of PPARγ and BDNF. Moreover, the inhibition of PPARγ attenuated the effects of AS-IV on BDNF, neuroflammation, and pyroptosis in AD-like mice. Taken together, AS-IV could prevent AD-like phenotypes and reduce tau hyperphosphorylation, synaptic deficits, neuroinflammation, and pyroptosis, possibly via regulating PPARγ.

Cycloastragenol, a Triterpenoid Saponin, Regulates Oxidative Stress, Neurotrophic Dysfunctions, Neuroinflammation and Apoptotic Cell Death in Neurodegenerative Conditions.

Here, we have unveiled the effects of cycloastragenol against Aß (Amyloid-beta)-induced oxidative stress, neurogenic dysfunction, activated mitogen-activated protein (MAP) kinases, and mitochondrial apoptosis in an Aß-induced mouse model of Alzheimer's disease (AD). The Aß-induced mouse model was developed by the stereotaxic injection of amyloid-beta (5 µg/mouse/intracerebroventricular), and cycloastragenol was given at a dose of 20 mg/kg/day/p.o for 6 weeks daily. For the biochemical analysis, we used immunofluorescence and Western blotting. Our findings showed that the injection of Aß elevated oxidative stress and reduced the expression of neurogenic markers, as shown by the reduced expression of brain-derived neurotrophic factor (BDNF) and the phosphorylation of its specific receptor tropomyosin receptor kinase B (p-TrKB). In addition, there was a marked reduction in the expression of NeuN (neuronal nuclear protein) in the Aß-injected mice brains (cortex and hippocampus). Interestingly, the expression of Nrf2 (nuclear factor erythroid 2-related factor 2), HO-1 (heme oxygenase-1), p-TrKB, BDNF, and NeuN was markedly enhanced in the Aß + Cycloastragenol co-treated mice brains. We have also evaluated the expressions of MAP kinases such as phospho c-Jun-N-terminal kinase (p-JNK), p-38, and phospho-extracellular signal-related kinase (ERK1/2) in the experimental groups, which suggested that the expression of p-JNK, p-P-38, and p-Erk were significantly upregulated in the Aß-injected mice brains; interestingly, these markers were downregulated in the Aß + Cycloastragenol co-treated mice brains. We also checked the expression of activated microglia and inflammatory cytokines, which showed that cycloastragenol reduced the activated microglia and inflammatory cytokines. Moreover, we evaluated the effects of cycloastragenol against mitochondrial apoptosis and memory dysfunctions in the experimental groups. The findings showed significant regulatory effects against apoptosis and memory dysfunction as revealed by the Morris water maze (MWM) test. Collectively, the findings suggested that cycloastragenol regulates oxidative stress, neurotrophic processes, neuroinflammation, apoptotic cell death, and memory impairment in the mouse model of AD.

Morin attenuates memory deficits in a rat model of Alzheimer's disease by ameliorating oxidative stress and neuroinflammation.

This study aimed to investigate the effect of flavonoid morin on oxidative/nitrosative stress, neuroinflammation, and histological, molecular, and behavioral changes caused by amyloid-beta (Aß)1-42 in male Wistar rats (Alzheimer's disease model). Rats received morin (20 mg/kg, oral gavage) for 14 consecutive days after intrahippocampal injection of Aß1-42. Morin decreased the levels of malondialdehyde and nitric oxide, increased glutathione content, and enhanced catalase activity in the hippocampus of animals receiving Aß1-42. It also reduced the expression of tumor necrosis factor-α, interleukin-1ß, interleukin-6, nuclear factor-kappa B, and N-methyl-D-aspartate receptor subunits 2A and 2B and increased the expression of brain-derived neurotrophic factor and α7 nicotinic acetylcholine receptor in the hippocampus of Aß1-42-injected rats. Besides, morin modified neuronal loss and histological changes in the CA1 region of the hippocampus. Morin allowed Aß1-42-infused rats to swim more time in the target quadrant in the Morris water maze test. It is concluded that morin may be suitable for the prevention and treatment of Alzheimer's disease by strengthening the antioxidant system, inhibiting neuroinflammation, preventing neuronal death, and enhancing memory function.

