Enriched endogenous n-3 polyunsaturated fatty acids alleviate cognitive and behavioral deficits in a mice model of Alzheimer's disease

Mechanisms by which microbiome-derived metabolites exert their impacts on neurodegeneration

Recent developments in microbiome research suggest that the gut microbiome may remotely modulate central and peripheral neuronal processes, ranging from early brain development to age-related changes. Dysbiotic microbiome configurations have been increasingly associated with neurological disorders, such as neurodegeneration, but causal understanding of these associations remains limited. Most mechanisms explaining how the microbiome may induce such remote neuronal effects involve microbially modulated metabolites that influx into the 'sterile' host. Some metabolites are able to cross the blood-brain barrier (BBB) to reach the central nervous system, where they can impact a variety of cells and processes. Alternatively, metabolites may directly signal to peripheral nerves to act as neurotransmitters or exert modulatory functions, or impact immune responses, which, in turn, modulate neuronal function and associated disease propensity. Herein, we review the current knowledge highlighting microbiome-modulated metabolite impacts on neuronal disease, while discussing unknowns, controversies and prospects impacting this rapidly evolving research field.

Unraveling the Omega-3 Puzzle: Navigating Challenges and Innovations for Bone Health and Healthy Aging

Omega-3 polyunsaturated fatty acids (ω-3 PUFAs, n-3 PUFAs), including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and alpha-linolenic acid (ALA), are essential polyunsaturated fats primarily obtained from fatty fish and plant-based sources. Compelling evidence from preclinical and epidemiological studies consistently suggests beneficial effects of ω-3 PUFAs on bone health and healthy aging processes. However, clinical trials have yielded mixed results, with some failing to replicate these benefits seen in preclinical models. This contraindication is mainly due to challenges such as low bioavailability, potential adverse effects with higher doses, and susceptibility to oxidation of ω-3 fatty acids, hindering their clinical effectiveness. This review comprehensively discusses recent findings from a clinical perspective, along with preclinical and epidemiological studies, emphasizing the role of ω-3 PUFAs in promoting bone health and supporting healthy aging. Additionally, it explores strategies to improve ω-3 PUFA efficacy, including nanoparticle encapsulation and incorporation of specialized pro-resolving mediators (SPM) derived from DHA and EPA, to mitigate oxidation and enhance solubility, thereby improving therapeutic potential. By consolidating evidence from various studies, this review underscores current insights and future directions in leveraging ω-3 PUFAs for therapeutic applications.

A Mixture of Soybean Oil and Lard Alleviates Postpartum Cognitive Impairment via Regulating the Brain Fatty Acid Composition and SCFA/ERK(1/2)/CREB/BDNF Pathway

Lard is highly appreciated for its flavor. However, it has not been elucidated how to consume lard while at the same time eliminating its adverse effects on postpartum cognitive function. Female mice were divided into three groups (n = 10): soybean oil (SO), lard oil (LO), and a mixture of soybean oil and lard at a ratio of 1:1 (LS). No significant difference was observed between the SO and LS groups in behavioral testing of the maternal mice, but the LO group was significantly worse compared with these two groups. Moreover, the SO and LS supplementation increased docosahexaenoic acid (DHA) and total n-3 polyunsaturated fatty acid (PUFA) levels in the brain and short-chain fatty acid (SCFA)-producing bacteria in feces, thereby mitigating neuroinflammation and lowering the p-ERK(1/2)/ERK(1/2), p-CREB/CREB, and BDNF levels in the brain compared to the LO group. Collectively, the LS group inhibited postpartum cognitive impairment by regulating the brain fatty acid composition, neuroinflammation, gut microbiota, and the SCFA/ERK(1/2)/CREB/BDNF signaling pathway compared to lard.

