Rat Model Of Alzheimer's Disease Research Articles

Interferon beta attenuates recognition memory impairment and improves brain glucose uptake in a rat model of Alzheimer's disease: Involvement of mitochondrial biogenesis and PI3K pathway

Interferon beta (IFNβ) is a cytokine with anti-apoptotic and anti-inflammatory properties, and its beneficial effects on Alzheimer's disease (AD) have been recently shown. The alterations in cerebral glucose uptake are closely linked to memory deficit and AD progression. The current study was designed to determine if IFNβ can improve recognition memory and brain glucose uptake in a rat model of AD. The lentiviruses expressing mutant human amyloid precursor protein were injected bilaterally to the rat hippocampus. From day 23 after virus injection, rats were intranasally treated with recombinant IFNβ protein (68,000 IU/rat) every other day until day 50. Recognition memory performance was evaluated by novel object recognition test on days 46–49. The 18F-2- fluoro-deoxy-d-glucose positron emission tomography (18F-FDG-PET) was used to determine changes in brain glucose metabolism on day 50. The expression of the PI3K/Akt pathway components, neurotrophins and mitochondrial biogenesis factors were also measured by qPCR in the hippocampus. Our results showed that IFNβ treatment improves recognition memory performance in parallel with increased glucose uptake and neuronal survival in the hippocampus of the AD rats. The neuroprotective effect of IFNβ could be attributed, at least partly, to activation of PI3K-Akt-mTOR signaling pathway, increased expression of NGF, and mitochondrial biogenesis. Taken together, our findings suggest the therapeutic potential of IFNβ for AD.

RETRACTED: Iranian thyme honey plays behavioral, cellular and molecular important roles as an amazing preventive and therapeutic agent in the brain of Alzheimer's rat model

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder with neuronal loss in the hippocampus. Our aim was to evaluate the effects of Iranian thyme honey (single dose: 2 gr/kg) vs rivastigmine (0.3 mg/kg) in vivo on spatial memory and in vitro on important parameters of oxidative stress as well as quantitative and qualitative studies of hippocampal neurons of AD rat models with this design that 30 days after oral administration of 17 mg/kg AlCl3, 20 AD rats were received that underwent a 6-weeks therapeutic period and another 20 rats underwent a 6-weeks preventive period and also 20 rats were as controls. Y-Maze test was performed to show memory deficiency as well as TBARS and FRAP assays to measure malondialdehyde (MDA) and total antioxidant, respectively. In addition, H&E staining was also done for cell counting and morphological changes. We observed that AD rats with hippocampal damage had more significant errors during the Y-maze test than the control and other rats. Likewise, MDA and neurodegeneration increased in the AD group while in all preventive and therapeutic group's especially Iranian thyme honey, they decreased and conversely, total antioxidant and number of normal cells elevated and healthy neurons were observed in all parts of the hippocampus and cortex. Our results despite the limitations showed the powerful antioxidant properties and cytoprotective effects of Iranian thyme honey vs rivastigmine on hippocampal neurons that consequently enhanced memory and if advanced diagnostic tests in human clinical patients show other more pronounced effects, we have certainly started a key and targeted strategy.

Transferrin decorated-nanostructured lipid carriers (NLCs) are a promising delivery system for rapamycin in Alzheimer's disease: An in vivo study.

Alzheimer's disease (AD), the most common neurodegenerative disorder, is characterized by progressive cognitive impairment and memory loss. The mammalian target of rapamycin (mTOR) signaling pathway could regulate learning and memory. The effect of rapamycin (Rapa) on mTOR activity could slow or prevent the progression of AD by affecting various essential cellular processes. Previously, we prepared transferrin (Tf) decorated-nanostructured lipid carriers (NLCs) for rapamycin (150±9nm) to protect the drug from chemical and enzymatic degradation and for brain targeted delivery of rapamycin. Herein, the effect of Tf-NLCs compared to untargeted anionic-NLCs and free rapamycin, were studied in amyloid beta (Aβ) induced rat model of AD. Behavioral test revealed that the Rapa Tf-NLCs were able to significantly improve the impaired spatial memory induced by Aβ. Histopathological studies of hippocampus also showed neural survival in Rapa Tf-NLCs treated group. The immunosuppressive, and delayed wound healing adverse effects in the rapamycin solution treated group were abolished by incorporating the drug into NLCs. The Aβ induced oxidative stress was also reduced by Rapa Tf-NLCs. Molecular studies on the level of Aβ, autophagy (LC3) and apoptotic (caspase-3) markers, and mTOR activity revealed that the Rapa Tf-NLCs decreased the Aβ level and suppressed the toxic effects of Aβ plaques by modulating the mTOR activity and autophagy, and decreasing the apoptosis level. As a conclusion, the designed Tf-NLCs could be an appropriate and a safe brain delivery system for rapamycin and make this drug more efficient in AD for improving memory and neuroprotection.

