Brain metabolism in health, aging, and neurodegeneration

Brain-thyroid crosstalk: 18F-FDG-PET/MRI evidence in patients with follicular thyroid adenomas

OBJECTIVE

The hypothalamic-pituitary-thyroid axis has been well-known. However, whether follicular thyroid adenoma (FTA) could affect brain glucose metabolism is still unknown. Therefore, we explored the brain glucose metabolic characteristics of FTA with Fluorodeoxyglucose F18 positron emission tomography/magnetic resonance imaging.

METHODS

Totally 30 FTA patients without clinical symptoms (FTA group), and 60 age- and sex-matched healthy controls (HC group) were included and randomly divided into cohort A and B in 2:1 ratio. Cohort A was analyzed with scaled sub-profile model/principal component analysis (SSM/PCA) for pattern identification. Cohort B was calculated the individual scores to validate expression of the pattern. Then we calculated the metabolic connectivity based on characteristics of the pattern to investigate the underlying mechanism. Finally, we constructed metabolic brain networks and analyzed the topological properties to further explore the brain metabolic model.

RESULTS

In SSM/PCA, FTA group showed an almost global, left-right symmetrical pattern. In metabolic connectivity, FTA group showed increased metabolic connectivity in brain regions of the sensorimotor network, ventral default mode network (DMN), posterior salient network, right executive control network (ECN), visuospatial network and language network when compared to HC group, and showed decreased connectivity in dorsal DMN and left ECN. In topological properties of brain network, FTA group showed an increased betweenness centrality (BC) in left rolandic operculum, a decreased BC in superior temporal gyrus, increased BC and Degree in right precentral gyrus, increased D in right parahippocampal gyrus and left hippocampus, and decreased D and efficiency in right orbital part of middle frontal gyrus (FDR correction for multiple comparisons, P < 0.05).

CONCLUSION

Although FTA patients are not yet symptomatic, their brain metabolic characteristics include extensive brain alterations, disrupted internal connectivity, not only involving brain regions associated with endocrine activity, but also brain networks and regions associated with motor, emotion and cognition.

Mitochondrial dysfunction in Alzheimer's disease

Alzheimer's disease (AD) is a chronic neurodegenerative disease characterized by progressive cognitive decline and distinct neuropathological features. The absence of a definitive cure presents a significant challenge in neurology and neuroscience. Early clinical manifestations, such as memory retrieval deficits and apathy, underscore the need for a deeper understanding of the disease's underlying mechanisms. While amyloid-β plaques and tau neurofibrillary tangles have dominated research efforts, accumulating evidence highlights mitochondrial dysfunction as a central factor in AD pathogenesis. Mitochondria, essential cellular organelles responsible for energy production necessary for neuronal function become impaired in AD, triggering several cellular consequences. Factors such as oxidative stress, disturbances in energy metabolism, failures in the mitochondrial quality control system, and dysregulation of calcium release are associated with mitochondrial dysfunction. These abnormalities are closely linked to the neurodegenerative processes driving AD development and progression. This review explores the intricate relationship between mitochondrial dysfunction and AD pathogenesis, emphasizing its role in disease onset and progression, while also considering its potential as a biomarker and a therapeutic target.

Dose-Dependent Effect of a New Biotin Compound in Hippocampal Remyelination in Rats

Demyelination is commonly observed in neurodegenerative disorders, including multiple sclerosis (MS). Biotin supplementation is known to stabilize MS progression. To reduce the effective dose of biotin, we synthesized a new and superior form of biotin, a complex of magnesium ionically bound to biotin (MgB) and compared its dose-dependent effect with biotin alone after inducing demyelination using lysolecithin (LPC) in rats. Myelination was assessed using luxol fast blue staining and immunostaining against MBP protein, revealing that the most significant remyelination occurred in the MgB groups. Additionally, both biotin and MgB-treated animals showed dose-dependent improvements in spatial memory. Moreover, we detected a decrease in inflammatory proteins in both treatment groups, which was more prominent in high-dose MgB-treated animals and correlated with decreased expression of NF-κB p65, OP, and MMP-9 proteins. Further analysis of biotin-related proteins demonstrated that both biotin and, notably, MgB reversed the demyelination-dependent reduction of these proteins. Furthermore, biotin, particularly MgB, improved neuronal transmission proteins, Synapsin-1, PSD-93, and PSD-95. Additionally, both treatment groups exhibited increased BDNF, GAP43, and ICAM levels, with significant increments observed in high-dose MgB-treated animals. Increased GFAP, indicative of reactive gliosis, was observed in LPC-treated animals, and this effect was notably reversed by high-dose MgB treatment. The current data emphasize the dose-dependent beneficial effect on the remyelination process. Furthermore, the combination of biotin with Mg resulted in a more potent effect compared to biotin by itself. The strong influence of MgB encourages proof-of-concept studies using MgB in patients with MS.

Elevated brain manganese induces motor disease by upregulating the kynurenine pathway of tryptophan metabolism

Elevated brain levels of the essential metals manganese (Mn), copper, or iron induce motor disease. However, mechanisms of metal-induced motor disease are unclear and treatments are lacking. Elucidating the mechanisms of Mn-induced motor disease is particularly important because occupational and environmental Mn overexposure is a global public health problem. To address this, here we combined unbiased transcriptomics and metabolomics with functional studies in a mouse model of human environmental Mn exposure. Transcriptomics unexpectedly revealed that Mn exposure up-regulated expression of metabolic pathways in the brain and liver. Notably, genes in the kynurenine pathway of tryptophan metabolism, which produces neuroactive metabolites that impact neurological function, were up-regulated by Mn. Subsequent unbiased metabolomics revealed that Mn treatment altered kynurenine pathway metabolites in the brain and liver. Functional experiments then demonstrated that pharmacological inhibition of the first and rate-limiting step of the kynurenine pathway fully rescued Mn-induced motor deficits. Finally, elevated Mn directly activates hypoxia-inducible factor (HIF) transcription factors, and additional mechanistic assays identified a role for HIF1, but not HIF2, in regulating expression of hepatic kynurenine pathway genes under physiological or Mn exposure conditions, suggesting that Mn-induced HIF1 activation may contribute to the dysregulation of the kynurenine pathway in Mn toxicity. These findings (1) identify the upregulation of the kynurenine pathway by elevated Mn as a fundamental mechanism of Mn-induced motor deficits; (2) provide a pharmacological approach to treat Mn-induced motor disease; and (3) should broadly advance understanding of the general principles underlying neuromotor deficits caused by metal toxicity.

Exploring the link between estimated glucose disposal rate and Parkinson's disease: cross-sectional and mortality analysis of NHANES 2003-2016

Objectives

To investigate the association between estimated glucose disposal rate (eGDR), a surrogate marker of insulin resistance, and Parkinson's disease (PD) risk, and to examine the relationship between eGDR and all-cause mortality among PD patients.

Methods

Using data from the National Health and Nutrition Examination Survey (NHANES) 2003-2016, we conducted a cross-sectional study of 20,767 participants aged ≥40 years. eGDR was calculated using waist circumference, hypertension status, and HbA1c levels. PD cases were identified through anti-parkinsonian medication use. The association between eGDR and PD was examined using weighted logistic regression models with progressive adjustment for potential confounders. Survival analysis was performed in 255 PD patients to assess the relationship between eGDR and all-cause mortality.

Results

Among participants, 256 had PD (weighted prevalence: 1.23%). Higher eGDR was associated with lower odds of PD in crude analysis (OR: 0.906, 95% CI: 0.856-0.960, P < 0.001). After full adjustment, the highest eGDR tertile showed significantly lower odds of PD compared to the lowest tertile (OR: 0.574, 95% CI: 0.337-0.976, P = 0.040). Restricted cubic spline analysis revealed a significant M-shaped non-linear relationship between eGDR and PD risk (P for non-linearity < 0.001). In survival analysis, higher eGDR was associated with lower mortality risk (adjusted HR: 0.875, 95% CI: 0.775-0.987, P = 0.030), with an inverted U-shaped relationship observed (P for non-linearity = 0.0352).

Conclusion

Higher eGDR levels are associated with lower PD risk and better survival in PD patients, suggesting that insulin sensitivity might play a role in PD pathogenesis and progression. These findings highlight the potential importance of metabolic health in PD.