Exogenous Aß seeds induce Aß depositions in the blood vessels rather than the brain parenchyma, independently of Aß strain-specific information.

Little is known about the effects of parenchymal or vascular amyloid ß peptide (Aß) deposition in the brain. We hypothesized that Aß strain-specific information defines whether Aß deposits on the brain parenchyma or blood vessels. We investigated 12 autopsied patients with different severities of Aß plaques and cerebral amyloid angiopathy (CAA), and performed a seeding study using an Alzheimer's disease (AD) mouse model in which brain homogenates derived from the autopsied patients were injected intracerebrally. Based on the predominant pathological features, we classified the autopsied patients into four groups: AD, CAA, AD + CAA, and less Aß. One year after the injection, the pathological and biochemical features of Aß in the autopsied human brains were not preserved in the human brain extract-injected mice. The CAA counts in the mice injected with all four types of human brain extracts were significantly higher than those in mice injected with PBS. Interestingly, parenchymal and vascular Aß depositions were observed in the mice that were injected with the human brain homogenate from the less Aß group. The Aß and CAA seeding activities, which had significant positive correlations with the Aß oligomer ratio in the human brain extracts, were significantly higher in the human brain homogenate from the less Aß group than in the other three groups. These results indicate that exogenous Aß seeds from different Aß pathologies induced Aß deposition in the blood vessels rather than the brain parenchyma without being influenced by Aß strain-specific information, which might be why CAA is a predominant feature of Aß pathology in iatrogenic transmission cases. Furthermore, our results suggest that iatrogenic transmission of Aß pathology might occur due to contamination of brain tissues from patients with little Aß pathology, and the development of inactivation methods for Aß seeding activity to prevent iatrogenic transmission is urgently required.

Importance of extracellular vesicle secretion at the blood-cerebrospinal fluid interface in the pathogenesis of Alzheimer's disease.

Increasing evidence indicates that extracellular vesicles (EVs) play an important role in the pathogenesis of Alzheimer's disease (AD). We previously reported that the blood-cerebrospinal fluid (CSF) interface, formed by the choroid plexus epithelial (CPE) cells, releases an increased amount of EVs into the CSF in response to peripheral inflammation. Here, we studied the importance of CP-mediated EV release in AD pathogenesis. We observed increased EV levels in the CSF of young transgenic APP/PS1 mice which correlated with high amyloid beta (Aß) CSF levels at this age. The intracerebroventricular (icv) injection of Aß oligomers (AßO) in wild-type mice revealed a significant increase of EVs in the CSF, signifying that the presence of CSF-AßO is sufficient to induce increased EV secretion. Using in vivo, in vitro and ex vivo approaches, we identified the CP as a major source of the CSF-EVs. Interestingly, AßO-induced, CP-derived EVs induced pro-inflammatory effects in mixed cortical cultures. Proteome analysis of these EVs revealed the presence of several pro-inflammatory proteins, including the complement protein C3. Strikingly, inhibition of EV production using GW4869 resulted in protection against acute AßO-induced cognitive decline. Further research into the underlying mechanisms of this EV secretion might open up novel therapeutic strategies to impact the pathogenesis and progression of AD.

Antioxidative and Anti-inflammatory Effects of Kojic Acid in Aß-Induced Mouse Model of Alzheimer's Disease.