N-3 polyunsaturated fatty acids attenuate amyloid-beta-induced toxicity in AD transgenic Caenorhabditis elegans via promotion of proteasomal activity and activation of PPAR-gamma

Alzheimer's disease (AD) is a common neurodegenerative disease that causes progressive cognitive decline. A major pathological characteristic of AD brain is the presence of senile plaques composed of β-amyloid (Aβ), the accumulation of which induces toxic cascades leading to synaptic dysfunction, neuronal apoptosis, and eventually cognitive decline. Dietary n-3 polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are beneficial for patients with early-stage AD; however, the mechanisms are not completely understood. In this study, we investigated the effects of n-3 PUFAs on Aβ-induced toxicity in a transgenic AD Caenorhabditis elegans (C. elegans) model. The results showed that EPA and DHA significantly inhibited Aβ-induced paralytic phenotype and decreased the production of reactive oxygen species while reducing the levels of Aβ in the AD worms. Further studies revealed that EPA and DHA might reduce the accumulation of Aβ by restoring the activity of proteasome. Moreover, treating worms with peroxisome proliferator-activated receptor (PPAR)-γ inhibitor GW9662 prevented the inhibitory effects of n-3 PUFAs on Aβ-induced paralytic phenotype and diminished the elevation of proteasomal activity by n-3 PUFAs, suggesting that PPARγ-mediated signals play important role in the protective effects of n-3 PUFAs against Aβ-induced toxicity.

Omega-3 Fatty Acids for Depression in the Elderly and Patients with Dementia: A Systematic Review and Meta-Analysis

This study aimed to evaluate the efficacy of omega-3 fatty acid supplementation interventions in improving depression in patients with dementia. To achieve this objective, randomized controlled trials (RCTs) were identified from primary electronic databases, focusing on the relationship between omega-3 fatty acids and depression in patients with dementia. The primary outcome was the impact of omega-3 fatty acids on post-intervention depression in patients with dementia, with subgroup analyses conducted based on the type of intervention (docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) combination), duration of intervention (3 months, 6 months, 12 months, ≥24 months), cognitive function (ranging from mild cognitive impairment (MCI) to severe dementia), and daily dosage (high, medium, low, applicable to both DHA and EPA). The study has been duly registered with PROSPERO (registration ID: CRD42023408744). A meta-analysis of five studies (n = 517) included in nine systematic reviews showed that omega-3 supplementation had a non-significant trend toward affecting depressive symptoms in patients with dementia (standardized mean difference (SMD): 0.147; 95% confidence interval (CI): -0.324 to 0.049; p = 0.141). Subgroup analyses revealed that DHA supplementation significantly reduced depressive symptoms (SMD: -0.247; p = 0.039). There was no significant effect for high (SMD: -0.169; 95% CI: -0.454 to 0.116; p = 0.246) or medium (SMD: -0.061; 95% CI: -0.228 to 0.105; p = 0.470) doses of EPA. However, low doses of EPA were significantly effective (SMD: -0.953; 95% CI: -1.534 to -0.373; p = 0.001), with notable improvements in patients with MCI (SMD: -0.934; p < 0.001). The study concludes that omega-3 fatty acids, particularly through DHA supplementation, may alleviate depressive symptoms in patients with MCI. Given the limited sample size, further long-term RCTs are recommended to better understand the efficacy and optimal management of omega-3 supplementation in this population using different dosages.

Unraveling the impact of Omega-3 polyunsaturated fatty acids on blood-brain barrier (BBB) integrity and glymphatic function

Alzheimer's disease (AD) and other forms of dementia represent major public health challenges but effective therapeutic options are limited. Pathological brain aging is associated with microvascular changes and impaired clearance systems. The application of omega-3 polyunsaturated fatty acids (n-3 or omega-3 PUFAs) is one of the most promising nutritional interventions in neurodegenerative disorders from epidemiological data, clinical and pre-clinical studies. As essential components of neuronal membranes, n-3 PUFAs have shown neuroprotection and anti-inflammatory effects, as well as modulatory effects through microvascular pathophysiology, amyloid-beta (Aβ) clearance and glymphatic pathways. This review meticulously explores these underlying mechanisms that contribute to the beneficial effects of n-3 PUFAs against AD and dementia, synthesizing evidence from both animal and interventional studies.