Modulatory effect of zeolite in an experimental rat model of Alzheimer's disease

Modulatory effect of zeolite in an experimental rat model of Alzheimer's disease

Effects of HSYA on serum and brain cholesterol levels in AD rats based on quantitative proteomics

Backgroud: Hydroxysafflor yellow A (HSYA) has a certain improvement effect on Alzheimer’s disease (AD) rats, but its specific mechanism is still unclear. The purpose of this study was to observe the regulatory effect of HSYA on learning and memory ability of AD rats induced by Aβ1-42. Materials and methods: Morris water maze test was used to evaluate the effect of HSYA on the learning and memory ability of AD model rats. To explore the effective targets and potential molecular mechanisms of HSYA in AD treatment based on quantitative proteomics. Results: Through the Morris water maze experiment, we found that after HSYA treatment, the learning ability of rats in the model group has been significantly improved. Quantitative proteomics results showed that among the 11 common differential proteins between the “model/sham operation” comparison group and the “HSYA treatment/model” comparison group, the cholesterol synthesis rate-limiting enzyme mevalonate decarboxylase (Mvd) Western Blot results are consistent with the results of quantitative proteomics analysis. We found that HSYA can inhibit the expression of BACE protein in hippocampus of AD rats and decrease the level of Aβ1-42. Besides, HSYA could also reduce cholesterol levels in serum and hippocampus. Conclusion: In summary, HSYA can effectively improve learning and memory disorders in AD rats, and exert neuroprotective effects by effectively controlling serum and brain cholesterol to down-regulate the expression of BACE and thus reduce the content of Aβ1-42.

Aluminum chloride impaired spatial memory, but not senile plaques formation in the rat model of Alzheimer’s disease

Aluminum compounds can be easily found in the environment. Aluminum contamination is the environmental factor as one of the risk factors for Alzheimer's disease (AD). In the animal model, aluminum chloride (AlCl3) induces inflammation and oxidative stress. Inflammation and oxidative stress are important pathogenesis pathways in the AD. This study was conducted to determine whether AlCl3 can impair spatial memory and induce senile plaques formation. A total of 24 young adult Wistar rats were used in this study. The rats were divided into four groups; one control group and three AlCl3 treated groups with doses of 150 mg/kg, 300 mg/kg, and 600 mg/kg, respectively for 8 weeks. The spatial memory test was measured using Morris water maze and the histopathology was done by identification of senile plaques formation in the hippocampal tissue. Statistical analysis was performed using one-way analysis of variance (ANOVA) followed by Tukey's test for multiple comparisons. The level of statistical significance was set at a p value < 0.05. This study showed that there are significant differences (p<0,05) between the control group and all the AlCl3 treatment groups in the memory test, however, there is no change in the senile plaque’s expression in all groups. Administration of AlCl3 for 8 weeks can cause the impaired of spatial memory without senile plaques formation.

Initial assessment of the spatial learning, reversal, and sequencing task capabilities of knock-in rats with humanizing mutations in the Aβ-coding region of App.

Model organisms mimicking the pathogenesis of human diseases are useful for identifying pathogenic mechanisms and testing therapeutic efficacy of compounds targeting them. Models of Alzheimer's disease (AD) and related dementias (ADRD) aim to reproduce the brain pathology associated with these neurodegenerative disorders. Transgenic models, which involve random insertion of disease-causing genes under the control of artificial promoters, are efficient means of doing so. There are confounding factors associated with transgenic approaches, however, including target gene overexpression, dysregulation of endogenous gene expression at transgenes' integration sites, and limitations in mimicking loss-of-function mechanisms. Furthermore, the choice of species is important, and there are anatomical, physiological, and cognitive reasons for favoring the rat over the mouse, which has been the standard for models of neurodegeneration and dementia. We report an initial assessment of the spatial learning, reversal, and sequencing task capabilities of knock-in (KI) Long-Evans rats with humanizing mutations in the Aβ-coding region of App, which encodes amyloid precursor protein (Apph/h rats), using the IntelliCage, an automated operant social home cage system, at 6-8 weeks of age, then again at 4-5 months of age. These rats were previously generated as control organisms for studies on neurodegeneration involving other knock-in rat models from our lab. Apph/h rats of either sex can acquire place learning and reversal tasks. They can also acquire a diagonal sequencing task by 6-8 weeks of age, but not a more advanced serial reversal task involving alternating diagonals, even by 4-5 months of age. Thus, longitudinal behavioral analysis with the IntelliCage system can be useful to determine, in follow-up studies, whether KI rat models of Familial AD (FAD), sporadic late onset AD (LOAD), and of ADRD develop aging-dependent learning and memory deficits.

