Search Results (333)

Background: Human dental pulp stem cells (hDPSCs) are a promising source of multipotent mesenchymal stem cells (MSCs) for regenerative neurology because of their inherent neurogenic potential. However, robust and reproducible protocols for driving their terminal neuronal maturation in a fully defined, xeno-free environment are lacking. Methods: hDPSCs were isolated from a donor tooth and characterized for mesenchymal (CD105, CD90, CD73, CD13) and stemness-associated markers (SOX2, Oct3/4 and Nanog). Cells were differentiated in a novel, fully chemically defined medium 1% ITS medium (ITS: Insulin, Transferrin, Selenium) supplemented with glial cell line-derived neurotrophic factor (GDNF) or brain-derived neurotrophic factor (BDNF). Neuronal commitment and partial maturation were assessed via immunofluorescence, Western blot, and RT-PCR for markers such as NeuN (Neuronal nuclei) and NF-M (Neurofilament medium chain), and functionally by whole-cell patch-clamp electrophysiology. Results: Although undifferentiated hDPSCs expressed neural progenitor markers (βIII-tubulin and Nestin), only GDNF treatment in a chemically defined medium significantly upregulated mature neuronal markers (NeuN and NF-M) and downregulated mesenchymal markers. Importantly, GDNF-treated cells exhibited key functional changes, including hyperpolarized resting membrane potentials, increased membrane capacitance, and elevated input resistance, which are electrophysiological hallmarks of neural precursor or early neuronal maturation, compared to control cells cultured in medium containing fetal bovine serum (FBS). Although action potentials were not elicited, this represents a significant advancement toward achieving a functional neuronal state. Conclusion: This study demonstrates that a fully chemically defined medium enables GDNF to drive hDPSCs beyond the neural progenitor state towards a partially mature neuronal phenotype. This defined medium protocol eliminates serum variability, enhances reproducibility, and provides a critical step towards standardizing hDPSC-derived neuronal cells for disease modeling and cell-based therapy. Full article

Background: Postmenopausal women are at high risk of Alzheimer’s disease (AD) incidence and progression. Irisin, an exercise-induced myokine, has neuroprotective and antiaging effects against AD, especially in menopausal women suffering from insulin resistance (IR). For the first time, the novel role of irisin induced by melatonin (MTN) or/and physical exercise (PHE) was investigated in the current ovariectomized (OVX)/AD rat model by modulating brain neuroinflammation and IR-related markers. Methods: Fifty female Wistar rats were divided into five groups, with one representing a sham group. AD was induced in the other four bilateral OVX rat groups by daily intraperitoneal injection of D-galactose/AlCl₃ (60 and 10 mg/kg, respectively) for 42 days. Group III–V: Animals were exposed to MTN (10 mg/kg/day; i.p.), PHE, and a combination of these, respectively, in the final 14 days of the experiment. Results: The OVX/AD rats showed significant deterioration in learning, memory, neurochemical, and histopathological examinations, while the MTN or/and PHE treatments significantly increased serum and brain irisin, improving memory in a Y-maze assessment. Thus, hippocampal histopathological alterations and IR-related markers decreased. In addition, suppressed hippocampal amyloid-beta protein expression and neuroinflammatory content of tumor necrosis factor-alpha (TNF-α), p38 mitogen-activated protein kinase (p38 MAPK), and NOD-like receptor protein-3 (NLRP3) were associated with an increase in peroxisome proliferator-activated receptor-gamma (PPAR-γ) protein expression and insulin-like growth factor-1 content in hippocampal tissues, collectively suppressing glial fibrillary acidic protein (GFAP) content, leading to an increase in brain-derived neurotrophic factor expression. Conclusions: Irisin induction may serve as a novel avenue in AD/menopause treatment and prevention via modulating the TNF-α/p38 MAPK/PPAR-γ/NLRP3/GFAP pathway. Full article

