Rat Model Of Alzheimer's Disease Research Articles

Protective effects of myricetin and morin on neurological damage in Aβ1–42/Al3+ -induced Alzheimer’s disease model of rats

Alzheimer's disease (AD) is a degenerative neurological disorder with unclear pathogenesis. Single-target drugs have very limited efficacy in treating AD, but synthetic multi-target drugs have poor efficacy and safety. Therefore, finding suitable natural multi-target drugs against AD is of great interest for research studies. We chose two flavonols, myricetin and morin, for the relevant study. In this study, we used microinjection of Aβ1–42 oligomers into the CA1 region of rat hippocampus, combined with gavage of Aluminum chloride hexahydrate (AlCl3·6H2O) solution to establish AD rat models, and myricetin and morin were selected as intervening drugs to explore the protective effects against neurological impairment. Experimental results showed that myricetin or morin could reduce the production of Aβ, Tubulin-associated unit (Tau), and Phosphorylated tubulin-associated unit (p-Tau), down-regulate the expression of relevant inflammatory factors, reduce hippocampal cell apoptosis in rats. There was a significant increase in the activity of adenosine triphosphatase, catalase, total superoxide dismutase, and the content of glutathione in the brain tissue. However, the content of malondialdehyde, inducible nitric oxide synthase, and the activity of acetylcholinesterase were decreased in the brain tissue. These two flavonols can regulate the imbalance of monoamine and amino acid neurotransmitter levels. In conclusion, Myricetin or morin can effectively improve learning and memory dysfunction in AD rats induced by Aβ1–42/Al3+ through anti-oxidative stress and anti-apoptotic features.

Neuroprotective Effect of Aurothioglucose-Loaded PLGA Nanoparticles in an Aluminum Chloride-Induced Rat Model of Alzheimer's Disease

Background: In Ayurvedic medicine, herbal, metallic, and herbometalic preparations gain recognition for treating physiological maladies. Aurothioglucose serves as a pharmaceutical intervention for the management of rheumatoid arthritis and can be potential as a potential pharmacological agent for mitigating neuronal toxicity. Objective: The current study was planned to explore the neuroprotective potential of aurothioglucose-loaded poly (lactic-co-glycolic acid) nanoparticles against aluminum chloride (AlCl3) induced Alzheimer's Disease. Method: In the in vivo study, AlCl3 (100 mg/kg, 21 days) was orally administered to rats, while, Aurothioglucose (ATG) and ATG NPs (Nanoparticles) (5, 10 mg/kg and 2.5 and 5 mg/kg, s.c.) were administered sub-cutaneous for a duration of 2 weeks. Following the treatment regimen, neurobehavioral evaluations were conducted utilizing the Open Field Test (OFT), Morris Water Maze (MWM), and Object Recognition Test (ORT). Subsequently, the rats were euthanized, and hippocampal tissue samples were procured for the assessment of biochemical and neuroinflammatory markers. Results: In the in-vivo experiment, the administration of both ATG and ATGNPs elicited a noteworthy reversal of cognitive impairments, biochemical perturbations, and neuroinflammatory markers induced by AlCl3. These observations suggest that ATG NPs demonstrate superior neuroprotective capabilities compared to ATG alone. Conclusion: The observed therapeutic outcomes imply that ATG and ATG NPs conferred amelioration against AlCl3-induced neurotoxicity in rats through mechanisms involving antioxidative and anti-inflammatory effects. Hence, ATG NPs could be a potential drug for correcting Alzheimer’s disease.

Neuroprotective mechanism of trans,trans-Farnesol in an ICV-STZ-induced rat model of Alzheimer's pathology.