Exploring Human Brain Metabolism via Genome-Scale Metabolic Modeling with Highlights on Multiple Sclerosis

Cerebral dysfunctions give rise to a wide range of neurological diseases due to the structural and functional complexity of the human brain stemming from the interactive cellular metabolism of its specific cells, including neurons and glial cells. In parallel with advances in isolation and measurement technologies, genome-scale metabolic models (GEMs) have become a powerful tool in the studies of systems biology to provide critical insights into the understanding of sophisticated eukaryotic systems. In this study, brain cell-specific GEMs were reconstructed for neurons, astrocytes, microglia, oligodendrocytes, and oligodendrocyte precursor cells by integrating single-cell RNA-seq data and global Human1 via a task-driven integrative network inference for tissues (tINIT) algorithm. Then, intercellular reactions among neurons, astrocytes, microglia, and oligodendrocytes were added to generate a combined brain model, iHumanBrain2690. This brain network was used in the prediction of metabolic alterations in glucose, ketone bodies, oxygen change, and reporter metabolites. Glucose supplementation increased the subsystems' activities in glycolysis, and ketone bodies elevated those in the TCA cycle and oxidative phosphorylation. Reporter metabolite analysis identified L-carnitine and arachidonate as the top reporter metabolites in gray and white matter microglia in multiple sclerosis (MS), respectively. Carbamoyl-phosphate was found to be the top reporter metabolite in primary progressive MS. Taken together, single and integrated iHumanBrain2690 metabolic networks help us elucidate complex metabolism in brain physiology and homeostasis in health and disease.

Biological Effects of Dietary Restriction on Alzheimer's Disease: Experimental and Clinical Investigations

BACKGROUNDS

Dementia can impose a heavy economic burden on both society and families. Alzheimer's disease (AD), the most prevalent form of dementia, is a complex neurodegenerative disease characterized by the abnormal deposition of extracellular amyloid β-protein (Aβ) and the aggregation of intracellular Tau protein to form neurofibrillary tangles (NFTs). Given the limited efficacy of pharmacological treatment, scientists have already paid more attention to non-pharmacological strategies, including dietary restriction (DR). DR refers to a nutritional paradigm aimed at promoting overall health by modifying the balance between energy consumption and expenditure. Studies have demonstrated that DR effectively extends the healthy lifespan, delays the aging process, and achieves promising results in the prevention and treatment of AD in preclinical studies.

METHODS

In this review we collected related studies and viewpoints by searching on PubMed database using the keywords. Most of the citations were published between 2015 and 2025. A few older literatures were also included due to their relevance and significance in this field.

RESULTS

We first provide a concise overview of the current therapeutic and preventive strategies for AD. Then, we introduce several specific DR protocols and their favorable effects on AD. Furthermore, the potential mechanisms underlying the benefits of DR on AD are discussed. Finally, we briefly highlight the role of DR in maintaining brain health.

CONCLUSION

This review may offer valuable insights into the development of innovative non-pharmacological strategies for AD treatment.

A ketogenic diet decreases sevoflurane-induced burst suppression in rats

BACKGROUND

The brain requires a continuous fuel supply to support cognition and can get energy from glucose and ketones. Dysregulated brain metabolism is thought to contribute to perioperative neurocognitive disorders and anesthesia-induced burst suppression. Therefore, we investigated the relationship between brain metabolites and neurophysiology during the behavioral states of sleep and anesthesia under a standard diet (SD) or a ketogenic diet (KD).

METHODS

We measured prefrontal cortex glucose, lactate, and electroencephalogram in Fischer344 rats during spontaneous sleep/wake followed by 3 % sevoflurane anesthesia. Nine rats were fed a KD and 8 rats a SD. To assess the role of adenosine receptor-mediated ketone activity on burst suppression, 5 additional rats on the KD received an intraperitoneal injection of vehicle or the adenosine A1 receptor antagonist, DPCPX, before 3 % sevoflurane.

RESULTS

Sevoflurane induced larger fluctuations in glucose (p < 0.001) and lactate (p = 0.015) concentrations compared to sleep as measured by the standard deviation (glucose 0.085 mM and lactate 0.16 mM in sleep/wake and 0.25 mM and 0.41 mM during sevoflurane respectively). Changes in glucose and lactate were closely tied to electrophysiological oscillations. Animals on the KD had reduced burst suppression ratio (mean 10 % in KD vs 30 % in SD) (p = 0.007) as well as increased time to loss of movement (mean 14 min in KD vs 8 min in SD) (p = 0.003) compared to SD. DPCPX in KD rats showed a trend to increased burst suppression, reduced the time to start of burst suppression (45 min in KD+vehicle to 37 min KD+DPCPX) (p = 0.007), and increased duration of burst suppression (49 min in KD+vehicle to 90 min in KD+DPCPX) (p = 0.046) compared to KD+vehicle.

CONCLUSIONS

It is thought that anesthesia-induced burst suppression reflects an underlying deficiency in brain energy. Accordingly, we found that upregulating ketones, which increase available brain ATP levels, delayed anesthetic induction and decreased burst suppression consistent with the idea that the underlying metabolic state of the brain influences an anesthetic's effect on the brain. These findings suggest that metabolic interventions could be useful therapeutic targets to modulate brain activity during sleep and anesthesia. Future studies will examine whether ketones can reduce the cognitive symptoms associated with postoperative delirium.

The role of estrogen in Alzheimer's disease pathogenesis and therapeutic potential in women

Estrogens are pivotal regulators of brain function throughout the lifespan, exerting profound effects from early embryonic development to aging. Extensive experimental evidence underscores the multifaceted protective roles of estrogens on neurons and neurotransmitter systems, particularly in the context of Alzheimer's disease (AD) pathogenesis. Studies have consistently revealed a greater risk of AD development in women compared to men, with postmenopausal women exhibiting heightened susceptibility. This connection between sex factors and long-term estrogen deprivation highlights the significance of estrogen signaling in AD progression. Estrogen's influence extends to key processes implicated in AD, including amyloid precursor protein (APP) processing and neuronal health maintenance mediated by brain-derived neurotrophic factor (BDNF). Reduced BDNF expression, often observed in AD, underscores estrogen's role in preserving neuronal integrity. Notably, hormone replacement therapy (HRT) has emerged as a sex-specific and time-dependent strategy for primary cardiovascular disease (CVD) prevention, offering an excellent risk profile against aging-related disorders like AD. Evidence suggests that HRT may mitigate AD onset and progression in postmenopausal women, further emphasizing the importance of estrogen signaling in AD pathophysiology. This review comprehensively examines the physiological and pathological changes associated with estrogen in AD, elucidating the therapeutic potential of estrogen-based interventions such as HRT. By synthesizing current knowledge, it aims to provide insights into the intricate interplay between estrogen signaling and AD pathogenesis, thereby informing future research directions and therapeutic strategies for this debilitating neurodegenerative disorder.

Increased White Matter Aerobic Glycolysis in Multiple Sclerosis

OBJECTIVE

Despite treatments which reduce relapses in multiple sclerosis (MS), many patients continue to experience progressive disability accumulation. MS is associated with metabolic disruptions and cerebral metabolic stress predisposes to tissue injury and possibly impaired remyelination. Additionally, myelin homeostasis is metabolically expensive and reliant on glycolysis. We investigated cerebral metabolic changes in MS and when in the disease course they occurred, and assessed their relationship with microstructural changes.

METHODS

This study used combined fluorodeoxyglucose (FDG) positron emission tomography (PET) and magnetic resonance imaging (MRI) to measure cerebral metabolic rate of glucose and oxygen, thereby quantifying glycolysis. Twelve healthy controls, 20 patients with relapsing MS, and 13 patients with non-relapsing MS were studied. Relapsing patients with MS were treatment naïve and scanned pre- and post-initiation of high efficacy disease modifying therapy.

RESULTS

In normal appearing white matter, we observed increased glucose utilization and reduced oxygen utilization in newly diagnosed MS, consistent with increased glycolysis. Increased glycolysis was greater in patients with a longer disease duration course and higher disability. Among newly diagnosed patients, different treatments had differential impacts on glucose utilization. Last, whereas hypermetabolism within lesions was clearly associated with inflammation, no such relationship was found within normal appearing white matter.

INTERPRETATION

Increased white matter glycolysis is a prominent feature of cerebral metabolism in MS. It begins early in the disease course, increases with disease duration and is independent of microstructural evidence of inflammation in normal appearing white matter. Optimization of the metabolic environment may be an important component of therapies designed to reduce progressive disability. ANN NEUROL 2025;97:766-778.