Alzheimer's disease (AD) is a common cause of dementia that is clinically characterized by the loss of memory and cognitive functions. Currently, there is no specific cure for the management of AD, although natural compounds are showing promising therapeutic potentials because of their safety and easy availability. Herein, we evaluated the neuroprotective properties of kojic acid (KA) in an AD mouse model. Intracerebroventricular injection (i.c.v) of Aß1-42 (5 µL/5 min/mouse) into wild-type adult mice induced AD-like pathological changes in the mouse hippocampus by increasing oxidative stress and neuroinflammation, affecting memory and cognitive functions. Interestingly, oral treatment of kojic acid (50 mg/kg/mouse for 3 weeks) reversed the AD pathology by reducing the expression of amyloid-beta (Aß) and beta-site amyloid precursor protein cleaving enzyme1 (BACE-1). Moreover, kojic acid reduced oxidative stress by enhancing the expression of nuclear factor erythroid-related factor 2 (Nrf2) and heme oxygenase 1 (HO1). Also, kojic acid reduced the lipid peroxidation and reactive oxygen species in the Aß + kojic acid co-treated mice brains. Moreover, kojic acid decreased neuroinflammation by inhibiting Toll-like receptor 4, phosphorylated nuclear factor-κB, tumor necrosis factor-alpha, interleukin 1-beta (TLR-4, p-NFκB, TNFα, and IL-1ß, respectively), and glial cells. Furthermore, kojic acid enhanced synaptic markers (SNAP-23, SYN, and PSD-95) and memory functions in AD model mice. Additionally, kojic acid treatment also decreased Aß expression, oxidative stress, and neuroinflammation in vitro in HT-22 mouse hippocampal cells. To the best of our knowledge, this is the first study to show the neuroprotective effects of kojic acid against an AD mouse model. Our findings could serve as a favorable and alternative strategy for the discovery of novel drugs to treat AD-related neurodegenerative conditions.

GW9508 ameliorates cognitive dysfunction via the external treatment of encephalopathy in Aß1-42 induced mouse model of Alzheimer's disease.

The functions and mechanisms of GPR40 receptor to ameliorating the Alzheimer's disease (AD) by external treatment of encephalopathy remain unknown. In present study, the typical Aß1-42 induced mice model was applied to explore the functions and mechanisms of GPR40 receptor by external treatment of encephalopathy in AD. GPR40 agonist GW9508 and antagonist GW1100 were given by i.g injection to activate/inhibit the GPR40 receptor respectively in the gut of AD mouse which illustrated the function and mechanism of GPR40 receptor in ameliorating AD symptoms by external treatment of encephalopathy. A series of behavioral experiments were used to investigate the cognitive function and memory ability of mice, while molecular biology experiments such as Western blot, ELISA, flow cytometry were used to detect the corresponding changes of signaling pathways. The results revealed that intragastric administrated GW9508 could significantly ameliorate cognitive deficits of AD mouse, up-regulate the expression levels of gut-brain peptides both in blood circulation and hypothalamus thus up-regulate the expression levels of α-MSH in hypothalamus, while the negative autophagy-related proteins and inflammation-related proteins were down-regulated correspondingly. Meanwhile, GW9508 could also inhibit the pathological process of neuroinflammation in microglia. GW1100 reversed the effects of GW9508 significantly. These results suggested that GPR40 was an underlying therapeutic target for the external treatment of encephalopathy related to AD and GPR40 agonist could be explored as the emerging AD therapeutic drug.

Sustained Hippocampal Neural Plasticity Questions the Reproducibility of an Amyloid-ß-Induced Alzheimer's Disease Model.

BACKGROUND: The use of Alzheimer's disease (AD) models obtained by intracerebral infusion of amyloid-ß (Aß) has been increasingly reported in recent years. Nonetheless, these models may present important challenges. OBJECTIVE: We have focused on canonical mechanisms of hippocampal-related neural plasticity to characterize a rat model obtained by an intracerebroventricular (icv) injection of soluble amyloid-ß42 (Aß42). METHODS: Animal behavior was evaluated in the elevated plus maze, Y-Maze spontaneous or forced alternation, Morris water maze, and open field, starting 2 weeks post-Aß42 infusion. Hippocampal neurogenesis was assessed 3 weeks after Aß42 injection. Aß deposition, tropomyosin receptor kinase B levels, and neuroinflammation were appraised at 3 and 14 days post-Aß42 administration. RESULTS: We found that immature neuronal dendritic morphology was abnormally enhanced, but proliferation and neuronal differentiation in the dentate gyrus was conserved one month after Aß42 injection. Surprisingly, animal behavior did not reveal changes in cognitive performance nor in locomotor and anxious-related activity. Brain-derived neurotrophic factor related-signaling was also unchanged at 3 and 14 days post-Aß icv injection. Likewise, astrocytic and microglial markers of neuroinflammation in the hippocampus were unaltered in these time points. CONCLUSION: Taken together, our data emphasize a high variability and lack of behavioral reproducibility associated with these Aß injection-based models, as well as the need for its further optimization, aiming at addressing the gap between preclinical AD models and the human disorder.