Alzheimer's disease (AD) is a prominent cause of dementia, resulting in neurodegeneration and memory impairment. This condition imposes a considerable public health burden on both patients and their families due to the patients' functional impairments as well as the psychological and financial constraints. It has been well demonstrated that its aetiology involves proteinopathy, mitochondriopathies, and enhanced reactive oxygen species (ROS) generation, which are some of the key features of AD brains that further result in oxidative stress, excitotoxicity, autophagy, and mitochondrial dysfunction. The current investigation was created with the aim of elucidating the neurological defence mechanism of trans,trans-Farnesol (TF) against intracerebroventricular-streptozotocin (ICV-STZ)-induced Alzheimer-like symptoms and related pathologies in rodents. The current investigation involved male SD rats receiving TF (25-100mg/kg, per oral) consecutively for 21days in ICV-STZ-treated animals. An in silico study was carried out to explore the possible interaction between TF and NADH dehydrogenase and succinate dehydrogenase. Further, various behavioural (Morris water maze and novel object recognition test), biochemical (oxidants and anti-oxidant markers), activities of mitochondrial enzyme complexes and acetylcholinesterase (AChE), pro-inflammatory (tumor necrosis factor-alpha; TNF-α) levels, and histopathological studies were evaluated in specific brain regions. Rats administered ICV-STZ followed by treatment with TF (25, 50, and 100mg/kg) for 21days had significantly better mental performance (reduced escape latency to access platform, extended time spent in target quadrant, and improved differential index) in the Morris water maze test and new object recognition test models when compared to control (ICV-STZ)-treated groups. Further, TF treatment significantly restored redox proportion, anti-oxidant levels, regained mitochondrial capacities, attenuated altered AChE action, levels of TNF-α, and histopathological alterations in certain brain regions in comparison with control. In in silico analysis, TF caused greater interaction with NADH dehydrogenase and succinate dehydrogenase. The current work demonstrates the neuroprotective ability of TF in an experimental model with AD-like pathologies. The study further suggests that the neuroprotective impacts of TF may be related to its effects on TNF-α levels, oxidative stress pathways, and mitochondrial complex capabilities.

Neuroprotective effect of chrysophanol in Alzheimer disease via modulating the Ca2+/EGFR-PLCγ pathway

Chrysophanol (CHR) is an anthraquinone compound found in rhubarb, and it possesses neuroprotective properties. The purpose of this study was to gain a better understanding of its role in Alzheimer's disease (AD). In vivo study, D-galactose combined with intracerebral injection of β-protein 25–35(Aβ25-35) were used to establish AD model rats. In vitro study, Aβ25-35 was used to induce AD model cells. Our results indicated that CHR improves learning and memory in AD model rats and provides protection against neuronal damage in both AD model rats and cells. Additionally, we observed that CHR suppressed the protein expression of p-tau, EGFR, PLCγ, IP3R, and CAM, as well as the mRNA levels of tau, EGFR, PLCγ, IP3R, and CAM. Furthermore, we have confirmed that CHR inhibited the fluorescence expression of calcium ions (Ca2+). In conclusion, the CHR may exert neuroprotective effects in AD by reducing tau phosphorylation through the Ca2+/EGFR-PLCγ pathway.

Memantine versus Ginkgo biloba Extract: A Comparative Study on Cognitive Dysfunction Treatment in a Novel Rat Model.

Extracellular senile plaques and intraneuronal neurofibrillary tangles are two devastating brain proteinopathies that are indicative of Alzheimer's disease, the most prevalent type of dementia. Currently, no effective medications are available to stop or reverse Alzheimer's disease. Ginkgo biloba extract, commonly referred to as EGb 761, is a natural product made from the leaves of the G. biloba tree. It has long been demonstrated to have therapeutic benefits in Alzheimer's disease. The current study assessed the beneficial effects of EGb 761 against Alzheimer's disease in comparison with memantine, a standard treatment for Alzheimer's disease. The scopolamine-heavy metals mixture rat Alzheimer's disease model is a newly created model to study the effects of EGb 761 oral therapy on cognitive performance and other Alzheimer's disease-like changes over a 28-day experimental period. This new Alzheimer's disease model provides better criteria for Alzheimer's disease hallmarks than the conventional scopolamine model. The EGb 761 reversed memory and learning deficits induced by the scopolamine-heavy metals mixture. These outcomes were linked to a more pronounced inhibitory effect on acetylcholinesterase, caspase-3, hippocampal amyloid-beta protein (Aβ1 - 42), phosphorylated tau protein counts, and proinflammatory cytokines (tumor necrosis factor-α and interleukin-1β) compared to the memantine-treated group. Furthermore, EGb 761 treatment considerably reduced lipid peroxidation (malondialdehyde) and improved reduced glutathione levels compared to memantine. Our results suggest EGb 761's potential in treating central nervous system disorders. It's a promising candidate for future Alzheimer's disease therapeutic exploration. This study also highlights the need for future research to focus on the positive benefits of herbal medicines.

Nanoencapsulated Curcumin: Enhanced Efficacy in Reversing Memory Loss in An Alzheimer Disease Model.

