Alzheimer's Disease Rats Research Articles

Dose-dependent neuroprotective effects of adipose-derived mesenchymal stem cells on amyloid β-induced Alzheimer's disease in rats

AimMesenchymal stem cells (MSCs) have emerged as an intriguing candidate in cell therapy for treating neurodegenerative diseases, including Alzheimer's disease (AD). To achieve the maximum efficiency of cell therapy, determining the optimal dose of MSCs is essential. This study was conducted to assess the dose-dependent therapeutic response of MSCs against pathological and behavioral AD-associated alterations. MethodsAβ1-42 was injected intrahippocampally to establish an AD rat model. The MWM test was utilized to evaluate the animal's behavioral functions after receiving low and high doses of MSCs in the hippocampus region. ELISA and RT-qPCR were also employed to assess the concentration of markers related to antioxidant activity and inflammation and the gene expression related to apoptosis in the hippocampus region, respectively. ResultsLow-dose MSC transplantation by increasing the concentrations of the antioxidant GSH, the anti-inflammatory cytokine IL-10, as well as by lowering the concentrations of TNF-α, and the expression levels of apoptotic factors (Bax and caspase 3), exerted a neuroprotective effect in the hippocampus of AD rats and relatively ameliorated spatial learning and memory impairments. However, increasing the dose of MSCs decreased the therapeutic benefits of these cells and had no significant effect on the recovery of behavioral disorders. ConclusionOur findings reveal the dose-dependent neuroprotective effect of MSCs in AD. The therapeutic response of MSCs to ameliorate the pathological and behavioral alterations associated with AD is attenuated when the dosage of MSCs is increased.

Integrated brain and plasma dual-channel metabolomics to explore the treatment effects of Alpinia oxyphyllaFructus on Alzheimer's disease.

Alpinia oxyphylla Fructus, called Yizhi in Chinese, is the dried fruit of Alpinia oxyphylla Miquel. It has been used in traditional Chinese medicine to treat dementia and memory defects of Alzheimer's disease for many years. However, the underlying mechanism is still unclear. In this study, we used a rat Alzheimer's disease model on intrahippocampal injection of aggregated Aβ1-42 to study the effects of Alpinia oxyphylla Fructus. A brain and plasma dual-channel metabolomics approach combined with multivariate statistical analysis was further performed to determine the effects of Alpinia oxyphylla Fructus on Alzheimer's disease animals. As a result, in the Morris water maze test, Alpinia oxyphylla Fructus had a clear ability to ameliorate the impaired learning and memory of Alzheimer's disease rats. 11 differential biomarkers were detected in AD rats' brains. The compounds mainly included amino acids and phospholipids; after Alpinia oxyphylla Fructus administration, 9 regulated biomarkers were detected compared with the AD model group. In the plasma of AD rats, 29 differential biomarkers, primarily amino acids, phospholipids and fatty acids, were identified; After administration, 23 regulated biomarkers were detected. The metabolic pathways of regulated metabolites suggest that Alpinia oxyphylla Fructus ameliorates memory and learning deficits in AD rats principally by regulating amino acid metabolism, lipids metabolism, and energy metabolism. In conclusion, our results confirm and enhance our current understanding of the therapeutic effects of Alpinia oxyphylla Fructus on Alzheimer's disease. Meanwhile, our work provides new insight into the potential intervention mechanism of Alpinia oxyphylla Fructus for Alzheimer's disease treatment.

Simvastatin improves learning and memory impairment via gut-brain axis regulation in an ovariectomized/D-galactose Alzheimer's rat model

AimAlzheimer’s disease (AD) is the most prevalent form of dementia with multiple etiology and no effective remedy. Statins are a group of medicines that are basically used to lower cholesterol. However, several studies have recently done to assess the potential relationship between statins use and dementia but presented controversial results. MethodsIn this study, using ovariectomy and D‐galactose injection, a model of AD was induced in female rats, and then the protective effects of oral administration of simvastatin were investigated. shuttle box and Y-maze tests were done to assess the animals’ learning and memory performance. Using GC-MC, ELISA, Immunohistochemistry and tissue staining techniques, changes in the amount of short-chain fatty acids (SCFAs), plasma and hippocampus neuroinflammatory markers and histological changes in the intestine and hippocampus were assessed in sham, disease and treatment groups. Key findingsOral administration of simvastatin improved the gut microbiome activity (increased the amount of SCFAs in fecal samples) and strengthened the tight junctions of intestinal cells. Moreover, simvastatin reduced the amount of TNF-α and IL-1β in plasma and hippocampus. Also, cell death and Amyloid plaques notably decreased in the simvastatin-treated hippocampal tissue. All these physiological changes led to better performance in behavioral tasks in the treatment group in comparison to the disease group. SignificanceThese findings provide evidence that simvastatin may improve gut-brain axis followed by improvement in learning and memory via an anti-inflammatory effect.