Intra-nasal administration of sperm head turns neutrophil into reparative mode after PGE1- and/or Ang II receptor-mediated phagocytosis followed by expression of sperm head's coding RNA.

Having played homeostatic role, the immune system maintains the integrity of the body. Such a characteristic makes immune system as an attractive candidate for resolution of inflammatory disease followed by tissue repair. As first responder cells, neutrophils direct immune response playing key role in tissue remodeling. Previous studies revealed that sperm attracts neutrophils and promotes uterine remodeling suitable for fetus growth. Accordingly, sperm and more efficiently sperm head had remodeling effects on damaged brain in Alzheimer's disease (AD) model. To further reveal the mechanism, two kinds of in vivo study, including kinetic study and inhibition of neutrophil phagocytosis on AD model, as well as in vitro study using co-culture of neutrophil and sperm head were performed. Kinetic study revealed that sperm head recruited neutrophil to nasal mucosa similar to that of uterus and sperm head-phagocytizing neutrophils acquired new activation status comparing to control. In vitro study also demonstrated that sperm head-phagocytizing neutrophils acquire new activation status and express coding RNAs of sperm head. Accordingly, inhibition of neutrophil phagocytic activity abrogated therapeutic effects of sperm head. Neutrophils activation status is important in the fate of inflammatory process. Modulation but not suppression of neutrophils helps remodeling and repair of damaged tissue. Sperm head is an intelligent cell and not just a simple particle to remove by phagocytosis but instead can program neutrophils and consequently immune response into reparative mode after phagocytosis.

Ang(1-7) exerts Nrf2-mediated neuroprotection against amyloid beta-induced cognitive deficits in rodents.

Alzheimer's disease (AD) is a neurodegenerative disorder with cognitive deficits in an individual. Ang(1-7) exhibits neuroprotection against amyloid beta (Aß)-induced mitochondrial dysfunction and neurotoxicity in experimental conditions. Further, Ang(1-7) also exhibits nrf2-mediated antioxidant activity in experimental conditions. However, its therapeutic role on nrf2-mediated mitochondrial function is yet to be established in the Aß-induced neurotoxicity. The experimental dementia was induced in the male rats by intracerebroventricular administration of Aß(1-42) on day-1 (D-1) of the experimental schedule of 14 days. Ang(1-7) was administered once daily from D-1 toD-14 to the Aß-challenged rodents. Ang(1-7) attenuated Aß-induced increase in escape latency and decrease in the time spent in the target quadrant during Morris water maze and percentage of spontaneous alteration behavior during Y-maze tests in the rats. Further, Ang(1-7) attenuated Aß-induced cholinergic dysfunction in terms of decrease in the level of acetylcholine and activity of choline acetyltransferase, and increase in the activity of acetylcholinesterase, and increase in the level of Aß in rat hippocampus, pre-frontal cortex and amygdala. Furthermore, Ang(1-7) reversed Aß-induced decrease in the mitochondrial function, integrity and bioenergetics in all brain regions. Additionally, Ang(1-7) attenuated Aß-induced increase in the extent of apoptosis and decrease in the level of heme oxygenase-1 in all selected brain regions. Trigonelline significantly abolished the therapeutic effectiveness of Ang(1-7) on Aß-induced alterations in the behavioral, neurochemicals and molecular observations in the animals. Ang(1-7) may exhibit nrf2-mediated neuroprotection in these rodents. Hence, Ang(1-7) could be a potential therapeutic option in the pharmacotherapy of AD.

Heparanase overexpression impedes perivascular clearance of amyloid-ß from murine brain: relevance to Alzheimer's disease.