The brain has a higher energy demand per unit weight than any other organ in the body; however, links between metabolism, diet and neurological function have historically been underexplored. This partly stems from early assumptions that brain metabolism is primarily dependent on glucose and ketone bodies, whereas more recent evidence indicates broader metabolic flexibility and complex cell-type specialisation. In the past few decades, brain metabolism has become increasingly recognised as relevant to neurological and mental health, and many neurodegenerative disorders are accompanied by changes in brain energy utilisation. In parallel, epidemiological studies associate hypercaloric dietary patterns and metabolic disorders—particularly type-2 diabetes mellitus—with increased risk of later cognitive decline and sporadic Alzheimer’s disease, although causal pathways remain difficult to establish in humans. In this narrative review, we summarise selected findings linking “unhealthy” diets to synaptic function, focusing on synaptic plasticity, neuroinflammation and adult hippocampal neurogenesis, and we distinguish between evidence from human observational studies and mechanistic insights from animal and cellular models. We also discuss candidate mechanisms—including insulin resistance-linked signalling changes, lipid-driven inflammatory amplification, oxidative stress, and altered lipid handling—that may contribute to synaptic vulnerability. Finally, we outline translational considerations and key knowledge gaps (including physiological exposure levels and heterogeneity of experimental paradigms) that currently limit inference from preclinical models to clinical intervention. Full article

Parkinson’s disease (PD) is traditionally defined by dopaminergic loss in the substantia nigra, yet its heterogeneous phenotypes and prodromal trajectories challenge a linear, dopamine-centered model. The α-synuclein origin and connectome (SOC) model proposes two major trajectories: a brain-first pathway, with the pathology initiating in limbic and brainstem structures and spreading ipsilaterally to the nigrostriatal system, and a body-first pathway, with the pathology originating in enteric and peripheral autonomic nerves before ascending to the brain. In this review, we integrate the SOC model into a broader framework, reconceptualizing PD as a progressive disorder of spatial–temporal symmetry. Spatial symmetry encompasses left–right and cranio-caudal balance of neural and musculoskeletal systems, whereas temporal symmetry denotes the coherence of biological rhythms from circadian and autonomic cycles, coupled with metabolic health and mitochondrial function, to sub-second timing governed by dopaminergic and basal ganglia–cortical network dynamics. We outline how systemic insulin resistance and mitochondrial stress erode temporal symmetry, while cranio-cervical malalignment and temporomandibular disorders perturb spatial symmetry. We discuss the neurobiological implementation of these symmetry axes via large-scale networks and dopaminergic modulation of spatial–temporal sensorimotor dynamics, framing PD as a multiscale symmetry-breaking process, and explore the implications for symmetry-oriented biomarkers, subtyping, and future interventions. Full article

Background/Objectives: Metabolic dysfunction-associated steatohepatitis (MASH) is characterized by severe hepatic steatosis, lobular inflammation, and fibrosis. Although hesperidin, a citrus-derived flavanone, has been reported to exert metabolic and anti-inflammatory effects, its role in severe inflammatory and fibrotic conditions such as MASH remains incompletely understood. This study aimed to evaluate the effects of hesperidin in MASH using integrated in silico and in vivo approaches. Methods: Potential targets of hesperidin were identified using network pharmacology and molecular docking. For in vivo validation, C57BL/6 mice were fed a methionine- and choline-deficient (MCD) diet for five weeks, with oral administration of hesperidin (150 or 300 mg/kg/day) starting from week two. The MCD model induces severe hepatic inflammation and fibrosis but does not fully reflect metabolic features such as obesity and insulin resistance. Hepatic histology, serum transaminases, immune cell populations, and hypothalamic neuroinflammatory markers were assessed. Results: In silico analyses suggested that hesperidin interacts with key regulators associated with MASH, including PPARG, TGFB1, and TNF. In the in vivo MCD-induced model, hesperidin treatment reduced hepatic lipid accumulation and collagen deposition, accompanied by significant decreases in serum ALT and AST levels (by approximately 30–34% and 42–53%, respectively, depending on dose). These effects were associated with downregulation of pro-inflammatory and pro-fibrogenic gene expression and increased expression of antioxidant markers. In addition, hesperidin decreased circulating Ly6C^high monocytes and hepatic Kupffer cells, along with reduced hypothalamic microglial and astrocyte activation. Conclusions: Hesperidin attenuated key pathological features of MASH, including steatosis, inflammation, and fibrosis, and was associated with modulation of peripheral immune responses and central neuroinflammatory markers. These findings suggest that hesperidin may influence the liver–immune–brain axis and warrant further investigation in models that more closely reflect human metabolic conditions. Full article