Synthesis of Novel Magnetic Quercetin-Neuropeptide Nanocomposite as a Smart Nano-Drug Shuttle System: Investigation of Its Effect on Behavior, Histopathological Characteristics, and Expression of MAPT and APP Genes in Alzheimer's Disease Rats.

Alzheimer's disease (AD) is the most common type of dementia. The drugs introduced for this disease have many side effects and limitations in use, so the production of a suitable herbal medicine to cure AD patients is essential. The aim of this research is to make a magnetic neuropeptide nano shuttle as a targeted carrier for the transfer of quercetin to the brains of AD model rats. In this work, a magnetic quercetin-neuropeptide nanocomposite (MQNPN) was fabricated and administered to the rat's brain by the shuttle drug of the Margatoxin scorpion venom neuropeptide, and will be a prospect for targeted drug delivery in AD. The MQNPN has been characterized by FTIR, spectroscopy, FE-SEM, XRD, and VSM. Investigations into the efficacy of MQNPN, MTT, and real Time PCR for MAPT and APP genes expression were performed. After 7 days treatment with Fe3O4 (Ctr) and MQNPN treatment in AD rat, superoxide dismutase activity and quercetin in blood serum and brain was detected. Hematoxylin-Eosin staining was applied for histopathological analysis. Analysis of data showed that MQNPN increased the activity of superoxide dismutase. The histopathology results of the hippocampal region of AD rats also confirmed their improvement after treatment with MQNPN. MQNPN treatment caused a significant decrease in the relative expression of MAPT and APP genes. MQNPN is a suitable carrier for the transfer of quercetin to the rat hippocampus, and has a significant effect in reducing AD symptoms in terms of histopathology, behavioral testing, and changing the expression of AD-related genes.

Exercised blood plasma promotes hippocampal neurogenesis in the Alzheimer's disease rat brain

BackgroundExercise training promotes brain plasticity and is associated with protection against cognitive impairment and Alzheimer's disease (AD). These beneficial effects may be partly mediated by blood-borne factors. Here we used an in vitro model of AD to investigate effects of blood plasma from exercise-trained donors on neuronal viability, and an in vivo rat model of AD to test whether such plasma impacts cognitive function, amyloid pathology, and neurogenesis. MethodsMouse hippocampal neuronal cells were exposed to AD-like stress using amyloid-β and treated with plasma collected from human male donors 3 h after a single bout of high-intensity exercise. For in vivo studies, blood was collected from exercise-trained young male Wistar rats (high-intensity intervals 5 days/week for 6 weeks). Transgenic AD rats (McGill-R-Thy1-APP) were injected 5 times/fortnight for 6 weeks at 2 months or 5 months of age with either (a) plasma from the exercise-trained rats, (b) plasma from sedentary rats, or (c) saline. Cognitive function, amyloid plaque pathology, and neurogenesis were assessed. The plasma used for the treatment was analyzed for 23 cytokines. ResultsPlasma from exercised donors enhanced cell viability by 44.1% (p = 0.032) and reduced atrophy by 50.0% (p < 0.001) in amyloid-β-treated cells. In vivo exercised plasma treatment did not alter cognitive function or amyloid plaque pathology but did increase hippocampal neurogenesis by ∼3 fold, regardless of pathological stage, when compared to saline-treated rats. Concentrations of 7 cytokines were significantly reduced in exercised plasma compared to sedentary plasma. ConclusionOur proof-of-concept study demonstrates that plasma from exercise-trained donors can protect neuronal cells in culture and promote adult hippocampal neurogenesis in the AD rat brain. This effect may be partly due to reduced pro-inflammatory signaling molecules in exercised plasma.

MiRNAs and Stem Cells as Promising Diagnostic and Therapeutic Targets for Alzheimer's Disease.

