Apelin-13 Improves Cognitive Impairment and Repairs Hippocampal Neuronal Damage by Activating PGC-1α/PPARγ Signaling

Exercise-mediated muscle-hypothalamus crosstalk: Improvement for cognitive dysfunction caused by disrupted circadian rhythm

In contemporary societal evolution, the increasing disruption of the natural sleep-wake cycle, attributable to factors such as shift work and overexposure to artificial light, has been paralleled by a marked escalation in the incidence of cognitive impairments and the prevalence of neurodegenerative diseases. Current management strategies for cognitive impairments include pharmacological and non-pharmacological interventions. Pharmacological interventions for cognitive impairments typically involve medications to manage cognitive symptoms and improve neurological functions. However, these drugs show limited long-term efficacy in slowing disease progression and may cause side effects. Given the widespread occurrence of cognitive dysfunction, it is crucial to develop accessible non-pharmacological interventions. Physical activity and exercise have emerged as pivotal lifestyle determinants known to exert a modulatory effect on the risk profile for cognitive dysfunction caused by disrupted circadian rhythms. The skeletal muscle, a dynamic tissue, undergoes a profound morphological and metabolic reconfiguration in response to physical exertion, along with the secretion of myokines. Additionally, the hypothalamus, particularly the ventromedial nuclei, arcuate nuclei, and the suprachiasmatic nucleus, have crucial functions in regulating physical activity, influencing energy metabolism, and managing circadian cycles. Nevertheless, the communication between the hypothalamus and skeletal muscle during exercise is not fully understood. This narrative review integrates current knowledge on the interaction between the hypothalamus and skeletal muscle during exercise, emphasizing its neuroendocrine effects and potential therapeutic implications for alleviating cognitive dysfunction associated with disrupted circadian rhythms.

Gut microbiota regulation by Lactiplantibacillus plantarum SG5 enhances mitochondrial function in Parkinson's disease mice via the GLP-1/PGC-1α pathway

Motor dysfunction constitutes a prominent characteristic of Parkinson's disease (PD), a neurodegenerative disorder associated with compromised mitochondrial activity, perturbed gut microbial composition, and neuronal loss. In this study, we examined the regulatory mechanisms of Lactiplantibacillus plantarum SG5 (SG5) on mitochondrial function in PD mouse models, with a particular emphasis on its interaction with the GLP-1/PGC-1α pathway. Findings revealed that MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, MPTP) induced (male 6-8 weeks C57BL/6 mice) motor impairments and damage to dopaminergic (DA) neurons in PD mice, resulting in mitochondrial dysfunction, decreased mitochondrial biogenesis, disrupted dynamics, and autophagy, while promoting fission and apoptosis. Additionally, MPTP modified gut microbial diversity and community structure. Nevertheless, supplementation with SG5 alleviated motor deficits and DA neurons damage in PD mice, enhancing mitochondrial quality by elevating PGC-1α expression and restoring biogenesis, dynamics, and autophagy levels. Mechanistic investigations demonstrated that SG5 increased colonic GLP-1 expression, suggesting that GLP-1 might regulate mitochondrial function via the GLP-1R-mediated PGC-1α. Furthermore, SG5 counteracted MPTP-induced gut dysbiosis. Notably, both GLP-1R antagonists and PGC-1α inhibitors attenuated the protective effects of SG5 in PD mice. In conclusion, L. plantarum SG5 may enhance mitochondrial function in the substantia nigra (SN) of PD mice through the GLP-1/PGC-1α pathway, potentially delaying neurodegeneration. Its mechanism is closely related to the regulation of the gut microenvironment and GLP-1 levels, presenting novel microbiota-based therapeutic targets for PD.

Apelin-13 enhances neurofunctional recovery and suppresses neuroinflammation via the SIRT1/NF-κB axis in ischemic stroke

BACKGROUND

Ischemic stroke is a major cause of mortality and disability, with neuroinflammation driving secondary brain injury. Microglial activation contributes to neuronal apoptosis, BBB disruption, and prolonged neurological deficits. Apelin-13, an endogenous peptide, has demonstrated neuroprotective potential, but its precise mechanisms remain unclear. This study investigates how Apelin-13 modulates neuroinflammation and the molecular pathways involved in ischemic stroke.

