Brain-derived neurotrophic factor is produced by skeletal muscle cells in response to contraction and enhances fat oxidation via activation of AMP-activated protein kinase

From a Solitary Blood-Derived Biomarker to Combined Biomarkers of Sarcopenia: Experiences From the Korean Frailty and Aging Cohort Study

Sarcopenia is recognized as a complex and multifactorial disorder that includes nutritional deficiency, inactivity, proinflammatory status, hormonal changes, neurological degeneration, and metabolic disturbances. It's pathogenesis is not fully understood. Therefore, identifying specific biomarkers of sarcopenia will help us understand its pathophysiology. The most frequently reported blood-derived biomarkers of sarcopenia are growth factors, neuromuscular junctions, endocrine systems, mitochondrial dysfunction, inflammation-mediated and redox processes, muscle protein turnover, blood metabolomics, and behavior-mediated biomarkers. Here, we address the implications of sarcopenia biomarkers based on our research experience with Korean Frailty and Aging Cohort Study cohort data. It includes free testosterone, myostatin, fibroblast growth factor 21 (FGF-21), growth differentiation factor 15 (GDF-15), procollagen type III N-terminal peptide (P3NP), creatinine-based biomarkers, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), brain-derived neurotrophic factor (BDNF), metabolites (proline, alanine, tryptophan), and multi-biomarker risk score. We attempted to explain the paradoxical findings of myostatin and FGF-21 levels in relation to sarcopenia. GDF-15 levels were associated with sarcopenia prevalence but not its incidence. Plasma P3NP and BDNF levels may be biomarkers of muscle quality rather than quantity. Lower erythrocyte eicosapentaenoic acid (EPA) and docosahexaenoic acid levels were associated with slow gait speed, and erythrocyte EPA levels were associated with low handgrip strength. We developed a multi-biomarker risk score for sarcopenia and found that its accuracy in diagnosing sarcopenia was higher than that of any single biomarker.

Peripheral tissue BDNF expression is affected by promoter IV defect and enriched environments in mice: negative hippocampus-intestine and positive thymus-serum-muscle correlations

BACKGROUND

Brain-derived neurotrophic factor (BDNF) expression is reduced in the brain of various central nervous system (CNS) disorders, but its relation to peripheral expression remains unclear. This study aimed to determine peripheral BDNF expression affected by BDNF promoter IV defect and enriched environment treatment (EET). Promoter IV defect is associated with CNS disorders and chronic stress, whereas EET increases hippocampal BDNF expression and ameliorates CNS dysfunctions.

METHODS

Enzyme-linked immunosorbent assay measured BDNF protein levels in eleven regions (hippocampus, frontal cortex, heart, lung, liver, spleen, intestine, kidney, intestine, thymus, muscle, serum) in wild-type and knock-in promoter IV (KIV) mice with or without 3 weeks of EET provided after weaning.

RESULTS

Knock-in promoter IV resulted in BDNF levels significantly decreased in muscle, but significantly increased in intestine, liver, thymus, and serum, which suggests compensatory upregulation of other promoters in those tissues. EET increased BDNF levels in muscle and serum of KIV mice and thymus of wild-type mice, suggesting EET's beneficial effects in muscle motor and adaptive immune regulation. EET increased hippocampal BDNF levels in both genotypes, which significantly negatively correlated with intestine BDNF levels, suggesting its role in the brain-gut axis. EET reduced wild-type heart BDNF levels, possibly through parasympathetic regulation. Significant positive BDNF correlations were observed among serum-muscle, serum-thymus, lung-spleen, and intestine-liver, suggesting inter-organ interaction and regulation of BDNF. Partial Least Squares discriminant analyses (PLS-DA) identified that variations in BDNF levels in intestine, liver, frontal cortex, and serum contribute most to classify promoter IV defect, and those in hippocampus, serum, heart, thymus, and liver contribute most to classify EET effects.

CONCLUSION

This is the first study to demonstrate how genetic and environmental factors affect BDNF expression in peripheral tissues, highlighting the complex BDNF correlations across organ systems and suggesting usefulness of multivariate BDNF analyses for detecting promoter IV defect and enriched environment effects. Elucidation of BDNF's role and regulatory mechanisms in peripheral organ systems may help better our understanding of its connection to CNS disorders and their treatments.

Role of brain-derived neurotrophic factor in frailty: From mechanisms to interventions

Frailty is a common medical syndrome which largely increases the risk of disability, depression, falls, hospitalization and mortality. An increasing number of research suggests that frailty is reversible by medical interventions at its early stage. Therefore, efficient detection is utterly important for frail population. Since numerous biological processes have been indicated in frail population, the critical regulators in these biological processes could provide biomarkers for early detection or treatment for frailty. The brain-derived neurotrophic factor (BDNF) has been associated with several biological process ranging from cognitive function to inflammation, therefore it could be an important regulator for frailty. In this review, we would discuss the mechanism association between different indicators of frailty and BDNF. Furthermore, we summarize the approaches to interfere with BDNF in healthy and pathologic condition, which could lead to identification of potential interventional strategies for frailty.

BDNF coexpresses with MTOR and is associated with muscle fiber size, lean mass and power-related traits

PURPOSE

Recent research suggests a link between brain-derived neurotrophic factor (BDNF) and the mTOR signaling pathway, a key regulator of protein synthesis and muscle growth. However, it remains unclear whether BDNF influences muscle growth and power performance. Our study aimed to investigate the relationship between the expression of BDNF and MTOR genes in human skeletal muscle and examine the association between genetically predicted higher expression of the BDNF gene and muscle fiber size, lean mass, power performance, and power athlete status.

METHODS

The study involved 456,382 subjects, including 285 athletes, 112 physically active individuals with muscle fiber composition data, 291 sedentary individuals with gene expression data, 5451 controls, and 450,243 UK Biobank participants. The muscle fiber composition was evaluated using immunohistochemistry, while gene expression analysis was performed using RNA sequencing. BDNF genotyping was carried out using real-time PCR or microarrays.

RESULTS

We found that BDNF gene expression was positively associated with MTOR gene expression in the vastus lateralis (p < 0.0001). Furthermore, genetically predicted higher BDNF expression (i.e., carriage of the C allele of the rs6265 (Val66Met) BDNF polymorphism) was positively associated with the cross-sectional area of fast-twitch muscle fibers in athletes (p = 0.0069), appendicular lean mass (p = 2.6 × 10⁻⁷), personal best scores of power athletes (p = 0.029), and power athlete status (p = 0.0056).

CONCLUSION

Our study demonstrates a positive correlation between BDNF and MTOR gene expression in human skeletal muscle, with genetically predicted higher BDNF expression associated with greater muscle fiber size, lean mass, enhanced power performance, and power athlete status.

Sarcopenia in Parkinson's disease: from pathogenesis to interventions

Parkinson's disease (PD) and sarcopenia are prevalent age-related conditions that often coexist in affected individuals. Sarcopenia is particularly common among PD patients, with severe cases affecting approximately one in five individuals with the disease. Furthermore, sarcopenia is closely linked to the accelerated progression of PD, diminished quality of life, greater susceptibility to falls and fractures, and increased mortality risk. Although the precise mechanisms remain unclear, numerous studies suggest that factors such as the accumulation of α-Synuclein in skeletal muscle, loss of motor neurons, inflammation, phosphate toxicity, hormonal dysregulation, vitamin D deficiency, intestinal flora imbalances, and dysfunction of the gut-muscle-brain axis contribute to sarcopenia in PD. Understanding these mechanisms provides valuable insights into the relationship between PD and sarcopenia and establishes a foundation for future research and therapeutic strategies. This review examines the mechanisms underlying sarcopenia in PD, methods for its screening and assessment, and potential avenues for future research, including strategies for risk reduction and treatment.

Arterial-venous differences of brain-derived neurotrophic factor isoforms across the brain and muscle after exercise at different intensities

Brain-derived neurotrophic factor (BDNF) is essential for neuroplasticity. Exercise can induce increases in forearm venous plasma and serum BDNF, often assumed to be indicative of release from the brain. We investigated the effects of exercise on circulating levels of mature BDNF (mBDNF) and its precursor proBDNF. Sixteen healthy, physically fit adults (20-40 years old) cycled for 20 min at 40, 60 and 80% ofV ̇ O 2 max ${\dot V_{{{\mathrm{O}}_2}\max }}$ , separated by 30 min of rest. BDNF was analysed in blood samples from the brachial artery, internal jugular vein, femoral vein and antecubital vein. Brain/skeletal muscle exchange of BDNF, calculated as arterial-venous differences in BDNF multiplied by blood flow in the middle cerebral artery/common femoral artery, was measured simultaneously with blood sampling. Exercise intensity-dependent increases were observed in blood platelet count, forearm venous serum mBDNF and plasma proBDNF, but not in forearm venous plasma mBDNF. Brain release (or uptake) was not detected for either plasma mBDNF, serum mBDNF or plasma proBDNF. However, muscle uptake of plasma mBDNF and release of plasma proBDNF were observed after high-intensity exercise. Our findings demonstrate that exercise-dependent increases in serum mBDNF are not derived from the brain or the exercised skeletal muscle. Rather, the source of the increase appears to be the increase in platelets that are enriched with mBDNF. Furthermore, in physically fit adults, BDNF is not released from the brain into the bloodstream, after exercise, regardless of exercise intensity. Finally, changes in plasma proBDNF after exercise appear to be dependent on exercised skeletal muscle rather than brain release. KEY POINTS: Previously shown exercise-induced increases in forearm venous brain-derived neurotrophic factor (BDNF) are often assumed to be indicative of release from the brain. We investigated whether exercise-induced changes in forearm venous mature BDNF (mBDNF) and precursor proBDNF are paralleled by concomitant changes in BDNF exchange over the brain and skeletal muscle. We observed exercise intensity-dependent increases in platelet count, forearm venous serum mBDNF and plasma proBDNF, but not in forearm venous plasma mBDNF. We found muscle uptake of plasma mBDNF and release of plasma proBDNF after high-intensity exercise but no exercise intensity-dependent brain exchange of either plasma mBDNF, serum mBDNF or plasma proBDNF. Our findings suggest that acute exercise-induced increases in circulating serum mBDNF may be solely a result of increased platelet count, probably due to splenic platelet release; and that exercised skeletal muscle, and not the brain, responds to high-intensity exercise by releasing plasma proBDNF.