Defective amyloid-ß (Aß) clearance from the brain is a major contributing factor to the pathophysiology of Alzheimer's disease (AD). Aß clearance is mediated by macrophages, enzymatic degradation, perivascular drainage along the vascular basement membrane (VBM) and transcytosis across the blood-brain barrier (BBB). AD pathology is typically associated with cerebral amyloid angiopathy due to perivascular accumulation of Aß. Heparan sulfate (HS) is an important component of the VBM, thought to fulfill multiple roles in AD pathology. We previously showed that macrophage-mediated clearance of intracortically injected Aß was impaired in the brains of transgenic mice overexpressing heparanase (Hpa-tg). This study revealed that perivascular drainage was impeded in the Hpa-tg brain, evidenced by perivascular accumulation of the injected Aß in the thalamus of Hpa-tg mice. Furthermore, endogenous Aß accumulated at the perivasculature of Hpa-tg thalamus, but not in control thalamus. This perivascular clearance defect was confirmed following intracortical injection of dextran that was largely retained in the perivasculature of Hpa-tg brains, compared to control brains. Hpa-tg brains presented with thicker VBMs and swollen perivascular astrocyte endfeet, as well as elevated expression of the BBB-associated water-pump protein aquaporin 4 (AQP4). Elevated levels of both heparanase and AQP4 were also detected in human AD brain. These findings indicate that elevated heparanase levels alter the organization and composition of the BBB, likely through increased fragmentation of BBB-associated HS, resulting in defective perivascular drainage. This defect contributes to perivascular accumulation of Aß in the Hpa-tg brain, highlighting a potential role for heparanase in the pathogenesis of AD.

Roflumilast and tadalafil improve learning and memory deficits in intracerebroventricular Aß1-42 rat model of Alzheimer's disease through modulations of hippocampal cAMP/cGMP/BDNF signaling pathway.

BACKGROUND: Alzheimer's disease (AD) is the most prevalent age-dependent neurodegenerative disease characterized by progressive impairment of memory and cognitive functions. Cyclic nucleotides like cAMP and cGMP are well-known to play an important role in learning and memory functions. Enhancement of cAMP and cGMP levels in the hippocampus by phosphodiesterase (PDE) inhibitors might be a novel therapeutic approach for AD. Thus, the present study was planned to explore the therapeutic potential of roflumilast (RFM) and tadalafil (TDF) phosphodiesterase inhibitors in intracerebroventricular (ICV) Aß1-42 induced AD in rats. METHODS: ICV Aß1-42 was administered in rats followed by treatment with RFM (0.05 mg/kg) and TDF (0.51 mg/kg) for 15 days. Novel object recognition (NOR), and Morris water maze (MWM) test were performed during the drug treatment schedule. On the day, 22 rats were sacrificed, and hippocampus was separated for biochemical, neuroinflammation, and histopathological analysis. RESULTS: Aß1-42 infused rats were induce behavioral impairment and increased AChE, BACE-1, Aß1-42, GSK-3ß, phosphorylated tau (p-Tau), pro-inflammatory cytokines (TNF-α, IL-1ß, and IL-6) levels, oxidative stress (increased MDA, Nitrite and decreased GSH), histopathological changes, and reduced cAMP, cGMP, and BDNF levels. RFM and TDF significantly attenuated Aß1-42 induced memory deficits and neuropathological alterations in the hippocampus. CONCLUSION: The outcomes of the current study indicate that RFM and TDF lead to memory enhancement through upregulation of cAMP/cGMP/BDNF pathway, thus they may have a therapeutic potential in cognitive deficits associated with AD.

The effect of intracerebroventricular amyloid beta 1-42 application on cognitive functions in aged rats supplemented with taurine and the change of peroxisomal proteins in this process.