Epidemiological and clinical research on neurodegenerative diseases has shown that metabolic dysregulations increase the risk of developing Alzheimer’s Disease (AD). Many metabolic changes can be grouped into metabolic syndrome (MetS), which is defined as the presence of three or more risk factors, including insulin resistance, hyperglycemia, hypertension, central obesity, and dyslipidemia. These changes cause systemic effects that are crucial in triggering neuroinflammation and neurodegeneration, key factors in AD development. All these factors impair energy metabolism in peripheral tissues and the brain by decreasing glucose utilization, leading to alterations in O-GlcNAcylation, glycosylation, mitochondrial function, oxidative stress, chronic inflammation, synaptic dysfunction, autophagy impairment, and blood–brain barrier (BBB) dysfunction. However, these factors are modified and largely influenced by lifestyle choices. A newer perspective emphasizes that regular exercise is vital for maintaining brain metabolism as we age. Current evidence suggests that engaging in physical activity for individuals with metabolic syndrome reduces their risk of Alzheimer’s disease, enhances prognosis, and improves cognitive abilities. This review explores how metabolic syndrome relates to Alzheimer’s and highlights possible strategies for prevention and treatment. Full article

Leucine-rich repeat kinase 2 (LRRK2) is a multidomain serine/threonine kinase and a major genetic contributor to Parkinson’s disease (PD). Although LRRK2 has been extensively studied in neurodegeneration, emerging evidence indicates that it also plays a critical role in systemic metabolism. LRRK2 regulates glucose homeostasis through modulation of insulin signaling, vesicle trafficking, mitochondrial function, and inflammatory responses. Studies using LRRK2 knockout and knock-in models, including the pathogenic G2019S mutation, have revealed abnormalities in insulin sensitivity, adipose tissue inflammation, hepatic glucose production, and skeletal muscle metabolism. Mechanistically, LRRK2 phosphorylates Rab GTPases, thereby controlling insulin receptor trafficking and GLUT4 translocation. In addition, LRRK2 influences mitochondrial dynamics and reactive oxygen species production, linking metabolic stress to inflammatory signaling. Importantly, LRRK2 also regulates innate immune pathways, including TLR4–NFκB signaling and inflammasome activation, thereby connecting peripheral metabolic dysfunction to neuroinflammation. Here, we propose an integrated metabolic–neuroinflammatory crosstalk model in which LRRK2 functions as a molecular coordinator linking peripheral metabolic dysfunction to central neurodegeneration. In this framework, systemic metabolic stress—characterized by insulin resistance, chronic inflammation, advanced glycation end product (AGE) accumulation, and blood–brain barrier disruption—drives microglial activation and neurodegenerative processes. Understanding this systemic axis may provide new therapeutic opportunities targeting both metabolic dysfunction and neurodegeneration in PD. Full article

The increasing prevalence of obesity and Alzheimer’s disease (AD) in the aging population underscores an urgent need to understand the common cellular and metabolic mechanisms they share. Accumulated evidence suggests that overlapping metabolic disturbances contribute to the pathogenesis of these two conditions. In this review, we highlight key underlying interconnecting metabolic pathways: (1) adipose-brain crosstalk mediated by adipokines and adipose tissue-derived extracellular vesicles that can modulate neuronal function and amyloid pathology, (2) dysregulated lipid metabolism affecting cholesterol, sphingolipids, and phospholipids and thereby promoting inflammation, amyloid precursor protein processing, and tau hyperphosphorylation, (3) impaired glycolysis and insulin resistance, which accelerate both obesity and neurodegenerative processes, (4) mitochondrial dysfunction marked by disrupted tricarboxylic acid cycle enzymes and electron transport chain complexes, leading to elevated reactive oxygen species and driving both obesity and AD pathology, and (5) gut microbiota dysbiosis, which can trigger inflammation as well as amyloid and tau aggregation. Together, these mechanisms show that metabolic alterations appear early, preceding clinical disease, and that understanding these underlying connections can provide strategies to protect metabolic health and prevent disease progression. Full article