Physical activity in Alzheimer's disease prevention: Sex differences and the roles of BDNF and irisin

Alzheimer's disease (AD) disproportionately affects women, with postmenopausal hormonal changes contributing to elevated risk. Physical exercise is a promising, non-pharmacological strategy to mitigate cognitive decline and AD progression. Brain-derived neurotrophic factor (BDNF) and irisin are key molecular mediators of exercise-induced brain health and protection against AD pathology by promoting synaptic plasticity, neurogenesis, and reducing amyloidosis, tau pathology, and neuroinflammation in sex-specific mechanisms. This review explores sex and gender influences on exercise outcomes and their interaction with FNDC5/irisin and BDNF signaling pathways in the context of AD prevention. We highlight emerging evidence on the interplay between exercise, sex, and neuroprotective pathways, emphasizing the need for sex-sensitive research designs to advance precision approaches for AD prevention.

Cellular deconstruction of the human skeletal muscle microenvironment identifies an exercise-induced histaminergic crosstalk

Plasticity of skeletal muscle is induced by transcriptional and translational events in response to exercise, leading to multiple health and performance benefits. The skeletal muscle microenvironment harbors myofibers and mononuclear cells, but the rich cell diversity has been largely ignored in relation to exercise adaptations. Using our workflow of transcriptome profiling of individual myofibers, we observed that their exercise-induced transcriptional response was surprisingly modest compared with the bulk muscle tissue response. Through the integration of single-cell data, we identified a small mast cell population likely responsible for histamine secretion during exercise and for targeting myeloid and vascular cells rather than myofibers. We demonstrated through histamine H1 or H2 receptor blockade in humans that this paracrine histamine signaling cascade drives muscle glycogen resynthesis and coordinates the transcriptional exercise response. Altogether, our cellular deconstruction of the human skeletal muscle microenvironment uncovers a histamine-driven intercellular communication network steering muscle recovery and adaptation to exercise.

Myokines as potential mediators of changes in glucose homeostasis and muscle mass after bariatric surgery

Myokines are bioactive peptides released by skeletal muscle. Myokines exert auto-, para-, or endocrine effects, enabling them to regulate many aspects of metabolism in various tissues. However, the contribution of myokines to the dramatic changes in glucose homeostasis and muscle mass induced by bariatric surgery has not been established. Our review highlights that myokines such as brain-derived neurotrophic factor (BDNF), meteorin-like protein (Metrnl), secreted protein acidic and rich in cysteine (SPARC), apelin (APLN) and myostatin (MSTN) may mediate changes in glucose homeostasis and muscle mass after bariatric surgery. Our review also identifies myonectin as an interesting candidate for future studies, as this myokine may regulate lipid metabolism and muscle mass after bariatric surgery. These myokines may provide novel therapeutic targets and biomarkers for obesity, type 2 diabetes and sarcopenia.

Dietary timing enhances exercise by modulating fat-muscle crosstalk via adipocyte AMPKα2 signaling

Feeding rhythms regulate exercise performance and muscle energy metabolism. However, the mechanisms regulating adipocyte functions remain unclear. Here, using multi-omics analyses, involving (phospho-)proteomics and lipidomics, we found that day-restricted feeding (DRF) regulates diurnal rhythms of the mitochondrial proteome, neutral lipidome, and nutrient-sensing pathways in mouse gonadal white adipose tissue (GWAT). Adipocyte-specific knockdown of Prkaa2 (the gene encoding AMPKα2) impairs physical endurance. This defect is associated with altered rhythmicity in acyl-coenzyme A (CoA) metabolism-related genes, a loss of rhythmicity in the GWAT lipidome, and circadian remodeling of serum metabolites-in particular, lactate and succinate. We also found that adipocyte Prkaa2 regulates muscle clock genes during DRF. Notably, oral administration of the AMPK activator C29 increases endurance and muscle functions in a time-of-day manner, which requires intact adipocyte AMPKα2 signaling. Collectively, our work defines adipocyte AMPKα2 signaling as a critical regulator of circadian metabolic coordination between fat and muscle, thereby enhancing exercise performance.

Exercise Mimetics in Aging: Suggestions from a Systematic Review

Background/Objectives: Growth in the aging world population is accompanied by an increase in comorbidities, profoundly impacting the quality of life of older people. This development has motivated a large effort to investigate the mechanisms underlying aging and the search for countermeasures. The most investigated strategies envisage the control of diet and physical exercise, which exploit both common and distinct mechanisms to promote health. Since the application of nutritional and exercise protocols to aged persons introduces several issues due to their disabled state, some strategies have been developed. The nutritional approach exploits a wide range of compounds, including calorie restriction mimetics, supplements, antioxidants, and others. In the context of exercise, in recent years, molecules able to provide similar effects to exercise, the so-called exercise mimetics, have been developed. Methods: To have a better perspective on exercise mimetics and their connection with nutrition, we performed a systematic search of the PubMed and Scopus databases using the term "exercise mimetics". Results: In total, 97 research articles were selected and discussed. The present review provides evidence of the presence of multiple exercise-mimetic compounds and physical strategies that can target metabolic pathways, oxidative stress defense mechanisms, or myokine modulation. Conclusions: Interestingly, this review highlights that an important number of exercise mimetics are represented by products of natural origin and supplements assimilable with diet. This evidence provides a further link between exercise and nutrition and confers a central role on nutrition in the context of exercise mimetics.

Charting the Molecular Terrain of Exercise: Energetics, Exerkines, and the Future of Multiomic Mapping

Physical activity plays a fundamental role in human health and disease. Exercise has been shown to improve a wide variety of disease states, and the scientific community is committed to understanding the precise molecular mechanisms that underlie the exquisite benefits. This review provides an overview of molecular responses to acute exercise and chronic training, particularly energy mobilization and generation, structural adaptation, inflammation, and immune regulation. Furthermore, it offers a detailed discussion of known molecular signals and systemic regulators activated during various forms of exercise and their role in orchestrating health benefits. Critically, the increasing use of multiomic technologies is explored with an emphasis on how multiomic and multitissue studies contribute to a more profound understanding of exercise biology. These data inform anticipated future advancement in the field and highlight the prospect of integrating exercise with pharmacology for personalized disease prevention and treatment.

Increase in Brain-Derived Neurotrophic Factor After Cycling Exercise Resisting Electrically Stimulated Antagonist Muscle Contractions in Overweight Japanese People: A Randomized, Controlled, Single-Blind, Crossover Trial

BACKGROUND

A hybrid training system (HTS) combining antagonist muscle electrical stimulation and voluntary muscle contraction has been developed using electrically stimulated eccentric antagonist muscle contractions. The exercise method that combines a conventional cycle ergometer with HTS (HERG) adds additional exercise intensity to the conventional cycle ergometer through electrical stimulation. Exercise-induced brain-derived neurotrophic factor (BDNF) production appears to have neuroprotective effects and contributes to improved metabolic regulation. Changes in BDNF after exercise are related to exercise intensity. Therefore, combining a cycle ergometer with electrical stimulation may be an effective approach.

PURPOSE

The purpose of this study was to evaluate the effect of the HERG on BDNF secretion.

PARTICIPANTS AND METHODS

Fourteen healthy adults participated in the study. The participants performed two types of exercise at the anaerobic threshold: HERG and a cycling ergometer alone (CERG). A comparative study using a 2×2 crossover method was conducted to examine the differences in BDNF and lactate levels after HERG and CERG. A linear mixed model was used to compare changes in BDNF between HERG and CERG.

RESULTS

Both HERG and CERG significantly increased BDNF and lactate levels after exercise. In overweight individuals with a BMI of 25 or higher, the change in BDNF levels after HERG was significantly greater than after CERG [ΔBDNF: 5500.96±7965.83 ng/ml, 1921.29±5308.22 ng/ml, respectively; p=0.0339]. There was no significant difference in the change in lactate levels after exercise between HERG and CERG (p=0.8632).

CONCLUSION

In overweight individuals, HERG increased post-exercise serum BDNF levels more than ergometer exercise alone, despite the exercise intensity remaining the same at the anaerobic threshold. The exercise method that combines the HERG may be a useful form of exercise for overweight individuals.

Causal association of sarcopenia-related traits with brain cortical structure: a bidirectional Mendelian randomization study

BACKGROUND

Patients with sarcopenia often experience cognitive decline, affecting cortical structures, but the causal link remains unclear. We used bidirectional Mendelian randomization (MR) to explore the relationship between sarcopenia-related traits and cortical structure.