Anchoring of Amyloid-β onto Polyunsaturated Phospholipid Membranes

The interaction between the toxic amyloid-β and phospholipid membranes in the early stage of Alzheimer's disease is complicated and depends on many factors. It was found that polyunsaturated fatty acids affect the incidence of Alzheimer's disease. The number of double bonds in the phospholipid layer may play an important role in the molecular dynamic behavior of amyloid-β on cell membranes. In the present paper, the interactions between Aβ(25-35) and each of four phospholipids, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1-stearoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (SAPC), 1-stearoyl-2-docosahexaenooyl-sn-glycero-3-phosphocholine (SDPC), and 1,2-diarachidonoyl-sn-glycero-3-phosphocholine (DAPC), are investigated by using all-atom molecular dynamics simulation. It is interesting that, as the number of double bonds in the membrane increases, the peptide fragment prefers to stay in the surface region of the membrane rather than penetrates deeply into the membrane. With the increasing number of double bonds, the interaction between Aβ(25-35) and the membrane surface becomes stronger, especially for the interaction between the residue 28 (LYS28) in Aβ(25-35) and the phospholipids, anchoring Aβ(25-35) onto the membrane. The double bonds in phospholipid determine not only the adsorption of the peptide fragment Aβ(25-35) but also its conformation, which will influence further aggregation of Aβ in later stages.Communicated by Ramaswamy H. Sarma.

Discrepant modulating effects of dietary docosahexaenoic acid on cerebral lipids, fatty acid transporter expression and soluble beta-amyloid levels in ApoE-/- and C57BL/6J mice

AIMS

The study was designed to explore the role of apolipoprotein E (ApoE) deficiency concomitant with dietary docosahexaenoic acid (DHA) treatment on brain β-amyloid (Aβ) and lipid levels.

METHOD

A 5-month dietary DHA intervention was conducted in ApoE-deficient (ApoE^-/- ) mice and wild-type C57BL/6J (C57 wt) mice. The Morris water maze test was performed to assess the behaviour of the animals. The cortical contents of soluble Aβ_1-40 and Aβ_1-42 were detected by enzyme-linked immunosorbent assay (ELISA). Cortical fatty acid levels were detected by gas chromatography. Gene and protein expression of molecules associated with cerebral Aβ and lipid metabolism were measured using real-time polymerase chain reaction (PCR), Western blot and histological methods.

RESULTS

DHA treatment increased the content of cortical DHA and n-3 polyunsaturated fatty acids (n-3 PUFAs) but decreased the ratio of n-6/n-3 PUFAs in ApoE^-/- mice; whereas the content of cortical DHA and n-3 PUFAs in C57 wt mice remained unchanged after DHA treatment. Cerebral Fabp5 and Cd36 gene expression were significantly downregulated in DHA-fed C57 wt mice; cerebral Cd36 and Scarb1 gene expression were significantly upregulated, whereas Fabp5 gene expression was downregulated in DHA-fed ApoE^-/- mice. In comparison with C57 wt mice, the content of cortical soluble Aβ_1-42 , total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) increased, whereas the level of high-density lipoprotein cholesterol (HDL-C) decreased in ApoE^-/- mice. Interestingly, these differences were significantly reversed by DHA dietary treatment.

CONCLUSION

DHA intervention has discrepant impacts on cerebral lipids, fatty acid transporter expression and soluble Aβ levels in ApoE^-/- and C57 wt mice, suggesting the modifying role of ApoE status on the responses of cerebral lipids and Aβ metabolism to DHA treatment.