Micro- and nanoplastics (MPs/NPs) have emerged as pervasive environmental contaminants with increasing implications for human health, particularly within the digestive system. This review critically examines the role of MPs/NPs as disruptors of gastrointestinal and liver homeostasis through the lens of the plastic–gut–liver axis. We synthesize current evidence on primary exposure routes—including ingestion, inhalation, dermal contact, and transplacental transfer—and highlight their intestinal uptake, systemic dissemination, and tissue accumulation. Mechanistically, MPs/NPs compromise intestinal barrier integrity, promote oxidative stress, and induce microbiota dysbiosis, facilitating the translocation of microbial-derived signals to the liver via the portal circulation. This process triggers inflammatory signaling cascades, metabolic reprogramming, and immune dysregulation, contributing to hepatic steatosis, insulin resistance, and potential carcinogenic processes. Emerging evidence also implicates pancreatic dysfunction and β-cell stress within a broader gut–liver axis context. We further discuss the systemic propagation of MPs/NPs-induced dysbiosis along multi-organ axes, including gut–lung and gut–brain interactions. Despite robust preclinical data, human evidence remains limited due to methodological heterogeneity and the lack of standardized biomarkers. This review underscores critical knowledge gaps and emphasizes the need for integrative, translational approaches to clarify long-term health risks and inform regulatory strategies within the environmental exposome framework. Full article

Background/Objectives: Western and Mediterranean diets have divergent effects on the brain. The gut microbiome may mediate diet effects, and specific microbes may be particularly significant contributors to these processes. Oscillospira, a genus of gut-dwelling bacteria, has been implicated as a key microbial target. Other peripheral contributors may include short-chain fatty acids (SCFAs), branched-chain amino acids (BCAAs), insulin resistance, and microbial translocation. Methods: We determined the effects of long-term (31 months, ~9 human years) consumption of a Mediterranean or Western-type diet on Oscillospira abundance, fecal SCFAs, plasma BCAAs, soluble CD14 (sCD14), and insulin responses in a randomized trial of 38 middle-aged female cynomolgus macaques (Macaca fascicularis). We determined diet effects and associations between dependent variables. For variables that were affected by diet composition and significantly associated with Oscillospira, we tested whether Oscillospira abundance mediated the effects of diet. Results: The Mediterranean diet resulted in higher Oscillospira (p = 0.004) and SCFAs (acetate p = 0.002; propionate p = 0.049) and lower BCAAs (isoleucine p = 0.035; leucine p = 0.007; valine p < 0.001). The Western diet increased insulin resistance (p = 0.040) and WM loss (p = 0.011). Oscillospira abundance was negatively associated with BCAAs (leucine p = 0.007; valine p = 0.005) and insulin resistance (insulin AUC: p = 0.024; increase in insulin AUC from pretreatment: p = 0.020), with trends for isoleucine (p = 0.066) and sCD14 (p = 0.103). Oscillospira abundance was positively associated with acetate (p = 0.032) and WM volume changes (p = 0.012). Oscillospira abundance significantly mediated the effects of diet on white matter volume changes (p = 0.020) and on insulin resistance (insulin AUC: p = 0.012 at study end; increase in insulin AUC during study: p = 0.020), presenting potential pathways through which diet may influence the brain. Conclusions: These findings suggest that diet-driven differences in Oscillospira are linked to metabolic regulation and white matter integrity, and Oscillospira may mediate the relationships. The results highlight a potential role for diet–microbiome interactions in shaping metabolic and brain aging trajectories. Full article