OBJECTIVE: The aim of our study is to investigate the change of peroxisomal proteins in the neurodegenerative and oxidative process caused by the neurotoxicity of Aß 1-42 in aged rats supplemented with taurine and to show the possible positive effects of taurine in this process. METHODS: 30 Wistar albino rats were randomly divided into 5 groups as control, sham, Aß 1-42, taurine, and Aß 1-42+taurine. Taurine administration continued for 6 weeks (1000 mg/kg/day with drinking water). Stereotaxic surgery was applied to all groups (intracerebroventricular per lateral ventricle needle only or 5 µl, PBS, or Aß 1-42). Spatial learning and memory performances of the animals were evaluated with Morris water maze and elevated plus maze. The levels of MDA and GSH were measured as oxidative stress parameters in the cerebral cortex and hippocampus. Expressions of CAT, PEX14, PMP70 of peroxisomal membrane proteins were indicated by Western blot analysis. RESULTS: Our results showed that injection of Aß 1-42 decreased the spatial learning and memory performance, cortex CAT and hippocampus PEX14, PMP70 and GSH levels, and increased cortex and hippocampus MDA levels (p < 0.05). Although the administration of taurine partially ameliorated the adverse effects of Aß 1-42 injection, a significant difference was found only at the hippocampus GSH levels (p < 0.05). Also, taurine caused anxiety at this dose (p < 0.05). DISCUSSION: In conclusion, decreased peroxisomal proteins and antioxidant capacity in neurodegenerative and oxidative processes induced by intracerebroventricular Aß 1-42 injection showed that peroxisomes may play a role in this process and taurine supplementation may have positive effects especially in increasing antioxidant capacity.

Dehydroeffusol Pprevents Amyloid ß1-42-mediated Hippocampal Neurodegeneration via Reducing Intracellular Zn2+ Toxicity.

Dehydroeffusol, a phenanthrene isolated from Juncus effusus, is a Chinese medicine. To explore an efficacy of dehydroeffusol administration for prevention and cure of Alzheimer's disease, here we examined the effect of dehydroeffusol on amyloid ß1-42 (Aß1-42)-mediated hippocampal neurodegeneration. Dehydroeffusol (15 mg/kg body weight) was orally administered to mice once a day for 6 days and then human Aß1-42 was injected intracerebroventricularly followed by oral administration for 12 days. Neurodegeneration in the dentate granule cell layer, which was determined 2 weeks after Aß1-42 injection, was rescued by dehydroeffusol administration. Aß staining (uptake) was not reduced in the dentate granule cell layer by pre-administration of dehydroeffusol for 6 days, while increase in intracellular Zn2+ induced with Aß1-42 was reduced, suggesting that pre-administration of dehydroeffusol prior to Aß1-42 injection is effective for Aß1-42-mediated neurodegeneration that was linked with intracellular Zn2+ toxicity. As a matter of fact, pre-administration of dehydroeffusol rescued Aß1-42-mediated neurodegeneration. Interestingly, pre-administration of dehydroeffusol increased synthesis of metallothioneins, intracellular Zn2+-binding proteins, in the dentate granule cell layer, which can capture Zn2+ from Zn-Aß1-42 complexes. The present study indicates that pre-administration of dehydroeffusol protects Aß1-42-mediated neurodegeneration in the hippocampus by reducing intracellular Zn2+ toxicity, which is linked with induced synthesis of metallothioneins. Dehydroeffusol, a novel inducer of metallothioneins, may protect Aß1-42-induced pathogenesis in Alzheimer's disease.

Maternal antibodies facilitate Amyloid-ß clearance by activating Fc-receptor-Syk-mediated phagocytosis.

Maternal antibodies (MAbs) protect against infections in immunologically-immature neonates. Maternally transferred immunity may also be harnessed to target diseases associated with endogenous protein misfolding and aggregation, such as Alzheimer's disease (AD) and AD-pathology in Down syndrome (DS). While familial early-onset AD (fEOAD) is associated with autosomal dominant mutations in the APP, PSEN1,2 genes, promoting cerebral Amyloid-ß (Aß) deposition, DS features a life-long overexpression of the APP and DYRK1A genes, leading to a cognitive decline mediated by Aß overproduction and tau hyperphosphorylation. Although no prenatal screening for fEOAD-related mutations is in clinical practice, DS can be diagnosed in utero. We hypothesized that anti-Aß MAbs might promote the removal of early Aß accumulation in the central nervous system of human APP-expressing mice. To this end, a DNA-vaccine expressing Aß1-11 was delivered to wild-type female mice, followed by mating with 5xFAD males, which exhibit early Aß plaque formation. MAbs reduce the offspring's cortical Aß levels 4 months after antibodies were undetectable, along with alleviating short-term memory deficits. MAbs elicit a long-term shift in microglial phenotype in a mechanism involving activation of the FcγR1/Syk/Cofilin pathway. These data suggest that maternal immunization can alleviate cognitive decline mediated by early Aß deposition, as occurs in EOAD and DS.