METHODS

Mice underwent middle cerebral artery occlusion-reperfusion (MCAO/R) to model ischemic stroke, followed by Apelin-13 administration. Neurological function was assessed using Garcia scoring, adhesive removal, rotarod, and grid-walking tests. Infarct volume was quantified via TTC staining, and MRI evaluated cerebral edema. Immunofluorescence staining and Western blotting were used to assess neuronal apoptosis and BBB integrity. Microglial activation and polarization were analyzed via Iba1 co-immunostaining with CD16 (pro-inflammatory) and Arg1 (anti-inflammatory) markers. In vitro, primary microglia and BV2 cells were exposed to oxygen-glucose deprivation (OGD) to mimic ischemia, and Apelin-13's effects on inflammatory signaling were examined. The role of the SIRT1/NF-κB axis was evaluated using the SIRT1 inhibitor EX-527.

RESULTS

Apelin-13 significantly improved post-stroke neurological function, reduced infarct volume, and alleviated cerebral edema. It preserved BBB integrity by reducing vascular leakage and albumin extravasation and suppressed neuronal apoptosis by downregulating cleaved caspase-3. Apelin-13 also mitigated neuroinflammation by decreasing microglial activation and shifting polarization toward an anti-inflammatory phenotype, as evidenced by reduced CD16+ and increased Arg1+ microglia. In vitro, Apelin-13 suppressed OGD-induced pro-inflammatory cytokine release while promoting anti-inflammatory responses. Mechanistically, Apelin-13 upregulated SIRT1, inhibiting NF-κB signaling and reducing inflammatory mediator expression. SIRT1 inhibition with EX-527 reversed these effects, restoring NF-κB activation and pro-inflammatory microglial polarization.

CONCLUSIONS

Apelin-13 exerts neuroprotective effects in ischemic stroke by preserving BBB integrity, reducing neuronal apoptosis, and suppressing neuroinflammation. These effects are mediated through SIRT1 activation and NF-κB inhibition. Targeting the Apelin-13/SIRT1/NF-κB axis may offer a promising therapeutic strategy for mitigating neuroinflammation and improving stroke recovery.

Evaluation of Orexin-A, Adiponectin and Apelin-13 Serum Levels in Children Diagnosed With Attention Deficit Hyperactivity Disorder

OBJECTIVE

This study investigates the role of orexin-a, adiponectin (HMWA) and apelin-13 serum levels in the etiopathogenesis of attention deficit hyperactivity disorder (ADHD), a neurodevelopmental disorder with unclear aetiology involving neuropathological, genetic and environmental factors.

METHODS

The study involved 37 children with ADHD and 35 healthy controls, aged 6-18 years, with no history of other physical or psychiatric illnesses and no psychotropic medication use in the last 6 months. Serum levels of orexin-a, adiponectin (HMWA) and apelin-13 were measured using enzyme-linked immunosorbent assay (ELISA). ADHD symptoms were assessed through Diagnostic and Statistical Manual of Mental Disorders-5 (DSM-5)-based clinical interviews, Conners Parent and Teacher Rating Scales and Wisconsin Card Sorting Test.

RESULTS

No significant differences in serum orexin-a, adiponectin (HMWA) and apelin-13 levels were found between the ADHD and control groups. Additionally, there was no relationship between orexin-a, apelin-13 and adinopectin levels and ADHD symptoms and Wisconsin Card Sorting Test results. Analysis of adiponectin levels in preadolescent children aged 6-11, adjusting for age and BMI, revealed a statistically significant reduction in the ADHD group (p = 0.002).

CONCLUSION

The results did not demonstrate any correlation between ADHD and the levels of orexin-a and apelin-13. However, the study revealed that children with ADHD, aged 6-11, exhibited decreased adiponectin concentrations. These results suggest that a decrease in serum adinopectin levels may be associated with ADHD in children.

Mitochondrial quality control disorder in neurodegenerative disorders: Potential and advantages of traditional Chinese medicines

Neurodegenerative disorders (NDDs) are prevalent chronic conditions characterized by progressive synaptic loss and pathological protein alterations. Increasing evidence suggested that mitochondrial quality control (MQC) serves as the key cellular process responsible for clearing misfolded proteins and impaired mitochondria. Herein, we provided a comprehensive analysis of the mechanisms through which MQC mediates the onset and progression of NDDs, emphasizing mitochondrial dynamic stability, the clearance of damaged mitochondria, and the generation of new mitochondria. In addition, traditional Chinese medicines (TCMs) and their active monomers targeting MQC in NDD treatment have been demonstrated. Consequently, we compiled the TCMs that show great potential in the treatment of NDDs by targeting MQC, aiming to offer novel insights and a scientific foundation for the use of MQC stabilizers in NDD prevention and treatment.