Background: Obesity is a chronic metabolic disease that has emerged as a major global public health concern. Obesity complications refer to a range of metabolic, neurological and behavioral disorders. Complex interaction mechanisms exist between obesity and the brain, including neuroendocrine regulation, center inflammatory responses, the gut–brain axis, and obesity-related cognitive impairment. Polyphenols are naturally occurring bioactive compounds widely found in plants. Recent research indicates that polyphenols may modulate the brain through multiple pathways, thereby ameliorating obesity complications. However, no data set available to summarize neuroregulatory effects of dietary polyphenols on obesity complication. Methods: The latest data available were collected to review research progress focusing on neuroregulatory roles of polyphenols on obesity complication. Results: This review summarizes the interaction between obesity and the brain and further explores the effects of polyphenols on obesity-related neurological disorders, with particular emphasis on their roles in appetite regulation, central neuroinflammation, brain leptin and insulin resistance, gut–brain axis modulation, and cognitive improvement. Finally, future perspectives are discussed. Conclusions: This paper may provide a new theoretical support and research direction for the potential of polyphenols against obesity-related neurological complications. Full article

The relationship between epilepsy, obesity, and metabolic syndrome (MetS) has emerged as a rapidly evolving area of neurobiology inquiry. Emerging evidence suggests that epilepsy extends beyond neuronal hyperexcitability, reframing it as a systemic condition characterized by significant metabolic dysregulation. Converging supports a bidirectional relationship while seizures, antiseizure medications (ASM), and neuroinflammation induce exacerbate potentiate epileptogenesis through shared molecular pathways. At the cellular level, chronic epileptic activity induces oxidative stress, mitochondrial dysfunction, and the activation of microglia and astrocytes. This, in turn, leads to the release of pro-inflammatory cytokines including TNF-α, IL-1β, and IL-6. These mediators traverse the blood-brain barrier (BBB), subsequently modifying insulin signaling, and disrupting glucose homeostasis, which collectively fosters a pro-inflammatory and insulin-resistant environment. Furthermore, antiseizure medications such as valproate can exacerbate these effects by directly impairing insulin receptor signaling and altering adipokine production, ultimately contributing to weight gain and systemic metabolic dysregulation. Obesity and MetS induce neuroinflammatory and excitotoxic states that promote seizure onset via leptin resistance, reduced adiponectin levels, and compromised AMP-activated protein kinase (AMPK) signaling. Emerging evidence emphasizes the gut-brain axis as a crucial regulator in this reciprocal interaction. Dysbiosis, altered microbial metabolites (e.g., short-chain fatty acids), and heightened intestinal permeability facilitate systemic inflammation and BBB disruption, enhancing neuronal excitability. Insulin resistance in the brain disrupts synaptic transmission, impairs mitochondrial biogenesis, and compromises redox equilibrium, perpetuating a pathological cycle linking metabolic stress to epileptic activity. This review synthesizes the cellular, molecular, and systemic pathways connecting epilepsy, obesity, and MetS, and proposes that epilepsy be reconceptualized as a neuro-metabolic disorder. Insights into these convergent pathways provide a rationale for novel therapeutic strategies that simultaneously target seizure control and metabolic regulation, encompassing microbiota modulation, antioxidant therapy, and insulin-sensitizing interventions with the overarching aim of restoring neuro-metabolic homeostasis. Full article

Insulin acts in the brain to promote satiety. Aging individuals may have brain insulin resistance and altered appetite perceptions. However, it is unclear if exercise impacts cerebral reward centers and appetite perception in middle-aged to older individuals. Purpose: To assess whether a single exercise bout alters cerebral blood flow (CBF) in reward centers in relation to appetite perceptions. Methods: Fifteen sedentary adults (12F; ~56 ± 2y; ~31 ± 1 kg/m²) completed a control and acute exercise condition (70% maximal oxygen consumption) in a randomized, counterbalanced order in the evening. Following an overnight fast, CBF in the accumbens, thalamus, and amygdala (pCASL MRI) was evaluated before and after intranasal insulin spray (INI, 40 IU) administration. Plasma glucose and insulin as well as an appetite visual analog scale (VAS) were assessed at fasting, 30, and 90 min post-INI, as well as at 30 min intervals of a 120 min 75 g oral glucose tolerance test (OGTT). Total area under the curve (tAUC) was calculated. Results: Exercise tended to lower blood glucose (p = 0.072) and plasma insulin (p = 0.007) tAUC, compared with rest. Exercise also raised right thalamus (p = 0.029) and left amygdala CBF (p = 0.023). The rise in fasting CBF in these regions, and the accumbens, correlated with reduced insulin tAUC (r = −0.55 to −0.73, p < 0.050). Although there was no difference in hunger, satisfaction, fullness, or prospective food consumption after exercise, changes in INI-stimulated thalamus CBF related to fullness tAUC after exercise (r = −0.57, p = 0.044). Conclusions: A single exercise bout might increase fasting CBF in some brain regions associated with appetite perception through a potential insulin-related mechanism. Full article