Metabolic landscape of disseminated cancer dormancy

Cancer dormancy is a phenomenon defined by the entry of cancer cells into a reversible quiescent, nonproliferative state, and represents an essential part of the metastatic cascade responsible for cancer recurrence and mortality. Emerging evidence suggests that metabolic reprogramming plays a pivotal role in enabling entry, maintenance, and exit from dormancy in the face of the different environments of the metastatic cascade. Here, we review the current literature to understand the dynamics of metabolism during dormancy, highlighting its fine-tuning by the host micro- and macroenvironment, and put forward the importance of identifying metabolic vulnerabilities of the dormant state as therapeutic targets to eradicate recurrent disease.

Hesperidin protects the cerebral cortex of albino Wistar rats from the toxic effects of palmitic acid and preserves neurotransmitters-associated enzymes

Palmitic acid (PMA) is abundantly present in substantial quantities within palm oil and manifests neurodegenerative propensities. Conversely, the ingestion of Hesperidin (HSD) is correlated with a reduction in inflammatory markers and mediators. This investigation was meticulously devised to scrutinize the protective potential of HSD against the deleterious repercussions of PMA administration on the cerebral cortex. A cohort comprising forty albino Wistar rats was stratified into four groups, each receiving supplements of HSD and PMA. Remarkably, HSD was observed to fortify the histological framework of the cerebral cortex subsequent to PMA exposure, concurrently diminishing the percentage of apoptotic cells. Furthermore, HSD upregulated the levels of antioxidant markers, preserved the levels of neurotransmitter-associated enzymes, and downregulated the expression of inflammation-regulating genes. In conclusion, PMA exerts toxic effects on the cerebral cortex of albino Wistar rats, leading to increased apoptosis and neuroinflammation, thereby reducing brain cholinergic activity. HSD was found to attenuate the cerebral cortex content of MPO, 5-NTD, ROS, MDA, and NF-κB. Additionally, it elevated the cerebral cortex content of antioxidants and anti-inflammatory markers, thereby shielding it from the deleterious effects of PMA.

Decoding brain aging trajectory: predictive discrepancies, genetic susceptibilities, and emerging therapeutic strategies

The global extension of human lifespan has intensified the focus on aging, yet its underlying mechanisms remain inadequately understood. The article highlights aspects of genetic susceptibility to impaired brain bioenergetics, trends in age-related gene expression related to neuroinflammation and brain senescence, and the impact of stem cell exhaustion and quiescence on accelerated brain aging. We also review the accumulation of senescent cells, mitochondrial dysfunction, and metabolic disturbances as central pathological processes in aging, emphasizing how these factors contribute to inflammation and disrupt cellular competition defining the aging trajectory. Furthermore, we discuss emerging therapeutic strategies and the future potential of integrating advanced technologies to refine aging assessments. The combination of several methods including genetic analysis, neuroimaging techniques, cognitive tests and digital twins, offer a novel approach by simulating and monitoring individual health and aging trajectories, thereby providing more accurate and personalized insights. Conclusively, the accurate estimation of brain aging trajectories is crucial for understanding and managing aging processes, potentially transforming preventive and therapeutic strategies to improve health outcomes in aging populations.

Parallel detection of MRI and 1H MRSI for multi-contrast anatomical and metabolic imaging

PURPOSE

MRI and MRSI provide unique and complementary information on anatomy, structure, function, and metabolism. The default strategy for a combined MRI and MRSI study is a sequential acquisition of both modalities, leading to long scan times. As MRI and MRSI primarily detect water and metabolites, respectively, the small frequency difference between resonances can be exploited with frequency-selective RF pulses to achieve interleaved or parallel detection of MRI and MRSI, without an increase in total scan time.

METHODS

Here, we describe the pulse sequence modifications necessary to allow acquisition of T1 and T2-weighted MRI and B0/B1 mapping in parallel with MRSI. In general, the MRSI module, including water suppression, can be used unmodified. MRI methods are executed in 3D using 3- to 4-ms frequency-selective Gaussian RF pulses with acceleration along the third dimension through repetitive small-angle nutation or multi-spin-echo acquisitions.

RESULTS

Phantom experiments demonstrated artifact-free 3D MRIs. MRSIs in the absence or presence of MRI elements were identical in sensitivity and spectral resolution (line width) and showed consistent water suppression. Parallel MRI-MRSI was applied to the brains of tumor-bearing rats in vivo. High-contrast, high-sensitivity metabolic MRSI data at 8 μL nominal resolution was acquired in parallel with 3D T1-weighted, T2-weighted, and B0/B1-weighted MRIs for an overall scan duration of 30 min.

CONCLUSION

Multi-contrast MRIs and MRSI can be acquired in parallel by utilizing the small frequency difference between water and metabolites. This opens the possibility for shorter overall scans times, or the acquisition of higher-resolution or additional contrast MRIs.

The control costs of human brain dynamics

The human brain is a complex system with high metabolic demands and extensive connectivity that requires control to balance energy consumption and functional efficiency over time. How this control is manifested on a whole-brain scale is largely unexplored, particularly what the associated costs are. Using the network control theory, here, we introduce a novel concept, time-averaged control energy (TCE), to quantify the cost of controlling human brain dynamics at rest, as measured from functional and diffusion MRI. Importantly, TCE spatially correlates with oxygen metabolism measures from the positron emission tomography, providing insight into the bioenergetic footing of resting-state control. Examining the temporal dimension of control costs, we find that brain state transitions along a hierarchical axis from sensory to association areas are more efficient in terms of control costs and more frequent within hierarchical groups than between. This inverse correlation between temporal control costs and state visits suggests a mechanism for maintaining functional diversity while minimizing energy expenditure. By unpacking the temporal dimension of control costs, we contribute to the neuroscientific understanding of how the brain governs its functionality while managing energy expenses.

Spatial metabolic analysis of the regulatory effects of DL-3-n-butylphthalide in a cerebral ischemia-reperfusion mouse model

DL-3-n-butylphthalide (NBP) exhibits promising pharmacological efficacy against ischemia-reperfusion injury, but its protective effects may involve many mechanisms that are yet to be fully understood. This study aimed to profile the metabolic alterations induced by NBP during the process of ischemia-reperfusion using spatial metabolomics. Our study found that NBP could significantly reduce the ischemic area and restore physical function by potentially modulating pathways of the citrate cycle, pyruvate metabolism, autophagy, and unsaturated fatty acid biosynthesis. During the process of ischemia-reperfusion, NBP played a therapeutic role in improving energy supply, decreasing autophagy, and improving unsaturated fatty acid biosynthesis. Subsequent studies confirmed improvements in relevant indices of mitochondrial morphology, autophagy, and ferroptosis after treatment with NBP. These findings shed light on novel mechanisms underlying the efficacy of NBP in treating cerebral ischemia/reperfusion injury associated with ischemic stroke.

Decoding TGR5: A comprehensive review of its impact on cerebral diseases

Currently, unraveling the enigmatic realm of drug targets for cerebral disorders poses a formidable challenge. Takeda G protein-coupled receptor 5 (TGR5), also known as G protein-coupled bile acid receptor 1, is a specific bile acid receptor. Widely distributed across various tissues, TGR5 orchestrates a myriad of biological functions encompassing inflammation, energy metabolism, fatty acid metabolism, immune responses, cellular proliferation, apoptosis, and beyond. Alongside its well-documented implications in liver diseases, obesity, type 2 diabetes, tumors, and cardiovascular diseases, a growing body of evidence accentuates the pivotal role of TGR5 in cerebral diseases. Thus, this comprehensive review aimed to scrutinize the current insights into the pathological mechanisms involving TGR5 in cerebral diseases, while contemplating its potential as a promising therapeutic target for cerebral diseases.

The Role of Mitochondrial Pyruvate Carrier in Neurological Disorders

The mitochondrial pyruvate carrier (MPC) is a specific protein complex located in the inner mitochondrial membrane. Comprising a heterodimer of two homodimeric membrane proteins, mitochondrial pyruvate carrier 1 and mitochondrial pyruvate carrier 2, MPC connects cytoplasmic metabolism to mitochondrial metabolism by transferring pyruvate from the cytoplasm to the mitochondria. The nervous system requires substantial energy to maintain its function, and the mitochondrial energy supply is closely linked to neurological function. Mitochondrial dysfunction can induce or exacerbate intracerebral pathologies. MPC influences mitochondrial function due to its specific role as a pyruvate transporter. However, recent studies on MPC and mitochondrial dysfunction in neurological disorders have yielded controversial results, and the underlying mechanisms remain unclear. In this brief review, we provide an overview of the structure and function of MPC. We further discuss the potential mechanisms and feasibility of targeting MPC in treating Parkinson's disease, Alzheimer's disease, and cerebral ischemia/hypoxia injury. This review aims to offer insights into MPC as a target for clinical treatment.