Protective Effects of Fish (Alaska Pollock) Protein Intake against Short-Term Memory Decline in Senescence-Accelerated Mice

Dietary fish intake has proven to have health benefits in humans. n-3 polyunsaturated fatty acids (PUFAs) in fish oil (FO), especially, may provide protection against age-related cognitive disorders. Owing to the unique benefits of n-3 PUFAs, other nutrients, such as fish protein (FP), have not been well studied. To clarify the effects of FO and FP on brain function, we investigated whether FO or FP feeding can prevent age-related cognitive dysfunction in senescence-accelerated mouse-prone 10 (SAMP10) mice. The FP group maintained a better working memory compared to the control and FO groups in the Y-maze test, but not episodic memory in the novel object recognition test. To evaluate demyelination levels, we measured neurofilament H (NfH) and myelin basic protein (MBP) immunoreactivity in the hippocampus (Hipp). Axon morphology was maintained in the FP group, but not in the control and FO groups. Additionally, the percentage of positive area for double-staining with NfH/MPB was significantly higher in the Hipp of FP-fed mice than in the control (p < 0.05). These results suggest that FP intake prevents age-related cognitive dysfunction by maintaining axonal morphology in the Hipp of SAMP10 mice.

N-3 polyunsaturated fatty acids prevent the D-galactose-induced cognitive impairment by up-regulating the levels of 5-hydroxymethylcytosine in the mouse brain

Decreased 5-hydroxymethylcytosine (5hmC) levels caused by mitochondrial dysfunction in the brain are closely associated with the development of neurodegenerative disease. It has been reported that n-3 polyunsaturated fatty acids (PUFAs) prevent cognitive dysfunction by improving mitochondrial function in the brain. However, whether n-3 PUFA prevents cognitive dysfunction by increasing the levels of 5hmC in the brain is undisclosed. Mice were randomly divided into six groups (n = 10), injected with D-galactose (200 mg kg-1 day-1) for the model group and given different oils [0.1 mL per 10 g body weight per day, fish oil (FO), peony seed oil (PSO), corn oil (CO) and olive oil (OO)] for the prevention groups, and injected with the same dose of saline for the normal control group (NC) for 10 weeks, respectively. Peony seed oil and fish oil have shown preventive effects on D-galactose-induced cognitive dysfunction in behavioral tests. The content of docosahexaenoic acid (C22:6n-3, DHA content) in the brain was significantly higher in FO and PSO groups than in the other groups. Brain oxidative stress and neuronal apoptosis were significantly lower in PSO and FO groups than in the other groups. RNA-seq results showed that the different genes between PSO and FO compared with the model group were involved in the DNA demethylation process and the 5-methylcytosine metabolic process. The brain levels of 5hmC and the ten-eleven translocation family of dioxygenases (TETs) were significantly higher in FO and PSO groups compared with the model group, as analyzed by dot-blot and western blot. In conclusion, peony seed oil and fish oil increased the C22:6n-3 content, which activated the TET activity, led to up-regulation of the 5hmc level, resulted in inhibition of neuronal apoptosis, and then improved the cognitive function in D-gal-induced mice.

Microglia and modifiable life factors: Potential contributions to cognitive resilience in aging

Given the increasing prevalence of age-related cognitive decline, it is relevant to consider the factors and mechanisms that might facilitate an individual's resiliency to such deficits. Growing evidence suggests a preeminent role of microglia, the prime mediator of innate immunity within the central nervous system. Human and animal investigations suggest aberrant microglial functioning and neuroinflammation are not only characteristic of the aged brain, but also might contribute to age-related dementia and Alzheimer's Disease. Conversely, accumulating data suggest that modifiable lifestyle factors (MLFs), such as healthy diet, exercise and cognitive engagement, can reliably afford cognitive benefits by potentially suppressing inflammation in the aging brain. The present review highlights recent advances in our understanding of the role for microglia in maintaining brain homeostasis and cognitive functioning in aging. Moreover, we propose an integrated, mechanistic model that postulates an individual's resiliency to cognitive decline afforded by MLFs might be mediated by the mitigation of aberrant microglia activation in aging, and subsequent suppression of neuroinflammation.

