AMPK in the brain: its roles in glucose and neural metabolism

The glucose metabolism reprogramming of yak Sertoli cells under hypoxia is regulated by autophagy

Hypoxia often has negative effects on testis development and spermatogenesis of mammals. Plateau yaks have lived in the hypoxia environment for generations, but have ensured testicular function, which is closely related to their unique hypoxia response mechanism. Glucose metabolic reprogramming is an important way for cells to respond to stressful environments, especially the metabolite lactate, which is the energy basis for the development and differentiation of germ cells. In this study, hypoxia (5% O2) effectively promoted yak Sertoli cell proliferation and decreased autophagy and apoptosis. It was found that the cells showed good hypoxic adaptation. Metabolomics results showed that glucose metabolism was enhanced in yak Sertoli cells in response to hypoxia, and 13 glucose metabolites were increased, including the production and transport level of lactic acid (LA), which may have changed the pentose phosphate metabolic pathway of cells, these changes are conducive to support the glucose metabolism balance of cells under hypoxia. Crucially, when autophagy is activated under hypoxia, GLUT3, GLUT8, and MCT4 proteins are degraded, while GLUT1 and MCT1 are not affected, suggesting that autophagy may achieve glucose metabolic reprogramming by selectively regulating the expression of functional factors of glucose metabolism, which is conducive to energy intake and spermatogenesis in testis of yaks.

Pyruvate kinase deficiency links metabolic perturbations to neurodegeneration and axonal protection

Neurons rely on tightly regulated metabolic networks to sustain their high-energy demands, particularly through the coupling of glycolysis and oxidative phosphorylation. Here, we investigate the role of pyruvate kinase (PyK), a key glycolytic enzyme, in maintaining axonal and synaptic integrity in the Drosophila melanogaster neuromuscular system. Using genetic deficiencies in PyK, we show that disrupting glycolysis induces progressive synaptic and axonal degeneration and severe locomotor deficits. These effects require the conserved dual leucine zipper kinase (DLK), Jun N-terminal kinase (JNK), and activator protein 1 (AP-1) Fos transcription factor axonal damage signaling pathway and the SARM1 NADase enzyme, a key driver of axonal degeneration. As both DLK and SARM1 regulate degeneration of injured axons (Wallerian degeneration), we probed the effect of PyK loss on this process. Consistent with the idea that metabolic shifts may influence neuronal resilience in context-dependent ways, we find that pyk knockdown delays Wallerian degeneration following nerve injury, suggesting that reducing glycolytic flux can promote axon survival under stress conditions. This protective effect is partially blocked by DLK knockdown and fully abolished by SARM1 overexpression. Together, our findings help bridge metabolism and neurodegenerative signaling by demonstrating that glycolytic perturbations causally activate stress response pathways that dictate the balance between protection and degeneration depending on the system's state. These results provide a mechanistic framework for understanding metabolic contributions to neurodegeneration and highlight the potential of metabolism as a target for therapeutic strategies.

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Overview of Metformin and Neurodegeneration: A Comprehensive Review

This comprehensive review examines the therapeutic potential of metformin, a well-established diabetes medication, in treating neurodegenerative disorders. Originally used as a first-line treatment for type 2 diabetes, recent studies have begun investigating metformin's effects beyond metabolic disorders, particularly its neuroprotective capabilities against conditions like Parkinson's disease, Alzheimer's disease, Huntington's disease, and multiple sclerosis. Key findings demonstrate that metformin's neuroprotective effects operate through multiple pathways: AMPK activation enhancing cellular energy metabolism and autophagy; upregulation of antioxidant defenses; suppression of inflammation; inhibition of protein aggregation; and improvement of mitochondrial function. These mechanisms collectively address common pathological features in neurodegeneration and neuroinflammation, including oxidative stress, protein accumulation, and mitochondrial dysfunction. Clinical and preclinical evidence supporting metformin's association with improved cognitive performance, reduced risk of dementia, and modulation of pathological hallmarks of neurodegenerative diseases is critically evaluated. While metformin shows promise as a therapeutic agent, this review emphasizes the need for further investigation to fully understand its mechanisms and optimal therapeutic applications in neurodegenerative diseases.

Disease-modifying strategies: Targeting protein kinases in multiple sclerosis and other autoimmune disorders

A wide variety of immunomodulatory therapies are already available for the treatment of multiple sclerosis (MS). Through fundamental insights from basic research with a gain of knowledge in the pathological processes underlying MS, the exploration of additional medical compounds within clinical trials has been ignited. Emerging novel medications with innovative mechanisms of action are being introduced. Those mechanisms of action include a broad therapeutic spectrum of substances targeting various protein kinases, some of which could also be used for the treatment of other autoimmune-mediated diseases. The advancement of new compounds could therefore enable a more personalized approach in treating MS, taking into consideration patients' co-existing autoimmune-mediated diseases. In this review, we discuss potential compounds targeting protein kinases, currently under investigation in clinical trials for various autoimmune diseases that could become viable treatment options for MS and comorbid autoimmune conditions in the future.

[Research progress on glycolipid metabolism of Sertoli cell in the development of spermatogenic cell]

Sertoli cells play an important role in the process of spermatogenesis, and the abnormalities in spermatogenesis are closely related to disruptions in glycolipid metabolism. The metabolic environment of Sertoli cells is hypoxic, with glycolysis and fatty acid β-oxidation being the primary metabolic pathways. In Sertoli cells, glycolysis produces lactate to provide energy for spermatogenic cells, while fatty acid β-oxidation generates ATP. Currently, the relationship between glycolipid metabolism in Sertoli cells and spermatogenic cell development, as well as the interplay between glucose and lipid metabolism remain unclear. Various hormones, including sex hormones, can affect glucose metabolism in Sertoli cells by endocrine regulation. The activation or inhibition of signaling pathways such as AMPK, mTOR, and Akt can alter the expression levels of glycolysis-related transporter genes and the synthesis of fatty acids, thereby affecting glycolipid metabolism in Sertoli cells. Some transcription factors such as PPARγ can regulate downstream fatty acid metabolism-related genes by directly binding to their response elements and promoting the oxidation of fatty acids in Sertoli cells. In this article we elaborate on the key factors influencing glycolipid metabolism in Sertoli cells and their interconnections, as well as their potential clinical implications, offering new insights for precisely targeted treatments of male infertility.

Moderate ethanol exposure disrupts energy homesotasis between central and peripheral system in APP/PS1 mice

To investigate the effects of moderate ethanol exposure on glucose metabolism in APP/PS1 mice, an early-onset Alzheimer's disease (AD) mouse model, we employed an fluoro-deoxy-glucose (FDG)-micro-positron emission tomography (PET). We also utilized the comprehensive lab animal monitoring system (CLAMS) to measure whole-body energy expenditure and respiratory exchange ratio (RER). We found that ethanol exposure increased glucose metabolism in the brain as measured by FDG-PET. Also, CLAMS data indicated a decrease in RER, suggesting a shift toward fat utilization as the primary energy source. Following ethanol exposure in APP/PS1 mice, these findings reveal a distinct metabolic difference between brain and peripheral tissues.

Acute Restraint Stress Induces Long-Lasting Synaptic Enhancement by Inhibiting AMPK Activation in AD Model Mice

BACKGROUND

Alzheimer's disease (AD) is characterized by a gradual synaptic loss. The progression of AD severely affects late-phase long-term potentiation (L-LTP), which is essential for long-term memory consolidation.

AIM

We have previously demonstrated the beneficial effects of acute restraint stress (ARS) on hippocampal LTP in AD mouse models. This study aimed to verify the effects and potential mechanisms of ARS on the maintenance of hippocampal L-LTP in two AD mouse models.

MATERIALS AND METHODS

5xFAD and Tg2576 mice underwent a 30-min body immobilization protocol to induce ARS, followed by electrophysiological recordings of L-LTP (> 3 h) in the CA1 region of thehippocampus.

RESULTS

The ARS-exposed group exhibited significantly enhanced L-LTP compared to the control group. Maintenance of L-LTP requires new protein synthesis and signaling via the mammalian target of rapamycin (mTOR) pathway. Our findings revealed that ARS increased hippocampal adenosine triphosphate (ATP) production and reduced AMPK activity. Inactivation of AMPK and subsequent activation of the mTOR pathway were strongly associated with the ARS-facilitated enhancement of L-LTP. Furthermore, our experiments using the mTOR inhibitor rapamycin demonstrated that it effectively prevented the enhancement of L-LTP following ARS, underscoring the pivotal role of mTOR in this process.

CONCLUSION

ARS may significantly modify AMPK activation and mTOR regulation in L-LTP, potentially triggering the mechanisms of long-term memory consolidation in AD mouse model mice. Identifying these underlying mechanisms could help promote the development of novel pharmaceutical agents for the treatment of AD.