Investigating new drugs or formulations that target Alzheimer disease (AD) is critical for advancing therapeutic interventions. Therefore, this study aimed to assess the effectiveness of nanoencapsulated curcumin (NC Curc) in alleviating memory impairment, oxidative stress, and neuroinflammation in a validated AD model. Male Wistar rats were given bilateral intracerebroventricular injections of either saline or streptozotocin (STZ) (3 mg/3 µL/site) to establish the AD model (day 0). On day 22, daily oral administrations of curcumin (6 mg/kg), NC Curc (6 mg/kg), or a vehicle (unloaded NC) were initiated and continued for 14 days. NC Curc significantly reversed memory deficits in object recognition and inhibitory avoidance tests induced by STZ. Both formulations of curcumin attenuated elevated acetylcholinesterase activity caused by STZ. Importantly, NC Curc alone effectively mitigated STZ-induced oxidative stress. Additionally, NC Curc treatment normalized GFAP levels, suggesting a potential reduction in neuroinflammation in STZ-treated rats. Our findings indicate that NC Curc improves memory in an AD rat model, highlighting its enhanced therapeutic effects compared to unencapsulated curcumin. This research significantly contributes to understanding the therapeutic and neurorestorative potential of NC Curc in AD, particularly in reversing pathophysiological changes.

Early ultrasonic vocalization deficits and related thyroarytenoid muscle pathology in the transgenic TgF344-AD rat model of Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurologic disease and the most common cause of dementia. Classic pathology in AD is characterized by inflammation, abnormal presence of tau protein, and aggregation of β-amyloid that disrupt normal neuronal function and lead to cell death. Deficits in communication also occur during disease progression and significantly reduce health, well-being, and quality of life. Because clinical diagnosis occurs in the mid-stage of the disease, characterizing the prodrome and early stages in humans is currently challenging. To overcome these challenges, we use the validated TgF344-AD (F344-Tg(Prp-APP, Prp-PS1)19/Rrrc) transgenic rat model that manifests cognitive, behavioral, and neuropathological dysfunction akin to AD in humans. The overarching goal of our work is to test the central hypothesis that pathology and related behavioral deficits such as communication dysfunction in part manifest in the peripheral nervous system and corresponding target tissues already in the early stages. The primary aims of this study are to test the hypotheses that: (1) changes in ultrasonic vocalizations (USV) occur in the prodromal stage at 6 months of age and worsen at 9 months of age, (2) inflammation as well as AD-related pathology can be found in the thyroarytenoid muscle (TA) at 12 months of age (experimental endpoint tissue harvest), and to (3) demonstrate that the TgF344-AD rat model is an appropriate model for preclinical investigations of early AD-related vocal deficits. USVs were collected from male TgF344-AD (N = 19) and wildtype (WT) Fischer-344 rats (N = 19) at 6 months (N = 38; WT: n = 19; TgF344-AD: n = 19) and 9 months of age (N = 18; WT: n = 10; TgF344-AD: n = 8) and acoustically analyzed for duration, mean power, principal frequency, low frequency, high frequency, peak frequency, and call type. RT-qPCR was used to assay peripheral inflammation and AD-related pathology via gene expressions in the TA muscle of male TgF344-AD rats (n = 6) and WT rats (n = 6) at 12 months of age. This study revealed a significant reduction in mean power of ultrasonic calls from 6 to 9 months of age and increased peak frequency levels over time in TgF344-AD rats compared to WT controls. Additionally, significant downregulation of AD-related genes Uqcrc2, Bace2, Serpina3n, and Igf2, as well as downregulation of pro-inflammatory gene Myd88 was found in the TA muscle of TgF344-AD rats at 12 months of age. Our findings demonstrate early and progressive vocal deficits in the TgF344-AD rat model. We further provide evidence of dysregulation of AD-pathology-related genes as well as inflammatory genes in the TA muscles of TgF344-AD rats in the early stage of the disease, confirming this rat model for early-stage investigations of voice deficits and related pathology.

Naringin Reduced the Density and Total Number of Aβ Plaques and Restored Memory Function and Volume of Hippocampal CA1 Area in Alzheimer's Disease Model Rats: A Stereological Study