Augmenting Clinical Interventions in Psychiatric Disorders: Systematic Review and Update on Nutrition

There is a strong relationship between a healthy diet and mental well-being. Several foods and food compounds are known to modulate biomarkers and molecular mechanisms involved in the aetiogenesis of several mental disorders, and this can be useful in containing the disease progression, including its prophylaxis. This is an updated systematic review of the literature to justify the inclusion and recognition of nutrition in the management of psychiatric illnesses. Such foods and their compounds include dietary flavanols from fruits and vegetables, notable antioxidant and anti-inflammatory agents, probiotics (fermented foods) known to protect good gut bacteria, foods rich in polyunsaturated fatty acids (e.g., Omega-3), and avoiding diets high in saturated fats and refined sugars among others. While the exact mechanism(s) of mitigation of many nutritional interventions are yet to be fully understood, the evidence-based approach warrants the inclusion and co-recognition of nutrition in the management of psychiatric illnesses. For the greater public health benefit, there is a need for policy advocacy aimed at bridging the knowledge gap and encouraging the integration of nutritional intervention with contemporary therapies in clinical settings, as deficiencies of certain nutrients make therapy difficult even with appropriate medication.

Functional Foods: An Approach to Modulate Molecular Mechanisms of Alzheimer's Disease

A new epoch is emerging with intense research on nutraceuticals, i.e., "food or food product that provides medical or health benefits including the prevention and treatment of diseases", such as Alzheimer's disease. Nutraceuticals act at different biochemical and metabolic levels and much evidence shows their neuroprotective effects; in particular, they are able to provide protection against mitochondrial damage, oxidative stress, toxicity of β-amyloid and Tau and cell death. They have been shown to influence the composition of the intestinal microbiota significantly contributing to the discovery that differential microorganisms composition is associated with the formation and aggregation of cerebral toxic proteins. Further, the routes of interaction between epigenetic mechanisms and the microbiota-gut-brain axis have been elucidated, thus establishing a modulatory role of diet-induced epigenetic changes of gut microbiota in shaping the brain. This review examines recent scientific literature addressing the beneficial effects of some natural products for which mechanistic evidence to prevent or slowdown AD are available. Even if the road is still long, the results are already exceptional.

Nutritional psychiatry: Towards improving mental health by what you eat

Does it matter what we eat for our mental health? Accumulating data suggests that this may indeed be the case and that diet and nutrition are not only critical for human physiology and body composition, but also have significant effects on mood and mental wellbeing. While the determining factors of mental health are complex, increasing evidence indicates a strong association between a poor diet and the exacerbation of mood disorders, including anxiety and depression, as well as other neuropsychiatric conditions. There are common beliefs about the health effects of certain foods that are not supported by solid evidence and the scientific evidence demonstrating the unequivocal link between nutrition and mental health is only beginning to emerge. Current epidemiological data on nutrition and mental health do not provide information about causality or underlying mechanisms. Future studies should focus on elucidating mechanism. Randomized controlled trials should be of high quality, adequately powered and geared towards the advancement of knowledge from population-based observations towards personalized nutrition. Here, we provide an overview of the emerging field of nutritional psychiatry, exploring the scientific evidence exemplifying the importance of a well-balanced diet for mental health. We conclude that an experimental medicine approach and a mechanistic understanding is required to provide solid evidence on which future policies on diet and nutrition for mental health can be based.

A Comprehensive Understanding of Dietary Effects on C. elegans Physiology

Diet has been shown to play an important role in human physiology. It is a predominant exogenous factor regulating the composition of gut microbiota, and dietary intervention holds promise for treatment of diseases such as obesity, type 2 diabetes, and malnutrition. Furthermore, it was reported that diet has significant effects on physiological processes of C. elegans, including reproduction, fat storage, and aging. To reveal novel signaling pathways responsive to different diets, C. elegans and its bacterial diet were used as an interspecies model system to mimic the interaction between host and gut microbiota. Most signaling pathways identified in C. elegans are highly conserved across different species, including humans. A better understanding of these pathways can, therefore, help to develop interventions for human diseases. In this article, we summarize recent achievements on molecular mechanisms underlying the response of C. elegans to different diets and discuss their relevance to human health.