Brain Glycogen-Its Metabolic Role in Neuronal Health and Neurological Disorders-An Extensive Narrative Review

Background: Brain glycogen is imperative for neuronal health, as it supports energy demands and metabolic processes. This review examines the pathways involved in glycogen storage and utilization in the central nervous system, emphasizing their role in both physiology and pathology. It explores how alterations in glycogen metabolism contribute to neurological disorders, including neurodegenerative diseases, epilepsy, and metabolic conditions while highlighting the bidirectional interaction between neurons and glia in maintaining brain homeostasis. Methods: A comprehensive search of articles published between 2015 and 2025 was conducted using the following databases: ScienceDirect, Scopus, Wiley, Web of Science, Medline, and PubMed. The selection of relevant studies was based on their focus on brain glycogen metabolism and its role in neurological conditions, with studies that did not meet the inclusion criteria being excluded. Results: The metabolic processes of brain glycogen are subject to rigorous regulation by astrocyte-neuron interactions, thereby ensuring metabolic homeostasis and energy availability. The dysregulation of glycogen storage and mobilization has been implicated in the development of synaptic dysfunction, excitotoxicity, and neurodegeneration in a variety of disorders. For instance, aberrant glycogen accumulation in diseases such as Lafora disease has been associated with severe neurodegeneration, while impaired glycogen mobilization has been shown to exacerbate energy deficits in Alzheimer's and epilepsy. Conclusions: Targeting brain glycogen metabolism represents a promising approach for therapeutic intervention in neurological disorders. However, the translation of these strategies to human models remains challenging, particularly with regard to the long-term safety and specificity of glycogen-targeted therapies.

Human herpesvirus-associated transposable element activation in human aging brains with Alzheimer's disease

INTRODUCTION

Human herpesvirus (HHV) has been linked to Alzheimer's disease (AD), but the underlying mechanisms remain unknown.

METHODS

We leveraged functional genomics data from Religious Orders Study or the Rush Memory and Aging Project (ROS/MAP) and Mount Sinai Brain Bank (MSBB) brain biobanks and single-cell RNA-sequencing data from HHV-infected forebrain organoids to investigate HHV-infection-associated transposable element (TE) dysregulation underlying AD etiologies.

RESULTS

We identified widespread TE dysregulation in HHV-positive human AD brains, including an astrocyte-specific upregulation of LINE1 subfamily TEs in HHV-positive human AD brains. We further pinpointed astrocyte-specific LINE1 upregulation that could potentially regulate target gene NEAT1 expression via long-range enhancer-promoter chromatin interactions. This LINE1 dysregulation can be partially reversed by the usage of anti-HHV drugs (valacyclovir and acyclovir) in a virus-infected human brain organoid model. Finally, we demonstrated that valacyclovir rescued tau-associated neuropathology and alleviated LINE1 activation in an experimental tau aggregation model.

DISCUSSION

Our analysis provides associations linking molecular, clinical, and neuropathological AD features with HHV infection, which warrants future clinical validation.

HIGHLIGHTS

Via analysis of bulk RNA-seq data in two large-scale human brain biobanks, ROS/MAP (n = 109 pathologically confirmed AD and n = 44 cognitively healthy controls) and MSBB (n = 284 AD and n = 150 cognitively healthy controls), we identified widespread TE activation in HHV-positive human AD brains and significantly positive associations of HHV RNA abundance with APOE4 genotype, Braak staging score, and CERAD score. We identified cell type-specific LINE1 upregulation in both microglia and astrocytes of human AD brains via long-range enhancer-promoter chromatin interactions on lncRNA nuclear enriched abundant transcript 1 (NEAT1). We determined that usage of valacyclovir and acyclovir was significantly associated with reduced incidence of AD in a large real-world patient database. Using the HEK293 tau P301S model and U2OS mt-Keima cell model, we determined that valacyclovir treatment rescued tau-associated neuropathology and alleviated activation of LINE1 with increased cellular autophagy-level mechanistically supported clinical benefits of valacyclovir in real-world patient data.

The potential therapeutic role of berberine in treating epilepsy focusing on temporal lobe epilepsy: State of art and ongoing perspective

Epilepsy is a neurological disease characterized by unprovoked recurrent epileptic seizures. Temporal lobe epilepsy (TLE) is the commonest type of focal epilepsy in adults that resist to the conventional anti-seizure medications (ASMs). Interestingly, ASMs do not affect the epileptogenesis and progression of disease. Therefore, repurposing of natural products with anti-inflammatory, anti-oxidant and anti-seizure effects such as berberine (BRB) may be logical in treating refractory epilepsy and TLE. However, the molecular mechanism of BRB against the development of epilepsy and progression of epileptic seizure mainly in TLE was not fully elucidated. Therefore, we attempt in this review to discuss the potential underlying molecular mechanism of BRB against the development and progression of epilepsy mainly the TLE.

Examining the Impact of Microglia on Ischemic Stroke With an Emphasis on the Metabolism of Immune Cells

BACKGROUND

Ischemic stroke, a major cause of disability and the second leading cause of death, poses a significant public health challenge. Post-stroke inflammation can harm the blood-brain barrier and worsen neurological deficits, which are key factors in neuronal damage in patients with ischemic stroke. Microglia are crucial in the central nervous system, involved in inflammation, neuronal damage, and repair after cerebral ischemia. While cellular immune metabolism has been widely studied, its role in ischamic stroke remains unclear.

AIM

This review aims to examine how inflammation affects the phenotypic characteristics of immune cells after ischemic stroke and to explore the effects of the immune metabolic microenvironment on the phenotypic profiles and functions of microglia in ischemic stroke.

METHOD

The review refers to the available literature in PubMed, searching for critical terms related to Ischemic stroke, neuroinflammation, microglia, and immunometabolism.

RESULT

In this review, we found that during stroke progression, microglia can dynamically switch between pro-inflammatory and anti-inflammatory phenotypes. Microglial glycometabolism includes oxidative phosphorylation and glycolysis, and lipid metabolism involves lipid synthesis and breakdown. Modulating the production of inflammatory mediator precursors can induce an anti-inflammatory phenotype in microglia.

CONCLUSION

Thus, studying microglial metabolic pathways and their products may offer new insights for ischemic stroke treatment.

Protective Role of Electroacupuncture Against Cognitive Impairment in Neurological Diseases

Many neurological diseases can lead to cognitive impairment in patients, which includes dementia and mild cognitive impairment and thus create a heavy burden both to their families and public health. Due to the limited effectiveness of medications in treating cognitive impairment, it is imperative to develop alternative treatments. Electroacupuncture (EA), a required method for Traditional Chinese Medicine, has the potential treatment of cognitive impairment. However, the molecular mechanisms involved have not been fully elucidated. Considering the current research status, preclinical literature published within the ten years until October 2022 was systematically searched through PubMed, Web of Science, MEDLINE, Ovid, and Embase. By reading the titles and abstracts, a total of 56 studies were initially included. It is concluded that EA can effectively ameliorate cognitive impairment in preclinical research of neurological diseases and induce potentially beneficial changes in molecular pathways, including Alzheimer's disease, vascular cognitive impairment, chronic pain, and Parkinson's disease. Moreover, EA exerts beneficial effects through the same or diverse mechanisms for different disease types, including but not limited to neuroinflammation, neuronal apoptosis, neurogenesis, synaptic plasticity, and autophagy. However, these findings raise further questions that need to be elucidated. Overall, EA therapy for cognitive impairment is an area with great promise, even though more research regarding its detailed mechanisms is warranted.

Discovery of Glucose Metabolism-Associated Genes in Neuropathic Pain: Insights from Bioinformatics

Metabolic dysfunction has been demonstrated to contribute to diabetic pain, pointing towards a potential correlation between glucose metabolism and pain. To investigate the relationship between altered glucose metabolism and neuropathic pain, we compared samples from healthy subjects with those from intervertebral disc degeneration (IVDD) patients, utilizing data from two public datasets. This led to the identification of 412 differentially expressed genes (DEG), of which 234 were upregulated and 178 were downregulated. Among these, three key genes (Ins, Igfbp3, Plod2) were found. Kyoto Encyclopedia of Genes and Genomes pathway analysis demonstrated the enrichment of hub genes in pathways such as the positive regulation of the ErbB signaling pathway, monocyte activation, and response to reactive oxygen species; thereby suggesting a potential correlation between these biological pathways and pain sensation. Further analysis identified three key genes (Ins, Igfbp3, and Plod2), which showed significant correlations with immune cell infiltration, suggesting their roles in modulating pain through immune response. To validate our findings, quantitative real-time polymerase chain reaction (qPCR) analysis confirmed the expression levels of these genes in a partial sciatic nerve ligation (PSNL) model, and immunofluorescence studies demonstrated increased immune cell infiltration at the injury site. Behavioral assessments further corroborated pain hypersensitivity in neuropathic pain (NP) models. Our study sheds light on the molecular mechanisms underlying NP and aids the identification of potential therapeutic targets for future drug development.

The Role of AMP-activated Protein Kinase in Oxytosis/Ferroptosis: Protector or Potentiator?