Protein Kinase C Involvement in Neuroprotective Effects of Thymol and Carvacrol Against Toxicity Induced by Amyloid-β in Rat Hippocampal Neurons.

We have reported that thymol and carvacrol can improve cognitive abilities in Alzheimer Disease (AD) rat models. However, the mechanism of their action is not yet fully understood. Recently, our in vitro results suggested that PC12 cell death induced by Aβ25-35 can be protected by thymol and carvacrol via Protein Kinase C (PKC) and Reactive Oxygen Species (ROS) pathways. So, we hypothesize that the mechanisms of thymol and carvacrol in improving the learning impairment in the AD rat model may be related to their effects on PKC. So, the activity of PKC and protein expression levels of PKCα were examined in the hippocampal cells of the AD rat model. To examine the thymol and carvacrol effects, we performed a behavioral test in AD rat models induced by Aβ25-35 neurotoxicity. To access the underlying mechanism of the protective effects, western blotting was performed with antibodies against PKCα. We also measured the PKC activity assay by Elisa. Histopathological studies were carried out in the hippocampus with Hematoxylin and Eosin (H&E) staining. The escape latency increased in Aβ-received rats compared to the control group, and thymol and carvacrol reversed this deficit. Furthermore, these compounds could enhance the PKC activity and increase the PKCα expression ratio. Moreover, H&E staining showed that Aβ caused shrinkage of the CA1 pyramidal neurons. However, thymol and carvacrol treatments could prevent this effect of Aβ peptides. This study suggests that Amyloid-Beta (Aβ) results in memory decline and histochemical disturbances in the hippocampus. Moreover, these results revealed that thymol and carvacrol could have protective effects on cognition in AD-like models via PKC activation. Rat's ability to find the invisible platform in the Morris Water Maze (MWM) was impaired by Amyloid-Beta (Aβ) infusion in the hippocampus, while this effect was reversed by thymol or carvacrol administration.Aβ significantly downregulated the Protein Kinase C (PKC) activity in rats' hippocampus.Western blot analysis demonstrated that Aβ significantly reduced PKCα protein expression in AD rat model hippocampal cells.The expression ratio of PKCα was upregulated following the injection of thymol and carvacrol in rats.Injection of Aβ in the hippocampus resulted in histochemical disturbances in CA1 pyramidal neurons.Carvacrol and thymol can prevent several histological changes induced by Aβ. Alzheimer's disease is one of the most important brain diseases in which the learning and memory are impaired. One of the main causes of Alzheimer's disease is the presence of amyloid beta plaques in the neurons. Protein kinase C enzyme reduces amyloid production and accumulation in the brain. In the present study, we tested the possible effects of carvacrol and thymol in a rat model of Alzheimer's disease. Memory impairment was induced in adult rats by intra-cerebral infusion of amyloid β. One week later, the memory-impaired animals were treated with carvacrol and thymol. Finally, we tested their memory in a Morris water maze apparatus. Furthermore, their hippocampus was dissected and PKC activity and the neuronal injury was evaluated. Our findings exhibited that thymol and carvacrol improved rats' memory performance. In addition, thymol and carvacrol significantly increased PKC activity and prevented neuronal cell loss in the rat hippocampus. This study shows that thymol and carvacrol have beneficial effects on memory and cognitive function via PKC activation.

Impairments in Fear Extinction Memory and Basolateral Amygdala Plasticity in the TgF344-AD Rat Model of Alzheimer's Disease Are Distinct from Nonpathological Aging.

Fear-based disorders such as post-traumatic stress disorder (PTSD) steepen age-related cognitive decline and double the risk for developing Alzheimer’s disease (AD). Because of the seemingly hyperactive properties of fear memories, PTSD symptoms can worsen with age. Perturbations in the synaptic circuitry supporting fear memory extinction are key neural substrates of PTSD. The basolateral amygdala (BLA) is a medial temporal lobe structure that is critical in the encoding, consolidation, and retrieval of fear memories. As little is known about fear extinction memory and BLA synaptic dysfunction within the context of aging and AD, the goal of this study was to investigate how fear extinction memory deficits and basal amygdaloid nucleus (BA) synaptic dysfunction differentially associate in nonpathologic aging and AD in the TgF344AD (TgAD) rat model of AD. Young, middle-aged, and older-aged WT and TgAD rats were trained on a delay fear conditioning and extinction procedure before ex vivo extracellular field potential recording experiments in the BA. Relative to young WT rats, long-term extinction memory was impaired, and in general, was associated with a hyperexcitable BA and impaired LTP in TgAD rats at all ages. In contrast, long-term extinction memory was impaired in aged WT rats and was associated with impaired LTP but not BA hyperexcitability. Interestingly, the middle-aged TgAD rats showed intact short-term extinction and BA LTP, which is suggestive of a compensatory mechanism, whereas differential neural recruitment in older-aged WT rats may have facilitated short-term extinction. As such, associations between fear extinction memory and amygdala deficits in nonpathologic aging and AD are dissociable.