Non-Alcoholic Fatty Liver Disease, and the Underlying Altered Fatty Acid Metabolism, Reveals Brain Hypoperfusion and Contributes to the Cognitive Decline in APP/PS1 Mice

Non-alcoholic fatty liver disease (NAFLD), the leading cause of chronic liver disease, is associated with cognitive decline in middle-aged adults, but the mechanisms underlying this association are not clear. We hypothesized that NAFLD would unveil the appearance of brain hypoperfusion in association with altered plasma and brain lipid metabolism. To test our hypothesis, amyloid precursor protein/presenilin-1 (APP/PS1) transgenic mice were fed a standard diet or a high-fat, cholesterol and cholate diet, inducing NAFLD without obesity and hyperglycemia. The diet-induced NAFLD disturbed monounsaturated and polyunsaturated fatty acid (MUFAs, PUFAs) metabolism in the plasma, liver, and brain, and particularly reduced n-3 PUFAs levels. These alterations in lipid homeostasis were associated in the brain with an increased expression of Tnfα, Cox2, p21, and Nox2, reminiscent of brain inflammation, senescence, and oxidative stress. In addition, compared to wild-type (WT) mice, while brain perfusion was similar in APP/PS1 mice fed with a chow diet, NAFLD in APP/PS1 mice reveals cerebral hypoperfusion and furthered cognitive decline. NAFLD reduced plasma β₄₀- and β₄₂-amyloid levels and altered hepatic but not brain expression of genes involved in β-amyloid peptide production and clearance. Altogether, our results suggest that in a mouse model of Alzheimer disease (AD) diet-induced NAFLD contributes to the development and progression of brain abnormalities through unbalanced brain MUFAs and PUFAs metabolism and cerebral hypoperfusion, irrespective of brain amyloid pathology that may ultimately contribute to the pathogenesis of AD.

Targeting mTORs by omega-3 fatty acids: A possible novel therapeutic strategy for neurodegeneration?

Neurodegenerative diseases (NDs) such as Parkinson's (PD), Alzheimer's (AD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS) cause significant world-wide morbidity and mortality. To date, there is no drug of cure for these, mostly age-related diseases, although approaches in delaying the pathology and/or giving patients some symptomatic relief have been adopted for the last few decades. Various studies in recent years have shown the beneficial effects of omega-3 poly unsaturated fatty acids (PUFAs) through diverse mechanisms including anti-inflammatory effects. This review now assesses the potential of this class of compounds in NDs therapy through specific action against the mammalian target of rapamycin (mTOR) signaling pathway. The role of mTOR in neurodegenerative diseases and targeted therapies by PUFAs are discussed.

Site-Specific Fat-1 Knock-In Enables Significant Decrease of n-6PUFAs/n-3PUFAs Ratio in Pigs

The fat-1 gene from Caenorhabditis elegans encodes a fatty acid desaturase which was widely studied due to its beneficial function of converting n-6 polyunsaturated fatty acids (n-6PUFAs) to n-3 polyunsaturated fatty acids (n-3PUFAs). To date, many fat-1 transgenic animals have been generated to study disease pathogenesis or improve meat quality. However, all of them were generated using a random integration method with variable transgene expression levels and the introduction of selectable marker genes often raise biosafety concern. To this end, we aimed to generate marker-free fat-1 transgenic pigs in a site-specific manner. The Rosa26 locus, first found in mouse embryonic stem cells, has become one of the most common sites for inserting transgenes due to its safe and ubiquitous expression. In our study, the fat-1 gene was inserted into porcine Rosa 26 (pRosa26) locus via Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated 9 (Cas9) system. The Southern blot analysis of our knock-in pigs indicated a single copy of the fat-1 gene at the pRosa26 locus. Furthermore, this single-copy fat-1 gene supported satisfactory expression in a variety of tissues in F1 generation pigs. Importantly, the gas chromatography analysis indicated that these fat-1 knock-in pigs exhibited a significant increase in the level of n-3PUFAs, leading to an obvious decrease in the n-6PUFAs/n-3PUFAs ratio from 9.36 to 2.12 (***P < 0.0001). Altogether, our fat-1 knock-in pigs hold great promise for improving the nutritional value of pork and serving as an animal model to investigate therapeutic effects of n-3PUFAs on various diseases.