Alzheimer's disease (AD) is a cumulative progressive neurodegenerative disease characterized mainly by impairment in cognitive functions accompanied by memory loss, disturbance in behavior and personality, and difficulties in learning. Although the main causes of AD pathogenesis are not fully understood yet, amyloid-β peptides and tau proteins are supposed to be responsible for AD onset and pathogenesis. Various demographic, genetic, and environmental risk factors are involved in AD onset and pathogenesis such as age, gender, several genes, lipids, malnutrition, and poor diet. Significant changes were observed in microRNA (miRNA) levels between normal and AD cases giving hope for a diagnostic procedure for AD through a simple blood test. As yet, only two classes of AD therapeutic drugs are approved by FDA. They are classified as acetylcholinesterase inhibitors and N-methyl-D-aspartate antagonists (NMDA). Unfortunately, they can only treat the symptoms but cannot cure AD or stop its progression. New therapeutic approaches were developed for AD treatment including acitretin due to its ability to cross blood-brain barrier in the brain of rats and mice and induce the expression of ADAM 10 gene, the α-secretase of human amyloid-β protein precursor, stimulating the non-amyloidogenic pathway for amyloid-β protein precursor processing resulting in amyloid-β reduction. Also stem cells may have a crucial role in AD treatment as they can improve cognitive functions and memory in AD rats through regeneration of damaged neurons. This review spotlights on promising diagnostic techniques such as miRNAs and therapeutic approaches such as acitretin and/or stem cells keeping in consideration AD pathogenesis, stages, symptoms, and risk factors.

Cognitive enhancing effects of pazopanib in D‑galactose/ovariectomized Alzheimer's rat model: insights into the role of RIPK1/RIPK3/MLKL necroptosis signaling pathway.

Necroptosis, a programmed form of necrotic cell death carried out by receptor-interacting serine/threonine protein kinase 1 (RIPK1) and RIPK3, has been found to be implicated in the pathogenesis of Alzheimer's disease (AD). An FDA-approved anti-cancer drug, pazopanib, is reported to possess potent inhibitory effect against necroptosis via interfering with RIPK1. So far, there are no existing data on the influence of pazopanib on necroptotic pathway in AD. Thus, this study was designed to explore the impact of pazopanib on cognitive impairment provoked by ovariectomy (OVX) together with D-galactose (D-Gal) administration in rats and to scrutinize the putative signaling pathways underlying pazopanib-induced effects. Animals were allocated into four groups; the first and second groups were exposed to sham operation and administered normal saline and pazopanib (5mg/kg/day, i.p.), respectively, for 6weeks, while the third and fourth groups underwent OVX then were injected with D-Gal (150mg/kg/day, i.p.); concomitantly with pazopanib in the fourth group for 6weeks. Pazopanib ameliorated cognitive deficits as manifested by improved performance in the Morris water maze besides reversing the histological abnormalities. Pazopanib produced a significant decline in p-Tau and amyloid beta (Aβ) plaques. The neuroprotective effect of pazopanib was revealed by hampering neuroinflammation, mitigating neuronal death and suppressing RIPK1/RIPK3/MLKL necroptosis signaling pathway. Accordingly, hindering neuroinflammation and the necroptotic RIPK1/RIPK3/MLKL pathway could contribute to the neuroprotective effect of pazopanib in D-Gal/OVX rat model. Therefore, this study reveals pazopanib as a valuable therapeutic agent in AD that warrants future inspection to provide further data regarding its neuroprotective effect.

A new automatic method for tracking rats in the Morris water maze

Morris water maze (MWM) test is widely used to evaluate the learning and memory deficits in rodents. Image processing and pattern recognition can be used to analyse videos and recognize automatically the tracking in MWM. There are several commercial and free access software that allows analyzing the behavioral tasks although they also have limitations such as automation, cost, user intervention among other things. The aim of this paper was to develop a new image processing technique to automatically analyse the track of the rat in the MWM, which we called RatsTrack. The MWM test was performed with an animal model for Alzheimer, and the videos were recorded to measure the distance, time, and speed. The segmentation method based on the projection of the video frames was made for pool identification, eliminating the rat, while conserving the shape of the pool. Then, the Hough transformation was used to recognize the position and radius of the pool. Finally, the frame in which the rat is released into the pool was established automatically using mathematical morphology techniques and added as a plugin on free access ImageJ software. The new image processing technique, RatsTrack, successfully detected and located the pool and rat without user intervention, significantly decreasing operational time and providing results for distance, time, speed, and acceleration parameters of the MWM test. Alzheimer's rats compared with the control group presented significant data measured with the RatsTrack. RatsTrack is a plugin of ImageJ software and will be made freely available for public use.

Obesity during preclinical Alzheimer's disease development exacerbates brain metabolic decline.