Background: Alzheimer's disease (AD), the most prevalent form of dementia worldwide, is characterized by memory impairment and the accumulation of tau and beta-amyloid (Aβ) plaques. Naringin, a flavonoid, has exhibited strong anti-inflammatory, anti-oxidant, and anti-apoptotic properties. Objectives: In this study, we aimed to demonstrate the neuroprotective effects of naringin on memory function, the total number and density of Aβ plaques, and the volume of the hippocampal CA1 region in a scopolamine (SCO)-induced AD model in rats. Methods: Forty male Wistar rats were randomly divided into the following groups: A control group, a saline + SCO (3 mg/kg) group (pretreated with 200 µL saline), and 3 treatment groups receiving naringin at doses of 50 mg/kg/day + SCO, 100 mg/kg/day + SCO, and 200 mg/kg/day + SCO (pretreated with 50, 100, or 200 mg/kg of naringin) for 14 consecutive days via intraperitoneal (IP) injection. After the 14-day pretreatment period, the saline + SCO and 3 naringin treatment groups received SCO (3 mg/kg) to induce an AD-like condition. Memory function was assessed using the inhibitory passive avoidance test. Following brain harvesting, paraffin-embedded coronal brain slices were stained with Congo red, and the density and the total number of Aβ plaques and the volume of the hippocampal CA1 area were estimated using unbiased stereological techniques. Results: The results indicated that naringin significantly improved memory function, with the most pronounced effect observed in the naringin 200 mg/kg + SCO group. Stereological analysis revealed that SCO reduced the volume of the hippocampal CA1 area and increased the total number and density of Aβ plaques. Pretreatment with naringin significantly restored the hippocampal CA1 volume in the 200 mg/kg + SCO group compared to the saline + SCO group. Additionally, naringin reduced the total number and density of Aβ plaques, with the most significant decrease observed in the 200 mg/kg + SCO group. Conclusions: Naringin restored memory function and the volume of the hippocampal CA1 region while reducing the total number and density of Aβ plaques in a SCO-induced AD model in rats. This stereological study complements previous molecular research on naringin's neuroprotective effects in AD-like pathogenesis.

Simple and Complex Wheel Running Effect on Depression, Memory, Neuroinflammation, and Neurogenesis in Alzheimer's Rat Model.

The aim of this study was to investigate 12 wk of simple and complex voluntary wheel running on Alzheimer's disease (AD), associated biomarkers, and behaviors. Sixty male Wistar rats were randomly divided into six groups: healthy control (Con-Sed), AD only (AD-Sed), simple wheel control (SWC), complex wheel control (CWC), simple wheel AD (SWAD), and complex wheel AD (CWAD). Novelty-suppressed feeding test and the Morris water maze test were used to evaluate depression and memory, respectively. Ki67 was measured in the hippocampus, whereas interleukin (IL)-1β and neural/glial antigen 2 (NG2) were measured in both the hippocampus and the prefrontal cortex. One-way ANOVA with Tukey's post hoc test was performed. AD-Sed group had significantly lower spacial memory ( P < 0.001) compared with Con-Sed. Simple and complex wheel running attenuated these deficits in the SWAD and CWAD groups, respectively ( P < 0.001). Only the CWAD group had significantly improved novelty-suppressed feeding test time compared with AD-Sed ( P < 0.001), equivalent to the healthy wheel running groups. AD-Sed has significantly higher hippocampal concentrations of Ki67 ( P = 0.01) compared with the Con-Sed. Both SWAD and CWAD had significantly reduced Ki67 with similar concentrations compared with the SWC and CWC groups ( P > 0.05). AD-Sed animals also presented with significantly higher hippocampal and prefrontal cortex concentrations of IL-1β compared with Con-Sed ( P < 0.001). SWAD and CWAD had no effect in changing these concentrations. Complex wheel running significantly increased NG2 in the healthy control and AD models, whereas simple wheel running significantly increased NG2 in the AD model. The results of our study suggest that complex wheel running might be more advantageous in promoting memory and neuroplasticity while reducing depression that is associated with AD.

Protective effect of a hydromethanolic extract from Fraxinus excelsior L. bark against a rat model of aluminum chloride-induced Alzheimer's disease: Relevance to its anti-inflammatory and antioxidant effects

Ethnopharmacological relevanceFraxinus excelsior L. (FE), commonly known as the ash, belongs to the Oleaceae family and has shown several pharmacological and biological properties, such as antioxidant, immunomodulatory, neuroprotective, and anti-inflammatory effects. It has also attracted the most attention toward neuroinflammation. Moreover, FE bark and leaves have been used to treat neurological disorders, aging, neuropathic pain, urinary complaints, and articular pain in traditional and ethnomedicine. Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder resulting from the involvement of amyloid-beta, metal-induced oxidative stress, and neuroinflammation. Aim of the studyThe objective of the current study was to assess the neuroprotective effects of hydromethanolic extract from FE bark in an AlCl3-induced rat model of AD. Materials and methodsThe maceration process was utilized to prepare the hydromethanolic extract of FE bark, and characterized by LC-MS/MS. To assess the anti-AD effects of the FE extract, rats were categorized into five different groups, AlCl3; normal control; FE-treated groups at 50, 100, and 200 mg/kg. Passive avoidance learning test, Y-maze, open field, and elevated plus maze behavioral tests were evaluated on days 7 and 14 to analyze the cognitive impairments. Zymography analysis, biochemical tests, and histopathological changes were also followed in different groups. ResultsLC-MS/MS analysis indicated the presence of coumarins, including isofraxidin7-O-diglucoside in the methanolic extract of FE as a new isofraxidin derivative in this genus. FE significantly improved memory and cognitive function, maintained weight, prevented neuronal damages, and preserved the hippocampus's histological features, as demonstrated by behavioral tests and histopathological analysis. FE increased anti-inflammatory MMP-2 activity, whereas it decreased that of inflammatory MMP-9. Moreover, FE increased plasma antioxidant capacity by enhancing CAT and GSH while decreasing nitrite levels in the serum of treated groups. In comparison between the treated groups, the rats that received high doses of the FE extract (200 mg/kg) showed the highest therapeutic effect. ConclusionFE rich in coumarins could be an effective anti-AD adjunct agent, passing through antioxidant and anti-inflammatory pathways. These results encourage further studies for the development of this extract as a promising agent in preventing, managing, or treating AD and related diseases.