Role of PGC-1α in the proliferation and metastasis of malignant tumors

Malignant tumors are among the major diseases threatening human survival in the world, and advancements in medical technology have led to a steady increase in their detection rates worldwide. Despite unique clinical presentations across the spectrum of malignancies, treatment modalities generally adhere to common strategies, encompassing primarily surgical intervention, radiation therapy, chemotherapy, and targeted treatments. Uncovering the genetic elements contributing to cancer cell proliferation, metastasis, and drug resistance remains a pivotal pursuit in the development of novel targeted therapeutics. Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A/PGC-1α) is a transcriptional coactivator that influences most cellular metabolic pathways. Its aberrant expression is associated with numerous chronic diseases, including diabetes, heart failure, neurodegenerative disorders, and cancer development. This study primarily discusses the structure, physiological functions, regulatory mechanisms, and research advancement concerning the role of PGC-1α in the proliferation and metastasis of malignant tumors. Targeting PGC-1α and its related regulatory pathways for therapeutic interventions holds promise in facilitating precise and individualized oncological treatments. This approach is expected to counteract drug resistance in patients with cancer and offer a novel direction for the treatment of malignant tumors.

The interaction between sleep patterns and oxidative balance scores on the risk of cognitive function decline: Results from the national health and nutrition examination survey 2011-2014

BACKGROUND

Unhealthy sleep and exposures to oxidative factors are both associated with poor cognitive performance (PCP), but limited evidence has been found regarding the relationship between sleep patterns and oxidative factor exposures independently or jointly with the risk of PCP.

METHODS

We analyzed data from 2249 adults aged ≥60 years in the National Health and Nutrition Examination Survey (NHANES) database (2011-2014). Self-reported questionnaires were used to collect data on sleep duration and sleep disorder, categorizing sleep duration into three groups based on responses: short (6 hours or less per night), normal (7-8 hours per night), or long (9 hours or more per night). Sleep disorder were categorized into two groups: sleep disorder, non-sleep disorder. Oxidative balance score (OBS) was calculated based on 20 oxidative stress exposures related to diet and lifestyle factors, with higher scores indicating greater antioxidant exposures. Survey-based multivariable adjusted regression analyses were conducted to examine the associations between sleep patterns or OBS alone and in combination with overall and PCP risks.

RESULTS

Compared to the normal sleep duration group, the long sleep duration group had a higher risk of PCP (DSST<34) (OR = 1.91, 95% CI = 1.05-3.48, P = 0.021); while OBS was negatively correlated with the risk of PCP (DSST<34) [Q4 vs Q1 (OR = 0.50, 95% CI = 0.29-0.92, P = 0.004)]. There was an interaction effect between sleep patterns (sleep duration, sleep disturbances) and OBS on PCP (DSST<34) (P = 0.002). Further stratified analysis showed that in individuals with normal sleep duration, long sleep duration, or no sleep disturbances, antioxidant exposures, compared to pro-oxidant exposures, reduced the risk of low cognitive function occurrence.

CONCLUSIONS

In older populations, unhealthy sleep patterns (especially excessive sleep duration) and low OBS alone or in combination increase the risk of cognitive decline. Healthy sleep and lifestyle habits rich in antioxidant factors are crucial for protecting cognitive function in older adults.

Apelin-13 alleviates osteoclast formation and osteolysis through Nrf2-pyroptosis pathway

Wear particle-induced periprosthetic osteolysis is the key to aseptic loosening after artificial joint replacement. Osteoclastogenesis plays a central role in this process. Apelin-13 is a member of the adipokine family with anti-inflammatory effects. Here, we report that apelin-13 alleviates RANKL-mediated osteoclast differentiation and titanium particle-induced osteolysis in mouse calvaria. Mechanistically, apelin-13 inhibits NLRP3 inflammasome-mediated pyroptosis by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. In summary, apelin-13 is expected to be a potential drug for relieving aseptic osteolysis. RESEARCH HIGHLIGHTS: This study reveals the molecular mechanism by which apelin-13 inhibits NLRP3 inflammasome activation and pyroptosis by promoting Nrf2. This study confirms that apelin-13 alleviates osteoclast activation by inhibiting pyroptosis. In vivo studies further confirmed that apelin-13 alleviated mouse skull osteolysis by inhibiting the activation of NLRP3 inflammasome.

Intranasal Administration of Apelin-13 Ameliorates Cognitive Deficit in Streptozotocin-Induced Alzheimer's Disease Model via Enhancement of Nrf2-HO1 Pathways

BACKGROUND

The discovery of novel diagnostic methods and therapies for Alzheimer's disease (AD) faces significant challenges. Previous research has shed light on the neuroprotective properties of Apelin-13 in neurodegenerative disorders. However, elucidating the mechanism underlying its efficacy in combating AD-related nerve injury is imperative. In this study, we aimed to investigate Apelin-13's mechanism of action in an in vivo model of AD induced by streptozocin (STZ).