Intermittent fasting and neurodegenerative diseases: Molecular mechanisms and therapeutic potential

Neurodegenerative disorders are straining public health worldwide. During neurodegenerative disease progression, aberrant neuronal network activity, bioenergetic impairment, adaptive neural plasticity impairment, dysregulation of neuronal Ca2+ homeostasis, oxidative stress, and immune inflammation manifest as characteristic pathological changes in the cellular milieu of the brain. There is no drug for the treatment of neurodegenerative disorders, and therefore, strategies/treatments for the prevention or treatment of neurodegenerative disorders are urgently needed. Intermittent fasting (IF) is characterized as an eating pattern that alternates between periods of fasting and eating, requiring fasting durations that vary depending on the specific protocol implemented. During IF, depletion of liver glycogen stores leads to the production of ketone bodies from fatty acids derived from adipocytes, thereby inducing an altered metabolic state accompanied by cellular and molecular adaptive responses within neural networks in the brain. At the cellular level, adaptive responses can promote the generation of synapses and neurons. At the molecular level, IF triggers the activation of associated transcription factors, thereby eliciting the expression of protective proteins. Consequently, this regulatory process governs central and peripheral metabolism, oxidative stress, inflammation, mitochondrial function, autophagy, and the gut microbiota, all of which contribute to the amelioration of neurodegenerative disorders. Emerging evidence suggests that weight regulation significantly contributes to the neuroprotective effects of IF. By alleviating obesity-related factors such as blood-brain barrier dysfunction, neuroinflammation, and β-amyloid accumulation, IF enhances metabolic flexibility and insulin sensitivity, further supporting its potential in mitigating neurodegenerative disorders. The present review summarizes animal and human studies investigating the role and underlying mechanisms of IF in physiology and pathology, with an emphasis on its therapeutic potential. Furthermore, we provide an overview of the cellular and molecular mechanisms involved in regulating brain energy metabolism through IF, highlighting its potential applications in neurodegenerative disorders. Ultimately, our findings offer novel insights into the preventive and therapeutic applications of IF for neurodegenerative disorders.

Neuron-specific isoform of PGC-1α regulates neuronal metabolism and brain aging

The brain is a high-energy tissue, and although aging is associated with dysfunctional inflammatory and neuron-specific functional pathways, a direct connection to metabolism is not established. Here, we show that isoforms of mitochondrial regulator PGC-1α are driven from distinct brain cell-type specific promotors, repressed with aging, and integral in coordinating metabolism and growth signaling. Transcriptional and proteomic profiles of cortex from male adult, middle age, and advanced age mice reveal an aging metabolic signature linked to PGC-1α. In primary culture, a neuron-exclusive promoter produces the functionally dominant isoform of PGC-1α. Using growth repression as a challenge, we find that PGC-1α is regulated downstream of GSK3β independently across promoters. Broad cellular metabolic consequences of growth inhibition observed in vitro are mirrored in vivo, including activation of PGC-1α directed programs and suppression of aging pathways. These data place PGC-1α centrally in a growth and metabolism network directly relevant to brain aging.

Unravelling Shared Pathways Linking Metabolic Syndrome, Mild Cognitive Impairment, Dementia, and Sarcopenia

Background: Aging is characterized by shared cellular and molecular processes, and aging-related diseases might co-exist in a cluster of comorbidities, particularly in vulnerable individuals whose phenotype meets the criteria for frailty. Whilst the multidimensional definition of frailty is still controversial, there is an increasing understanding of the common pathways linking metabolic syndrome, cognitive decline, and sarcopenia, frequent conditions in frail elderly patients. Methods: We performed a systematic search in the electronic databases Cochrane Library and PubMed and included preclinical studies, cohort and observational studies, and trials. Discussion: Metabolic syndrome markers, such as insulin resistance and the triglyceride/HDL C ratio, correlate with early cognitive impairment. Insulin resistance is a cause of synaptic dysfunction and neurodegeneration. Conversely, fasting and fasting-mimicking agents promote neuronal resilience by enhancing mitochondrial efficiency, autophagy, and neurogenesis. Proteins acting as cellular metabolic sensors, such as SIRT1, play a pivotal role in aging, neuroprotection, and metabolic health. In AD, β-amyloid accumulation and hyperphosphorylated tau in neurofibrillary tangles can cause metabolic reprogramming in brain cells, shifting from oxidative phosphorylation to aerobic glycolysis, similar to the Warburg effect in cancer. The interrelation of metabolic syndrome, sarcopenia, and cognitive decline suggests that targeting these shared metabolic pathways could mitigate all the conditions. Pharmacological interventions, including GLP-1 receptor agonists, metformin, and SIRT 1 inducers, demonstrated neuroprotective effects in animals and some preliminary clinical models. Conclusions: These findings encourage further research on the prevention and treatment of neurodegenerative diseases as well as the drug-repurposing potential of molecules currently approved for diabetes, dyslipidemia, and metabolic syndrome.

Glutamatergic argonaute2 promotes the formation of the neurovascular unit in mice

Proper formation of the complex neurovascular unit (NVU) along with the blood-brain barrier is critical for building and sustaining a healthy, functioning central nervous system. The RNA binding protein argonaute2 (Ago2) mediates microRNA (miRNA)-mediated gene silencing, which is critical for many facets of brain development, including NVU development. Here, we found that Ago2 in glutamatergic neurons was critical for NVU formation in the developing cortices of mice. Glutamatergic neuron-specific loss of Ago2 diminished synaptic formation, neuronal-to-endothelial cell contacts, and morphogenesis of the brain vasculature, ultimately compromising the integrity of the blood-brain barrier. Ago2 facilitated miRNA targeting of phosphatase and tensin homolog (Pten) mRNA, which encodes a phosphatase that modulates reelin-dependent phosphatidylinositol 3-kinase (PI3K)-Akt signaling within the glutamatergic subpopulation. Conditionally deleting Pten in Ago2-deficient neurons restored Akt2 phosphorylation as well as postnatal development and survival. Several mutations in AGO2 impair small RNA silencing and are associated with Lessel-Kreienkamp syndrome, a neurodevelopmental disorder. When expressed in a neuronal cell line, these human AGO2 loss-of-function variants failed to suppress PTEN, resulting in attenuated PI3K-Akt signaling, further indicating that dysregulation of Ago2 function may contribute to both impaired development and neurological disorders. Together, these results identify Ago2 as central to the engagement of neurons with blood vessels in the developing brain.

Dietary Natural Melanin Nanozymes Delay Aging and Ameliorate Neurodegeneration via Improving Gut Microbiota and Redox Homeostasis

Aging is an inevitable multifactor process that causes a decline in organ function and increases the risk of age-related diseases and death. Thus, the development of highly effective and safe therapeutic strategies to delay aging and age-related diseases is urgently required. In this study, we isolated natural melanin nanozymes (NMNs) from the ink sacs of live octopuses. The NMNs exhibited excellent superoxide-dismutase-mimicking and radical scavenging activities. In SAMP8 mice, treatment with NMNs improved their cognition and memory functions while restoring their aging-impaired liver function and lipid metabolism, thereby prolonging their lifespan. Moreover, the NMNs reversed metabolic changes in their aged brains and reconstructed their gut microbiota composition by enhancing microbial community diversity. Our findings indicate that NMNs treatment could be a promising approach for delaying aging and preventing age-associated physiological decline in humans.

Neuroimmunometabolism: how metabolism orchestrates immune response in healthy and diseased brain

Neuroimmunometabolism describes how neuroimmune cells, such as microglia, adapt their intracellular metabolic pathways to alter their immune functions in the central nervous system (CNS). Emerging evidence indicates that neurons also orchestrate the microglia-mediated immune response through neuro-immune cross talk, perhaps through metabolic signaling. However, little is known about how the brain's metabolic microenvironment and microglial intracellular metabolism orchestrate the neuroimmune response in healthy and diseased brains. This review addresses the balance of immunometabolic substrates in healthy and diseased brains, their metabolism by brain-resident microglia, and the potential impact of metabolic dysregulation of these substrates on the neuroimmune response and pathophysiology of psychiatric disorders. This review also suggests metabolic reprogramming of microglia as a preventive strategy for the management of neuroinflammation-related brain disorders, including psychiatric diseases.