Crocin nano-chitosan-coated compound improves anxiety disorders, learning, and spatial memory in Alzheimer's model induced by beta-amyloid in rats.

Alzheimer's disease (AD) is a neurodegenerative disease that results in the gradual breakdown of brain tissue, causing the deterioration of intellectual function and ability. Crocin is a saffron carotenoid compound proven to have excellent neuroprotective and anti-inflammation properties, although it has some limitations such as low stability and bioavailability. Therefore, in the current research, we tried to improve these limitations by using nanotechnology and chitosan as the carrier. Our study examined the therapeutic effects of crocin nano-chitosan-coated compound and compared it with intact crocin in lower dosages than other studies in AD rat models. Encapsulating crocin into chitosan nanoparticles was done through a modified technique to improve its limitations. The AD rat model was induced by bilaterally injecting beta-amyloid (Aβ) peptide into the frontal lobe using a stereotaxic device. To evaluate memory, we conducted the Barnes maze test, and to evaluate anxiety, we used the elevated plus maze test. Also, histological tests were conducted to evaluate neuronal damage in each group. Crocin nano-chitosan-coated administration significantly improved specific memory indicators compared to the Aβ and other treated groups. A significant decrease in anxiety indicators was detected compared to the Aβ and other treated groups. Finally, the results of hippocampus staining indicated a meaningful difference between the Aβ group and other treated groups, compared to the crocin nano-chitosan-coated group. Treatment with low dosages of crocin in the nano-coated form exhibited great efficacy in reducing AD's adverse effects compared to the same dosage of intact crocin.

Intranasal CEPO-FC prevents attention deficits in streptozotocin-induced rat model of Alzheimer's disease: Focus on synaptic plasticity-related factors.

Alzheimer's disease remains an issue of great controversy due to its pathology. It is characterized by cognitive impairments and neuropsychiatric symptoms. The FDA approved medications for this disease, can only mitigate the symptoms. One reason for the lack of effective medications is the inaccessibility of the brain which is encompassed by the blood-brain barrier, making intranasal (IN) route of administration potentially advantageous. Male Wistar rats underwent stereotaxic surgery to induce an Alzheimer's disease model via intracerebroventricular (ICV) streptozotocin injection, and Carbamylated Erythropoietin-Fc (CEPO-FC), a derivative of Erythropoietin without its harmful characteristics, was administered intranasally for ten consecutive days. Cognition performance for memory and attention was assessed using the Novel Object Recognition Test and the Object-Based Attention Test respectively. Depression like behavior was evaluated using the Forced Swim Test. Western blotting was done on the extracted hippocampus to quantify STIM proteins. Calbindin, PSD-95, Neuroplastin, Synaptophysin and GAP-43 genes were assessed by Realtime PCR. Behavioral tests demonstrated that IN CEPO-FC could halt cognition deficits and molecular investigations showed that, STIM proteins were decreased in Alzheimer's model, and increased after IN CEPO-FC treatment. Calbindin and PSD-95 were downregulated in our disease model and upregulated when treated with IN CEPO-FC. While Neuroplastin, and GAP-43 expressions remained unchanged. This study suggests that IN CEPO-FC in low doses could be promising for improving cognition and synaptic plasticity deficits in Alzheimer's disease and since IN route of administration is a convenient way, choosing IN CEPO-FC for clinical trial might worth consideration. See also the graphical abstract(Fig. 1).