Flavonoids from Stems and Leaves of Scutellaria baicalensis Georgi Regulate the Brain Tau Hyperphosphorylation at Multiple Sites Induced by Composited Aβ in Rats.

Neurofibrillary Tangles (NFTs), formed by hyperphosphorylation of Tau protein in Alzheimer's Disease (AD), arethe main pathomechanisms of neuronal degeneration, which indicate a sign of brain disorder. NFTs are positively correlated with the degree of cognitive impairment in AD. The objective of this study isto investigate the effect of flavonoids from the stems and leaves of Scutellaria baicalensis Georgi (SSF) on the hyperphosphorylated expression levels at multiple sites of Tau protein induced by β-amyloid protein 25-35 (Aβ25-35) in combination with aluminum trichloride (AlCl3) and recombinant human transforming growth factor-β1(RHTGF-β1) (composited Aβ) in rats. The AD rat models were established by intracerebroventricular injection of Aβ25-35 and AlCl3 combined with RHTGF-β1. On day 45, after the operation, the Morris water maze test was conducted to screen the memory impairment of AD models. The successful model rats were randomly divided into the model group and the three-dose drug group. The drug group rats were orally administered SSF daily for 38 days. Western blotting was performed to detect the protein expression of P-Tau (Thr 181), P-Tau (Thr 217), P-Tau (Thr 231), P-Tau (Ser 199), P-Tau (Ser 235), P-- Tau (Ser 396), and P-Tau (Ser 404) in the hippocampus and cerebral cortex of rats. Compared with the sham group, the expression of P-Tau (Thr 181), P-Tau (Thr 217), P-- Tau (Thr 231), P-Tau (Ser 199), P-Tau (Ser 235), P-Tau (Ser 396), and P-Tau (Ser 404)was significantly increased in the hippocampus and cerebral cortex of the model group (P < 0.01). However, the three doses of SSF, i.e., 35, 70, and 140 mg/kg, regulated the expression of phosphorylated Tau proteinto varying degrees in the hippocampus and cerebral cortex of AD model rats (P < 0.01). SSF could significantly reduce the protein expression levels of P-Tau (Thr 181), PTau (Thr 217), P-Tau (Thr 231), P-Tau (Ser 199), P-Tau (Ser 235), P-Tau (Ser 396), and P-Tau (Ser 404), induced by the intracerebroventricular injection of composited Aβ, in rats' brain. These results indicated that the neuro-protection and the improvement in the impaired memory of rats by SSF were due to the inhibition of hyperphosphorylation of Tau protein at multiple sites in rats' brain.

Investigating White Matter Inflammatory Cells and their Relationship with Beta‐Amyloid in Alzheimer's Disease