Mitochondrial ROS modulate presynaptic plasticity in the drosophila neuromuscular junction

The elevated emission of reactive oxygen species (ROS) from presynaptic mitochondria is well-documented in several inflammatory and neurodegenerative diseases. However, the potential role of mitochondrial ROS in presynaptic function and plasticity remains largely understudied beyond the context of disease. Here, we investigated this potential ROS role in presynaptic function and short-term plasticity by combining optogenetics, whole cell electrophysiological recordings, and live confocal imaging using a well-established protocol for induction and measurement of synaptic potentiation in Drosophila melanogaster neuromuscular junctions (NMJ). Optogenetic induction of ROS emission from presynaptic motorneuron mitochondria expressing mitokiller red (mK) resulted in synaptic potentiation, evidenced by an increase in the frequency of spontaneous mini excitatory junction potentials. Notably, this effect was not observed in flies co-expressing catalase, a cytosolic hydrogen peroxide (H2O2) scavenging enzyme. Moreover, the increase in electrical activity did not coincide with synaptic structural changes. The absence of Wnt1/Wg release from synaptic boutons suggested involvement of alternative or non-canonical signaling pathway(s). However, in existing boutons we observed an increase in the active zone (AZ) marker Brp/Erc1, which serves as docking site for the neurotransmitter vesicle release pool. We propose the involvement of putative redox switches in AZ components as the molecular target of mitochondrial H2O2. These findings establish a novel framework for understanding the signaling role of mROS in presynaptic structural and functional plasticity, providing insights into redox-based mechanisms of neuronal communication.

Effects of Pretreatment With Coenzyme Q10 (CoQ10) and High-Intensity Interval Training (HIIT) on FNDC5, Irisin, and BDNF Levels, and Amyloid-Beta (Aβ) Plaque Formation in the Hippocampus of Aβ-Induced Alzheimer's Disease Rats

AIMS

Physical exercise has been shown to protect against cognitive decline in Alzheimer's disease (AD), likely through the upregulation of brain-derived neurotrophic factor (BDNF). Recent studies have reported that exercise activates the FNDC5/irisin pathway in the hippocampus of mice, triggering a neuroprotective gene program that includes BDNF. This study aimed to investigate the effects of 8 weeks of pretreatment with coenzyme Q10 (CoQ10) and high-intensity interval training (HIIT), both individually and in combination, on FNDC5, irisin, BDNF, and amyloid-beta (Aβ) plaque formation in the hippocampus of Aβ-related AD rats.

METHODS

In this study, 72 male Wistar rats were randomly assigned to one of the following groups: control, sham, HIIT (low intensity: 3 min running at 50%-60% VO2max; high intensity: 4 min running at 85%-90% VO2max), Q10 (50 mg/kg, orally administered), Q10 + HIIT, AD, AD + HIIT, AD + Q10, and AD + Q10 + HIIT.

RESULTS

Aβ injection resulted in a trend toward decreased levels of FNDC5, irisin, and BDNF, alongside increased Aβ plaque formation in the hippocampus of Aβ-induced AD rats. However, pretreatment with CoQ10, HIIT, or their combination significantly restored hippocampal levels of FNDC5, irisin, and BDNF, while also inhibiting Aβ plaque accumulation in these rats.

CONCLUSION

Pretreatment with CoQ10 and HIIT improved the Aβ-induced reduction in BDNF levels probably through the FNDC5/irisin pathway and preventing Aβ plaque formation.

Lessons from the physiological role of guanosine in neurodegeneration and cancer: Toward a multimodal mechanism of action?

Neurodegenerative diseases and brain tumours represent important health challenges due to their severe nature and debilitating consequences that require substantial medical care. Interestingly, these conditions share common physiological characteristics, namely increased glutamate, and adenosine transmission, which are often associated with cellular dysregulation and damage. Guanosine, an endogenous nucleoside, is safe and exerts neuroprotective effects in preclinical models of excitotoxicity, along with cytotoxic effects on tumour cells. However, the lack of well-defined mechanisms of action for guanosine hinders a comprehensive understanding of its physiological effects. In fact, the absence of specific receptors for guanosine impedes the development of structure-activity research programs to develop guanosine derivatives for therapeutic purposes. Alternatively, given its apparent interaction with the adenosinergic system, it is plausible that guanosine exerts its neuroprotective and anti-tumorigenic effects by modulating adenosine transmission through undisclosed mechanisms involving adenosine receptors, transporters, and purinergic metabolism. Here, several potential molecular mechanisms behind the protective actions of guanosine will be discussed. First, we explore its potential interaction with adenosine receptors (A1R and A2AR), including the A1R-A2AR heteromer. In addition, we consider the impact of guanosine on extracellular adenosine levels and the role of guanine-based purine-converting enzymes. Collectively, the diverse cellular functions of guanosine as neuroprotective and antiproliferative agent suggest a multimodal and complementary mechanism of action.

Neurons Specialize in Presynaptic Autophagy: A Perspective to Ameliorate Neurodegeneration

The efficient and prolonged neurotransmission is reliant on the coordinated action of numerous synaptic proteins in the presynaptic compartment that remodels synaptic vesicles for neurotransmitter packaging and facilitates their exocytosis. Once a cycle of neurotransmission is completed, membranes and associated proteins are endocytosed into the cytoplasm for recycling or degradation. Both exocytosis and endocytosis are closely regulated in a timely and spatially constrained manner. Recent research demonstrated the impact of dysfunctional synaptic vesicle retrieval in causing retrograde degeneration of midbrain neurons and has highlighted the importance of such endocytic proteins, including auxilin, synaptojanin1 (SJ1), and endophilin A (EndoA) in neurodegenerative diseases. Additionally, the role of other associated proteins, including leucine-rich repeat kinase 2 (LRRK2), adaptor proteins, and retromer proteins, is being investigated for their roles in regulating synaptic vesicle recycling. Research suggests that the degradation of defective vesicles via presynaptic autophagy, followed by their recycling, not only revitalizes them in the active zone but also contributes to strengthening synaptic plasticity. The presynaptic autophagy rejuvenating terminals and maintaining neuroplasticity is unique in autophagosome formation. It involves several synaptic proteins to support autophagosome construction in tiny compartments and their retrograde trafficking toward the cell bodies. Despite having a comprehensive understanding of ATG proteins in autophagy, we still lack a framework to explain how autophagy is triggered and potentiated in compact presynaptic compartments. Here, we reviewed synaptic proteins' involvement in forming presynaptic autophagosomes and in retrograde trafficking of terminal cargos. The review also discusses the status of endocytic proteins and endocytosis-regulating proteins in neurodegenerative diseases and strategies to combat neurodegeneration.

Brain network and energy imbalance in Parkinson's disease: linking ATP reduction and α-synuclein pathology

Parkinson's disease (PD) involves the disruption of brain energy homeostasis. This encompasses broad-impact factors such as mitochondrial dysfunction, impaired glycolysis, and other metabolic disturbances, like disruptions in the pentose phosphate pathway and purine metabolism. Cortical hubs, which are highly connected regions essential for coordinating multiple brain functions, require significant energy due to their dense synaptic activity and long-range connections. Deficits in ATP production in PD can severely impair these hubs. The energy imbalance also affects subcortical regions, including the massive axonal arbors in the striatum of substantia nigra pars compacta neurons, due to their high metabolic demand. This ATP decline may result in α-synuclein accumulation, autophagy-lysosomal system impairment, neuronal network breakdown and accelerated neurodegeneration. We propose an "ATP Supply-Demand Mismatch Model" to help explain the pathogenesis of PD. This model emphasizes how ATP deficits drive pathological protein aggregation, impaired autophagy, and the degeneration of key brain networks, contributing to both motor and non-motor symptoms.