Melatonin ameliorates Aβ1-42-induced Alzheimer's cognitive deficits in mouse model

Objectives

The objective of this study was to evaluate whether melatonin could ameliorate cognitive function in Aβ1-42-induced mouse model and its underlying mechanisms.

Methods

Series behaviour tests were performed to demonstrate the amelioration of cognitive function of the Alzheimer's disease (AD) mice induced by Aβ1-42. Additionally, enzyme-linked immunosorbent assay was applied to detect the expression of Aβ1-42, BACE1 and p-tau protein in the brain of the AD mice. JC-1 was performed to investigate the role in alleviating mitochondrial damage by melatonin in vitro. Western blot was used to detect the expression of melatonin on apoptosis-related factors caspase-3 and Bcl-2, as well as the expressions of GSK-3β and PP2A to further determine the mechanisms of melatonin on the expression of p-tau protein.

Key findings

Melatonin significantly ameliorated the cognitive function and mitochondrial damage in AD mice, reduced the expression levels of GSK-3β, caspase-3, Aβ1-42, BACE1, p-tau protein and increased the expressions of PP2A and Bcl-2.

Conclusion

From the overall results, we concluded that melatonin alleviated the mitochondrial damage effectively and decreased the expressions of the p-tau and some key proteins of apoptosis, leading to the improvement of cognitive function of the mice induced by Aβ1-42.

The Potassium Channel KCa3.1 Represents a Valid Pharmacological Target for Astrogliosis-Induced Neuronal Impairment in a Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive decline of cognitive function. Astrogliosis plays a critical role in AD by instigating neuroinflammation, which leads ultimately to cognition decline. We previously showed that the intermediate-conductance Ca²⁺-activated potassium channel (KCa3.1) is involved in astrogliosis-induced by TGF-β in vitro. In the present study, we investigated the contribution of KCa3.1 channels to astrogliosis-mediated neuroinflammation, using Tg^APP/PS1 mice as a model for AD. We found that KCa3.1 expression was increased in reactive astrocytes as well as in neurons in the brains of both Tg^APP/PS1 mice and AD patients. Pharmacological blockade of KCa3.1 significantly reduced astrogliosis, microglial activation, neuronal loss, and memory deficits. KCa3.1 blockade inhibited astrocyte activation and reduced brain levels of IL-1β, TNF-α, iNOS, and COX-2. Furthermore, we used primary co-cultures of cortical neurons and astrocytes to demonstrate an important role for KCa3.1 in the process of astrogliosis-induced neuroinflammatory responses during amyloid-β (Aβ)-induced neuronal loss. KCa3.1 was found to be involved in the Aβ-induced activated biochemical profile of reactive astrocytes, which included activation of JNK MAPK and production of reactive oxygen species. Pharmacological blockade of KCa3.1 attenuated Aβ-induced reactive astrocytes and indirect, astrogliosis-mediated damage to neurons. Our data clearly indicate a role for astrogliosis in AD pathogenesis and suggest that KCa3.1 inhibition might represent a good therapeutic target for the treatment of AD. Highlights: (1) Blockade of KCa3.1 in APP/PS1 transgenic mice attenuated astrogliosis and neuron loss, and an attenuation of memory deficits. (2) Blockade of KCa3.1 attenuated Aβ-induced indirect, astrogliosis-mediated damage to neurons in vitro via activation of JNK and ROS.