Alzheimer’s disease (AD) is a chronic neurodegenerative condition affecting millions of people worldwide. With an aging population, it is predicted that by 2050 the number of individuals living with AD will triple, resulting in an increased social and economic burden. Previous research has demonstrated that the pathological process leading to AD occurs years before a positive diagnosis. Therefore, identifying biomarkers that co‐occur within the early stage of AD progression and that predict worsening cognitive outcomes are critically needed. AD is characterized by the presence of beta‐amyloid plaques, neurofibrillary tangles and neuroinflammation. Clinically, being unable to recall new information is the most common outcome of AD. White matter inflammation is mediated by microglial activation and astrocytosis and are thought to be important underlying mechanisms involved in the pathogenesis of AD progression, while also being predictive of future cognitive decline. In a transgenic rat model of AD, it has been previously found that microglial activation within the white matter tracts was strongly associated with impairments in executive function. Age‐related differences in inflammatory cells have also been identified. One study found a significant increase in age‐associated white matter inflammatory cells in amyloid‐plaque negative rats at 7‐and‐8‐months of age. Sex‐and‐age related differences in inflammatory cells and amyloid‐beta have been identified, however, they remain poorly understood in the white matter. The purpose of this study was to investigate the sex‐specific‐age trajectory of white matter inflammatory cells in a wildtype rat model of normal aging and in two transgenic rat models of AD: one in an amyloid‐plaque negative, and one in an amyloid‐plaque positive environment. We hypothesized that microglial activation increases with normal aging and is further exacerbated by the presence of beta‐amyloid deposition. Male (n=5) and female (n=5) Fischer 344 wildtype, transgenic APP21 (amyloid‐plaque negative) and APP/PS1 (amyloid‐plaque positive) rats at 3, 9 and 15‐months of age were included in the experimental design. Immunohistochemical analyses were conducted to detect the presence of microglial activation, pro‐inflammatory M1 microglial activation, astrocytosis and beta‐amyloid. Results demonstrate unique age‐dependant trajectories in microglial activation, particularly in the corpus callosum, supraventricular corpus callosum and internal capsule of the wildtype, transgenic APP/21 and APP/PS1 rat genotypes. Given that only the APP/PS1 rats demonstrated age‐dependant plaque deposition, our results indicate that microglial activation within the white matter is associated with changes in amyloid‐plaque deposition. Future work will aim to better understand the mechanisms related to the relationship between white matter microglial activation, amyloid‐plaque deposition and cognitive impairment. A better understanding of this relationship can aid in the development of an earlier method of detecting AD, which in turn can better define a new therapeutic window of opportunity to target microglial activation and prevent neurodegeneration and cognitive decline associated with AD.

The Effects and Regulatory Mechanism of Flavonoids from Stems and Leaves of Scutellaria baicalensis Georgi in Promoting Neurogenesis and Improving Memory Impairment Mediated by the BDNF-ERK-CREB Signaling Pathway in Rats.

It is well known that Alzheimer's Disease (AD) is a neurodegenerative disease accompanied by memory impairment and major pathological changes of the extracellular Senile Plaque (SP) and intracellular Neurofibrillary Tangles (NFTs). However, many pieces of evidence indicate that neurogenesis disorders are also regarded as a new opinion in AD. This study aims to investigate the effects and regulatory mechanism of flavonoids from the stems and leaves of Scutellaria baicalensis Georgi in promoting neurogenesis and improving memory impairment mediated by BDNF-ERK-CREB signaling pathway in rats. Male Wistar rats were intracerebroventricularly injected with amyloid-beta protein 25-35 (Aβ25-35) in combination with Aluminum Trichloride (Alcl3) and recombinant human transforming growth factor-β1 (RHTGF-β1) (composited Aβ), to establish an AD model. Morris water maze was used to screen AD model rats and measure the learning and memory ability of model rats. The expression of Ki67 protein, which is involved in cell neurogenesis, in the hippocampal gyrus of rats was detected by the immunohistochemical method. The mRNA and protein expression levels of Grb2, SOS1, Ras, ERK, and BDNF, in the BDNF-ERK-CREB signaling pathway, in the hippocampus and cerebral cortex regions of rats were assayed by the Quantitative real-time PCR (qPCR) and Western blotting methods, respectively. Intracerebroventricular injection of composited Aβ could induce rats' memory impairment, decrease the protein expression of Ki67 in the hippocampal gyrus, and increase the mRNA and protein expression levels of Grb2, SOS1, Ras, ERK, and BDNF in the hippocampus and cerebral cortex. However, SSF could significantly ameliorate rats' memory impairment induced by composited Aβ, lower the Ki67 protein expression in the hippocampal gyrus, and regulate the abnormal mRNA and protein expression levels of Grb2, SOS1, Ras, ERK and BDNF in the hippocampus and cerebral cortex regions of rat brains. Composited Aβ induced memory impairment, decreased neurogenesis and initiated the abnormal mRNA and protein expressions of Grb2, SOS1, Ras, ERK, and BDNF in the BDNF- ERK-CREB signaling pathway. The effects of SSF in promoting neurogenesis and improving memory impairment may be related to the regulation of the abnormal expressions of Grb2, SOS1, Ras, ERK, and BDNF molecules in the BDNF-ERK-CREB signaling pathway.