Significance: Evidence for a role for the oxytosis/ferroptosis regulated cell death pathway in aging and neurodegenerative diseases has been growing over the past few years. Because of this, there is an increasing necessity to identify endogenous signaling pathways that can be modulated to protect cells from this form of cell death. Recent Advances: Recently, several studies have identified a protective role for the AMP-activated protein kinase (AMPK)/acetyl CoA carboxylase 1 (ACC1) pathway in oxytosis/ferroptosis. However, there are also a number of studies suggesting that this pathway contributes to cell death initiated by various inducers of oxytosis/ferroptosis. Critical Issues: The goals of this review are to provide an overview and analysis of the published studies and highlight specific areas where more research is needed. Future Directions: Much remains to be learned about AMPK signaling in oxytosis/ferroptosis, especially the conditions where it is protective. Furthermore, the role of AMPK signaling in the brain and especially the aging brain needs further investigation.

Protein kinase N1 deficiency results in upregulation of cerebral energy metabolism and is highly protective in in vivo and in vitro stroke models

BACKGROUND AND AIM

We recently identified protein kinase N1 (PKN1) as a master regulator of brain development. However, its function in the adult brain has not been clearly established. In this study, we assessed the cerebral energetic phenotype of wildtype (WT) and global Pkn1 knockout (Pkn1-/-) animals under physiological and pathophysiological conditions.

METHODS

Cerebral energy metabolism was analyzed by 13C6-glucose tracing in vivo and real time seahorse analysis of extracellular acidification rates as well as mitochondrial oxygen consumption rates (OCR) of brain slice punches in vitro. Isolated WT and Pkn1-/- brain mitochondria were tested for differences in OCR with different substrates. Metabolite levels were determined by mass spectrometric analysis in brain slices under control and energetic stress conditions, induced by oxygen-glucose deprivation and reperfusion, an in vitro model of ischemic stroke. Differences in enzyme activities were assessed by enzymatic assays, western blotting and bulk RNA sequencing. A middle cerebral artery occlusion stroke model was used to analyze lesion volumes and functional recovery in WT and Pkn1-/- mice.

RESULTS

Pkn1 deficiency resulted in a remarkable upregulation of cerebral energy metabolism, in vivo and in vitro. This was due to two separate mechanisms involving an enhanced glycolytic flux and higher pyruvate-induced mitochondrial OCR. Mechanistically we show that Pkn1-/- brain tissue exhibits an increased activity of the glycolysis rate-limiting enzyme phosphofructokinase. Additionally, glucose-1,6-bisphosphate levels, a metabolite that increases mitochondrial pyruvate uptake, were elevated upon Pkn1 deficiency. Consequently, Pkn1-/- brain slices had more ATP and a greater accumulation of ATP degradation metabolites during energetic stress. This translated into increased phosphorylation and activity of adenosine monophosphate (AMP)-activated protein kinase (AMPK) during in vitro stroke. Accordingly, Pkn1-/- brain slices showed a post-ischemic transcriptional upregulation of energy metabolism pathways and Pkn1 deficiency was strongly protective in in vitro and in vivo stroke models. While inhibition of mitochondrial pyruvate uptake only moderately affected the protective phenotype, inhibition of AMPK in Pkn1-/- slices increased post-ischemic cell death in vitro.

CONCLUSION

This is the first study to comprehensively demonstrate an essential and unique role of PKN1 in cerebral energy metabolism, regulating glycolysis and mitochondrial pyruvate-induced respiration. We further uncovered a highly protective phenotype of Pkn1 deficiency in both, in vitro and in vivo stroke models, validating inhibition of PKN1 as a promising new therapeutic target for the development of novel stroke therapies.

Down syndrome frontal cortex layer III and layer V pyramidal neurons exhibit lamina specific degeneration in aged individuals

Selective vulnerability of neuronal populations occurs in both Down syndrome (DS) and Alzheimer's disease (AD), resulting in disproportional degeneration of pyramidal neurons (PNs) affecting memory and executive function. Elucidating the cellular mechanisms underlying the selective vulnerability of these populations will provide pivotal insights for disease progression in DS and AD. Single population RNA-sequencing analysis was performed on neurons critical for executive function, prefrontal cortex Brodmann area 9 (BA9) layer III (L3) and layer V (L5) excitatory PNs in postmortem human DS and age- and sex-matched control (CTR) brains. Data mining was performed on differentially expressed genes (DEGs) from PNs in each lamina with DEGs divergent between lamina identified and interrogated. Bioinformatic inquiry of L3 PNs revealed more unique/differentially expressed DEGs (uDEGs) than in L5 PNs in DS compared to CTR subjects, indicating gene dysregulation shows both spatial and cortical laminar projection neuron dependent dysregulation. DS triplicated human chromosome 21 (HSA21) comprised a subset of DEGs only dysregulated in L3 or L5 neurons, demonstrating partial cellular specificity in HSA21 expression. These HSA21 uDEGs had a disproportionally high number of noncoding RNAs, suggesting lamina specific dysfunctional gene regulation. L3 uDEGs revealed overall more dysregulation of cellular pathways and processes, many relevant to early AD pathogenesis, while L5 revealed processes suggestive of frank AD pathology. These findings indicate that trisomy differentially affects a subpopulation of uDEGs in L3 and L5 BA9 projection neurons in aged individuals with DS, which may inform circuit specific pathogenesis underlying DS and AD.

ATP Restoration by ATP-Deprived Cultured Primary Astrocytes

A high cellular concentration of adenosine triphosphate (ATP) is essential to fuel many important functions of brain astrocytes. Although cellular ATP depletion has frequently been reported for astrocytes, little is known on the metabolic pathways that contribute to ATP restoration by ATP-depleted astrocytes. Incubation of cultured primary rat astrocytes in glucose-free buffer for 60 min with the mitochondrial uncoupler BAM15 lowered the cellular ATP content by around 70%, the total amount of adenosine phosphates by around 50% and the adenylate energy charge (AEC) from 0.9 to 0.6. Testing for ATP restoration after removal of the uncoupler revealed that the presence of glucose as exclusive substrate allowed the cells to restore within 6 h around 80% of the initial ATP content, while coapplication of adenosine plus glucose enabled the cells to fully restore their initial ATP content within 60 min. A rapid but incomplete and transient ATP restoration was found for astrocytes that had been exposed to adenosine alone. This restoration was completely prevented by application of the pyruvate uptake inhibitor UK5099, the respiratory chain inhibitor antimycin A or by the continuous presence of BAM15. However, the presence of these compounds strongly accelerated the release of lactate from the cells, suggesting that the ribose moiety of adenosine can serve as substrate to fuel some ATP restoration via mitochondrial metabolism. Finally, the adenosine-accelerated ATP restoration in glucose-fed astrocytes was inhibited by the presence of the adenosine kinase inhibitor ABT-702. These data demonstrate that astrocytes require for a rapid and complete ATP restoration the presence of both glucose as substrate and adenosine as AMP precursor.

AMPK activation; a potential strategy to mitigate TKI-induced cardiovascular toxicity

The introduction of Tyrosine Kinase Inhibitors (TKIs) has revolutionised cancer treatment, yet concerns regarding cardiovascular toxicity have surfaced. This piece delves into the interplay between AMP-activated protein kinase (AMPK) signalling and TKI-induced cardiovascular toxicity. The study unravels the intricate relationship between AMPK activation and TKI-induced cardiovascular toxicity, aiming to ascertain whether AMPK can play a strategic role in mitigating adverse effects. Beyond unravelling mechanistic insights, the research sets the stage for future therapeutic approaches, envisioning AMPK activation as a pivotal connection for balancing effective cancer treatment with cardiovascular well-being. As research advances, the potential of AMPK activation not only addresses challenges in TKI-induced cardiovascular toxicity but also shapes the future landscape of personalised anticancer therapies. The article explores the mechanisms of TKI-induced toxicity, AMPK's impact on cardiovascular health, and the potential therapeutic implications of AMPK activation in alleviating TKI-associated toxicities.

Impaired brain glucose metabolism as a biomarker for evaluation of dodecyl creatine ester in creatine transporter deficiency: Insights from patient brain-derived organoids and in vivo [18F]FDG PET imaging in a mouse model

Creatine transporter deficiency (CTD) is an inborn error of creatine (Cr) metabolism in which Cr is not properly distributed to the brain due to a mutation in the Cr transporter (CrT) SLC6A8 gene. CTD is associated with developmental delays and with neurological disability in children. Dodecyl creatine ester (DCE), as a Cr prodrug, is a promising drug to treat CTD after administration by the nasal route, taking advantage of the nose-to-brain pathway. In this study, the potential adaptive response to energy imbalance in glucose metabolism was investigated in CTD using both SLC6A8-deficient mice (CrT KO) and brain organoids derived from CTD patient cells. Longitudinal brain [18F]FDG PET imaging in CrT KO mice compared to wild-type mice demonstrated that CTD was associated with a significant loss and decline in brain glucose metabolism. In CrT KO mice, intranasal supplementation with DCE for a month significantly mitigated the decline in brain glucose metabolism compared to untreated (vehicle) animals. Mechanistic investigations in CrT KO mice and cerebral organoids derived from CTD patient cells suggest that intracellular trafficking of glucose transporter (Glut) may be altered by lack of activation of AMP-activated protein kinase (AMPK). Consistency between observations in the CrT KO mouse model and cerebral organoids derived from CTD patient cells supports the value of this new model for drug discovery and development. In addition, these results suggest that [18F]FDG PET imaging may offer a unique and minimally-invasive biomarker to monitor the impact of investigational treatment on CTD pathophysiology, with translational perspectives.