Chitosan/PLA-loaded Magnesium oxide nanocomposite to attenuate oxidative stress, neuroinflammation and neurotoxicity in rat models of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disease characterized by amyloid-beta (Aβ) aggregation, neuroinflammation, oxidative stress, and dysfunction in the mitochondria and cholinergic system. In this study, the synthesis of chitosan-polylactic acid-loaded magnesium oxide nanocomposite (CH/PLA/MgONCs) was examined using the green precipitation method. The synthesized CH/PLA/MgONCs were confirmed by using the UV-Vis spectrum, FT-IR, SEM-EDAX, and physical properties. The experiments were carried out using male Wistar rats by injecting streptozotocin (STZ) bilaterally into the brain's ventricles through the intracerebroventricular (ICV) route at a dose of 3mg/kg. We also evaluated the effects of CH/PLA/MgONCs at doses of 10mg/kg. To assess the cognitive dysfunction induced by ICV-STZ, we performed behavioral, biochemical, and histopathological analyses. In our study results, UV-Vis spectrum analysis of CH/PLA/MgONCs showed 285nm, FT-IR analyses confirmed that the various functional groups were present, and SEM-EDAX analysis confirmed that a cauliflower-like spherical shape, Mg and O were present. Treatment with CH/PLA/MgONCs (10mg/kg) showed a significant improvement in spatial and non-spatial memory functions. This was further supported by biochemical analysis showing improved antioxidant enzyme (GSH, SOD, CAT, and GPx activity) activities that significantly attenuated cholinergic activity and oxidative stress. In the CH/PLA/MgONCs-treated group, significant improvement was observed in the mitochondrial complex activity. ICV-STZ-induced neuroinflammation, as indicated by increased levels of TNF-α, IL-6, and CRP, was significantly reduced by CH/PLA/MgONCs treatment. Additionally, CH/PLA/MgONCs treated histological results showed improved healthy neuronal cells in the brain. Furthermore, in silico studies confirm that these molecules have good binding affinity and inhibit Aβ aggregation. In conclusion, CH/PLA/MgONCs treatment reversed AD pathology by improving memory and reducing oxidative stress, neuroinflammation, and mitochondrial dysfunction. These findings recommend that CH/PLA/MgONCs are possible therapeutic agents to treat AD.

Coconut oil ameliorates behavioral and biochemical alterations induced by D-GAL/AlCl3 in rats

Alzheimer's disease (AD) is a chronic, progressive neurodegenerative condition marked by cognitive impairment. Although coconut oil has been shown to be potentially beneficial in reducing AD-related cognitive deficits, information on its mechanism of action is limited. Thus, we investigated the effects of coconut oil on spatial cognitive ability and non-cognitive functions in a rat model of AD induced by G-galactose (D-GAL) and aluminum chloride (AlCl3), and examined the changes in synaptic transmission, cholinergic activity, neurotrophic factors and oxidative stress in this process. The AD model was established by administering D-GAL and AlCl3 for 90 days, while also supplementing with coconut oil during this time. Cognitive and non-cognitive abilities of the rats were evaluated at the end of the 90-day supplementation period. In addition, biochemical markers related to the pathogenesis of the AD were measures in the hippocampus tissue. Exposure to D-GAL/AlCl3 resulted in a reduction in locomotor activity, an elevation in anxiety-like behavior, and an impairment of spatial learning and memory (P < 0.05). The aforementioned behavioral disturbances were observed to coincide with increased oxidative stress and cholinergic impairment, as well as reduced synaptic transmission and levels of neurotrophins in the hippocampus (P < 0.05). Interestingly, treatment with coconut oil attenuated all the neuropathological changes mentioned above (P < 0.05). These findings suggest that coconut oil shows protective effects against cognitive and non-cognitive impairment, AD pathology markers, oxidative stress, synaptic transmission, and cholinergic function in a D-GAL/AlCl3-induced AD rat model.

Effects of the ethanolic extract of white tea (Camellia Sinensis) on metabolic functions in Alzheimer's disease rat model

Effects of the ethanolic extract of white tea (Camellia Sinensis) on metabolic functions in Alzheimer's disease rat model

The Effect of Hippo Pathway Inhibitor Xmu‐mp‐1 on Cognitive Impairment in a Rat Model of Alzheimer’s Disease: Protection against Oxidative Stress, Tau Hyperphosphorylation, and Neurodegeneration