METHODS

We selected genetic variables from genome-wide association study data. Three different MR methods were used: inverse-variance weighted analysis, MR-Egger regression, and the weighted median test. For significant estimates, we further conducted Cochran's Q test, MR-Egger intercept test, leave-one-out analyses, and MR-PRESSO to assess heterogeneity.

RESULTS

In forward MR analysis, appendicular lean mass (ALM) decreased the thickness (TH) of lateral occipital gyrus and increased the TH of pars opercularis gyrus (β = -0.0079 mm, 95% CI: -0.0117 mm to -0.0041 mm, P < 0.0001; β = 0.0080 mm, 95% CI: 0.0042 mm to 0.0117 mm, P < 0.0001). In reverse MR analysis, a significant negative correlation was found between the TH of bankssts and ALM, while positive correlations were observed between the TH of frontal pole, rostral anterior cingulate, temporal pole, and ALM. The TH of temporal pole was positively correlated with right hand grip strength (HGS-R) (β = 0.1596 mm, 95% CI: 0.1349 mm to 0.1843 mm, P < 0.0001), and the TH of pars triangularis was positively correlated with left-hand grip strength (HGS-L) (β = 0.3251 mm, 95% CI: 0.2339 mm to 0.4163 mm, P < 0.0001).

CONCLUSIONS

Sarcopenia-related traits and cortical structure have bidirectional effects, supporting the muscle-brain axis theory. This links sarcopenia to neurocognitive diseases and provides new strategies for the prevention and intervention of both sarcopenia and cognitive decline.

No long-term benefits from resistance training on brain grey matter volumes in active older adults at retirement age

BACKGROUND

Resistance training and other forms of physical exercise are commonly suggested to promote brain health, yet the relationship between resistance training and brain structure in aging is poorly understood. We examined the short- and long-term influence of one year of supervised resistance training at two different loadings on brain structure in aging.

METHODS

In the LISA (LIve active Successful Ageing) study, well-functioning older adults at retirement age (mean age: 66 ± 2 years) were randomized to one year of heavy resistance training (HRT), moderate intensity training (MIT), or a non-exercising control group (CON). Magnetic resonance imaging (MRI) of the brain was performed at baseline, 1-, 2-, and 4-years follow ups. Trajectories of total grey matter, hippocampus, dorsolateral prefrontal cortex (dlPFC), ventrolateral prefrontal cortex (vlPFC), and white matter hyperintensities were analyzed in relation to changes in muscle strength.

RESULTS

Individuals (n = 276) with MRI scans at all 4 timepoints were included (HRT, n = 96; MIT, n = 95; CON, n = 85). Total grey matter volume decreased with time across all groups (F3,819 = 231.549, p < 0.001,η 2 = 0.46), as did hippocampal (F3,819 = 310.07, p < 0.001,η 2 = 0.53), vlPFC (F3,818 = 74.380, p < 0.001,η 2 = 0.21), and dlPFC (F3,818 = 3.640, p = 0.013,η 2 = 0.01) volumes. White matter hyperintensity volumes increased (F3,819 = 101.876, p < 0.001,η 2 = 0.27). There were no significant group x time interactions for any of the brain structures. Additional cortical and subcortical vertex-wise analyses showed no group differences. Change in isometric leg strength was weakly associated with change in white matter hyperintensity volume across all individuals (r2 = 0.01, p = 0.048).

CONCLUSIONS

One year of resistance training in well-functioning older adults at retirement age did not influence volume changes in selected brain regions over a 4-year period.

TRIAL REGISTRATION

The study was approved by the regional ethics committee and registered on clinicaltrials.gov 2014-04-24 (NCT02123641).

Exerkines: Potential regulators of ferroptosis

Ferroptosis is a programmed cell death, and its mechanism involves multiple metabolic pathways, such as iron and lipid metabolism, and redox homeostasis. Exerkines are important mediators that optimize cellular homeostasis and maintain physiological health during exercise stimulation. This article comprehensively examines the mechanisms and regulatory networks for governing ferroptosis and summarizes the impact of exercise and exerkines on ferroptosis under varying load intensities and disease contexts. Notably, despite its significant efficacy and minimal side effects, the therapeutic and prognostic potential of exercise in ferroptosis-related diseases remains largely unexplored. This article, by summarizing recent progresses in the regulation of exerkines-mediated ferroptosis, could further uncover the preventive or alleviative mechanisms of some diseases upon exercise interventions, which will be beneficial to design exercise interventional strategies for alleviating disease progression through the regulation of ferroptosis.

The Influence of Physical Exercise, Ketogenic Diet, and Time-Restricted Eating on De Novo Lipogenesis: A Narrative Review

De novo lipogenesis (DNL) is a metabolic pathway that converts carbohydrates into fatty acids, primarily occurring in the liver and, to a lesser extent, in adipose tissue. While hepatic DNL is highly responsive to dietary carbohydrate intake and regulated by insulin via transcription factors like SREBP-1c, adipose DNL is more modest and less sensitive to dietary overfeeding. Dysregulated DNL contributes to metabolic disorders, including metabolic dysfunction-associated steatotic liver disease (MASLD). Lifestyle interventions, such as physical exercise, ketogenic diets, and time-restricted eating (TRE) offer promising strategies to regulate DNL and improve metabolic health. Physical exercise enhances glucose uptake in muscles, reduces insulin levels, and promotes lipid oxidation, thereby suppressing hepatic DNL. Endurance and resistance training also improve mitochondrial function, further mitigating hepatic triglyceride accumulation. Ketogenic diets shift energy metabolism toward fatty acid oxidation and ketogenesis, lower insulin, and directly downregulate lipogenic enzyme activity in the liver. TRE aligns feeding with circadian rhythms by optimizing AMP-activated protein kinase (AMPK) activation during fasting periods, which suppresses DNL and enhances lipid metabolism. The combined effects of these interventions demonstrate significant potential for improving lipid profiles, reducing hepatic triglycerides, and preventing lipotoxicity. By addressing the distinct roles of the liver and adipose DNL, these strategies target systemic and localized lipid metabolism dysregulation. Although further research is needed to fully understand their long-term impact, these findings highlight the transformative potential of integrating these approaches into clinical practice to manage metabolic disorders and their associated complications.

The link between sarcopenic obesity and Alzheimer's disease: a brain-derived neurotrophic factor point of view

Age-related diseases are becoming more prominent as the lifespan of the global population rises. Many of these diseases coincide with each other and can even influence the onset of additional comorbidities. Sarcopenic obesity is described as age-related loss of muscle mass that concurs with excessive weight gain and tends to increase the risk of comorbidity development, including Alzheimer's disease (AD). Though the exact link between sarcopenic obesity and AD is not known, this review explores the possibility that reduced levels of brain-derived neurotrophic factor (BDNF) throughout the body may serve as the underlying commonality. In AD, reductions in BDNF signalling through its receptor promote the activation of glycogen synthase kinase 3 beta (GSK3β), which subsequently increases the production of amyloid beta (Aβ) peptides and neurofibrillary tangles (NFTs). In the skeletal muscle, lower BDNF concentrations are linked to impaired muscle fibre repair and regeneration, increasing the likelihood of sarcopenia. Furthermore, the absence of BDNF impairs mitochondrial function, leading to insulin resistance and increased adiposity. BDNF concentration has a negative relationship with obesogenic markers in adipose tissue, and as such, lower concentrations of BDNF lead to weight gain. Collectively, current literature suggests that BDNF attenuates AD pathology while improving skeletal muscle mitochondrial function, whole-body insulin resistance and facilitating adipocyte browning. Therefore, BDNF may be a viable target for multiple age-related diseases, but more research is required to substantiate this claim, with a particular focus on examining any potential influence of biological sex, as women are at a higher risk for both AD and sarcopenic obesity.

Brain-derived neurotrophic factor drives muscle adaptation similar to aerobic training in mice

This study, in vivo and in vitro, investigated the role of brain-derived neurotrophic factor (BDNF) in skeletal muscle adaptations to aerobic exercise. BDNF is a contraction-induced protein that may play a role in muscle adaptations to aerobic exercise. BDNF is involved in muscle repair, increased fat oxidation, and mitochondrial biogenesis, all of which are adaptations observed with aerobic training. The purpose of this study was two-pronged and investigated the skeletal muscle BDNF response to (1) acute and (2) chronic exercise in male C57BL/6J mice. It also examined if chronic BDNF treatment resulted in similar adaptations to chronic exercise. In aim 1, mice underwent a 2 hr. treadmill exercise bout. In aim 2, mice were assigned to one of four groups: (1) control (CON); (2) endurance training (ET; treadmill running 1 h/day, 5 days/wk); (3) BDNF (BDNF; 0.5 mg/kg·bw, 5 days/wk); (4) endurance training and BDNF (ET + BDNF) for 8 weeks. Results demonstrated that the soleus (SOL) had higher BDNF content compared with the extensor digitorum longus (EDL) and that SOL BDNF increased with acute exercise. After chronic exercise and BDNF treatment, treadmill testing to exhaustion demonstrated a main effect of BDNF and ET on increasing exercise capacity. In vitro contractile assessment of the EDL revealed BDNF treatment resulted in similar increases in the max rate of relaxation as ET. EDL force-frequency analysis showed ET + BDNF produced higher force than CON and BDNF, indicating an additive effect. BDNF increased EDL mitochondrial proteins, COXIV, and CS. These results demonstrate that BDNF contributes to muscle adaptations observed with ET.

Age, cancer, and the dual burden of cancer and doxorubicin in skeletal muscle wasting in female rats: which one to blame?