Alzheimer's disease (AD) is the most common form of dementia. Obesity in middle age increases AD risk and severity, which is alarming given that obesity prevalence peaks at middle age and obesity rates are accelerating worldwide. Midlife, but not late-life obesity increases AD risk, suggesting that this interaction is specific to preclinical AD. AD pathology begins in middle age, with accumulation of amyloid beta (Aβ), hyperphosphorylated tau, metabolic decline, and neuroinflammation occurring decades before cognitive symptoms appear. We used a transcriptomic discovery approach in young adult (6.5 months old) male and female TgF344-AD rats that overexpress mutant human amyloid precursor protein and presenilin-1 and wild-type (WT) controls to determine whether inducing obesity with a high-fat/high-sugar "Western" diet during preclinical AD increases brain metabolic dysfunction in dorsal hippocampus (dHC), a brain region vulnerable to the effects of obesity and early AD. Analyses of dHC gene expression data showed dysregulated mitochondrial and neurotransmission pathways, and up-regulated genes involved in cholesterol synthesis. Western diet amplified the number of genes that were different between AD and WT rats and added pathways involved in noradrenergic signaling, dysregulated inhibition of cholesterol synthesis, and decreased intracellular lipid transporters. Importantly, the Western diet impaired dHC-dependent spatial working memory in AD but not WT rats, confirming that the dietary intervention accelerated cognitive decline. To examine later consequences of early transcriptional dysregulation, we measured dHC monoamine levels in older (13 months old) AD and WT rats of both sexes after long-term chow or Western diet consumption. Norepinephrine (NE) abundance was significantly decreased in AD rats, NE turnover was increased, and the Western diet attenuated the AD-induced increases in turnover. Collectively, these findings indicate obesity during prodromal AD impairs memory, potentiates AD-induced metabolic decline likely leading to an overproduction of cholesterol, and interferes with compensatory increases in NE transmission.

Evaluation of molecular mechanisms responsible for in vivo anti-Alzheimer’s property of Euphorbia cotinifolia methanol extract

Alzheimer's is considered as the most prevalent neurological disease; it is a degenerative and progressive disease that affects brain’s neurons causing memory, language and thinking loss, as well as behavioral abnormalities. This study was performed to assess the anti-Alzheimer features of Euphorbia cotinifolia methanol extract (ECM). Antioxidant activity was performed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and high-performance liquid chromatography (HPLC) was performed to identify some constituents present in ECM. Aluminum chloride-induced Alzheimer's Wistar rats were used to access the therapeutic potential of ECM. Several behavioral experiments were conducted to assess the impact of ECM treatment on motor dysfunction and cognitive abilities. Quantitative polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA) studies were conducted to explore the effect of ECM treatment of different biomarkers. Half-maximal inhibitory concentration (IC50) of ECM and standard (ascorbic acid) in DPPH assay was found to be 18.61 and 11.37 µg/mL, respectively. The HPLC confirms the presence of chlorogenic acid, gallic acid, caffeic acid, sinapic acid, quercetin, and benzoic acid in ECM. Data from in vivo behavioral studies showed a significant improvement in motor dysfunctions and cognitive abilities of animals treated with ECM. ECM treatment also elevated the acetylcholine, superoxide dismutase, catalases, glutathione peroxidase, and glutathione levels. Histopathological examination showed a reduction in neurofibrillary tangles and neuronal loss. qPCR studies showed reduced expression of interleukins (IL-1-α, IL-1-β), tumor necrosis factors (TNF-α and TNF-β) secretase in ECM-treated groups. Findings of the current study highlight the anti-Alzheimer’s potential of E. cotinifolia.

Cluster needling of scalp points improves cognitive dysfunction by regulating NF-κB activity in rats with Alzheimer's disease