Atmospheric pressure plasma preconditioning reduces oxygen and glucose deprivation induced human neuronal SH-SY5Y cells apoptosis by activating protective autophagy and ROS/AMPK/mTOR pathway

Reactive oxygen species (ROS)/reactive nitrogen species (RNS) exert a "double edged" effect on the occurrence and development of ischemic stroke. We previously indicate that atmospheric pressure plasma (APP) shows a neuroprotective effect in vitro based on the ROS/RNS generations. However, the mechanism is still unknown. In this work, SH-SY5Y cells were treated with oxygen and glucose deprivation (OGD) injuries for stimulating the ischemic stroke pathological injury process. A helium APP was used for SH-SY5Y cell treatment for evaluating the neuroprotective impacts of APP preconditioning against OGD injuries with the optimized parameters. During the preconditioning, APP significantly raised the extracellular and intracellular ROS/RNS production. As a result, APP preconditioning increased SH-SY5Y cell autophagy by elevating LC3-II/LC3-I ratio and autophagosome formation. Meanwhile, APP preconditioning reduced cell apoptosis caused by OGD with the increased APP treatment time, which was abolished by pretreatment with autophagy inhibitor 3-methyladenine (3-MA). The ROS scavenger N-acetyl-L-cysteine (NAC) alone or combined with NO scavenger carboxy-PTIO abolished the APP preconditioning induced SH-SY5Y autophagy and the cytoprotection, whereas the NO scavenger alone did not. In addition, we observed the elevated phosphorylation of AMP-activated protein kinase (AMPK) and decreased phosphorylation of mammalian target of rapamycin (mTOR) in APP treated SH-SY5Y cells. This effect was attenuated by AMPK inhibitor Compound C (CC), the ROS scavenger NAC and autophagy inhibitor 3-MA. Furthermore, the cytoprotective effect of APP was preliminarily confirmed in the rats of middle cerebral artery occlusion (MCAO) model. Results showed that APP inhalation by rats during MCAO process could improve neurological functions, reduce cell apoptosis in brain tissues and decrease cerebral infarct volume. Our data suggested that ROS produced by APP preconditioning played a vital role in the neuroprotective effect of SH-SY5Y cells against OGD injuries by activating autophagy and ROS/AMPK/mTOR pathway.

"NO" controversy?: A controversial role in insulin signaling of diabetic encephalopathy

Insulin, a critical hormone in the human body, exerts its effects by binding to insulin receptors and regulating various cellular processes. While nitric oxide (NO) plays an important role in insulin secretion and acts as a mediator in the signal transduction pathway between upstream molecules and downstream effectors, holds a significant position in the downstream signal network of insulin. Researches have shown that the insulin-NO system exhibits a dual regulatory effect within the central nervous system, which is crucial in the regulation of diabetic encephalopathy (DE). Understanding this system holds immense practical importance in comprehending the targets of existing drugs and the development of potential therapeutic interventions. This review extensively examines the characterization of insulin, NO, Nitric oxide synthase (NOS), specific NO pathway, their interconnections, and the mechanisms underlying their regulatory effects in DE, providing a reference for new therapeutic targets of DE.

Brain Metabolism in Health and Neurodegeneration: The Interplay Among Neurons and Astrocytes

The regulation of energy in the brain has garnered substantial attention in recent years due to its significant implications in various disorders and aging. The brain's energy metabolism is a dynamic and tightly regulated network that balances energy demand and supply by engaging complementary molecular pathways. The crosstalk among these pathways enables the system to switch its preferred fuel source based on substrate availability, activity levels, and cell state-related factors such as redox balance. Brain energy production relies on multi-cellular cooperation and is continuously supplied by fuel from the blood due to limited internal energy stores. Astrocytes, which interface with neurons and blood vessels, play a crucial role in coordinating the brain's metabolic activity, and their dysfunction can have detrimental effects on brain health. This review characterizes the major energy substrates (glucose, lactate, glycogen, ketones and lipids) in astrocyte metabolism and their role in brain health, focusing on recent developments in the field.

Lactiplantibacillus plantarum SG5 inhibits neuroinflammation in MPTP-induced PD mice through GLP-1/PGC-1α pathway

Mounting evidence suggests that alterations in gut microbial composition play an active role in the pathogenesis of Parkinson's disease (PD). Probiotics are believed to modulate gut microbiota, potentially influencing PD development through the microbiota-gut-brain axis. However, the potential beneficial effects of Lactiplantibacillus plantarum SG5 (formerly known as Lactobacillus plantarum, abbreviated as L. plantarum) on PD and its underlying mechanisms remain unclear. In this study, we employed immunofluorescence, Western blotting, ELISA, and 16S rRNA gene sequencing to investigate the neuroprotective effects of L. plantarum SG5 against neuroinflammation in an MPTP-induced PD model and to explore the underlying mechanisms. Our results demonstrated that L. plantarum SG5 ameliorated MPTP-induced motor deficits, dopaminergic neuron loss, and elevated α-synuclein protein levels. Furthermore, SG5 inhibited MPTP-triggered overactivation of microglia and astrocytes in the substantia nigra (SN), attenuated disruption of both blood-brain and intestinal barriers, and suppressed the release of inflammatory factors in the colon and SN. Notably, SG5 modulated the composition and structure of the gut microbiota in mice. The MPTP-induced decrease in colonic GLP-1 secretion was reversed by SG5 treatment, accompanied by increased expression of GLP-1R and PGC-1α in the SN. Importantly, the GLP-1R antagonist Exendin 9-39 and PGC-1α inhibitor SR18292 attenuated the protective effects of SG5 in PD mice. In conclusion, we demonstrate a neuroprotective role of L. plantarum SG5 in the MPTP-induced PD mouse model, which likely involves modulation of the gut microbiota and, significantly, the GLP-1/PGC-1α signaling pathway.

Olfactory dysfunction as an early pathogenic indicator in C. elegans models of Alzheimer's and polyglutamine diseases

Neurodegenerative diseases such as Alzheimer's disease and polyglutamine diseases are characterized by abnormal accumulation of misfolded proteins, leading to neuronal dysfunction and subsequent neuron death. However, there is a lack of studies that integrate molecular, morphological, and functional analyses in neurodegenerative models to fully characterize these time-dependent processes. In this study, we used C. elegans models expressing Aβ1-42 and polyglutamine to investigate early neuronal pathogenic features in olfactory neurons. Both models demonstrated significant reductions in odor sensitivity in AWB and AWC chemosensory neurons as early as day 1 of adulthood, while AWA chemosensory neurons showed no such decline, suggesting cell-type-specific early neuronal dysfunction. At the molecular level, Aβ1-42 or Q40 expression caused age-dependent protein aggregation and morphological changes in neurons. By day 6, both models displayed prominent protein aggregates in neuronal cell bodies and neurites. Notably, AWB neurons in both models showed significantly shortened cilia and increased instances of enlarged cilia as early as day 1 of adulthood. Furthermore, AWC neurons expressing Aβ1-42 displayed calcium signaling defects, with significantly reduced responses to odor stimuli on day 1, further supporting early behavioral dysfunction. In contrast, AWA neuron did not exhibit reduced calcium responses, consistent with the absence of detectable decreases in olfactory sensitivity in these neurons. These findings suggest that decreased calcium signaling and dysfunction in specific sensory neuron subtypes are early indicators of neurodegeneration in C. elegans, occurring prior to the formation of visible protein aggregates. We found that the ER unfolded protein response (UPR) is significantly activated in worms expressing Aβ1-42. Activation of the AMPK pathway alleviates olfactory defects and reduces fibrillar Aβ in these worms. This study underscores the use of C. elegans olfactory neurons as a model to elucidate mechanisms of proteostasis in neurodegenerative diseases and highlights the importance of integrated approaches.

Maternal gut Bifidobacterium breve modifies fetal brain metabolism in germ-free mice

BACKGROUND

Recent advances have significantly expanded our understanding of the gut microbiome's influence on host physiology and metabolism. However, the specific role of certain microorganisms in gestational health and fetal development remains underexplored.

OBJECTIVE

This study investigates the impact of Bifidobacterium breve UCC2003 on fetal brain metabolism when colonized in the maternal gut during pregnancy.

METHODS

Germ-free pregnant mice were colonized with or without B. breve UCC2003 during pregnancy. The metabolic profiles of fetal brains were analyzed, focusing on the presence of key metabolites and the expression of critical metabolic and cellular pathways.

RESULTS

Maternal colonization with B. breve resulted in significant metabolic changes in the fetal brain. Specifically, ten metabolites, including citrate, 3-hydroxyisobutyrate, and carnitine, were reduced in the fetal brain. These alterations were accompanied by increased abundance of transporters involved in glucose and branched-chain amino acid uptake. Furthermore, supplementation with this bacterium was associated with elevated expression of critical metabolic pathways such as PI3K-AKT, AMPK, STAT5, and Wnt-β-catenin signaling, including its receptor Frizzled-7. Additionally, there was stabilization of HIF-2 protein and modifications in genes and proteins related to cellular growth, axogenesis, and mitochondrial function.