Sarcopenia and cancer cachexia are two life-threatening conditions often misdiagnosed. The skeletal muscle is one of the organs most adversely affected by these conditions, culminating in poor quality of life and premature mortality. In addition, it has been suggested that chemotherapeutic agents exacerbate cancer cachexia, as is the case of doxorubicin. Herein, we sought to investigate markers of inflammation and neuromuscular junction (NMJ) remodeling during aging and in response to cancer or cancer with chemotherapy. To address this, we utilized female rats across three age groups - young, adult, and old - to examine age-related changes, with old rats serving as a sarcopenia model. Additionally, a chemically-induced breast cancer (BCa) model was implemented in female adult rats, both without (adult BCa) or with doxorubicin administration (adult BCaDOX), to study cancer cachexia. The atrophy of the gastrocnemius muscle was observed in old, adult BCa and adult BCaDOX rats compared to adult ones. No signs of inflammation or NMJ impairment were observed in adult BCa or adult BCaDOX rats, except for the low levels of the subunit α1 of the acetylcholine receptor in adult BCaDOX rats compared to adult ones. In contrast, old rats presented high serum levels of interleukin 6, brain-derived neurotrophic factor (BDNF) and calcitonin gene-related peptide compared to young rats. In the gastrocnemius muscle, BDNF levels were decreased in old rats compared to adult rats, suggesting impaired skeletal muscle regeneration upon age-induced damage. The BDNF muscle levels were inversely correlated with its levels in circulation in adult and old rats. Hence, this work highlights BDNF as a specific biomarker of age-induced skeletal muscle atrophy, at least, in the differential diagnosis against cancer- or cancer with chemotherapy-induced muscle wasting.

Neurological mechanism-based analysis of the role and characteristics of physical activity in the improvement of depressive symptoms

Depression is a common mental disorder characterized by a high prevalence and significant adverse effects, making the searching for effective interventions an urgent priority. In recent years, physical activity (PA) has increasingly been recognized as a standard adjunctive treatment for mental disorders owing to its low cost, easy application, and high efficiency. Epidemiological data shows positive preventive and therapeutic effects of PA on mental illnesses such as depression. This article systematically describes the prophylactic and therapeutic effects of PA on depression and its biological basis. A comprehensive literature analysis reveals that PA significantly improves depressive symptoms by upregulating the expression of "exerkines" such as irisin, adiponectin, and BDNF to positively impacting neuropsychiatric conditions. In particular, lactate could also play a critical role in the ameliorating effects of PA on depression due to the findings about protein lactylation as a novel protein post-transcriptional modification. The literature also suggests that in terms of brain structure, PA may improve hippocampal volume, basal ganglia (neostriatum, caudate-crustal nucleus) and PFC density in patients with MDD. In summary, this study elucidates the multifaceted positive effects of PA on depression and its potential biological mechanisms with a particular emphasis on the roles of various exerkines. Future research may further investigate the effects of different types, intensities, and durations of PA on depression, as well as how to better integrate PA interventions into existing treatment strategies to achieve optimal outcomes in mental health interventions.

ProBDNF as a Myokine in Skeletal Muscle Injury: Role in Inflammation and Potential for Therapeutic Modulation of p75NTR

Brain-derived neurotropic factor (BDNF) is expressed by skeletal muscle as a myokine. Our previous work showed that the active precursor, proBDNF, is the predominant form of BDNF expressed in skeletal muscle, and that following skeletal muscle injury, proBDNF levels are significantly increased. However, the function of the muscle-derived proBDNF in injury-induced inflammation has yet to be fully understood. Using a model of tourniquet-induced ischemia-reperfusion (IR) injury of the hindlimb, this study presents, for the first time, strong and novel evidence that following IR injury, proBDNF is released from skeletal muscle into circulation as an endocrine signaling molecule. Further, this study shows that 1 day post-IR injury, the proBDNF receptor, p75NTR, is upregulated 12-fold in splenic monocytes, which are known to be quickly mobilized to the injury site. We demonstrate that p75NTR plays a role in the activation of splenic monocytes, and that treatment with a p75NTR small-molecule modulator, LM11A-31, significantly reduced monocyte inflammatory responses upon lipopolysaccharide stimulation. Overall, the present study establishes proBDNF as a myokine that plays a significant role in skeletal muscle injury-induced inflammation through its receptor, p75NTR, which may be modulated using LM11A-31 as potential translational therapeutic against injury and inflammation.

Causal association between sarcopenia and cognitive impairment contributes to the muscle-brain axis: A bidirectional Mendelian randomization study

AIM

There is a growing body of evidence suggesting a correlation between sarcopenia (SP) and cognitive impairment (CI), but with conflict. This study employed a bidirectional Mendelian randomization (MR) approach to ascertain the causality between SP and CI.

METHOD

This study looked at whether there might be causality between SP and CI by using a bidirectional MR analysis on the GWAS summary datasets, which anyone can publicly access. The primary analysis employed inverse variance weighting (IVW), with MR-Egger, weighted median, and mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) serving as supplements. Multiple sensitivity analyses were performed to enhance the stability of the results, which encompassed heterogeneity tests and pleiotropy tests.

RESULTS

Appendicular lean mass (ALM), walking pace (WP), and grip strength (GS) were found to be causally connected to cognitive performance in forward MR analysis. In the reverse MR study, cognitive performance also had a causal impact on ALM and WP. Additionally, we discovered comparable outcomes in the replication samples, which strengthens the validity of our findings.

CONCLUSIONS

The results of our MR investigation revealed a definitive cause-and-effect association between SP and CI. Our findings provide additional supporting evidence for the muscle-brain axis, which may suggest that muscle strengthening has a significant impact on the management and avoidance of CI. Geriatr Gerontol Int 2025; 25: 116-122.

Effects of traditional Chinese exercises on brain-derived neurotrophic factor in middle-aged and older adults: A systematic review and meta-analysis of randomized controlled trials

Background

Brain-derived neurotrophic factor (BDNF) may help middle-aged and older adults resist age-related neurodegenerative conditions and psychiatric disorders. Recent studies suggested that Traditional Chinese exercises (TCEs) may be a promising strategy to improve the BDNF levels of these populations, while the effectiveness has yet to be definitively confirmed due to the variances in the study designs and observations. Therefore, this systematic review and meta-analysis aimed to examine the effects of TCEs intervention on BDNF in middle-aged and older adults.

Methods

The search was conducted in November 2024 in seven Chinese and English databases. Two reviewers independently reviewed the search results, extracted the data, and assessed the risk of bias and certainty of evidence. Meta-analyses and meta-regressions were performed to determine the overall effect size and the impact of potential moderators.

Results

Ten publications consisting of 543 participants were included. The overall effect size of TCEs on BDNF was large and significant [Hedges'g = 0.82, 95 % CI (0.55, 1.09), p < 0.01]. Subgroup analysis revealed that the effect size was non-significant for participants with mild cognitive impairment (MCI) (p = 0.08), while significant for participants with normal cognitive function (p < 0.01). In the meta-regression, moderators such as the mean age, sex, and baseline BDNF levels of participants, as well as total TCEs time were not associated with outcome variables. The certainty of the evidence was assessed as moderate.

Conclusions

This systematic review and meta-analysis indicates that TCEs intervention could increase the levels of BDNF in middle-aged and older adults with normal cognitive function.

Systematic review registration

www.crd.york.ac.uk/PROSPERO/, identifier: CRD42023484121.

Borax attenuates oxidative stress, inflammation, and apoptosis by modulating Nrf2/ROS balance in acrylamide-induced neurotoxicity in rainbow trout

Acrylamide (ACR) can have adverse environmental effects because of its multiple applications. Relevant scientific literatures of the existence of ACR residues in foods following processing steps have raised concern in the biochemistry, chemistry and safety of this vinyl substance. The interest has focused on the hepatotoxicity of ACR in animals and humans and on the ACR content mitigation and its detoxification. Borax (BX), as a naturally occurring antioxidant featured boron compound, was selected in this investigation to assess its possible neuro-protective potential against ACR-induced neurotoxicity. Nrf2 axis signaling pathways and detoxification response to oxidative stress after exposure to ACR in brains of rainbow trout, and the effect of BX application on reducing ACR-induced neurotoxicity were investigated. Rainbow trout were acutely exposed to ACR (12.5 mg/L) alone or simultaneously treated with BX (0.75 mg/L) during 96h. The exposed fish were sampled at 48th and 96th and oxidative stress response endpoints, 8-OHdG, Nrf2, TNF-α, caspase-3, in addition to IL-6 activities and the levels of AChE and BDNF in brain tissues of rainbow trout (Oncorhynchus mykiss) were evaluated. Samples showed decreases in the levels of ACR-mediated biomarkers used to assess neural toxicity (SOD, CAT, GPx, AChE, BDNF, GSH), increased levels of MDA, MPO, DNA damage and apoptosis. ACR disrupted the Nrf2 pathway, and induced neurotoxicity. Inhibited activities' expressions under simultaneous administration experiments, revealed the protective effects of BX against ACR-induced toxicity damage. The obtained data allow the outline of early multi-parameter signaling pathways in rainbow trout.