To observe the effect of cluster needling of scalp points on nuclear transcription factor kappa B p65 (NF-κB p65)，NF-κB inhibitory protein α (IKBα)，β secretase 1 (BACE1)，beta-amyloid protein (Aβ) and hippocampal morphology in Alzheimer's disease (AD) rats，so as to reveal its mechanism underlying improvement of AD. Male Wistar rats were randomly divided into sham operation，model，clustering acupuncture and medication groups，with 12 trats in each group. AD model was induced by Aβ1-42 injection into bilateral hippocampus. In the clustering acupuncture group，"Baihui" (DU20) and 1 mm on left and right sides of DU20 were needled for 30 min，once daily for 14 d. Rats of the medication group were given donepezil hydrochloride (0.5 mg·kg-1·d-1) intragastric perfusion once a day for 14 d. Morris water maze test was used to evaluate the cognitive function of rats. HE staining was used to observe the structure changes of hippocampal tissue. The expressions of NF-κB p65，IKBα and BACE1 in hippocampus were detected by Western blot. ELISA was used to detect the levels of Aβ in hippocampus and serum of rats. Compared with sham operation group，the escape latency of Morris water maze test in the model group was prolonged，the number of crossing the original platform was decreased(P<0.01)，the protein expressions of NF-κB p65 and BACE1 in hippocampus，and the levels of Aβ in hippocampus and serum of AD rats were increased (P<0.01，P<0.05)，while the expression of IKBα protein was decreased (P<0.01). Compared with the model group，the escape latency of Morris water maze test was shortened and the number of crossing the original platform was increased in the clustering acupuncture and medication groups (P<0.01，P<0.05)，and the protein expressions of NF-κB p65 and BACE1 in hippocampus，the levels of Aβ in hippocampus and serum were decreased (P<0.01，P<0.05)，while the expression of IKBα protein was increased (P<0.01). In comparison of the medication group，the protein expressions of NF-κB p65 and IKBα was lower in the clustering acupuncture group (P<0.05). HE staining showed that cells in the hippocampus were arranged loosely and disordered，some cytoplasm was hyperchromatic，nucleus was pyknotic，inflammatory cells were infiltrated in the model group，which were relatively milder in the clustering acupuncture and medication groups. Cluster needling at scalp points may improve the cognitive impairment in AD rats by reducing inflammatory infiltration in hippocampus，regulating the expressions of NF-κB p65，IKBα and BACE1，and inhibiting the aggregation of Aβ.

Mechanisms of moxibustion preconditioning underlying improving learning-memory ability by regulating polarization of microglia via TLR4/NF-κB signaling pathway in AD rats

To observe the effect of moxibustion preconditioning on learning-memory ability, Toll like receptor 4(TLR4)/nuclear factor-kappa B(NF-κB) signal pathway related proteins and microglia in rats with Alzheimer's disease (AD), so as to explore its possible mechanisms underlying improvement of AD. Male SD rats were randomly divided into normal, sham operation, AD model and pre-moxibustion groups, with 9 rats in each group. Moxibustion was applied to "Baihui"(GV20), "Shenshu"(BL23) and "Zusanli"(ST36) for 15 min, once daily, 6 days as a course of treatment for 3 courses. At the end of moxibustion, the AD model was established by injection of Aβ25-35 aggregation solution into the bilateral hippocampus. The sham operation group was only injected with the same amount of 0.9% Nacl solution. The spatial learning-memory ability of rats was detected by Morris water maze test, the ultrastructure of hippocampal neurons was observed by transmission electron microscope (TEM). The histopathological changes of hippocampus tissue were observed by HE staining, and the protein expression levels of TLR4 and NF-κB p65 in the hippocampus detected by Western blot, and the positive expressions of Iba-1, CD80 and CD206 in the hippocampal CA1 region were detected by immunofluorescence labeling. The contents of inflammatory factors IL-1β, TNF-α and IL-10 in the hippocampus were measured by ELISA. Compared with the sham operation group, the escape latency was significantly increased (P<0.01), and the number of platform quadrant crossing times was decreased (P<0.01) in the model group. In comparison with the model group, the increased escape latency and the decreased platform quadrant crossing times were reversed in the pre-moxibustion group (P<0.01). TEM and light microscope observation showed loose arrangement of cells, enlarged cell space, degeneration, swelling and deformation of hippocampal neurons, rupture of membranes of a large number of cells, reduction of mitochondria, dilation of endoplasmic reticulum, and matrix vacuoles, uneven distribution of organelles and cytoplasm, and being difficult in distinguishing the nuclear cytoplasm in the model group, which was relatively milder in the pre-moxibustion group. The expression levels of hippocampal NF-κB p65 and TLR4, the mean immunofluorescence density of Iba-1 and CD80, as well as the contents of IL-1β and TNF-α in hippocampal CA1 region were significantly increased in the model group than those in the sham operation group (P<0.01), and obviously decreased in the pre-moxibustion group than those in the model group (P<0.05, P<0.01). Whereas the expression of CD206 and the content of IL-10 were evidently decreased in the model group than those in the sham operation group (P<0.01), and strikingly increased in the pre-moxibustion group than those in the model group (P<0.01). No significant differences were found between the sham operation group and the normal group in all the indexes mention above (P>0.05). Pre-moxibustion at GV20, BL23 and ST36 can improve learning-memory ability in AD rats, which may be associated with its functions in promoting the polarization of microglia from M1 to M2 and reducing the neuroinflammatory response by way of TLR4/NF-κB signaling pathway.