Concussion and the Autonomic, Immune, and Endocrine Systems: An Introduction to the Field and a Treatment Framework for Persisting Symptoms

A significant proportion of patients who sustain a concussion/mild traumatic brain injury endorse persisting, lingering symptoms. The symptoms associated with concussion are nonspecific, and many other medical conditions present with similar symptoms. Medical conditions that overlap symptomatically with concussion include anxiety, depression, insomnia, chronic pain, chronic fatigue, fibromyalgia, and cervical strain injuries. One of the factors that may account for these similarities is that these conditions all present with disturbances in the optimal functioning of the autonomic nervous system and its intricate interactions with the endocrine system and immune system-the three primary regulatory systems in the body. When clinicians are working with patients presenting with persisting symptoms after concussion, evidence-based treatment options drawn from the literature are limited. We present a framework for the assessment and treatment of persisting symptoms following concussion based on the available evidence (treatment trials), neuroanatomical principles (research into the physiology of concussion), and clinical judgment. We review the research supporting the premise that behavioral interventions designed to stabilize and optimize regulatory systems in the body following injury have the potential to reduce symptoms and improve functioning in patients. Foundational concussion rehabilitation strategies in the areas of sleep stabilization, fatigue management, physical exercise, nutrition, relaxation protocols, and behavioral activation are outlined along with practical strategies for implementing intervention modules with patients.

The role of vitamin K2 in cognitive impairment: linking vascular health to brain health

Cognitive impairment, marked by a decline in essential mental aspects such as attention, memory, and problem-solving, is significantly correlated with advancing age. This condition presents a major challenge for the elderly, adversely affecting quality of life, diminishing independence, and imposing substantial burdens on healthcare systems. Recent research indicates that vitamin K2 may be vital for preserving brain health and cognitive function. Traditionally recognized primarily for its role in blood coagulation, vitamin K has emerged in recent years as a nutrient with diverse biological effects essential for healthy aging. A growing body of evidence from both observational and interventional studies underscores the pivotal role of vitamin K2 in mitigating arterial calcification. This mechanism may link vascular health to cognitive function, suggesting that vitamin K2 could play a critical role in the prevention of cognitive impairment in aging populations.

Atlas of plasma metabolic markers linked to human brain morphology

Background

Metabolic processes form the basis of the development, functioning and maintenance of the brain. Despite accumulating evidence of the vital role of metabolism in brain health, no study to date has comprehensively investigated the link between circulating markers of metabolic activity and in vivo brain morphology in the general population.

Methods

We performed uni- and multivariate regression on metabolomics and MRI data from 24,940 UK Biobank participants, to estimate the individual and combined associations of 249 circulating metabolic markers with 91 measures of global and regional cortical thickness, surface area and subcortical volume. We investigated similarity of the identified spatial patterns with brain maps of neurotransmitters, and used Mendelian randomization to uncover causal relationships between metabolites and the brain.

Results

Intracranial volume and total surface area were highly significantly associated with circulating lipoproteins and glycoprotein acetyls, with correlations up to .15. There were strong regional associations of individual markers with mixed effect directions, with distinct patterns involving frontal and temporal cortical thickness, brainstem and ventricular volume. Mendelian randomization provided evidence of bidirectional causal effects, with the majority of markers affecting frontal and temporal regions.

Discussion

The results indicate strong bidirectional causal relationships between circulating metabolic markers and distinct patterns of global and regional brain morphology. The generated atlas of associations provides a better understanding of the role of metabolic pathways in structural brain development and maintenance, in both health and disease.

Cerebral Metabolic Rate of Oxygen and Accelerometry-Based Fatigability in Community-Dwelling Older Adults

Alterations in energy metabolism may drive fatigue in older age, but prior research primarily focused on skeletal muscle energetics without assessing other systems, and utilized self-reported measures of fatigue. We tested the association between energy metabolism in the brain and an objective measure of fatigability in the Study of Muscle, Mobility and Aging (N=119, age 76.8±4.0 years, 59.7% women). Total brain cerebral metabolic rate of oxygen (CMRO 2 ) was measured using arterial spin labeling and T 2 -relaxation under spin tagging MRI protocols. Accelerometry-based fatigability status during a fast-paced 400m walk was determined using the Pittsburgh Fatigability Index (PPFI, higher=worse). Confounders included skeletal muscle energetics, measured in vivo using spectroscopy and ex vivo using respirometry, cardiorespiratory fitness (VO 2 peak), weight, medication count, and multimorbidity. Multivariable logistic regression models were used to estimate the association (odds ratio (OR)) of CMRO 2 with PPFI>0 compared to the referent group PPFI=0. Models were first adjusted for age and sex, and further adjusted for confounders. In this sample, 41.2% had PPFI>0 (median 3.3% [0.4-8.0%]). CMRO 2 was positively associated with PPFI>0 (age and sex adjusted OR=1.61, 95% CI: 1.06, 2.45, p=0.03); adjustment for confounders attenuated the association. The positive association of brain energetics and fatigability warrants further study in older adults.

Reversal of neuronal tau pathology via adiponectin receptor activation

Changes in brain mitochondrial metabolism are coincident with functional decline; however, direct links between the two have not been established. Here, we show that mitochondrial targeting via the adiponectin receptor activator AdipoRon (AR) clears neurofibrillary tangles (NFTs) and rescues neuronal tauopathy-associated defects. AR reduced levels of phospho-tau and lowered NFT burden by a mechanism involving the energy-sensing kinase AMPK and the growth-sensing kinase GSK3b. The transcriptional response to AR included broad metabolic and functional pathways. Induction of lysosomal pathways involved activation of LC3 and p62, and restoration of neuronal outgrowth required the stress-responsive kinase JNK. Negative consequences of NFTs on mitochondrial activity, ATP production, and lipid stores were corrected. Defects in electrophysiological measures (e.g., resting potential, resistance, spiking profiles) were also corrected. These findings reveal a network linking mitochondrial function, cellular maintenance processes, and electrical aspects of neuronal function that can be targeted via adiponectin receptor activation.

Mitostasis in age-associated neurodegeneration

Mitochondria are essential organelles that play crucial roles in various metabolic and signalling pathways. Proper neuronal function is highly dependent on the health of these organelles. Of note, the intricate structure of neurons poses a critical challenge for the transport and distribution of mitochondria to specific energy-intensive domains, such as synapses and dendritic appendages. When faced with chronic metabolic challenges and bioenergetic deficits, neurons undergo degeneration. Unsurprisingly, disruption of mitostasis, the process of maintaining cellular mitochondrial content and function within physiological limits, has been implicated in the pathogenesis of several age-associated neurodegenerative disorders. Indeed, compromised integrity and metabolic activity of mitochondria is a principal hallmark of neurodegeneration. In this review, we survey recent findings elucidating the role of impaired mitochondrial homeostasis and metabolism in the onset and progression of age-related neurodegenerative disorders. We also discuss the importance of neuronal mitostasis, with an emphasis on the major mitochondrial homeostatic and metabolic pathways that contribute to the proper functioning of neurons. A comprehensive delineation of these pathways is crucial for the development of early diagnostic and intervention approaches against neurodegeneration.

High-Resolution Respirometry Methodology for Bioenergetic and Metabolic Studies in Intact Brain Slices

The brain is critically dependent on energetic substrates as it consumes circa 20% of glucose and oxygen under normal physiological conditions. Although different cell types and at different locations might experience particular specificities in the utilization of these substrates, overall, mitochondrial oxidative phosphorylation supports the most efficient energy transduction process, enabling the complete oxidation of glucose to CO2 coupled to ATP synthesis in the presence of O2. Impairment of mitochondrial bioenergetics has been identified as an early event in many brain diseases and aging. Thus, novel methodologies to readily assess mitochondrial respiration in brain tissue, while preserving cellular and mitochondrial architecture and overcoming the serious drawbacks of studies using isolated mitochondrial preparations, are needed. Here we describe a methodology for studying functional parameters defining tissue metabolic respiration in brain hippocampal slices. The methodology can be used for physiological, pharmacological, and toxicological studies.

Simultaneous noninvasive quantification of redox and downstream glycolytic fluxes reveals compartmentalized brain metabolism

Brain metabolism across anatomic regions and cellular compartments plays an integral role in many aspects of neuronal function. Changes in key metabolic pathway fluxes, including oxidative and reductive energy metabolism, have been implicated in a wide range of brain diseases. Given the complex nature of the brain and the need for understanding compartmentalized metabolism noninvasively in vivo, new tools are required. Herein, using hyperpolarized (HP) magnetic resonance imaging coupled with in vivo isotope tracing, we develop a platform to simultaneously probe redox and energy metabolism in the murine brain. By combining HP dehydroascorbate and pyruvate, we are able to visualize increased lactate production in the white matter and increased redox capacity in the deep gray matter. Leveraging positional labeling, we show differences in compartmentalized tricarboxylic acid cycle entry versus downstream flux to glutamate. These findings lay the foundation for clinical translation of the proposed approach to probe brain metabolism.