Exercise training alters resting brain-derived neurotrophic factor concentration in older adults: A systematic review with meta-analysis of randomized-controlled trials

This systematic review with meta-analysis investigated the effects of exercise training on brain-derived neurotrophic factor (BDNF) in older adults. Electronic databases of PubMed, Web of Science and Scopus were searched for studies investigating the effect of exercise training ≥4 weeks on resting BDNF levels in older adults. A standardized mean difference (SMD) was generated through random effects model. Thirty-five randomized-controlled trials met the inclusion criteria. Exercise training significantly increased resting BDNF levels [SMD = 0.56 (95 % CI 0.28 to 0.85)] both in plasma (SMD = 0.63) and serum (SMD = 0.54). Regarding exercise modality, aerobic (SMD = 0.48), resistance (SMD = 0.76) and combined exercise training (SMD = 0.55) increased BDNF levels. Exercise training with the duration of 12 weeks (SMD =0.65), moderate-to-vigorous (SMD = 0.83) and vigorous intensity (SMD = 0.71), and 3-4 sessions per week frequency (SMD = 0.78) yielded the largest effects on BDNF elevation. Since BDNF represents a fundamental contribution in neuronal processes and is linked to brain health, exercise training may help delay aging-related neuro-degenerative processes. REGISTRATION NUMBER: CRD42024499195.

Molecular biomarkers of dysphagia targeted exercise induced neuroplasticity: A review of mechanistic processes and preliminary data on detraining effects

While molecular adaptations accompanying neuroplasticity during physical exercises are well-established, little is known about adaptations during dysphagia-targeted exercises. This research article has two primary purposes. First, we aim to review the existing literature on the intersection between resistance (strength) training, molecular markers of neuroplasticity, and dysphagia rehabilitation. Specifically, we discuss the molecular mechanisms of two potential molecular markers: brain-derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1) in exercise-induced neuroplasticity. Second, we present preliminary data on the effects of two weeks of detraining on circulating serum BDNF, IGF-1 levels, and expiratory muscle strength. This subset is a part of our more extensive studies related to dysphagia-targeted resistance exercise and neuroplasticity. Five young adult males underwent four weeks of expiratory muscle strength training, followed by two weeks of detraining. We measured expiratory strength, circulating levels of BDNF, and IGF-1 at post-training and detraining conditions. Our results show that expiratory muscle strength, serum BDNF, and IGF-1 levels decreased after detraining; however, this effect was statistically significant only for serum BDNF levels. Oropharyngeal and upper airway musculature involved in swallowing undergoes similar adaptation patterns to skeletal muscles during physical exercise. To fully comprehend the mechanisms underlying the potential neuroplastic benefits of targeted exercise on swallowing functions, mechanistic studies (models) investigating neuroplasticity induced by exercises addressing dysphagia are critical. Such models would ensure that interventions effectively and efficiently achieve neuroplastic benefits and improve patient outcomes, ultimately advancing our understanding of dysphagia-targeted exercise-induced neuroplasticity.

Rhoifolin, baicalein 5,6-dimethyl ether and agathisflavone prevent amnesia induced in scopolamine zebrafish (Danio rerio) model by increasing the mRNA expression of bdnf, npy, egr-1, nfr2α, and creb1 genes

The increasing attention towards age-related diseases has generated significant interest in the concept of cognitive dysfunction associated with Alzheimer's disease (AD). Certain limitations are associated with the current therapies, and flavonoids have been reported to exhibit multiple biological activities and anti-AD effects in several AD models owing to their antioxidative, anti-inflammatory, and anti-amyloidogenic properties. In this study, we performed an initial in silico predictions of the pharmacokinetic properties of three flavonoids (rhoifolin, baicalein 5,6-dimethyl ether and agathisflavone). Subsequently, we evaluated the antiamnesic and antioxidant potential of flavonoids in concentrations of 1, 3, and 5 μg/L in scopolamine (100 μM)-induced amnesic zebrafish (Danio rerio) model. Zebrafish behavior was analyzed by novel tank diving test (NTT), Y-maze, and novel object recognition test (NOR). Acetylcholinesterase (AChE) activity, brain antioxidant status and the expression of bdnf, npy, egr1, nrf2α, creb1 genes, and CREB-1 protein level was measured to elucidate the underlying mechanism of action. Our flavonoids improved memory and decreased anxiety-like behavior of scopolamine-induced amnesia in zebrafish. Also, the studied flavonoids reduced AChE activity and brain oxidative stress and upregulated the gene expression, collectively contributing to neuroprotective properties. The results of our study add new perspectives on the properties of flavonoids to regulate the evolution of neurodegenerative diseases, especially AD, by modulating the expression of genes involved in the regulation of synaptic plasticity, axonal growth, and guidance, sympathetic and vagal transmission, the antioxidant response and cell proliferation and growth.

Deficiency of muscle-generated brain-derived neurotrophic factor causes inflammatory myopathy through reactive oxygen species-mediated necroptosis and pyroptosis

Idiopathic inflammatory myopathy (commonly known as myositis) is a group of immune-related diseases characterized by muscle damage, weakness, and fatigue with unknown causes. Although overactivated innate immunity is a widely believed cause of myositis onset, the mechanism that provokes and maintains a high immune response in myositis patients is still unclear. This study aims to test if brain-derived neurotrophic factor (BDNF) deficiency per se is sufficient to cause myositis and determine its underlying mechanism. We found that ablating BDNF production in skeletal muscle is sufficient to trigger myositis development in mice. Muscle-specific Bdnf knockout (MBKO) mice displayed extensive myocyte necrosis, mononuclear cell infiltration, and myophagocytosis. In association with these damages, elevated production of pro-inflammatory cytokines such as interleukin (IL) 23, IL-1β, IL-18, and tumor necrosis factor α (TNFα) was found in the muscle of MBKO mice. Disruption of sarcolemma integrity was also detected in MBKO mice, which is a result of necroptosis executioner Mixed lineage kinase domain-like protein (MLKL) and pyroptosis executioner Gasdermin D (GSDMD) activation. Mechanistically, diminishing BDNF synthesis in myotubes enhances the accumulation of mitochondrial reactive oxygen species (mtROS), which sensitizes the cells towards TNFα-induced receptor-interacting protein kinase (RIPs) activation and promotes the formation of NLR family pyrin domain containing 3 (NLRP3)-containing inflammasome. BDNF deficiency-induced cell death could be alleviated by scavenging mtROS, suppressing the activity of GSDMD, or inhibiting receptor-interacting kinase 3 (RIP3). Similarly, supplementation of BDNF mimetics, suppression of RIP3 activity, increasing the intramyocellular antioxidant, or enhancing mitophagy ameliorated the myopathies of MBKO mice and improved their muscle strength. Together, our study demonstrates that insufficient BDNF production in mouse muscle causes the development of pathological features of myositis via enhancing oxidative stress, necroptosis, and pyroptosis in myofibers.

Effects of high intensity interval training on serum brain-derived neurotrophic factor in individuals with PTSD

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is a protein important for synaptic plasticity and formation of memory. It is suggested to play an important role in the development of psychiatric disorders like post-traumatic stress disorder (PTSD). Individuals with PTSD usually show decreased BDNF levels in serum. Physical exercise has shown to be effective in increasing serum BDNF levels.

OBJECTIVE

As the most beneficial form of exercise to raise serum BDNF levels in individuals with PTSD is yet to be determined, we compared two training protocols and their effects on BDNF release. We expected that a training with higher intensity increases BDNF serum levels more than a low intensity training (LIT).

METHOD

40 participants (80% female) diagnosed with PTSD were randomized to either high-intensity interval training (HIIT) or a low intensity training group (LIT). They underwent a 12-day training period. We measured serum BDNF levels pre- and post-exercise on first and last intervention day. BDNF was controlled for platelet counts.

RESULTS

In the HIIT group there was a significant increase in serum BDNF post-exercise on both days measured, respectively when controlled for platelets. The increase was transient. Both groups did not show an increase in serum BDNF over the course of the 12-day training period.

CONCLUSION

A single session of HIIT raised serum BDNF levels in individuals with PTSD transiently. Neither HIIT nor LIT raised serum BDNF levels over the course of 12 days.

Identification of key genes and signaling pathways based on transcriptomic studies of aerobic and resistance training interventions in sarcopenia in SAMP8 mice

We examined the effects of resistance and aerobic exercise on the gene expression and biometabolic processes of aging skeletal muscle in senescence-accelerated mouse/prone 8 mice, a model of sarcopenia, and compared them with senescence-accelerated mouse/resistant 1 mice acting as controls. We found that exercise improved muscle strength, endurance, fiber size, also modulated genes and pathways related to synaptic transmission, potassium transport, JAK-STAT signaling, and PI3K-Akt signaling. Our results suggested that BDNF, JAK2, RhoC, Myh6, Stat5a, Tnnc1, and other genes may mediate the beneficial effects of exercise on sarcopenia through these pathways.

Brain-Derived neurotrophic factor and inflammatory biomarkers are unaffected by acute and chronic intermittent hypoxic-hyperoxic exposure in geriatric patients: a randomized controlled trial

BACKGROUND

Animal and human studies have shown that exposure to hypoxia can increase brain-derived neurotrophic factor (BDNF) protein transcription and reduce systematic inflammatory cytokine response. Therefore, the aim of this study was to investigate the acute and chronic effects of intermittent hypoxic-hyperoxic exposure (IHHE) prior to aerobic exercise on BDNF, interleukin-6 (IL-6), and C-reactive protein (CRP) blood levels in geriatric patients.