Abelmoschus eculentus Seed Extract Exhibits In Vitro and In Vivo Anti-Alzheimer's Potential Supported by Metabolomic and Computational Investigation.

Abelmoschus esculentus Linn. (okra, F. Malvaceae) is a fruit widely consumed all over the world. In our study, the anti-Alzheimer's potential of A. esculentus was evaluated. An in vitro DPPH free radical assay on A. esculentus seed's total extract and AChE inhibition potential screening indicated a significant anti-Alzheimer's activity of the extract, which was confirmed through an in vivo study in an aluminum-intoxicated rat model. Additionally, in vivo results demonstrated significant improvement in Alzheimer's rats, which was confirmed by improving T-maze, beam balance tests, lower serum levels of AChE, norepinephrine, glycated end products, IL-6, and MDA. The levels of dopamine, BDNF, GSH, and TAC returned to normal values during the study. Moreover, histological investigations of brain tissue revealed that the destruction in collagen fiber nearly returns back to the normal pattern. Metabolomic analysis of the ethanolic extract of A. esculentus seeds via LC-HR-ESI-MS dereplicated ten compounds. A network pharmacology study displayed the relation between identified compounds and 136 genes, among which 84 genes related to Alzheimer's disorders, and focused on AChE, APP, BACE1, MAPT and TNF genes with interactions to all Alzheimer's disorders. Consequently, the results revealed in our study grant potential dietary elements for the management of Alzheimer's disorders.

Benzenesulfonamide as a novel, pharmaceutical small molecule inhibitor on Aβ gene expression and oxidative stress in Alzheimer's Wistar rats

Alzheimer's disease (AD) is the most prevalent acute neurodegenerative disease described by memory loss and other cognitive functions. Benzenesulfonamide, a novel, potent, and small organic molecule, was synthesized to investigate its effects on the levels of oxidative biomarkers (GPx, ROS, and MDA) and expression of beta-amyloid peptides (Aβ40 and Aβ42) in the pathology of AD. The results were compared with the rivastigmine drug. Applying benzenesulfonamide to Alzheimer's-induced Wistar rats showed a significant increase in the level of oxidative biomarkers (GPx, ROS, and MDA) in both the brain and blood serum as well as amyloid-β40 and 42 gene expressions. Therefore, benzenesulfonamide could be considered a novel therapeutic agent against AD.

Adipose tissue-derived mesenchymal stem cells ameliorate cognitive impairment in Alzheimer's disease rat model: Emerging role of SIRT1.

Alzheimer's disease (AD) is a complex form of neurodegenerative dementia. Growing body of evidence supports the cardinal role of sirtuin1 (SIRT1) in neurodegeneration and AD development. Recently, adipose tissue-derived mesenchymal stem cells (Ad-MSCs) have made their mark for a wide array of regenerative medicine applications, including neurodegenerative disorders. Therefore, the present study aimed to investigate the therapeutic potential of Ad-MSCs in AD rat model, and to explore the possible implication of SIRT1. Ad-MSCs were isolated from rat epididymal fat pads and properly characterized. Aluminum chloride was used to induce AD in rats, and afterward, a group of AD-induced rats received a single dose of Ad-MSCs (2 × 106 cell, I.V per rat). One month after Ad-MSCs transplantation, behavioral tests were done, brain tissues were collected, then histopathological and biochemical assessments were performed. Amyloid beta and SIRT1 levels were determined by enzyme-linked immunosorbent assay. Whereas expression levels of neprilysin, BCL2 associated X protein, B-cell lymphoma-2, interleukin-1β, interleukin-6, and nerve growth factor in hippocampus and frontal cortex brain tissues were assessed using reverse transcriptase quantitative polymerase chain reaction. Our data demonstrated that transplantation of Ad-MSCs alleviated cognitive impairment in AD rats. Additionally, they exhibited anti-amyloidogenic, antiapoptotic, anti-inflammatory, as well as neurogenic effects. Furthermore, Ad-MSCs were found to possibly mediate their therapeutic effects, at least partially, via modulating both central and systemic SIRT1 levels. Hence, the current study portrays Ad-MSCs as an effective therapeutic approach for AD management and opens the door for future investigations to further elucidate the role of SIRT1 and its interrelated molecular mediators in AD.