AbstractBackgroundAlzheimer’s Disease (AD), the most common form of dementia, is a growing global health concern with unmet clinical therapeutics. AD can be attributed to amyloid beta aggregation and tau hyperphosphorylation‐induced oxidative stress and neurodegeneration in the brain. Previous studies have implicated a hyper‐activated Hippo signaling pathway with neuronal loss in neurodegenerative disorders, including AD. However, it is still unknown if suppressing the Hippo pathway can rescue neuronal death in AD.MethodIn this study, we investigated the cognitive impairment ameliorative effect of the novel Hippo signaling inhibitor, Xmu‐mp‐1, in a rat model of AD. Adult male Wistar rats were stereotaxically injected with a well‐known AD inducer Streptozotocin (STZ), to mimic AD‐like features. A pharmacological antagonist of Hippo signaling component MST1 called Xmu‐mp‐1 was administered intraperitoneally at a dose of 0.5mg/kg body weight for 14 days. Then the effect of Xmu‐mp‐1 on cognitive impairment was assessed using the Morris water maze test and novel object recognition test. Further, we did biochemical and histopathological studies to explore the effect of Xmu‐mp‐1 on several AD‐associated pathophysiological changes, including oxidative stress, tau hyperphosphorylation, and neurodegeneration.ResultXmu‐mp‐1 significantly improved the cognitive impairment of the AD rats in the Morris water maze test and the novel object recognition test (n = 7). Biochemical analysis of the brain hippocampal and cortical tissues revealed that Xmu‐mp‐1 also ameliorated the AD‐associated oxidative stress burden as the levels of anti‐oxidants (SOD, Catalase, GSH) significantly increased and the levels of oxidative stress biomarkers (protein carbonyl and lipid peroxidation) significantly reduced after Xmu‐mp‐1 treatment in the AD rats (n = 6). Moreover, the level of tau phosphorylation, a prime characteristic of AD, was also reduced following Xmu‐mp‐1 treatment (n = 3). Finally, neuronal death was also found to be rescued after Xmu‐mp‐1 treatment in AD rats (n = 3).ConclusionXmu‐mp‐1 exhibits a neuroprotective role against AD as it improves the cognitive impairment induced by STZ. Further mechanistic investigations into the neuroprotective role of Xmu‐mp‐1 revealed that Xmu‐mp‐1 provides protection from oxidative stress, tau hyperphosphorylation, and aberrant neurodegeneration under an AD background. Future studies can explore the therapeutic potential of Hippo signaling inhibition against AD in more detail.

Transcriptomic and proteomic characterization of the locus coeruleus in a rat model of Alzheimer’s disease

AbstractBackgroundThe noradrenergic locus coeruleus (LC) is the first region to accumulate hyperphosphorylated tau pathology (p‐tau) in Alzheimer’s disease (AD). Using TgF344‐AD transgenic rats, which develop endogenous p‐tau in the LC prior to pathology in forebrain regions, we have recently demonstrated age‐dependent effects of p‐tau on LC firing rates. Specifically, LC neurons exhibit early hyperactivity followed by late hypoactivity. These changes in LC firing rates are coincident with the emergence of behavioral phenotypes that characterize different stages of AD (neuropsychiatric symptoms followed by cognitive deficits). Here, we sought to identify molecular mechanisms that could contribute to these changes using RNAscope and proteomics in TgF344‐AD rats.Methods32 male and female TgF344‐AD rats and wild‐type (WT) littermates aged 6 and 15 months were used for this study. Brains were flash‐frozen in isopentane on dry ice and stored at ‐80°C until being sectioned. At the level of the LC, the left hemisphere LC was collected with a 1 mm tissue punch. Punches of the cerebellum were taken as a control to verify LC enrichment in the brainstem punches. The right LC hemisphere was sectioned at 16 µm for processing with fluorescent in situ hybridization using the RNAscope Multiplex Fluorescent V2 Assay according to the manufacturer’s protocol. Probes included noradrenergic markers (tyrosine hydroxylase, norepinephrine transporter) and those that influence LC activity (α2‐adrenergic receptors, GRIA2, GRIN, ADCYAP1R1). Separately, tissue punches were submitted to the Emory Integrated Proteomics Core for label‐free quantification of proteins.ResultsRNAscope revealed no differences in transcript levels of noradrenergic markers at either age. Similarly, there were no differences in transcript levels of α2‐adrenergic receptors, GRIA, or ADCYAP1R1 at either age, or GRIN in 6‐month animals. We observed an increase of GRIN mRNA in 15‐month TgF344‐AD animals, suggesting an upregulation of excitatory neurotransmission.ConclusionsNoradrenergic neuronal identity remains in‐tact up to 15 months of age, a timepoint when there is no LC cell death in these rats. We have also uncovered a potential compensatory mechanism to maintain LC activity in late stages of disease. Proteomics and RNAscope analysis of other markers that may affect LC activity are ongoing.