PATIENTS AND METHODS

Twenty-five geriatric patients (83.1 ± 5.0 yrs, 71.1 ± 10.0 kg, 1.8 ± 0.9 m) participated in a placebo-controlled, single-blinded trial and were randomly assigned to either an intervention (IG) or control group (CG) performing an aerobic cycling training (17 sessions, 20 min·session-1, 3 sessions·week-1). Prior to aerobic cycling exercise, the IG was additionally exposed to IHHE for 30 min, whereas the CG received continuous normoxic air. Blood samples were taken immediately before (pre-exercise) and 10 min (post-exercise) after the first session as well as 48 h (post-training) after the last session to determine serum (BDNFS) and plasma BDNF (BDNFP), IL-6, and CRP levels. Intervention effects were analyzed using a 2 x 2 analysis of covariance with repeated measures. Results were interpreted based on effect sizes with a medium effect considered as meaningful (ηp2 ≥ 0.06, d ≥ 0.5).

RESULTS

CRP was moderately higher (d = 0.51) in the CG compared to the IG at baseline. IHHE had no acute effect on BDNFS (ηp2 = 0.01), BDNFP (ηp2 < 0.01), BDNF serum/plasma-ratio (ηp2 < 0.01), IL-6 (ηp2 < 0.01), or CRP (ηp2 = 0.04). After the 6-week intervention, an interaction was found for BDNF serum/plasma-ratio (ηp2 = 0.06) but not for BDNFS (ηp2 = 0.04), BDNFP (ηp2 < 0.01), IL-6 (ηp2 < 0.01), or CRP (ηp2 < 0.01). BDNF serum/plasma-ratio increased from pre-exercise to post-training (d = 0.67) in the CG compared to the IG (d = 0.51). A main effect of time was found for BDNFP (ηp2 = 0.09) but not for BDNFS (ηp2 = 0.02). Within-group post-hoc analyses revealed a training-related reduction in BDNFP in the IG and CG by 46.1% (d = 0.73) and 24.7% (d = 0.57), respectively.

CONCLUSION

The addition of 30 min IHHE prior to 20 min aerobic cycling seems not to be effective to increase BDNFS and BDNFP or to reduce IL-6 and CRP levels in geriatric patients after a 6-week intervention.The study was retrospectively registered at drks.de (DRKS-ID: DRKS00025130).

Acute Effects of High-Intensity Resistance Exercise on Recognition of Relational Memory, Lactate, and Serum and Plasma Brain-Derived Neurotrophic Factor

ABSTRACT

Baumgartner, NW, Belbis, MD, Kargl, C, Holmes, MJ, Gavin, TP, Hirai, DM, and Kao, S-C. Acute effects of high-intensity resistance exercise on recognition of relational memory, lactate, and serum and plasma brain-derived neurotrophic factor. J Strength Cond Res 38(11): 1867-1878, 2024-Acute aerobic exercise improves memory, but this phenomenon is understudied in response to resistance exercise (RE) despite evidence that RE-induced increases in lactate and brain-derived neurotrophic factor (BDNF) play mechanistic roles in memory performance. To determine the acute effect of RE on lactate, BDNF, and their associations with object and relational memory, blood lactate, and serum and plasma BDNF were taken from 36 adults (average age 23.64 ± 3.89 years; 18 woman) before and immediately after 42 minutes of high-intensity RE and a rest condition on counterbalanced days. Subjects then immediately studied a series of paired objects and completed object and relational recognition tasks. Results revealed a condition by trial interaction, previously studied objects were remembered less accurately following RE ( d = 0.66) but recognition occurred faster ( d = 0.28), indicating a speed-accuracy tradeoff following RE. There was no effect of either intervention on relational recognition performance. Lactate ( d = 3.68) and serum BDNF ( d = 0.74) increased following RE, whereas there was no time-related change in lactate and serum BDNF following rest. However, changes in lactate and BDNF did not predict any measures of object ( rs < 0.25, p s > 0.16) or relation recognition ( rs < 0.28, p s > 0.13). Collectively, these findings suggest that acute high-intensity RE selectively improves the processing speed of recognizing objects at the cost of less accurate recognition of previously studied objects. Furthermore, changes in object and relational memory performance are unlikely driven by acute increases in lactate or BDNF following high-intensity RE.

Research Progress on the Effects of Different Exercise Modes on the Secretion of Exerkines After Spinal Cord Injury

Exercise training is a conventional treatment strategy throughout the entire treatment process for patients with spinal cord injury (SCI). Currently, exercise modalities for SCI patients primarily include aerobic exercise, endurance training, strength training, high-intensity interval training, and mind-body exercises. These exercises play a positive role in enhancing skeletal muscle function, inducing neuroprotection and regeneration, thereby influencing neural plasticity, reducing limb spasticity, and improving motor function and daily living abilities in SCI patients. However, the mechanism by which exercise training promotes functional recovery after SCI is still unclear, and there is no consensus on a unified and standardized exercise treatment plan. Different exercise methods may bring different benefits. After SCI, patients' physical activity levels decrease significantly due to factors such as motor dysfunction, which may be a key factor affecting changes in exerkines. The changes in exerkines of SCI patients caused by exercise training are an important and highly relevant and visual evaluation index, which may provide a new research direction for revealing the intrinsic mechanism by which exercise promotes functional recovery after SCI. Therefore, this article summarizes the changes in the expression of common exerkines (neurotrophic factors, inflammatory factors, myokines, bioactive peptides) after SCI, and intends to analyze the impact and role of different exercise methods on functional recovery after SCI from the perspective of exerkines mechanism. We hope to provide theoretical basis and data support for scientific exercise treatment programs after SCI.

Exercise, Neuroprotective Exerkines, and Parkinson's Disease: A Narrative Review

Parkinson's disease (PD) is a prevalent neurodegenerative disease in which treatment often includes an exercise regimen. Exercise is neuroprotective in animal models of PD, and, more recently, human clinical studies have verified exercise's disease-modifying effect. Aerobic exercise and resistance training improve many of PD's motor and non-motor symptoms, while neuromotor therapy and stretching/flexibility exercises positively contribute to the quality of life in people with PD. Therefore, understanding the role of exercise in managing this complex disorder is crucial. Exerkines are bioactive substances that are synthesized and released during exercise and have been implicated in several positive health outcomes, including neuroprotection. Exerkines protect neuronal cells in vitro and rodent PD models in vivo. Aerobic exercise and resistance training both increase exerkine levels in the blood, suggesting a role for exerkines in the neuroprotective theory. Many exerkines demonstrate the potential for protecting the brain against pathological missteps caused by PD. Every person (people) with Parkinson's (PwP) needs a comprehensive exercise plan tailored to their unique needs and abilities. Here, we provide an exercise template to help PwP understand the importance of exercise for treating PD, describe barriers confronting many PwP in their attempt to exercise, provide suggestions for overcoming these barriers, and explore the role of exerkines in managing PD. In conclusion, exercise and exerkines together create a powerful neuroprotective system that should contribute to slowing the chronic progression of PD.

Role of Cardiorespiratory Fitness, Aerobic, Exercise and Sports Participation in Female Cognition: A Scoping Review : Sports, Fitness, and Cognition

BACKGROUND

The impact of cardiorespiratory fitness (CRF) on cognition is thought to be mediated by brain-derived neurotrophic factor. Aerobic exercise can increase CRF through various activities, including sports participation. The relationship between these factors in females has yet to be elucidated.

OBJECTIVE

This review aims to map the current literature on the effects of aerobic exercise, sports participation, and CRF in healthy adult females, with sub-topics of pregnancy and menstrual cycle periodicity.

METHODS

A scoping review of the literature was conducted following PRISMA guidelines and the PCC mnemonic (population, concept, and context). The following five databases were screened: CINAHL, Medline, Web of Science, SPORTDiscus, and Scopus. Eligible articles included healthy adult females, investigated aerobic exercise, sports participation or CRF, and linked outcomes to cognition. Data from included manuscripts was extracted and analyzed. Two sub-population groupings (pregnant individuals and menstrual cycle) were established to further aid the interpretation of the findings.

RESULTS

Of the 300 titles and abstracts screened, 74 were eligible for full-text screening, and 28 were included in the scoping review. Of the 28 included, 14 did not control for or report on menstrual cycle phase or sex hormones.

CONCLUSION

This scoping review found an inverse 'U' relationship between aerobic exercise and cognition, demonstrating an optimal dose of aerobic exercise to benefit cognitive functions. As estrogen may impact the relationship between CRF and neural growth factors, more research is needed on this pathway, independent of the menstrual cycle, to determine potential beneficial effects. It is currently unknown whether sports participation can independently impact cognition.

How Can Promoting Skeletal Muscle Health and Exercise in Children and Adolescents Prevent Insulin Resistance and Type 2 Diabetes?

Skeletal muscle secretome, through its paracrine and endocrine functions, contributes to the maintenance and regulation of overall physiological health. We conducted a narrative review on the role of skeletal muscle and exercise in maintaining glucose homeostasis, driving insulin resistance (IR), and preventing type 2 diabetes in pediatric populations, especially in the context of overweight and obesity. Myokines such as interleukin (IL)-6, IL-8, and IL-15, as well as irisin, myonectin, and myostatin, appear to play a crucial role in IR. Skeletal muscle can also become a target of obesity-induced and IR-induced inflammation. In the correlation between muscle, IR, and inflammation, the role of infiltration of the immune cells and the microvasculature may also be considered. It remains unclear which exercise approach is the best; however, combining aerobic exercise with resistance training seems to be the most effective strategy for managing IR, with high-intensity activities offering superior metabolic benefits and long-term adherence. Encouraging daily participation in enjoyable and engaging exercise is key for long-term commitment and effective glucose metabolism management. Promoting physical activity in children and adolescents must be a top priority for public health, not only in terms of individual quality of life and well-being but also for community health.