CONCLUSIONS

The presence of maternal B. breve during pregnancy plays a crucial role in modulating fetal brain metabolism and growth. These findings suggest that Bifidobacterium could modify fetal brain development, potentially offering new avenues for enhancing gestational health and fetal development through microbiota-targeted interventions.

cAMP-PKA signaling pathway and anxiety: Where do we go next?

Cyclic adenosine monophosphate (cAMP) is an intracellular second messenger that is derived from the conversion of adenosine triphosphate catalysed by adenylyl cyclase (AC). Protein kinase A (PKA), the main effector of cAMP, is a dimeric protein kinase consisting of two catalytic subunits and two regulatory subunits. When cAMP binds to the regulatory subunits of PKA, it leads to the dissociation and activation of PKA, which allows the catalytic subunit of PKA to phosphorylate target proteins, thereby regulating various physiological functions and metabolic processes in cellular function. Recent researches also implicate the involvement of cAMP-PKA signaling in the pathologenesis of anxiety disorder. However, there are still debates on the prevention and treatment of anxiety disorders from this signaling pathway. To review the function of cAMP-PKA signaling in anxiety disorder, we searched the publications with the keywords including "cAMP", "PKA" and "Anxiety" from Pubmed, Embase, Web of Science and CNKI databases. The results showed that the number of publications on cAMP-PKA pathway in anxiety disorder tended to increase. Bioinformatics results displayed a close association between the cAMP-PKA pathway and the occurrence of anxiety. Mechanistically, cAMP-PKA signaling could influence brain-derived neurotrophic factor and neuropeptide Y and participate in the regulation of anxiety. cAMP-PKA signaling could also oppose the dysfunctions of gamma-aminobutyric acid (GABA), intestinal flora, hypothalamic-pituitary-adrenal axis, neuroinflammation, and signaling proteins (MAPK and AMPK) in anxiety. In addition, chemical agents with the ability to activate cAMP-PKA signaling demonstrated therapy potential against anxiety disorders. This review emphasizes the central roles of cAMP-PKA signaling in anxiety and the targets of the cAMP-PKA pathway would be potential candidates for treatment of anxiety. Nevertheless, more laboratory investigations to improve the therapeutic effect and reduce the adverse effect, and continuous clinical research will warrant the drug development.

Microglia signaling in health and disease - Implications in sex-specific brain development and plasticity

Microglia, the intrinsic neuroimmune cells residing in the central nervous system (CNS), exert a pivotal influence on brain development, homeostasis, and functionality, encompassing critical roles during both aging and pathological states. Recent advancements in comprehending brain plasticity and functions have spotlighted conspicuous variances between male and female brains, notably in neurogenesis, neuronal myelination, axon fasciculation, and synaptogenesis. Nevertheless, the precise impact of microglia on sex-specific brain cell plasticity, sculpting diverse neural network architectures and circuits, remains largely unexplored. This article seeks to unravel the present understanding of microglial involvement in brain development, plasticity, and function, with a specific emphasis on microglial signaling in brain sex polymorphism. Commencing with an overview of microglia in the CNS and their associated signaling cascades, we subsequently probe recent revelations regarding molecular signaling by microglia in sex-dependent brain developmental plasticity, functions, and diseases. Notably, C-X3-C motif chemokine receptor 1 (CX3CR1), triggering receptors expressed on myeloid cells 2 (TREM2), calcium (Ca2+), and apolipoprotein E (APOE) emerge as molecular candidates significantly contributing to sex-dependent brain development and plasticity. In conclusion, we address burgeoning inquiries surrounding microglia's pivotal role in the functional diversity of developing and aging brains, contemplating their potential implications for gender-tailored therapeutic strategies in neurodegenerative diseases.

AMPK inhibits voltage-gated calcium channel-current in rat chromaffin cells

Metabolic changes are critical in the regulation of Ca2+ influx in central and peripheral neuroendocrine cells. To study the regulation of L-type Ca2+ channels by AMPK we used biochemical reagents and ATP/glucose-concentration manipulations in rat chromaffin cells. AICAR and Compound-C, at low concentration, significantly induce changes in L-type Ca2+ channel-current amplitude and voltage dependence. Remarkably, an overlasting decrease in the channel-current density can be induced by lowering the intracellular level of ATP. Accordingly, Ca2+ channel-current density gradually diminishes by decreasing the extracellular glucose concentration. By using immunofluorescence, a decrease in the expression of CaV1.2 is observed while decreasing extracellular glucose, suggesting that AMPK reduces the number of functional Ca2+ channels into the plasma membrane. Together, these results support for the first time the dependence of metabolic changes in the maintenance of Ca2+ channel-current by AMPK. They reveal a key step in Ca2+ influx in secretory cells.

Microbial reconstitution reverses prenatal stress-induced cognitive impairment and synaptic deficits in rat offspring

Stress during pregnancy is often linked with increased incidents of neurodevelopmental disorders, including cognitive impairment. Here, we report that stress during pregnancy leads to alterations in the intestinal flora, which negatively affects the cognitive function of offspring. Cognitive impairment in stressed offspring can be reproduced by transplantation of cecal contents of stressed pregnant rats (ST) to normal pregnant rats. In addition, gut microbial dysbiosis results in an increase of β-guanidinopropionic acid in the blood, which leads to an activation of the adenosine monophosphate-activated protein kinase (AMPK) and signal transducer and activator of transcription 3 (STAT3) in the fetal brain. Moreover, β-guanidinopropionic acid supplementation in pregnant rats can reproduce pregnancy stress-induced enhanced glial differentiation of the fetal brain, resulting in impaired neural development. Using probiotics to reconstruct maternal microbiota can correct the cognitive impairment in the offspring of pregnant stressed rats. These findings suggest that microbial reconstitution reverses gestational stress-induced cognitive impairment and synaptic deficits in male rat offspring.

Fine-tuning AMPK in physiology and disease using point-mutant mouse models

AMP-activated protein kinase (AMPK) is an evolutionarily conserved serine/threonine kinase that monitors the cellular energy status to adapt it to the fluctuating nutritional and environmental conditions in an organism. AMPK plays an integral part in a wide array of physiological processes, such as cell growth, autophagy and mitochondrial function, and is implicated in diverse diseases, including cancer, metabolic disorders, cardiovascular diseases and neurodegenerative diseases. AMPK orchestrates many different physiological outcomes by phosphorylating a broad range of downstream substrates. However, the importance of AMPK-mediated regulation of these substrates in vivo remains an ongoing area of investigation to better understand its precise role in cellular and metabolic homeostasis. Here, we provide a comprehensive overview of our understanding of the kinase function of AMPK in vivo, as uncovered from mouse models that harbor phosphorylation mutations in AMPK substrates. We discuss some of the inherent limitations of these mouse models, highlight the broader implications of these studies for understanding human health and disease, and explore the valuable insights gained that could inform future therapeutic strategies for the treatment of metabolic and non-metabolic disorders.

Mechanical regulation of lipid and sugar absorption by Piezo1 in enterocytes

Obesity is primarily caused by excessive intake as well as absorption of sugar and lipid. Postprandial surge in distention pressure and intestinal motility accelerates the absorption of nutrients. The response of intestinal epithelial cells to mechanical stimulation is not fully understood. Piezo1, a mechanosensitive ion channel, is widely expressed throughout the digestive tract. However, its function in intestinal nutrient absorption is not yet clear. In our study, excessive lipid deposition was observed in the duodenum of obese patients, while duodenal Piezo1-CaMKK2-AMPKα was decreased when compared to normal-weight individuals. Under high-fat diet condition, the Piezo1 iKO mice exhibited abnormally elevated sugar and lipid absorption as well as severe lipid deposition in the duodenum and liver. These phenotypes were mainly caused by the inhibition of duodenal CaMKK2-AMPKα and the upregulation of SGLT1 and DGAT2. In contrast, Yoda1, a Piezo1 agonist, was found to reduce intestinal lipid absorption in diet induced obese mice. Overexpression of Piezo1, stretch and Yoda1 inhibited lipid accumulation and the expression of DGAT2 and SGLT1, whereas knockdown of Piezo1 stimulated lipid accumulation and DGAT2 in Caco-2 cells. Our study reveals a previously unexplored mechanical regulation of nutrient absorption in intestinal epithelial cells, which may shed new light on the therapy of obesity.