Diabetes mellitus is a rapidly escalating worldwide health issue that involves intricate molecular, metabolic, and systemic dysregulation. In addition to hyperglycemia, disease pathogenesis involves β-cell dysfunction, insulin resistance, mitochondrial dysfunction, endoplasmic reticulum stress (ER stress), redox imbalance, lipotoxicity, chronic inflammation, and inappropriate epigenetic modifications. New evidence also emphasizes the participation of mechanotransduction, ion channel signaling, circadian regulation, and organ cross-talk among the pancreas, liver, adipose tissue, skeletal muscle, heart, brain, and gut in modulating disease heterogeneity and progression. This review highlights updates of molecular mechanisms in diabetes, focusing on the β-cell response to stress, the AMPK–Sirtuin 1 (or PGC-1α) signaling pathway, mitochondrial quality control, mechanosensitive ion channels, immunometabolic crosstalk, and epigenetic regulation. We consider the increasing importance of multi-omics methods for early identification of pathogenic signatures and integration of artificial intelligence to enable precision stratification and therapeutic tailoring. Finally, we highlight novel experimental and translational tools, such as iPSC-derived β-cells or organoids, CRISPR-based gene editing, sophisticated metabolic imaging, and electrophysiology. Taken together, this review shifts the paradigm of diabetes as a system-level network disease and emphasizes the importance of data-driven multi-target strategies for prevention and reduction in long-term complications. Full article

Sex differences remain largely underexplored in metabolic disorders, particularly in the context of genetic predisposition to type 2 diabetes, the impact of aging, and environmental factors such as exposure to high-caloric diets. Previous studies using serotonin transporter (SERT)-knockout (SERT-KO) mice, which recapitulate metabolic conditions related to the lowered function of this transporter in humans, revealed an aggravated negative response of these mutants to housing on a high-fat/sugar ‘Western diet’ (WD). However, the role of sex in SERT-KO mice has not yet been studied. Available human and animal data suggest the differential regulation of insulin receptor-mediated signaling in males and females, which can be altered with aging. This study aimed to compare fat accumulation, blood biochemical changes, glucose tolerance, and insulin receptor (IR)-related signaling in the liver and various brain structures of 12-month-old male and female SERT-KO mice fed WD for 21 days. Relative to the dietary-unchallenged group and their wild-type (WT) littermates, WD-fed mutants of both sexes displayed markedly increased fat accumulation and impaired glucose and insulin tolerance. Body mass increase was more prominent in females than in males. The two sexes revealed a similar suppression of the gene expression of isoforms A and B of IR but distinct expression of IR-related factors. IR-related genes such as Cd36, Enpp, Ptpn1, Cyp4a14, Acsl1, and Pten showed differential expression between male and female SERT-KO mice fed WD. Several differences in gene expression were also found between the WT groups of the two sexes. Overall, the manifestations of hepatic steatosis, insulin resistance, and glucose tolerance were similar between the age groups of animals, whereas the gene expression of IR-related regulation differed between the groups. We conclude that aging and genetic absence of the serotonin transporter likely override sex differences in the end effects of WD challenge, while molecular mechanisms of adaptation of IR-mediated signaling are distinct between male and female SERT-KO mice fed WD. Full article