Preconditioning adipose-derived mesenchymal stem cells with dimethyl fumarate promotes their therapeutic efficacy in the brain tissues of rats with Alzheimer's disease

AimTransplantation of mesenchymal stem cell (MSC) has been suggested to be a promising method for treating neurodegenerative conditions, including Alzheimer's disease (AD). However, the poor survival rate of transplanted MSCs has limited their therapeutic application. This study aimed to evaluate whether preconditioning MSCs with dimethyl fumarate (DMF), a Nrf2 inducer, could enhance MSC therapeutic efficacy in an amyloid-β (Aβ1–42)-induced AD rat model. MethodsThe survival and antioxidant capacity of MSCs treated with DMF were assessed in vitro. Aβ1-42 intrahippocampal injection was used to create a rat model of AD. Following the transplantation of MSCs preconditioned with DMF and using the Morris blue maze test, spatial learning and memory were assessed. Using RT-qPCR, we evaluated the gene expression related to apoptosis and neurotrophins in the hippocampus region. ResultsTreatment with DMF enhanced cell survival and Nrf2 protein expression in MSCs in vitro. Preconditioning with DMF also enhanced the efficacy of transplanted MSCs in rescuing learning and spatial memory deficits in Aβ-AD rats. Besides, DMF preconditioning enhanced the neuroprotective effect of transplanted MSCs in the hippocampus of rats treated with Aβ1–42 by decreasing the expression of apoptotic markers (Bax, caspase 3, and cytochrome c), and elevating the expression of the anti-apoptotic marker Bcl2 and neurotrophins, including BDNF and NGF. ConclusionPreconditioning MSCs with DMF boosted the therapeutic efficacy of these cells; therefore, it could serve as a targeted strategy for increasing the therapeutic efficacy of MSCs in treating neurodegenerative disorders, including AD.

Microfluidic Synthesis of Ultrasmall Chitosan/Graphene Quantum Dots Particles for Intranasal Delivery in Alzheimer's Disease Treatment.

Nanoparticles (NPs) based therapies for Alzheimer's disease (AD) attract interest due to their ability to pass across or bypass the blood-brain barrier. Chitosan (CS) NPs or graphene quantum dots (GQDs) are promising drug carriers with excellent physicochemical and electrical properties. The current study proposes the combination of CS and GQDs in ultrasmall NP form not as drug carriers but as theranostic agents for AD. The microfluidic-based synthesis of the CS/GQD NPs with optimized characteristics makes them ideal for transcellular transfer and brain targeting after intranasal (IN) delivery. The NPs have the ability to enter the cytoplasm of C6 glioma cells in vitro and show dose and time-dependent effects on the viability of the cells. IN administration of the NPs to streptozotocin (STZ) induced AD-like models lead to a significant number of entrances of the treated rats to the target arm in the radial arm water maze (RAWM) test. It shows the positive effect of the NPs on the memory recovery of the treated rats. The NPs are detectable in the brain via in vivo bioimaging due to GQDs as diagnostic markers. The noncytotoxic NPs localize in the myelinated axons of hippocampal neurons. They do not affect the clearance of amyloid β (Aβ) plaques at intercellular space. Moreover, they showed no positive impact on the enhancement of MAP2 and NeuN expression as markers of neural regeneration. The memory improvement in treated AD rats may be due to neuroprotection via the anti-inflammation effect and regulation of the brain tissue microenvironment that needs to be studied.

NLRP3 inflammasome inhibition and M1-to-M2 microglial polarization shifting via scoparone-inhibited TLR4 axis in ovariectomy/D-galactose Alzheimer's disease rat model.

Neuroinflammation mediated by microglia activation is a critical contributor to Alzheimer's disease (AD) pathogenesis. Dysregulated microglia polarization in terms of M1 overactivation with M2 inhibition is involved in AD pathological damage. Scoparone (SCO), a coumarin derivative, displays several beneficial pharmacological effects including anti-inflammatory and anti-apoptotic properties, however, its neurological effect in AD is still elusive. This study investigated the neuroprotective potential of SCO in AD animal model focusing on determining its effect on M1/M2 microglia polarization and exploring the plausible mechanism involved via investigating its modulatory role on TLR4/MyD88/NF-κB and NLRP3 inflammasome. Sixty female Wistar rats were randomly allocated into four groups. Two groups were sham-operated and treated or untreated with SCO, and the other two groups were subjected to bilateral ovariectomy (OVX) and received D-galactose (D-Gal; 150mg/kg/day, i.p) alone or with SCO (12.5mg/kg/day, i.p) for 6weeks. SCO improved memory functions of OVX/D-Gal rats in the Morris water maze and novel object recognition tests. It also reduced the hippocampal burden of amyloid-β42 and p-Tau, additionally, the hippocampal histopathological architecture was prominently preserved. SCO inhibited the gene expression of TLR4, MyD88, TRAF-6, and TAK-1, additionally, p-JNK and NF-κBp65 levels were significantly curbed. This was associated with repression of NLRP3 inflammasome along with M1-to-M2 microglia polarization shifting as exemplified by mitigating pro-inflammatory M1 marker (CD86) and elevating M2 neuroprotective marker (CD163). Therefore, SCO could promote microglia transition towards M2 through switching off TLR4/MyD88/TRAF-6/TAK-1/NF-κB axis and inhibiting NLRP3 pathway, with consequent mitigation of neuroinflammation and neurodegeneration in OVX/D-Gal AD model.