Glucagon-like peptide 1 receptor activation: anti-inflammatory effects in the brain

The glucagon-like peptide 1 is a pleiotropic hormone that has potent insulinotropic effects and is key in treating metabolic diseases such as diabetes and obesity. Glucagon-like peptide 1 exerts its effects by activating a membrane receptor identified in many tissues, including different brain regions. Glucagon-like peptide 1 activates several signaling pathways related to neuroprotection, like the support of cell growth/survival, enhancement promotion of synapse formation, autophagy, and inhibition of the secretion of proinflammatory cytokines, microglial activation, and apoptosis during neural morphogenesis. The glial cells, including astrocytes and microglia, maintain metabolic homeostasis and defense against pathogens in the central nervous system. After brain insult, microglia are the first cells to respond, followed by reactive astrocytosis. These activated cells produce proinflammatory mediators like cytokines or chemokines to react to the insult. Furthermore, under these circumstances, microglia can become chronically inflammatory by losing their homeostatic molecular signature and, consequently, their functions during many diseases. Several processes promote the development of neurological disorders and influence their pathological evolution: like the formation of protein aggregates, the accumulation of abnormally modified cellular constituents, the formation and release by injured neurons or synapses of molecules that can dampen neural function, and, of critical importance, the dysregulation of inflammatory control mechanisms. The glucagon-like peptide 1 receptor agonist emerges as a critical tool in treating brain-related inflammatory pathologies, restoring brain cell homeostasis under inflammatory conditions, modulating microglia activity, and decreasing the inflammatory response. This review summarizes recent advances linked to the anti-inflammatory properties of glucagon-like peptide 1 receptor activation in the brain related to multiple sclerosis, Alzheimer's disease, Parkinson's disease, vascular dementia, or chronic migraine.

Mitochondrial quality control in non-exudative age-related macular degeneration: From molecular mechanisms to structural and functional recovery

Non-exudative age-related macular degeneration (NE-AMD) is the leading blindness cause in the elderly. Clinical and experimental evidence supports that early alterations in macular retinal pigment epithelium (RPE) mitochondria play a key role in NE-AMD-induced damage. Mitochondrial dynamics (biogenesis, fusion, fission, and mitophagy), which is under the central control of AMP-activated kinase (AMPK), in turn, determines mitochondrial quality. We have developed a NE-AMD model in C57BL/6J mice induced by unilateral superior cervical ganglionectomy (SCGx), which progressively reproduces the disease hallmarks circumscribed to the temporal region of the RPE/outer retina that exhibits several characteristics of the human macula. In this work we have studied RPE mitochondrial structure, dynamics, function, and AMPK role on these parameters' regulation at the nasal and temporal RPE from control eyes and at an early stage of experimental NE-AMD (i.e., 4 weeks post-SCGx). Although RPE mitochondrial mass was preserved, their function, which was higher at the temporal than at the nasal RPE in control eyes, was significantly decreased at 4 weeks post-SCGx at the same region. Mitochondria were bigger, more elongated, and with denser cristae at the temporal RPE from control eyes. Exclusively at the temporal RPE, SCGx severely affected mitochondrial morphology and dynamics, together with the levels of phosphorylated AMPK (p-AMPK). AMPK activation with metformin restored RPE p-AMPK levels, and mitochondrial dynamics, structure, and function at 4 weeks post-SCGx, as well as visual function and RPE/outer retina structure at 10 weeks post-SCGx. These results demonstrate a key role of the temporal RPE mitochondrial homeostasis as an early target for NE-AMD-induced damage, and that pharmacological AMPK activation could preserve mitochondrial morphology, dynamics, and function, and, consequently, avoid the functional and structural damage induced by NE-AMD.

Buyang Huanwu Decoction promotes neurovascular remodeling by modulating astrocyte and microglia polarization in ischemic stroke rats

ETHNOPHARMACOLOGICAL RELEVANCE

Buyang Huanwu Decoction (BYHWD), one of the most commonly utilized traditional Chinese medicine prescription for treatment of cerebral ischemic stroke. However, the understanding of BYHWD on neurovascular repair following cerebral ischemia is so far limited.

AIM OF THE STUDY

This research investigated the influence of BYHWD on neurovascular remodeling by magnetic resonance imaging (MRI) technology and revealed the potential neurovascular repair mechanism underlying post-treatment with BYHWD after ischemic stroke.

MATERIALS AND METHODS

Male Sprague-Dawley rats were utilized as an ischemic stroke model by permanent occlusion of the middle cerebral artery (MCAO). BYHWD was intragastrically administrated once daily for 30 days straight. Multimodal MRI was performed to detect brain tissue injuries, axonal microstructural damages, cerebral blood flow and intracranial vessels on the 30th day after BYHWD treatment. Proangiogenic factors, axonal/synaptic plasticity-related factors, energy transporters and adenosine monophosphate-activated protein kinase (AMPK) signal pathway were evaluated using western blot. Double immunofluorescent staining and western blot were applied to evaluate astrocytes and microglia polarization.

RESULTS

Administration of BYHWD significantly alleviated infarct volume and brain tissue injuries and ameliorated microstructural damages, accompanied with improved axonal/synaptic plasticity-related factors, axonal growth guidance factors and decreased axonal growth inhibitors. Meanwhile, BYHWD remarkably improved cerebral blood flow, cerebral vascular signal and promoted the expression of proangiogenic factors. Particularly, treatment with BYHWD obviously suppressed astrocytes A1 and microglia M1 polarization accompanied with promoted astrocyte A2 and microglia M2 polarization. Furthermore, BYHWD effectively improved energy transporters. Especially, BYHWD markedly increased expression of phosphorylated AMPK, cyclic AMP-response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF) accompanied by inactivation of the NF-κB.

CONCLUSION

Taken together, these findings identified that the beneficial roles of BYHWD on neurovascular remodeling were related to AMPK pathways -mediated energy transporters and NFκB/CREB pathways.

Phytochemicals targeting Alzheimer's disease via the AMP-activated protein kinase pathway, effects, and mechanisms of action

Alzheimer's disease (AD), characterized by cognitive dysfunction and other behavioral abnormalities, is a progressive neurodegenerative disease that occurs due to aging. Currently, effective drugs to mitigate or treat AD remain unavailable. AD is associated with several abnormalities in neuronal energy metabolism, such as decreased glucose uptake, mitochondrial dysfunction, and defects in cholesterol metabolism. Amp-activated protein kinase (AMPK) is an important serine/threonine protein kinase that regulates the energy status of cells. AMPK is widely present in eukaryotic cells and can sense and regulate energy metabolism to maintain energy supply and demand balance, making it a promising target for energy metabolism-based AD therapy. Therefore, this review aimed to discuss the molecular mechanism of AMPK in the pathogenesis of AD to provide a theoretical basis for the development of new anti-AD drugs. To review the mechanisms of phytochemicals in the treatment of AD via AMPK pathway regulation, we searched PubMed, Google Scholar, Web of Science, and Embase databases using specific keywords related to AD and phytochemicals in September 2023. Phytochemicals can activate AMPK or regulate the AMPK pathway to exert therapeutic effects in AD. The anti-AD mechanisms of these phytochemicals include inhibiting Aβ aggregation, preventing Tau hyperphosphorylation, inhibiting inflammatory response and glial activation, promoting autophagy, and suppressing anti-oxidative stress. Additionally, several AMPK-related pathways are involved in the anti-AD mechanism, including the AMPK/CaMKKβ/mTOR, AMPK/SIRT1/PGC-1α, AMPK/NF-κB/NLRP3, AMPK/mTOR, and PERK/eIF2α pathways. Notably, urolithin A, artemisinin, justicidin A, berberine, stigmasterol, arctigenin, and rutaecarpine are promising AMPK agonists with anti-AD effects. Several phytochemicals are effective AMPK agonists and may have potential applications in AD treatment. Overall, phytochemical-based drugs may overcome the barriers to the effective treatment of neurodegenerative diseases.

Pleiotropic attenuating effect of Ginkgo biloba against isoprenaline-induced myocardial infarction via improving Bcl-2/mTOR/ERK1/2/Na+, K+-ATPase activities

Objective

Myocardial infarction (MI) is linked to an imbalance in the supply and demand of blood oxygen in the heart muscles. Beta-blockers and calcium antagonists are just two of the common medications used to treat MI. However, these have reportedly been shown to be either ineffective or to have undesirable side effects. Extract of Ginkgo biloba leaves (GBE), a Chinese herbal product offers special compatibility benefits in therapeutic settings relating to inflammatory diseases and oxidative stress. In order to better understand how GBE affects MI in rats insulted by isoprenaline (ISO), the current study was designed.

Methods

The heart weight index, serum lipid profile, cardiac marker enzymes, endogenous antioxidants [catalase (CAT), superoxide dismutase (SOD), glutathione (GSH), nitrites and malondialdehyde (MDA)], inflammatory mediators [tumour necrosis factor alpha (TNF-α) and interleukin-6 (IL-6)], immunohistochemical expressions of B-cell lymphoma factor-2 (Bcl-2), extracellular signal-regulated kinase (ERK1/2), and mammalian target of rapamycin (mTOR) and histopathological analysis were used to assess the cardioprotective properties of GBE.

Results

The findings showed that GBE effectively attenuated myocardial infarction by boosting the body's natural antioxidant defense system and reducing the release of inflammatory cytokines as well as heart injury marker enzymes. The expression of Bcl-2, ERK1/2 and mTOR was increased while the histomorphological alterations were reversed.

Conclusion

The cardioprotective effects of GBE may be due to a mechanism involving increased Bcl-2/mTOR/ERK1/2/Na+, K+-ATPase activity.