Energy restriction inhibits β-catenin ubiquitination to improve ischemic stroke injury via USP18/SKP2 axis

Ischemic stroke (IS) remains a global health issue because of its great disability and mortality. Energy restriction (ER) has been justified to perform an inhibitory role in cerebral injury caused by IS. This research was purposed to inquire the potential molecular mechanism of ER in IS. To verify the function of ER in the animal and cell models of IS, rats were subjected to intermittent fasting (IF) and middle cerebral artery occlusion/reperfusion (MCAO/R) surgery and HAPI cells were treated with oxygen-glucose deprivation and reoxygenation (OGD/R) and 2-deoxyglucose (2-DG). It was disclosed that IF mitigated brain damage and inflammation in MCAO/R rats. Likewise, ER inhibited OGD/R-evoked microglial activation and inflammatory response. Of note, ubiquitin specific protease 18 (USP18) was uncovered to be the most significantly upregulated in MCAO/R rats receiving IF compared to free-feeding MCAO/R rats. Real-time quantitative polymerase chain reaction (RT-qPCR) and western blot verified that ER led to the promotion of USP18 expression. Moreover, downregulation of USP18 neutralized the meliorative effects of ER on OGD/R-treated HAPI cells. Functionally, USP18 restrained β-catenin ubiquitination to enhance its expression. In addition, our results manifested that S-phase kinase associated protein 2 (SKP2) contributed to degradation of β-catenin and USP18 abolished the role of SKP2 in β-catenin ubiquitination. Knockout of USP18 eliminated the protective effects of IF on MCAO/R rats, while SKP2 exacerbated brain damage and inflammation by decreasing β-catenin expression after IF. In summary, we validated that ER-induced USP18 exerts a suppressive function in IS damage through SKP2-mediated β-catenin ubiquitination.

Characterization of a natural model of adult mice with different rate of aging

Aging is a heterogeneous process, so individuals of the same age may be aging at a different rate. A natural model of premature aging in mice have been proposed based on the poor response to the T-maze. Those that take longer to cross the intersection are known as Prematurely Aging Mice (PAM), while those that show an exceptional response are known as Exceptional non-PAM (E-NPAM), being the rest non-PAM (NPAM). Although many aspects of PAM and E-NPAM have been described, some aspects of their brain aging have not been studied. Similarly, it is known that PAM, NPAM and E-NPAM show a different rate of aging and longevity, but the differences between these three groups in behavior, immune function and oxidative-inflammatory state are unknown. The present study aims to deepen the study of brain aging in PAM and E-NPAM, and to study the differences in behavior, immunity, and oxidative-inflammatory state of peritoneal leukocytes between PAM, NPAM and E-NPAM. Results show deteriorated brains in PAM. Moreover, NPAM show an oxidative state similar to E-NPAM, an anxiety similar to PAM, and an intermediate immunity and lifespan between PAM and E-NPAM. In conclusion, immune function seems to be more associated with the longevity achieved.

Non-canonical pathways associated to Amyloid beta and tau protein dyshomeostasis in Alzheimer's disease: A narrative review

Alzheimer's Disease (AD) is the most common form of dementia among elderly people. This disease imposes a significant burden on the healthcare system, society, and economy due to the increasing global aging population. Current trials with drugs or bioactive compounds aimed at reducing cerebral Amyloid beta (Aβ) plaques and tau protein neurofibrillary tangles, which are the two main hallmarks of this devastating neurodegenerative disease, have not provided significant results in terms of their neuropathological outcomes nor met the expected clinical end-points. Ageing, genetic and environmental risk factors, along with different clinical symptoms suggest that AD is a complex and heterogeneous disorder with multiple interconnected pathological pathways rather than a single disease entity. In the present review, we highlight and discuss various non-canonical, Aβ-independent mechanisms, like gliosis, unhealthy dietary intake, lipid and sugar signaling, and cerebrovascular damage that contribute to the onset and development of AD. We emphasize that challenging the traditional "amyloid cascade hypothesis" may improve our understanding of this age-related complex syndrome and help fight the progressive cognitive decline in AD.

Mitochondrial plasticity: An emergent concept in neuronal plasticity and memory

Mitochondria are classically viewed as 'on demand' energy suppliers to neurons in support of their activity. In order to adapt to a wide range of demands, mitochondria need to be highly dynamic and capable of adjusting their metabolic activity, shape, and localization. Although these plastic properties give them a central support role in basal neuronal physiology, recent lines of evidence point toward a role for mitochondria in the regulation of high-order cognitive functions such as memory formation. In this review, we discuss the interplay between mitochondrial function and neural plasticity in sustaining memory formation at the molecular and cellular levels. First, we explore the global significance of mitochondria in memory formation. Then, we will detail the memory-relevant cellular and molecular mechanisms of mitochondrial plasticity. Finally, we focus on those mitochondrial functions, including but not limited to ATP production, that give mitochondria their pivotal role in memory formation. Altogether, this review highlights the central role of mitochondrial structural and functional plasticity in supporting and regulating neuronal plasticity and memory.

Modulation of brain energy metabolism in hepatic encephalopathy: impact of glucose metabolic dysfunction

Cerebral function is linked to a high level of metabolic activity and relies on glucose as its primary energy source. Glucose aids in the maintenance of physiological brain activities; as a result, a disruption in metabolism has a significant impact on brain function, launching a chain of events that leads to neuronal death. This metabolic insufficiency has been observed in a variety of brain diseases and neuroexcitotoxicity disorders, including hepatic encephalopathy. It is a significant neurological complication that develops in people with liver disease, ranging from asymptomatic abnormalities to coma. Hyperammonemia is the main neurotoxic villain in the development of hepatic encephalopathy and induces a wide range of complications in the brain. The neurotoxic effects of ammonia on brain function are thought to be mediated by impaired glucose metabolism. Accordingly, in this review, we provide an understanding of deranged brain energy metabolism, emphasizing the role of glucose metabolic dysfunction in the pathogenesis of hepatic encephalopathy. We also highlighted the differential metabolic profiles of brain cells and the status of metabolic cooperation between them. The major metabolic pathways that have been explored are glycolysis, glycogen metabolism, lactate metabolism, the pentose phosphate pathway, and the Krebs cycle. Furthermore, the lack of efficacy in current hepatic encephalopathy treatment methods highlights the need to investigate potential therapeutic targets for hepatic encephalopathy, with regulating deficient bioenergetics being a viable alternative in this case. This review also demonstrates the importance of the development of glucose metabolism-focused disease diagnostics and treatments, which are now being pursued for many ailments.

The Impact of HIV on Early Brain Aging-A Pathophysiological (Re)View

Background/Objectives: This review aims to provide a comprehensive understanding of how HIV alters normal aging trajectories in the brain, presenting the HIV-related molecular mechanisms and pathophysiological pathways involved in brain aging. The review explores the roles of inflammation, oxidative stress, and viral persistence in the brain, highlighting how these factors contribute to neuronal damage and cognitive impairment and accelerate normal brain aging. Additionally, it also addresses the impact of antiretroviral therapy on brain aging and the biological markers associated with its occurrence. Methods: We extensively searched PubMed for English-language articles published from 2000 to 2024. The following keywords were used in the search: "HIV", "brain", "brain aging", "neuroinflammation", "HAART", and "HAND". This strategy yielded 250 articles for inclusion in our review. Results: A combination of blood-brain barrier dysfunction, with the direct effects of HIV on the central nervous system, chronic neuroinflammation, telomere shortening, neurogenesis impairments, and neurotoxicity associated with antiretroviral treatment (ART), alters and amplifies the mechanisms of normal brain aging. Conclusions: Current evidence suggests that HIV infection accelerates neurodegenerative processes of normal brain aging, leading to cognitive decline and structural brain changes at an earlier age than typically observed in the general population.

Fueling neurodegeneration: metabolic insights into microglia functions

Microglia, the resident immune cells of the central nervous system, emerge in the brain during early embryonic development and persist throughout life. They play essential roles in brain homeostasis, and their dysfunction contributes to neuroinflammation and the progression of neurodegenerative diseases. Recent studies have uncovered an intricate relationship between microglia functions and metabolic processes, offering fresh perspectives on disease mechanisms and possible treatments. Despite these advancements, there are still significant gaps in our understanding of how metabolic dysregulation affects microglial phenotypes in these disorders. This review aims to address these gaps, laying the groundwork for future research on the topic. We specifically examine how metabolic shifts in microglia, such as the transition from oxidative phosphorylation and mitochondrial metabolism to heightened glycolysis during proinflammatory states, impact the disease progression in Alzheimer's disease, multiple sclerosis, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease. Additionally, we explore the role of iron, fatty and amino acid metabolism in microglial homeostasis and repair. Identifying both distinct and shared metabolic adaptations in microglia across neurodegenerative diseases could reveal common therapeutic targets and provide a deeper understanding of disease-specific mechanisms underlying multiple CNS disorders.