Contribution of Beta‐amyloid Accumulation to Cerebral Hypoperfusion in Alzheimer's Disease

Alzheimer’s Disease (AD) is an emerging global health care crisis. However, underlying mechanisms are not understood well enough to translate to precision medicine. There is increasing evidence suggesting that AD is associated with brain hypoperfusion. However, it is unclear whether amyloid‐beta (Aβ) accumulation is a cause or consequence of AD, and how it contributes to cerebral hypoperfusion. The present study examined if Aβ accumulation induces cerebral hypoperfusion in AD by affecting cerebral vascular function via both anterograde (arteriole‐to‐capillary) and retrograde (capillary‐to‐arteriole) pathways in the TgF344‐AD rat model of Alzheimer's disease. We first confirmed that AD rats displayed hippocampal‐based cognitive dysfunction at 6 months of age using an eight‐arm water maze. We then found that AD rats exhibited impaired myogenic response (MR) of middle cerebral arteries (MCAs) and penetrating and parenchymal arterioles (PAs) two months earlier than the onset of cognitive deficits using a Living System pressure myograph. AD rats displayed poor surface and deep cortical cerebral blood flow (CBF) autoregulation recorded by laser Doppler flowmetry, and reduced functional hyperemic response induced by whisker stimulation. Moreover, cell contractile capabilities, detected by collagen gel based‐cell contraction kit, were reduced in Aβ‐treated cerebral VSMCs isolated from F344 rats, similar as seen in VSMCs isolated from AD rats. Furthermore, we found that the productions of reactive oxygen species (ROS) and mitochondrial superoxide in cerebral VSMCs isolated from AD rats were elevated using DHE staining and MitoSOX staining. Moreover, AD cells exhibited reduced mitochondrial respiration and ATP production detected by the Seahorse Cell Mito Stress Test kit. AD cerebral VSMCs also exhibited disrupted actin cytoskeleton and contractile units utilizing immunohistochemistry. Oxidative stress, mitochondrial dysfunction, and actin cytoskeleton disorganization are all factors that are associated with the reduced contractile capabilities of cerebral VSMCs mediated MR and CBF autoregulation. In other studies, we found that capillary endothelial cell‐derived inward rectifier potassium (Kir2.1) activity, which is responsible for retrograde CBF regulation, was reduced in the brain of AD rats using Western blot. PAs with capillaries isolated from AD rats dilated to a lesser degree than WT rats in response to moderately elevated extracellular K+ (10 mM) applied to capillaries. Inhibition of Kir2.1 channels with ML133 diminished the vasodilatory response to a greater extent in WT rats. These findings indicate that Aβ accumulation is associated with cerebral hypoperfusion in AD by affecting cerebral vascular function via both anterograde and retrograde pathways and provide novel insight into the vascular contribution to AD.

Therapeutic Effects of High-Intensity Interval Training Exercise Alone and Its Combination with Ecdysterone Against Amyloid Beta-Induced Rat Model of Alzheimer's Disease: A Behavioral, Biochemical, and Histological Study.

Hippocampal oxidative stress has a vital role in the pathophysiology of Alzheimer's disease (AD)-associated behavioral deficits. Ecdysterone (Ecdy), a natural product and primary steroid hormone, exhibits anti-oxidative and neuroprotective effects. High-intensity interval training (HIIT) has emerged as an effective method for improving physiological brain functions. The present study was designed to investigate the comparative effects of separate and combined HIIT and Ecdy treatment on behavioral functions, hippocampal oxidative status, histological changes in an amyloid-beta (Aβ)-induced rat model of AD. Adult male rats were treated simultaneously with HIIT exercise and Ecdy (10mg/kg/day; P.O.), starting ten days after Aβ-injection, and they continued for eight consecutive weeks. At the end of the treatment course, the behavioral functions of the rats were assessed by commonly-used behavioral paradigms. Subsequently, brain samples were collected for histological analysis and hippocampus samples were collected for biochemical analysis. Results illustrated that Aβ injection impaired learning and memory performances in both novel object recognition and Barnes maze tests, reduced exploratory/locomotor activities in open field test, enhanced anxiety-like behavior in elevated plus-maze (P < 0.05). These behavioral deficits accompanied hippocampal oxidative stress (decreased total antioxidant capacity content and glutathione peroxidase enzyme activity, increased total oxidant status and malondialdehyde level) and neuronal loss in the cerebral cortex and hippocampus in H&E staining (P < 0.05). HIIT and Ecdy improved anxiety-like behavior, attenuated total oxidant status and malondialdehyde, and prevented the neuronal loss (P < 0.05). However, their combination resulted in a more complete and powerful improvement in all the above-mentioned Aβ-related deficits (P < 0.05). Overall, these data provide evidence that a combination of HIIT and Ecdy treatment improves Aβ-induced behavioral deficits, possibly through ameliorating hippocampal oxidative status and preventing neuronal loss.