Unraveling the therapeutic efficacy of resveratrol in Alzheimer's disease: an umbrella review of systematic evidence

CONTEXT

Resveratrol (RV), a natural compound found in grapes, berries, and peanuts, has been extensively studied for its potential in treating Alzheimer's disease (AD). RV has shown promise in inhibiting the formation of beta-amyloid plaques (Aβ) and neurofibrillary tangles (NFTs), protecting against neuronal damage and oxidative stress, reducing inflammation, promoting neuroprotection, and improving the function of the blood-brain barrier (BBB). However, conflicting results have been reported, necessitating a comprehensive umbrella review of systematic reviews to provide an unbiased conclusion on the therapeutic effectiveness of RV in AD.

OBJECTIVE

The objective of this study was to systematically synthesize and evaluate systematic and meta-analysis reviews investigating the role of RV in AD using data from both human and animal studies.

DATA SOURCES AND EXTRACTION

Of the 34 systematic and meta-analysis reviews examining the association between RV and AD that were collected, six were included in this study based on specific selection criteria. To identify pertinent studies, a comprehensive search was conducted in English-language peer-reviewed journals without any restrictions on the publication date until October 15, 2023. The search was carried out across multiple databases, including Embase, MEDLINE (PubMed), Cochrane Library, Web of Science, and Google Scholar, utilizing appropriate terms relevant to the specific research field. The AMSTAR-2 and ROBIS tools were also used to evaluate the quality and risk of bias of the included systematic reviews, respectively. Two researchers independently extracted and analyzed the data, resolving any discrepancies through consensus. Of note, the study adhered to the PRIOR checklist.

DATA ANALYSIS

This umbrella review presented robust evidence supporting the positive impacts of RV in AD, irrespective of the specific mechanisms involved. It indeed indicated that all six systematic and meta-analysis reviews unanimously concluded that the consumption of RV can be effective in the treatment of AD.

CONCLUSION

RV exhibits promising potential for benefiting individuals with AD through various mechanisms. It has been observed to enhance cognitive function, reduce Aβ accumulation, provide neuroprotection, protect the BBB, support mitochondrial function, facilitate synaptic plasticity, stabilize tau proteins, mitigate oxidative stress, and reduce neuroinflammation commonly associated with AD.

Insulin signalling regulates Pink1 mRNA localization via modulation of AMPK activity to support PINK1 function in neurons

Mitochondrial quality control failure is frequently observed in neurodegenerative diseases. The detection of damaged mitochondria by stabilization of PTEN-induced kinase 1 (PINK1) requires transport of Pink1 messenger RNA (mRNA) by tethering it to the mitochondrial surface. Here, we report that inhibition of AMP-activated protein kinase (AMPK) by activation of the insulin signalling cascade prevents Pink1 mRNA binding to mitochondria. Mechanistically, AMPK phosphorylates the RNA anchor complex subunit SYNJ2BP within its PDZ domain, a phosphorylation site that is necessary for its interaction with the RNA-binding protein SYNJ2. Notably, loss of mitochondrial Pink1 mRNA association upon insulin addition is required for PINK1 protein activation and its function as a ubiquitin kinase in the mitophagy pathway, thus placing PINK1 function under metabolic control. Induction of insulin resistance in vitro by the key genetic Alzheimer risk factor apolipoprotein E4 retains Pink1 mRNA at the mitochondria and prevents proper PINK1 activity, especially in neurites. Our results thus identify a metabolic switch controlling Pink1 mRNA localization and PINK1 activity via insulin and AMPK signalling in neurons and propose a mechanistic connection between insulin resistance and mitochondrial dysfunction.

Zinc deficiency drives ferroptosis resistance by lactate production in esophageal squamous cell carcinoma

Trace metal zinc is involved in key processes of solid tumors by its antioxidant properties, while the role of zinc at the onset of esophageal squamous cell carcinoma (ESCC) remains controversial. This study aimed to determine whether zinc is associated with the ESCC and underlying molecular events involving malignant progression. Based on a case-control study, we found serum and urine zinc were decreased and correlated with ESCC progression. Thus, an in vitro model for zinc deficiency (ZD) was established, and we found that ZD contributed to the proliferation, migration, and invasion of EC109 cells. Untargeted metabolomics identified 59 upregulated metabolites and 6 downregulated metabolites, among which glycolysis and ferroptosis-related oxidation of chain fatty acids might play crucial steps in ZD-treated molecular events. Interestingly, ZD disrupted redox homeostasis and enhanced cytosolic Fe2+ of EC109 cells, while lipid peroxidation, the key marker of ferroptosis occurrence, was decreased after ZD treatment. The mechanism underlying these changes may involve ZD-enhanced ESCC glycolysis and lactate production, which confer ferroptosis resistance by inhibiting of p-AMPK and leading to the upregulation of SREBP1 and SCD1 to enhance the production of anti-ferroptosis monounsaturated fatty acids.

AMPK role in epilepsy: a promising therapeutic target?

Epilepsy is a complex and multifaceted neurological disorder characterized by spontaneous and recurring seizures. It poses significant therapeutic challenges due to its diverse etiology and often-refractory nature. This comprehensive review highlights the pivotal role of AMP-activated protein kinase (AMPK), a key metabolic regulator involved in cellular energy homeostasis, which may be a promising therapeutic target for epilepsy. Current therapeutic strategies such as antiseizure medication (ASMs) can alleviate seizures (up to 70%). However, 30% of epileptic patients may develop refractory epilepsy. Due to the complicated nature of refractory epilepsy, other treatment options such as ketogenic dieting, adjunctive therapy, and in limited cases, surgical interventions are employed. These therapy options are only suitable for a select group of patients and have limitations of their own. Current treatment options for epilepsy need to be improved. Emerging evidence underscores a potential association between impaired AMPK functionality in the brain and the onset of epilepsy, prompting an in-depth examination of AMPK's influence on neural excitability and ion channel regulation, both critical factors implicated in epileptic seizures. AMPK activation through agents such as metformin has shown promising antiepileptic effects in various preclinical and clinical settings. These effects are primarily mediated through the inhibition of the mTOR signaling pathway, activation of the AMPK-PI3K-c-Jun pathway, and stimulation of the PGC-1α pathway. Despite the potential of AMPK-targeted therapies, several aspects warrant further exploration, including the detailed mechanisms of AMPK's role in different brain regions, the impact of AMPK under various conditional circumstances such as neural injury and zinc toxicity, the long-term safety and efficacy of chronic metformin use in epilepsy treatment, and the potential benefits of combination therapy involving AMPK activators. Moreover, the efficacy of AMPK activators in refractory epilepsy remains an open question. This review sets the stage for further research with the aim of enhancing our understanding of the role of AMPK in epilepsy, potentially leading to the development of more effective, AMPK-targeted therapeutic strategies for this challenging and debilitating disorder.

miR-129-5p as a biomarker for pathology and cognitive decline in Alzheimer's disease

BACKGROUND

Alzheimer's dementia (AD) pathogenesis involves complex mechanisms, including microRNA (miRNA) dysregulation. Integrative network and machine learning analysis of miRNA can provide insights into AD pathology and prognostic/diagnostic biomarkers.

METHODS

We performed co-expression network analysis to identify network modules associated with AD, its neuropathology markers, and cognition using brain tissue miRNA profiles from the Religious Orders Study and Rush Memory and Aging Project (ROS/MAP) (N = 702) as a discovery dataset. We performed association analysis of hub miRNAs with AD, its neuropathology markers, and cognition. After selecting target genes of the hub miRNAs, we performed association analysis of the hub miRNAs with their target genes and then performed pathway-based enrichment analysis. For replication, we performed a consensus miRNA co-expression network analysis using the ROS/MAP dataset and an independent dataset (N = 16) from the Gene Expression Omnibus (GEO). Furthermore, we performed a machine learning approach to assess the performance of hub miRNAs for AD classification.

RESULTS

Network analysis identified a glucose metabolism pathway-enriched module (M3) as significantly associated with AD and cognition. Five hub miRNAs (miR-129-5p, miR-433, miR-1260, miR-200a, and miR-221) of M3 had significant associations with AD clinical and/or pathologic traits, with miR129-5p by far the strongest across all phenotypes. Gene-set enrichment analysis of target genes associated with their corresponding hub miRNAs identified significantly enriched biological pathways including ErbB, AMPK, MAPK, and mTOR signaling pathways. Consensus network analysis identified two AD-associated consensus network modules and two hub miRNAs (miR-129-5p and miR-221). Machine learning analysis showed that the AD classification performance (area under the curve (AUC) = 0.807) of age, sex, and APOE ε4 carrier status was significantly improved by 6.3% with inclusion of five AD-associated hub miRNAs.

CONCLUSIONS

Integrative network and machine learning analysis identified miRNA signatures, especially miR-129-5p, as associated with AD, its neuropathology markers, and cognition, enhancing our understanding of AD pathogenesis and leading to better performance of AD classification as potential diagnostic/prognostic biomarkers.