MicroRNA-140 silencing represses the incidence of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative condition leading to severe disability from progressive impairments in cognitive functions including memory and learning. Non-coding microRNAs (miRNAs or miRs) have been linked to the pathogenesis of AD. The present study aimed to investigate the clinical significance and biological function of miR-140 in AD. First, we examined the expression of miR-140 and PINK1 in brain tissues of the established AD model rats and neurons cultured with Aß-derived diffusible ligands (AßDDLs). We identified an interaction between miR-140 and PINK1, and measured spatial learning and memory abilities of the model rats using the Morris water maze (MWM) test. After ectopic expression and depletion experiments in neurons and AD rats, we measured the levels of reactive oxygen species (ROS), and mitochondrial membrane potential (MMP), along with mTOR expression and phosphorylation, and autophagy-related factors. Results showed up-regulation of miR-140 and down-regulation of PINK1 in AD model rats and neurons. PINK1 was verified to be a direct target of miR-140, and silencing of miR-140 suppressed mitochondrial dysfunction, and enhanced autophagy in AD model rats and neurons, as supported by decreased levels of mTOR expression and phosphorylation, ß-amyloid p-Tau (Ser396), p-Tau (Thr231), Tau and ROS, and increased MMP levels and expression of Beclin 1 expression and LC3-II/LC3-I. Collectively, functional suppression of miR-140 enhanced autophagy and prevented mitochondrial dysfunction by upregulating PINK1, ultimately suggesting a novel therapeutic target for AD.

Activated microglia-induced neuroinflammatory cytokines lead to photoreceptor apoptosis in Aß-injected mice.

Age-related macular degeneration (AMD) is mainly characterized by the progressive accumulation of drusen deposits and loss of photoreceptors and retinal pigment epithelial (RPE) cells. Because amyloid ß (Aß) is the main component of drusen, Aß-induced activated microglia most likely lead to neuroinflammation and play a critical role in the pathogenesis of AMD. However, the relationship between activated microglia-mediated neuroinflammatory cytokines and photoreceptor death has not been clarified. By subretinal injection of Aß42 in mice, we mimicked an inflammatory milieu of AMD to better understand how activated microglia-induced neuroinflammatory cytokines lead to photoreceptor apoptosis in the AMD progression. We demonstrated that subretinal injection of Aß42 induces microglial activation and increases inflammatory cytokine release, which gives rise to photoreceptor apoptosis in mice. Our results were verified in vitro by co-culture of Aß42 activated primary microglia and the photoreceptor cell line 661W. We also demonstrated that the p38 mitogen-activated protein kinase (MAPK) signaling pathway was involved in Aß42-induced microglial activation and inflammatory cytokine release. Overall, our findings indicate that activated microglia-derived neuroinflammatory cytokines could contribute to photoreceptor apoptosis under the stimulation of Aß42. Moreover, this study may provide a potential therapeutic approach for AMD. KEY MESSAGES: Further explore the association between activated microglia-derived neuroinflammatory cytokine secretion and photoreceptor apoptosis under the stimulation of Aß42. Subretinal injection of Aß42 induces the activation of microglia and increases proinflammatory cytokines IL-1ß and COX-2 expression in the retina, which could give rise to the deterioration of visual function and aggravate photoreceptor apoptosis in mice. Primary microglial are activated and the levels of proinflammatory cytokines are increased by Aß42 stimulation, which could increase the apoptosis of photoreceptor cell line 661W in vitro. The p38 MAPK signaling pathway is involved in microglial activation and photoreceptor apoptosis under Aß42 treatment.