Age‐ and sex‐dependent differences in cognitive decline in rat models of Alzheimer’s disease

AbstractBackgroundMemory loss has been a central focus of Alzheimer’s disease (AD) research but executive dysfunction may be one of the earliest indicators of AD (Baudic et al., 2006). Executive function refers to a group of cognitive processes that are required for goal directed behaviours, such as working memory and cognitive flexibility. Amyloid‐β (Aβ) plaques and neurofibrillary tangles are considered the pathological hallmarks of AD, but evidence suggests that these are not the earliest pathologies to appear in the AD brain (Sperling et al., 2011). This highlights the importance of assessing both the prodromal and more advanced phases of AD in preclinical modelling. This study aimed to characterize age‐ and sex‐related changes in executive function, learning, and memory across normal aging in rats as well as in two aging transgenic rat strains of AD: TgAPP21 (Aβ plaque‐negative) and TgAPP/PS1 (Aβ plaque‐positive).MethodMale and female wildtype Fischer 344, TgAPP21, and TgAPP/PS1 rats were used in this study. The TgAPP21 rat overexpresses the mutant human amyloid precursor protein but does not spontaneously develop Aβ plaques, serving as an important model of prodromal AD. The TgAPP/PS1 rat overexpresses mutant human forms of both the amyloid precursor protein and Presenilin‐1 and does develop age‐dependent Aβ plaques. These strains allowed us to assess cognition under three conditions (i) normal aging, (ii) increased Aβ without plaque deposition, and (iii) age‐dependent Aβ plaque deposition. At 3, 9, or 15 months of age the rats were tested for spatial learning and memory, working memory, and cognitive flexibility using the Morris water maze, the 8‐arm radial water maze, and a T‐maze set‐shifting task.ResultAge‐dependent cognitive decline was observed across all genotypes but was exacerbated in both transgenic models. Effects of age, sex, and genotype varied across the cognitive tasks, emphasizing the importance of assessing multiple cognitive domains.ConclusionThese findings expand our understanding of the roles of sex, age and Aβ plaque‐positive/negative environments in cognitive decline in preclinical rat strains of AD. Overall, this work supports further investigation into the pathologies driving these cognitive changes and potential biomarkers for earlier detection.

Different processed products of Polygonati Rhizoma treat Alzheimer's disease in rats: urine metabolomics based on UPLC-Q/TOF-MS

The study investigated the effects of different processed products of Polygonati Rhizoma(black bean-processed Polygonati Rhizoma, BBPR; stewed Polygonati Rhizoma, SPR) on the urinary metabolites in a rat model of Alzheimer's disease(AD). Sixty SPF-grade male SD rats were randomized into a control group, a model group, a donepezil group, a BBPR group, and a SPR group, with twelve rats in each group. Other groups except the control group were administrated with D-galactose injection(100 mg·kg~(-1)) once a day for seven weeks. The control group was administrated with an equal volume of normal saline once a day for seven consecutive weeks. After three weeks of D-galactose injection, bilateral hippocampal Aβ_(25-35) injections were performed for modeling. The rats were administrated with corresponding drugs(10 mL·kg~(-1)) by gavage since week 2, and the rats in the model and control group with an equal volume of double distilled water once a day for 35 continuous days. The memory behaviour and pathological changes in the hippocampal tissue were observed. The untargeted metabolites in the urine were detected by ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry(UPLC-Q/TOF-MS). Principal component analysis(PCA) and orthogonal partial least square-discriminant analysis(OPLS-DA) were employed to characterize and screen differential metabolites and potential biomarkers, for which the metabolic pathway enrichment analysis was conducted. The results indicated that BBPR and SPR increased the new object recognition index, shortened the escape latency, and increased the times of crossing the platform of AD rats in the Morris water maze test. The results of hematoxylin-eosin(HE) staining showed that the cells in the hippocampal tissue of the drug administration groups were closely arranged. Moreover, the drugs reduced the content of interleukin-6(IL-6, P&lt;0.01) and tumor necrosis factor-α(TNF-α) in the hippocampal tissue, which were more obvious in the BBPR group(P&lt;0.05). After screening, 15 potential biomarkers were identified, involving two metabolic pathways: dicoumarol pathway and piroxicam pathway. BBPR and SPR may alleviate AD by regulating the metabolism of dicoumarol and piroxicam.

Protective effects of Urolithins A and B on learning and memory and anxiety-like behaviors in streptozotocin-induced Alzheimer's rat model

Protective effects of Urolithins A and B on learning and memory and anxiety-like behaviors in streptozotocin-induced Alzheimer's rat model