From Brain to Muscle: The Role of Muscle Tissue in Neurodegenerative Disorders

Neurodegenerative diseases (NDs), like amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), and Parkinson's disease (PD), primarily affect the central nervous system, leading to progressive neuronal loss and motor and cognitive dysfunction. However, recent studies have revealed that muscle tissue also plays a significant role in these diseases. ALS is characterized by severe muscle wasting as a result of motor neuron degeneration, as well as alterations in gene expression, protein aggregation, and oxidative stress. Muscle atrophy and mitochondrial dysfunction are also observed in AD, which may exacerbate cognitive decline due to systemic metabolic dysregulation. PD patients exhibit muscle fiber atrophy, altered muscle composition, and α-synuclein aggregation within muscle cells, contributing to motor symptoms and disease progression. Systemic inflammation and impaired protein degradation pathways are common among these disorders, highlighting muscle tissue as a key player in disease progression. Understanding these muscle-related changes offers potential therapeutic avenues, such as targeting mitochondrial function, reducing inflammation, and promoting muscle regeneration with exercise and pharmacological interventions. This review emphasizes the importance of considering an integrative approach to neurodegenerative disease research, considering both central and peripheral pathological mechanisms, in order to develop more effective treatments and improve patient outcomes.

Exercise-Induced cytokines, diet, and inflammation and their role in adipose tissue metabolism

BACKGROUND

Obesity poses a significant global health challenge, necessitating effective prevention and treatment strategies. Exercise and diet are recognized as pivotal interventions in combating obesity. This study reviews the literature concerning the impact of exercise-induced cytokines, dietary factors, and inflammation on adipose tissue metabolism, shedding light on potential pathways for therapeutic intervention.

METHODOLOGY

A comprehensive review of relevant literature was conducted to elucidate the role of exercise-induced cytokines, including interleukin-6 (IL-6), interleukin-15 (IL-15), brain-derived neurotrophic factor (BDNF), irisin, myostatin, fibroblast growth factor 21 (FGF21), follistatin (FST), and angiopoietin-like 4 (ANGPTL4), in adipose tissue metabolism. Various databases were systematically searched using predefined search terms to identify relevant studies. Articles selected for inclusion underwent thorough analysis to extract pertinent data on the mechanisms underlying the influence of these cytokines on adipose tissue metabolism.

RESULTS AND DISCUSSION

Exercise-induced cytokines exert profound effects on adipose tissue metabolism, influencing energy expenditure (EE), thermogenesis, fat loss, and adipogenesis. For instance, IL-6 activates AMP-activated protein kinase (AMPK), promoting fatty acid oxidation and reducing lipogenesis. IL-15 upregulates peroxisome proliferator-activated receptor delta (PPARδ), stimulating fatty acid catabolism and suppressing lipogenesis. BDNF enhances AMPK-dependent fat oxidation, while irisin induces the browning of white adipose tissue (WAT), augmenting thermogenesis. Moreover, myostatin, FGF21, FST, and ANGPTL4 each play distinct roles in modulating adipose tissue metabolism, impacting factors such as fatty acid oxidation, adipogenesis, and lipid uptake. The elucidation of these pathways offers valuable insights into the complex interplay between exercise, cytokines, and adipose tissue metabolism, thereby informing the development of targeted obesity management strategies.

CONCLUSION

Understanding the mechanisms by which exercise-induced cytokines regulate adipose tissue metabolism is critical for devising effective obesity prevention and treatment modalities. Harnessing the therapeutic potential of exercise-induced cytokines, in conjunction with dietary interventions, holds promise for mitigating the global burden of obesity. Further research is warranted to delineate the precise mechanisms underlying the interactions between exercise, cytokines, and adipose tissue metabolism.

Myokines: A central point in managing redox homeostasis and quality of life

Redox homeostasis is a crucial phenomenon that is obligatory for maintaining the healthy status of cells. However, the loss of redox homeostasis may lead to numerous diseases that ultimately result in a compromised quality of life. Skeletal muscle is an endocrine organ that secretes hundreds of myokines. Myokines are peptides and cytokines produced and released by muscle fibers. Skeletal muscle secreted myokines act as a robust modulator for regulating cellular metabolism and redox homeostasis which play a prime role in managing and improving metabolic function in multiple organs. Further, the secretory myokines maintain redox homeostasis not only in muscles but also in other organs of the body via stabilizing oxidants and antioxidant levels. Myokines are also engaged in maintaining mitochondrial dynamics as mitochondria is a central point for the generation of reactive oxygen species (ROS). Ergo, myokines also act as a central player in communicating signals to other organs, including the pancreas, gut, liver, bone, adipose tissue, brain, and skin via their autocrine, paracrine, or endocrine effects. The present review provides a comprehensive overview of skeletal muscle-secreted myokines in managing redox homeostasis and quality of life. Additionally, probable strategies will be discussed that provide a solution for a better quality of life.

Levels of biomarkers associated with subconcussive head hits in mixed martial arts fighters

Background

Concussion and the damage resulting from this event related to brain function have been widely studied; however, little is known about subconcussive impacts, especially in Mixed Martial Arts (MMA) fighters, which is a combat and full contact sport in which most blows are aimed at the head.

Objective

This study aims to evaluate the biomarker levels associated with subconcussive hits to the head in MMA fighters.

Methods

This is an exploratory study in which 30 male subjects (10 MMA fighters, 10 healthy individuals who practice muscle training, and 10 healthy sedentary individuals) aged between 18 and 32 years (25.4 ± 3.8) were evaluated. These individuals underwent blood collection to assess their Ubiquitin C-terminal hydrolase (UCH-L1), Glial Fibrillary Acidic Protein (GFAP) and Brain Derived Neurotrophic Factor (BDNF) levels before, immediately after and 72 hours after the sparring session (for the fighters) and were compared between groups.

Results

Significant differences were found at baseline between active and healthy fighters in BDNF levels (p = 0.03). A significant reduction of BDNF levels were also observed between the post-immediate and 72h after the sparring session (p = 0.03). No differences were observed in the number or severity of symptoms reported by the fighters.

Conclusion

Despite the exploratory approach, the findings of this study may help to understand the influence of repeated subconcussive hits to the head in MMA fighters, as well as to propose preventive interventions which can minimize the effects of the impact of hits, preserving fighters' neuronal integrity and function.

The Role of Central and Peripheral Brain-Derived Neurotrophic Factor (BDNF) as a Biomarker of Anorexia Nervosa Reconceptualized as a Metabo-Psychiatric Disorder

Neurotrophic factors play pivotal roles in shaping brain development and function, with brain-derived neurotrophic factor (BDNF) emerging as a key regulator in various physiological processes. This review explores the intricate relationship between BDNF and anorexia nervosa (AN), a complex psychiatric disorder characterized by disordered eating behaviors and severe medical consequences. Beginning with an overview of BDNF's fundamental functions in neurodevelopment and synaptic plasticity, the review delves into recent clinical and preclinical evidence implicating BDNF in the pathophysiology of AN. Specifically, it examines the impact of BDNF polymorphisms, such as the Val66Met variant, on AN susceptibility, prognosis, and treatment response. Furthermore, the review discusses the interplay between BDNF and stress-related mood disorders, shedding light on the mechanisms underlying AN vulnerability to stress events. Additionally, it explores the involvement of BDNF in metabolic regulation, highlighting its potential implications for understanding the metabolic disturbances observed in AN. Through a comprehensive analysis of clinical data and animal studies, the review elucidates the nuanced role of BDNF in AN etiology and prognosis, emphasizing its potential as a diagnostic and prognostic biomarker. Finally, the review discusses limitations and future directions in BDNF research, underscoring the need for further investigations to elucidate the complex interplay between BDNF signaling and AN pathology.

PRG ameliorates cognitive impairment in Alzheimer's disease mice by regulating β-amyloid and targeting the ERK pathway

BACKGROUND

PRG is derived from Phellinus ribis and is a homogeneous polysaccharide with well-defined structural information. PRG was found to have significant in vitro neurotrophic and neuroprotective activities. Thus, PRG might be a potential treatment for Alzheimer's disease. However, the related mechanisms of action are still unclear, so deeper in vivo experimental validation and the potential mechanisms need to be investigated.

PURPOSE

The effects of PRG on AD mice were investigated using Senescence-accelerated SAMP8 mice as an AD model to elucidate the crucial molecular mechanisms.

METHODS

PRG was obtained from Phellinus ribis by water-alcohol precipitation, column chromatography, and ultrafiltration. The Morris water maze and novel object recognition behavioral assays were used to evaluate the effects of PRG in AD mice. Nissl staining, the TUNEL apoptosis assay, and Golgi staining were used to assess brain neuronal cell damage, apoptosis, and neuronal status. Enzyme-linked immunosorbent assays, Western blotting, and immunofluorescence were used to explore the impacts of correlated factors and protein pathways under relevant mechanisms.

RESULTS

The findings suggest that PRG improved learning ability and spatial memory capacity in SAMP8 mice. PRG hastened the disintegration of β-amyloid, reduced the content and abnormal accumulation of the toxic Aβ1-42 protein, and decreased apoptosis. PRG activated the BDNF/ERK/CREB signaling pathway through a cascade, exerted neurotrophic effects, regulated cell proliferation and differentiation, increased neuronal dendritic branching and spine density, and improved synaptic plasticity.