The neuroprotective effects of oxygen therapy in Alzheimer’s disease: a narrative review

Alzheimer’s disease (AD) is a degenerative neurological disease that primarily affects the elderly. Drug therapy is the main strategy for AD treatment, but current treatments suffer from poor efficacy and a number of side effects. Non-drug therapy is attracting more attention and may be a better strategy for treatment of AD. Hypoxia is one of the important factors that contribute to the pathogenesis of AD. Multiple cellular processes synergistically promote hypoxia, including aging, hypertension, diabetes, hypoxia/obstructive sleep apnea, obesity, and traumatic brain injury. Increasing evidence has shown that hypoxia may affect multiple pathological aspects of AD, such as amyloid-beta metabolism, tau phosphorylation, autophagy, neuroinflammation, oxidative stress, endoplasmic reticulum stress, and mitochondrial and synaptic dysfunction. Treatments targeting hypoxia may delay or mitigate the progression of AD. Numerous studies have shown that oxygen therapy could improve the risk factors and clinical symptoms of AD. Increasing evidence also suggests that oxygen therapy may improve many pathological aspects of AD including amyloid-beta metabolism, tau phosphorylation, neuroinflammation, neuronal apoptosis, oxidative stress, neurotrophic factors, mitochondrial function, cerebral blood volume, and protein synthesis. In this review, we summarized the effects of oxygen therapy on AD pathogenesis and the mechanisms underlying these alterations. We expect that this review can benefit future clinical applications and therapy strategies on oxygen therapy for AD.

Altered protein expression of membrane transporters in isolated cerebral microvessels and brain cortex of a rat Alzheimer's disease model

There is growing evidence that membrane transporters expressed at the blood-brain barrier (BBB) and brain parenchymal cells play an important role in Alzheimer's disease (AD) development and progression. However, quantitative information about changes in transporter protein expression at neurovascular unit cells in AD is limited. Here, we studied the changes in the absolute protein expression of five ATP-binding cassette (ABC) and thirteen solute carrier (SLC) transporters in the isolated brain microvessels and brain cortical tissue of TgF344-AD rats compared to age-matched wild-type (WT) animals using liquid chromatography tandem mass spectrometry based quantitative targeted absolute proteomic analysis. Moreover, sex-specific alterations in transporter expression in the brain cortical tissue of this model were examined. Protein expressions of Abcg2, Abcc1 and FATP1 (encoded by Slc27a1) in the isolated brain microvessels of TgF344-AD rats were 3.1-, 2.0-, 4.3-fold higher compared to WT controls, respectively (p < 0.05). Abcc1 and 4F2hc (encoded by Slc3a2) protein expression was significantly up-regulated in the brain cortical tissue of male TgF344-AD rats compared to male WT rats (p < 0.05). The study provides novel information for the elucidation of molecular mechanisms underlying AD and valuable knowledge about the optimal use of the TgF344-AD rat model in AD drug development and drug delivery research.

Multi-factor combined biomarker screening strategy to rapidly diagnose Alzheimer's disease and evaluate drug effect based on a rat model

Alzheimer's disease (AD) represents the main form of dementia; however, valid diagnosis and treatment measures are lacking. The discovery of valuable biomarkers through omics technologies can help solve this problem. For this reason, metabolomic analysis using ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS) was carried out on plasma, hippocampus, and cortex samples of an AD rat model. Based on the metabolomic data, we report a multi-factor combined biomarker screening strategy to rapidly and accurately identify potential biomarkers. Compared with the usual procedure, our strategy can identify fewer biomarkers with higher diagnostic specificity and sensitivity. In addition to diagnosis, the potential biomarkers identified using our strategy were also beneficial for drug evaluation. Multi-factor combined biomarker screening strategy was used to identify differential metabolites from a rat model of amyloid beta peptide 1–40 (Aβ1−40) plus ibotenic acid-induced AD (compared with the controls) for the first time; lysophosphatidylcholine (LysoPC) and intermediates of sphingolipid metabolism were screened as potential biomarkers. Subsequently, the effects of donepezil and pine nut were successfully reflected by regulating the levels of the abovementioned biomarkers and metabolic profile distribution in partial least squares-discriminant analysis (PLS-DA). This novel biomarker screening strategy can be used to analyze other metabolomic data to simultaneously enable disease diagnosis and drug evaluation.