An approach for in-situ detection of gold colloid aggregates amyloid formations within the hippocampus of the Cohen’s Alzheimer’s disease rat model by surface enhanced raman scattering methods

BackgroundAmyloid beta (Aβ) peptides, such as Aβ1–40 or Aβ1–42 are regarded as hallmark neuropathological biomarkers associated with Alzheimer’s disease (AD). The formation of an aggregates by Aβ1–40 or Aβ1–42-coated gold nano-particles are hypothesized to contain conformation of Aβ oligomers, which could exist only at an initial stage of fibrillogenesis. New MethodThe attempt of in-situ detection of externally initiated gold colloid (ca. 80 nm diameter) aggregates in the middle section of the hippocampus of the Long Evans Cohen’s Alzheimer’s disease rat model was conducted through the Surface Enhanced Raman Scattering (SERS) method. ResultsThe SERS spectral features contained modes associated with β-sheet interactions and a significant number of modes that were previously reported in SERS shifts for Alzheimer diseased rodent and human brain tissues; thereby, strongly implying a containment of amyloid fibrils. The spectral patterns were further examined and compared with those collected from in-vitro gold colloid aggregates which were formed from Aβ1–40 - or Aβ1–42 -coated 80 nm gold colloid under pH ∼4, pH ∼7, and pH ∼10, and the best matched datasets were found with that of the aggregates of Aβ1–42 -coated 80 nm gold colloid at ∼pH 4.0. The morphology and physical size of this specific gold colloid aggregate was clearly different from those found in-vitro. Comparison with Existing Method(s)The amyloid fibril with a β-sheet conformation identified in previously reported in AD mouse/human brain tissues was involved in a formation of the gold colloid aggregates. However, to our surprise, best explanation for the observed SERS spectral features was possible with those in vitro Aβ1–42 -coated 80 nm gold colloid under pH ∼4. ConclusionsA formation of gold colloid aggregates was confirmed in the AD rat hippocampal brain section with unique physical morphology compared to those observed in in-vitro Aβ1–42 or Aβ1–40 mediated gold colloid aggregates. It was concluded that a β-sheet conformation identified in previously reported in AD mouse/human brain tissues was in volved in a formation of the gold colloid aggregates.

Synthesis of Chiral Tricyclic Pyrone Molecules via Palladium(0)-Catalyzed Displacement Reactions of Chiral Tricyclic Pyrone Acetate With Azide or Amine.

Tricyclic pyrone (TP) molecules have shown protection of MC65 neuroblastoma cells death induced by amyloid-β proteins through SβC gene, a decrease of amyloid-β peptide levels, and improvement of motor functions and memory in Alzheimer's disease mouse and rat models. Mechanistic studies suggest TP molecules modulate N-methyl-D-aspartate receptor. A short synthesis of chiral TP analogs was sought using a Pd(0)-catalyzed displacement of TP allylic acetate intermediate with sodium azide or substituted benzylamines. A three-step sequence of reactions by the treatment of 2-{(5aS,7S)-3-methyl-1-oxo-1,5a,6,7,8,9-hexahydropyrano[4,3-b]chromen-7-yl}allyl acetate (9) with (Ph3P)4Pd and sodium azide, followed by reduction with Zn-NH4OCHO and coupling with 3-fluoro-4-hydroxybenzaldehyde and NaCNBH3 was found to give TP coupling molecule, (5aS,7S)-7-(1-(3-fluoro-4-hydroxybenzylamino)prop-2-en-2-yl)-3-methyl-6,7,8,9-tetrahydropyrano[4,3-b]chromen-1(5aH)-one (2), in a good yield. An alternative shorter pathway - a two-step sequence of reactions - by the displacement of 9 by 4-(t-butyldimethylsilyloxy)-3-fluoro-benzylamine with a catalytic amount of (Ph3P)4Pd in THF followed by removal of the silyl ether protecting group gave 2, albeit in a lower chemical yield. The described syntheses should provide general procedures for the synthesis of a library of TP molecules for the discovery of anti-Alzheimer drugs.