CONCLUSION

PRG promoted β-amyloid degradation to reduce neuronal damage and apoptosis. It exerted neurotrophic effects by activating the BDNF/ERK/CREB pathway, promoting neuronal dendritic branching and dendritic spine growth, regulating cell proliferation and differentiation, and improving synaptic plasticity, which improved AD. Taken together, as a novel natural active polysaccharide with a well-defined structure, PRG affected AD symptoms in senescence-accelerated mice by interacting with multiple targets. The results indicate that PRG is a promising potential anti-AD drug candidate.

Impact of Acute High-intensity Interval Training on Cortical Excitability, M1-related Cognitive Functions, and Myokines: A Randomized Crossover Study

High-intensity interval training (HIIT) is a time-efficient, safe, and feasible exercise type that can be utilized across different ages and health status. This randomized cross-over study aimed to investigate the effect of acute HIIT on cortical excitability, M1-related cognitive functions, cognition-related myokines, brain-derived neurotrophic factor (BDNF), and Cathepsin B (CTSB). Twenty-three sedentary young adults (mean age: 22.78 years ± 2.87; 14 female) participated in a cross-over design involving two sessions: either 23 min of HIIT or seated rest. Before and after the sessions, cortical excitability was measured using transcranial magnetic stimulation, and M1-related cognitive functions were assessed by the n-back test and mental rotation test. Serum levels of BDNF and CTSB were assessed using the ELISA method before and after the HIIT intervention. We demonstrated that HIIT improved mental rotation and working memory, and increased serum levels of BDNF and CTSB, whereas cortical excitability did not change. Our findings provide evidence that one session of HIIT is effective on M1-related cognitive functions and cognition-related myokines. Future research is warranted to determine whether such findings are transferable to different populations, such as cognitively at-risk children, adults, and older adults, and to prescribe effective exercise programs.

BDNF/TrkB signalling, in cooperation with muscarinic signalling, retrogradely regulates PKA pathway to phosphorylate SNAP-25 and Synapsin-1 at the neuromuscular junction

BACKGROUND

Protein kinase A (PKA) enhances neurotransmission at the neuromuscular junction (NMJ), which is retrogradely regulated by nerve-induced muscle contraction to promote Acetylcholine (ACh) release through the phosphorylation of molecules involved in synaptic vesicle exocytosis (SNAP-25 and Synapsin-1). However, the molecular mechanism of the retrograde regulation of PKA subunits and its targets by BDNF/TrkB pathway and muscarinic signalling has not been demonstrated until now. At the NMJ, retrograde control is mainly associated with BDNF/TrkB signalling as muscle contraction enhances BDNF levels and controls specific kinases involved in the neurotransmission. Neurotransmission at the NMJ is also highly modulated by muscarinic receptors M1 and M2 (mAChRs), which are related to PKA and TrkB signallings. Here, we investigated the hypothesis that TrkB, in cooperation with mAChRs, regulates the activity-dependent dynamics of PKA subunits to phosphorylate SNAP-25 and Synapsin-1.

METHODS

To explore this, we stimulated the rat phrenic nerve at 1Hz (30 minutes), with or without subsequent contraction (abolished by µ-conotoxin GIIIB). Pharmacological treatments were conducted with the anti-TrkB antibody clone 47/TrkB for TrkB inhibition and exogenous h-BDNF; muscarinic inhibition with Pirenzepine-dihydrochloride and Methoctramine-tetrahydrochloride for M1 and M2 mAChRs, respectively. Diaphragm protein levels and phosphorylation' changes were detected by Western blotting. Location of the target proteins was demonstrated using immunohistochemistry.

RESULTS

While TrkB does not directly impact the levels of PKA catalytic subunits Cα and Cβ, it regulates PKA regulatory subunits RIα and RIIβ, facilitating the phosphorylation of critical exocytotic targets such as SNAP-25 and Synapsin-1. Furthermore, the muscarinic receptors pathway maintains a delicate balance in this regulatory process. These findings explain the dynamic interplay of PKA subunits influenced by BDNF/TrkB signalling, M1 and M2 mAChRs pathways, that are differently regulated by pre- and postsynaptic activity, demonstrating the specific roles of the BDNF/TrkB and muscarinic receptors pathway in retrograde regulation.

CONCLUSION

This complex molecular interplay has the relevance of interrelating two fundamental pathways in PKA-synaptic modulation: one retrograde (neurotrophic) and the other autocrine (muscarinic). This deepens the fundamental understanding of neuromuscular physiology of neurotransmission that gives plasticity to synapses and holds the potential for identifying therapeutic strategies in conditions characterized by impaired neuromuscular communication.

Molecular Adaptations of BDNF/NT-4 Neurotrophic and Muscarinic Pathways in Ageing Neuromuscular Synapses

Age-related conditions, such as sarcopenia, cause physical disabilities for an increasing section of society. At the neuromuscular junction, the postsynaptic-derived neurotrophic factors brain-derived neurotrophic factor (BDNF) and neurotrophin 4 (NT-4) have neuroprotective functions and contribute to the correct regulation of the exocytotic machinery. Similarly, presynaptic muscarinic signalling plays a fundamental modulatory function in this synapse. However, whether or not these signalling pathways are compromised in ageing neuromuscular system has not yet been analysed. The present study analyses, through Western blotting, the differences in expression and activation of the main key proteins of the BDNF/NT-4 and muscarinic pathways related to neurotransmission in young versus ageing Extensor digitorum longus (EDL) rat muscles. The main results show an imbalance in several sections of these pathways: (i) a change in the stoichiometry of BDNF/NT-4, (ii) an imbalance of Tropomyosin-related kinase B receptor (TrkB)-FL/TrkB-T1 and neurotrophic receptor p 75 (p75NTR), (iii) no changes in the cytosol/membrane distribution of phosphorylated downstream protein kinase C (PKC)βI and PKCε, (iv) a reduction in the M2-subtype muscarinic receptor and P/Q-subtype voltage-gated calcium channel, (v) an imbalance of phosphorylated mammalian uncoordinated-18-1 (Munc18-1) (S313) and synaptosomal-associated protein 25 (SNAP-25) (S187), and (vi) normal levels of molecules related to the management of acetylcholine (Ach). Based on this descriptive analysis, we hypothesise that these pathways can be adjusted to ensure neurotransmission rather than undergoing negative alterations caused by ageing. However, further studies are needed to assess this hypothetical suggestion. Our results contribute to the understanding of some previously described neuromuscular functional age-related impairments. Strategies to promote these signalling pathways could improve the neuromuscular physiology and quality of life of older people.

Effects of Exercise-Induced Changes in Myokine Expression on the Tumor Microenvironment

In this narrative review, we summarize the direct and indirect effects that myokines have on the tumor microenvironment. We took studies of various cancer types and species into account. Systematic reviews and meta-analyses that matched the search terms were also considered. We searched databases for six months. As a narrative approach was chosen, no data was analyzed or reanalyzed. The goal of this narrative review is to create an overview on the topic to identify research gaps and answer the questions as to whether myokine expression may be relevant in cancer research in regard to the tumor microenvironment. Six commonly known myokines were chosen. We found strong links between the influence exercise has on interleukin-6, oncostatin M, secreted protein acidic and rich in cysteine, and irisin in the context of tumor progression and inhibition via interactions with the tumor microenvironment. It became clear that the effects of myokines on the tumor microenvironment can vary and contribute to disease progression or regression. Interactions among myokines and immune cells must also be considered and require further investigation. To date, no study has shown a clear connection, while multiple studies suggest further investigation of the topic, similar to the effects of exercise on myokine expression.

Mechanisms Underlying the Rarity of Skeletal Muscle Cancers

Skeletal muscle (SKM), despite comprising ~40% of body mass, rarely manifests cancer. This review explores the mechanisms that help to explain this rarity, including unique SKM architecture and function, which prohibits the development of new cancer as well as negates potential metastasis to SKM. SKM also presents a unique immune environment that may magnify the anti-tumorigenic effect. Moreover, the SKM microenvironment manifests characteristics such as decreased extracellular matrix stiffness and altered lactic acid, pH, and oxygen levels that may interfere with tumor development. SKM also secretes anti-tumorigenic myokines and other molecules. Collectively, these mechanisms help account for the rarity of SKM cancer.

Myokines: metabolic regulation in obesity and type 2 diabetes

Skeletal muscle plays a vital role in the regulation of systemic metabolism, partly through its secretion of endocrine factors which are collectively known as myokines. Altered myokine levels are associated with metabolic diseases, such as type 2 diabetes (T2D). The significance of interorgan crosstalk, particularly through myokines, has emerged as a fundamental aspect of nutrient and energy homeostasis. However, a comprehensive understanding of myokine biology in the setting of obesity and T2D remains a major challenge. In this review, we discuss the regulation and biological functions of key myokines that have been extensively studied during the past two decades, namely interleukin 6 (IL-6), irisin, myostatin (MSTN), growth differentiation factor 11 (GDF11), fibroblast growth factor 21 (FGF21), apelin, brain-derived neurotrophic factor (BDNF), meteorin-like (Metrnl), secreted protein acidic and rich in cysteine (SPARC), β-aminoisobutyric acid (BAIBA), Musclin, and Dickkopf 3 (Dkk3). Related to these, we detail the role of exercise in myokine expression and secretion together with their contributions to metabolic physiology and disease. Despite significant advancements in myokine research, many myokines remain challenging to measure accurately and investigate thoroughly. Hence, new research techniques and detection methods should be developed and rigorously tested. Therefore, developing a comprehensive perspective on myokine biology is crucial, as this will likely offer new insights into the pathophysiological mechanisms underlying obesity and T2D and may reveal novel targets for therapeutic interventions.