Upregulation of hypothalamic TRPV4 via S100a4/AMPKα signaling pathway promotes the development of diet-induced obesity

Obesity is associated with abnormal regulation of energy metabolism in the hypothalamus. Transient receptor potential vanilloid 4 (TRPV4) is involved in regulating osmotic pressure, temperature and mechanical force transmission, but little is known about its role in obesity. Herein, the present study aimed to elucidate the effect of hypothalamic TRPV4 on high-fat diet-induced obesity (DIO) and evaluate its potential for regulating energy metabolism. Here we show that hypothalamic TRPV4 content is increased in DIO rats. Central administration of adeno-associated virus expressing TRPV4 in these animals remarkably increased body weight and fat mass by activating the S100a4/AMPKα signaling pathway, thereby promoting positive energy metabolism. Overexpressed hypothalamic TRPV4 impaired glucose tolerance, while promoting the accumulation of fat in liver cells, resulting in hepatic steatosis. In addition, the upregulation of hypothalamic TRPV4 reduces high-fat induced central inflammation. This study provides evidence that hypothalamic TRPV4 plays a significant role in regulating homeostasis. Hypothalamic TRPV4 emerges as a target for therapeutic intervention against obesity.

Chronic AMPK inactivation slows SHH medulloblastoma progression by inhibiting mTORC1 signaling and depleting tumor stem cells

We show that inactivating AMPK in a genetic medulloblastoma model depletes tumor stem cells and slows progression. In medulloblastoma, the most common malignant pediatric brain tumor, drug-resistant stem cells co-exist with transit-amplifying cells and terminally differentiated neuronal progeny. Prior studies show that Hk2-dependent glycolysis promotes medulloblastoma progression by suppressing neural differentiation. To determine how the metabolic regulator AMPK affects medulloblastoma growth and differentiation, we inactivated AMPK genetically in medulloblastomas. We bred conditional Prkaa1 and Prkaa2 deletions into medulloblastoma-prone SmoM2 mice and compared SmoM2-driven medulloblastomas with intact or inactivated AMPK. AMPK-inactivation increased event-free survival (EFS) and altered cellular heterogeneity, increasing differentiation and decreasing tumor stem cell populations. Surprisingly, AMPK-inactivation decreased mTORC1 activity and decreased Hk2 expression. Hk2 deletion similarly depleted medulloblastoma stem cells, implicating reduced glycolysis in the AMPK-inactivated phenotype. Our results show that AMPK inactivation disproportionately impairs medulloblastoma stem cell populations typically refractory to conventional therapies.

Pretreatment with Lovastatin Improves Depression-Like Behavior After Traumatic Brain Injury Through Activation of the AMPK Pathway

BACKGROUND

The beneficial effect of pretreatment with statins on traumatic brain injury (TBI)-induced depression and anxiety and its mechanism of action remain unclear. In this study, we combined epidemiological and experimental animal data to clarify this issue.

METHODS

We used the Taiwan National Health Insurance database to identify patients who were diagnosed with TBI from 2000 to 2013 and compared patients with and without statin treatment matched by age, sex, and underlying comorbidities in a 1:1 ratio. The risk of developing depression and/or anxiety was compared between patients with and without a statin using Cox proportional hazards regression. We also used a rat model to assess the effect of lovastatin pretreatment on neurobehavioral and neuropathological changes following TBI.

RESULTS

The risk of developing depression was lower in the 41,803 patients in the statin cohort than nonstatin cohort (adjusted hazard ratio, 0.91 [95% confidence interval, 0.83-0.99]). In animal models, the lovastatin group had significantly reduced infarct volume, decreased immobility time and latency to eat, a reduced number of Fluoro- Jade-positive cells and levels of glial fibrillary acidic protein and tumor necrosis factor-alpha, and increased adenosine monophosphate -activated protein kinase (AMPK) and its upstream kinase liver kinase B1 in the hippocampal dentate gyrus. These effects were blocked in AMPK inhibitor-pretreated TBI rats.

CONCLUSIONS

Our epidemiological data showed that a decreased risk of depression was associated with statin pretreatment, which was supported by an animal study. The underlying mechanism for this appears to involve AMPK activation in the statin pretreatment-induced alleviation of TBI.

Metformin Prevents Cocaine Sensitization: Involvement of Adenosine Monophosphate-Activated Protein Kinase Trafficking between Subcellular Compartments in the Corticostriatal Reward Circuit

Repeated cocaine exposure produces an enhanced locomotor response (sensitization) paralleled by biological adaptations in the brain. Previous studies demonstrated region-specific responsivity of adenosine monophosphate-activated protein kinase (AMPK) to repeated cocaine exposure. AMPK maintains cellular energy homeostasis at the organismal and cellular levels. Here, our objective was to quantify changes in phosphorylated (active) and total AMPK in the cytosol and synaptosome of the medial prefrontal cortex, nucleus accumbens, and dorsal striatum following acute or sensitizing cocaine injections. Brain region and cellular compartment selective changes in AMPK and pAMPK were found with some differences associated with acute withdrawal versus ongoing cocaine treatment. Our additional goal was to determine the behavioral and molecular effects of pretreatment with the indirect AMPK activator metformin. Metformin potentiated the locomotor activating effects of acute cocaine but blocked the development of sensitization. Sex differences largely obscured any protein-level treatment group effects, although pAMPK in the NAc shell cytosol was surprisingly reduced by metformin in rats receiving repeated cocaine. The rationale for these studies was to inform our understanding of AMPK activation dynamics in subcellular compartments and provide additional support for repurposing metformin for treating cocaine use disorder.

A cholinergic circuit that relieves pain despite opioid tolerance

Chronic pain is a tremendous burden for afflicted individuals and society. Although opioids effectively relieve pain, significant adverse outcomes limit their utility and efficacy. To investigate alternate pain control mechanisms, we explored cholinergic signaling in the ventrolateral periaqueductal gray (vlPAG), a critical nexus for descending pain modulation. Biosensor assays revealed that pain states decreased acetylcholine release in vlPAG. Activation of cholinergic projections from the pedunculopontine tegmentum to vlPAG relieved pain, even in opioid-tolerant conditions, through ⍺7 nicotinic acetylcholine receptors (nAChRs). Activating ⍺7 nAChRs with agonists or stimulating endogenous acetylcholine inhibited vlPAG neuronal activity through Ca2+ and peroxisome proliferator-activated receptor α (PPAR⍺)-dependent signaling. In vivo 2-photon imaging revealed that chronic pain induces aberrant excitability of vlPAG neuronal ensembles and that ⍺7 nAChR-mediated inhibition of these cells relieves pain, even after opioid tolerance. Finally, pain relief through these cholinergic mechanisms was not associated with tolerance, reward, or withdrawal symptoms, highlighting its potential clinical relevance.

Calcium signals tune AMPK activity and mitochondrial homeostasis in dendrites of developing neurons

Dendritic outgrowth in immature neurons is enhanced by neuronal activity and is considered one of the mechanisms of neural circuit optimization. It is known that calcium signals affect transcriptional regulation and cytoskeletal remodeling necessary for dendritic outgrowth. Here, we demonstrate that activity-dependent calcium signaling also controls mitochondrial homeostasis via AMP-activated protein kinase (AMPK) in growing dendrites of differentiating mouse hippocampal neurons. We found that the inhibition of neuronal activity induced dendritic hypotrophy with abnormally elongated mitochondria. In growing dendrites, AMPK is activated by neuronal activity and dynamically oscillates in synchrony with calcium spikes, and this AMPK oscillation was inhibited by CaMKK2 knockdown. AMPK activation led to phosphorylation of MFF and ULK1, which initiate mitochondrial fission and mitophagy, respectively. Dendritic mitochondria in AMPK-depleted neurons exhibited impaired fission and mitophagy and displayed multiple signs of dysfunction. Genetic inhibition of fission led to dendritic hypoplasia that was reminiscent of AMPK-deficient neurons. Thus, AMPK activity is finely tuned by the calcium-CaMKK2 pathway and regulates mitochondrial homeostasis by facilitating removal of damaged components of mitochondria in growing neurons during normal brain development.

Valproate-induced murine autism spectrum disorder is associated with dysfunction of amygdala parvalbumin interneurons and downregulation of AMPK/SIRT1/PGC1α signaling

Autism spectrum disorder (ASD) is a neurodevelopmental condition that is characterized by difficulty in social behavior and restricted behaviors. Also, in ASD, several accompanying disorders such as anxiety are observed. Considering the important role of amygdala in the pathophysiology of ASD, the present study focused on the neuronal changes and it possible signaling pathway in amygdala. After prenatal exposure to valproate (VPA; 600 mg/kg, i.p, on embryonic day 12.5), amount of ROS, MMP, caspase-3 activity, AMPK, SIRT1 and PGC1α proteins, and parvalbumin interneurons in the amygdala were assessed following evaluation of ASD and anxiety-like behaviors. Amygdala analysis revealed ROS accumulation and decreased MMP in autistic rats. In addition, caspase-3 activation elevated and immunoreactivity for parvalbumin interneurons decreased. These were accompanied by anxiety and autistic-like behaviors in open field test, elevated zero maze and U-Shaped 2 Choice Field maze. Also, our data showed that in the valproate group, protein levels of AMPK, SIRT1 and PGC1α reduced. Collectively, our results indicate that prenatal exposure to valproate leads to anxiety and autistic-like behaviors, partly through its targeting amygdala parvalbumin interneurons dysfunction and this might be affected by disturbed AMPK/SIRT1/PGC1α signaling pathway.