Effects of the combination of high-intensity interval training and Ecdysterone on learning and memory abilities, antioxidant enzyme activities, and neuronal population in an Amyloid-beta-induced rat model of Alzheimer's disease

AimsOxidative stress and neuronal death are the primary reasons for the progression of amyloid-beta (Aβ) deposition and cognitive deficits in Alzheimer's disease (AD). Ecdysterone (ecdy), a common derivative of ecdysteroids, possesses free radical scavenging and cognitive-improving effects. High-intensity interval training (HIIT) can be a therapeutic strategy for improving cognitive decline and oxidative stress. The present study was aimed to evaluate the effect of HIIT exercise and ecdy consumption synergistically on the changes in learning and memory functions, activities of hippocampal antioxidant enzymes, and neuronal population after AD induced by Aβ in male rats. Materials and methodsFollowing ten days of Aβ injection, HIIT exercise and ecdy treatment (10 mg/kg/day; P.O.) were initiated and continued for eight consecutive weeks in rats. At the end of the treatment period, the rat's learning and memory functions were assessed using Morris water maze and passive avoidance tests. The activity of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GRx), and changes in neuronal population were evaluated in rats’ brains. ResultsThe results indicated that Aβ injection disrupted spatial/passive avoidance learning and memory in both tests, accompanied by a decrease in the SOD and CAT (as endogenous antioxidants) in rats’ hippocampus. Additionally, Aβ injection resulted in neuronal loss in the cerebral cortex and hippocampus. Although the consumption of ecdy separately improved spatial/passive avoidance learning and memory impairments, recovered hippocampal activity of SOD, CAT, GRx, and prevented the hippocampal neuronal loss, its combination along with HIIT resulted in a more powerful and effective amelioration in all the above-mentioned Aβ-neuropathological changes. ConclusionOur results confirm that a combination of HIIT and ecdy treatment could be a promising potential therapeutic option against AD-associated cognitive decline, owing to their free radical scavenging and neuroprotective properties.

Regulation of phase I and phase II neurosteroid enzymes in the hippocampus of an Alzheimer’s disease rat model: A focus on sulphotransferases and UDP-glucuronosyltransferases

Neurosteroids have been associated with neurodegenerative diseases because they are involved in the modulation of neurotransmitter, neurotropic and neuroprotective actions. Emerging evidence suggests that the enzymes responsible for the synthesis of neurosteroids change during the progression of Alzheimer’s disease (AD). The present study aimed to assess the changes in phase I and II enzymes involved in the metabolism of neurosteroids of the progestogen, androgenic and estrogenic steroidogenic pathways and the possibility that the neurosteroids are actively converted into the most abundant metabolites (i.e. glucuronides and sulphates). The gene expression for the phase I and II neurosteroid biosynthetic enzymes were studied in the hippocampus of streptozotocin AD rat model. Male Sprague-Dawley rats were randomly divided into control, sham (saline injected into the hippocampus) and 3 and 12 weeks post-STZ administration (STZ-G3w and STZ-G12w, respectively) groups. Behavioral assessments showed memory impairment in both STZ-injected groups, whereas the formation of amyloid-beta was more pronounced in the STZ-12w group. Gene expression of the hippocampus revealed that glucuronidation and sulphation enzymes transcript of the phase I metabolites were upregulated at the late stage of the disease progression (Hsd17b10, Hsd3b1, Akr1c3 and Cyp19a1) except for Sts. The phase II Sult and Ugt enzymes were mostly upregulated in the STZ-G12w rats (Sult1a1, Sult1e1, Ugt1a1, Ugt1a7c, Ugt1a6, Ugt2b35 and Ugt2b17) and normally expressed in the STZ-G3w group (Sult2a2, Sult2a6, Sult2b1, Ugt2b7, Sult4a1 and Ugt1a7c). In conclusion, changes occur in the phase I and II enzymes transcript of the progestogen, androgenic and estrogenic steroidogenic pathways during the progression of AD.

Investigating a Curcumin-Loaded PLGA-PEG-PLGA Thermo-Sensitive Hydrogel for the Prevention of Alzheimer’s Disease

In Alzheimer’s disease (AD), the most common cause of dementia, patients generally forget to take pills or skip medication due to side effects, affecting the treatment efficacy. In this study, we combined a poly(lactic-co-glycolic acid), (PLGA)-poly(ethylene glycol), and (PEG)-PLGA thermo-sensitive hydrogel with curcumin (PGC) to deliver an intramuscular injection that could continuously release curcumin and maintain it at a constant level in blood to prevent AD development or progression. We evaluated the drug release profile and cytotoxicity of PGC and its effects on AD pathology through in vitro and in vivo studies and on cognitive function through an aluminum-chloride-induced AD rat model. In the in vitro study, PGC exhibited a lack of cytotoxicity, excellent anti-inflammatory and antioxidant properties, and microglial modulation. In the Morris water maze test, the PGC injection-administered AD rats presented well-focused searching behavior with the shortest swimming path and longest retention times in the quadrant where the platform was initially located. Furthermore, PGC reduced amyloid-beta aggregation and deposition and significantly increased hippocampal activity. This study demonstrated that intramuscular PGC injection can effectively prevent AD development or progression in rats without inducing toxicity; therefore, this strategy could help overcome the present challenges in AD management in humans.