U-shaped relationship between triglyceride glucose-body mass index and suicide attempts in Chinese patients with untreated first-episode major depressive disorder

OBJECTIVE

An alternative metric for evaluating insulin resistance (IR) is the triglyceride glucose-body mass index (TyG-BMI). However, it is yet unclear how TyG-BMI and suicide attempts (SA) are related. The objective of this research was to explore the correlation between the TyG-BMI index and SA in individuals with untreated first-episode (UFE) major depressive disorder (MDD) in Shanxi Province.

METHODS

This cross-sectional study was conducted from September 2016 to December 2018 in the psychiatric outpatient clinic of Taiyuan General Hospital and included 1718 patients with UFE MDD, with a mean age of 34.9 ± 12.4 years. The relationship between TyG-BMI and SA was assessed using logistic regression modeling. We investigated threshold effects using a two-piecewise linear regression model.

RESULTS

Taking into consideration the potential influence of confounding variables, a comprehensive multivariate logistic regression analysis was conducted, which demonstrated the absence of a statistically significant association between the TyG-BMI index and the occurrence of SA, as evidenced by P-values that were all greater than 0.05. On the other hand, the visual analysis of the smoothed plots revealed a U-shaped relationship between the TyG-BMI index and the incidence of SA, with a notable inflection occurring at a TyG-BMI value of around 210. It was observed that the effect sizes flanking the inflection point, accompanied by their 95% confidence intervals, were 0.985 (95% CI: 0.972 to 0.999, P = 0.031) and 1.012 (95% CI: 1.003 to 1.047, P = 0.005), respectively.

CONCLUSIONS

In UFE MDD patients, a U-shaped link was observed between TyG-BMI and SA, with the minimal SA incidence noted at a TyG-BMI level of 210, signifying that an augmented risk for SA might be connected to both diminished and augmented TyG-BMI levels.

Multi-scale hierarchical brain regions detect individual and interspecies variations of structural connectivity in macaque monkeys and humans

Macaques are representative animal models in translational research. However, the distinct shape and location of the brain regions between macaques and humans prevents us from comparing the brain structure directly. Here, we calculated structural connectivity (SC) with multi-scale hierarchical regions of interest (ROIs) to parcel out human and macaque brain into 8 (level 1 ROIs), 28 (level 2 ROIs), or 46 (level 3 ROIs) regions, which consist of anatomically and functionally defined level 4 ROIs (around 100 parcellation of the brain). The SC with the level 1 ROIs showed lower individual and interspecies variation in macaques and humans. SC with level 2 and 3 ROIs shows that the several regions in frontal, temporal and parietal lobe show distinct connectivity between macaques and humans. Lateral frontal cortex, motor cortex and auditory cortex were shown to be important areas for interspecies differences. These results provide insights to use macaques as animal models for translational study.

Mitochondrial complex I inhibition enhances astrocyte responsiveness to pro-inflammatory stimuli

Inhibition of the mitochondrial oxidative phosphorylation (OXPHOS) system can lead to metabolic disorders and neurodegenerative diseases. In primary mitochondrial disorders, reactive astrocytes often accompany neuronal degeneration and may contribute to neurotoxic inflammatory cascades that elicit brain lesions. The influence of mitochondria to astrocyte reactivity as well as the underlying molecular mechanisms remain elusive. Here we report that mitochondrial Complex I dysfunction promotes neural progenitor cell differentiation into astrocytes that are more responsive to neuroinflammatory stimuli. We show that the SWItch/Sucrose Non-Fermentable (SWI/SNF/BAF) chromatin remodeling complex takes part in the epigenetic regulation of astrocyte responsiveness, since its pharmacological inhibition abrogates the expression of inflammatory genes. Furthermore, we demonstrate that Complex I deficient human iPSC-derived astrocytes negatively influence neuronal physiology upon cytokine stimulation. Together, our data describe the SWI/SNF/BAF complex as a sensor of altered mitochondrial OXPHOS and a downstream epigenetic regulator of astrocyte-mediated neuroinflammation.

The Role of Neuropeptide Y in the Pathogenesis of Alzheimer's Disease: Diagnostic Significance and Neuroprotective Functions

Background. Alzheimer's disease (AD) is one of the most common neurodegenerative diseases. It has been suggested that the factors that cause pathologic changes and lead to the development of AD may also include changes in certain neuropeptides. The implication of the neuropeptide (NPY) in the pathogenesis of AD and its potential therapeutic role is possible due to the following properties: involvement in adult neurogenesis, regulatory effects on the immune system, the inhibition of potential-dependent Ca2+ channels, and the reduction in glutamate excitotoxicity. The aim of our review was to summarize recent data on the role of NPY in AD development and to explore its potential as a biomarker and a possible therapeutic target. Materials and methods. We performed a systematic review of studies, for which we search using the keywords "Alzheimer's disease and neuropeptide Y", "Alzheimer's disease and NPY", "AD and NPY", "Neuropeptide Y and Neurodegenerative disease". Nineteen articles were included in the review. Results. The NPY levels in cerebrospinal fluid and plasma have been found to be reduced or unchanged in AD patients; however, these findings need to be confirmed in more recent studies. Data obtained in transgenic animal models support the role of NPY in AD pathogenesis. The neuroprotective effects of NPY have been demonstrated in vitro and in vivo in AD models. Conclusion. The findings may open new possibilities for using NPY as a diagnostic marker to detect AD at earlier stages of the disease or as a potential therapeutic target due to its neuroprotective properties.

High caloric intake improves neuronal metabolism and functional hyperemia in a rat model of early AD pathology

Introduction: While obesity has been linked to both increased and decreased rate of cognitive decline in Alzheimer's Disease (AD) patients, there is no consensus on the interaction between obesity and AD. Methods: The TgF344-AD rat model was used to investigate the effects of high carbohydrate, high fat (HCHF) diet on brain glucose metabolism and hemodynamics in the presence or absence of AD transgenes, in presymptomatic (6-month-old) vs. symptomatic (12-month-old) stages of AD progression using non-invasive neuroimaging. Results: In presymptomatic AD, HCHF exerted detrimental effects, attenuating both hippocampal glucose uptake and resting perfusion in both non-transgenic and TgAD cohorts, when compared to CHOW-fed cohorts. In contrast, HCHF consumption was beneficial in established AD, resolving the AD-progression associated attenuation in hippocampal glucose uptake and functional hyperemia. Discussion: Whereas HCHF was harmful to the presymptomatic AD brain, it ameliorated deficits in hippocampal metabolism and neurovascular coupling in symptomatic TgAD rats.

Functional correlates of executive dysfunction in primary progressive aphasia: a systematic review

Introduction

Recent research has recognized executive dysfunction as another component affected in Primary Progressive Aphasia (PPA). This systematic review aimed to examine what information distinctive neurophysiological markers can provide in the evaluation of executive function (EF) deficits in PPA, and to what effect executive function deficits can be assessed through the characteristics of functional markers.

Methods

We conducted a systematic literature search following the PRISMA guidelines across studies that employed neuropsychological assessments and neurophysiological imaging techniques (EEG, MEG; PET, SPECT, fMRI, fNIRS) to investigate executive dysfunction correlates in PPA.

Results

Findings from nine articles including a total number of 111 individuals with PPA met our inclusion criteria and were synthesized. Although research on the neural correlates of EF deficits is scarce, MEG studies revealed widespread oscillatory slowing, with increased delta and decreased alpha power, where alterations in alpha, theta, and beta activities were significant predictors of executive function deficits. PET findings demonstrated significant correlations between executive dysfunction and hypometabolism in frontal brain regions. fMRI results indicated elevated homotopic connectivity in PPA patients, with a broader and more anterior distribution of abnormal hippocampal connections of which were associated with reduced executive performance.

Conclusion

Our study provides indirect support for the assumption regarding the significance of the frontal regions and inferior frontal junction in executive control and demonstrates that neurophysiological tools can be a useful aid to further investigate clinical-neurophysiological correlations in PPA.