METHODS

We utilized an STZ-induced nerve injury model of AD in mice to investigate the effects of Apelin-13 administration. Apelin-13 was administered intranasally, and cognitive impairment was assessed using standardized behavioral tests, primarily, behavioral assessment, histological analysis, and biochemical assays, in order to evaluate synaptic plasticity and oxidative stress signaling pathways.

RESULTS

Our findings indicate that intranasal administration of Apelin-13 ameliorated cognitive impairment in the STZ-induced AD model. Furthermore, we observed that this effect was potentially mediated by the enhancement of synaptic plasticity and the attenuation of oxidative stress signaling pathways.

CONCLUSIONS

The results of this study suggest that intranasal administration of Apelin-13 holds promise as a therapeutic strategy for preventing neurodegenerative diseases such as AD. By improving synaptic plasticity and mitigating oxidative stress, Apelin-13 may offer a novel approach to neuroprotection in AD and related conditions.

Bridging neurotrophic factors and bioactive peptides to Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder. As the demographic shifting towards an aging population, AD has emerged as a prominent public health concern. The pathogenesis of AD is complex, and there are no effective treatment methods for AD until now. In recent years, neurotrophic factors and bioactive peptides including brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), irisin, melatonin, have been discovered to exert neuroprotective functions for AD. Bioactive peptides can be divided into two categories based on their sources: endogenous and exogenous. This review briefly elaborates on the pathogenesis of AD and analyzes the regulatory effects of endogenous and exogenous peptides on the pathogenesis of AD, thereby providing new therapeutic targets for AD and a theoretical basis for the application of bioactive peptides as adjunctive therapies for AD.

The function of previously unappreciated exerkines secreted by muscle in regulation of neurodegenerative diseases

The initiation and progression of neurodegenerative diseases (NDs), distinguished by compromised nervous system integrity, profoundly disrupt the quality of life of patients, concurrently exerting a considerable strain on both the economy and the social healthcare infrastructure. Exercise has demonstrated its potential as both an effective preventive intervention and a rehabilitation approach among the emerging therapeutics targeting NDs. As the largest secretory organ, skeletal muscle possesses the capacity to secrete myokines, and these myokines can partially improve the prognosis of NDs by mediating the muscle-brain axis. Besides the well-studied exerkines, which are secreted by skeletal muscle during exercise that pivotally exert their beneficial function, the physiological function of novel exerkines, e.g., apelin, kynurenic acid (KYNA), and lactate have been underappreciated previously. Herein, this review discusses the roles of these novel exerkines and their mechanisms in regulating the progression and improvement of NDs, especially the significance of their functions in improving NDs' prognoses through exercise. Furthermore, several myokines with potential implications in ameliorating ND progression are proposed as the future direction for investigation. Elucidation of the function of exerkines secreted by skeletal muscle in the regulation of NDs advances the understanding of its pathogenesis and facilitates the development of therapeutics that intervene in these processes to cure NDs.

NTRK1 knockdown induces mouse cognitive impairment and hippocampal neuronal damage through mitophagy suppression via inactivating the AMPK/ULK1/FUNDC1 pathway

Hippocampal neuronal damage may induce cognitive impairment. Neurotrophic tyrosine kinase receptor 1 (NTRK1) reportedly regulates neuronal damage, although the underlying mechanism remains unclear. The present study aimed to investigate the role of NTRK1 in mouse hippocampal neuronal damage and the specific mechanism. A mouse NTRK1-knockdown model was established and subjected to pre-treatment with BAY-3827, followed by a behavioral test, Nissl staining, and NeuN immunofluorescence (IF) staining to evaluate the cognitive impairment and hippocampal neuronal damage. Next, an in vitro analysis was conducted using the CCK-8 assay, TUNEL assay, NeuN IF staining, DCFH-DA staining, JC-1 staining, ATP content test, mRFP-eGFP-LC3 assay, and LC3-II IF staining to elucidate the effect of NTRK1 on mouse hippocampal neuronal activity, apoptosis, damage, mitochondrial function, and autophagy. Subsequently, rescue experiments were performed by subjecting the NTRK1-knockdown neurons to pre-treatment with O304 and Rapamycin. The AMPK/ULK1/FUNDC1 pathway activity and mitophagy were detected using western blotting (WB) analysis. Resultantly, in vivo analysis revealed that NTRK1 knockdown induced mouse cognitive impairment and hippocampal tissue damage, in addition to inactivating the AMPK/ULK1/FUNDC1 pathway activity and mitophagy in the hippocampal tissues of mice. The treatment with BAY-3827 exacerbated the mouse depressive-like behavior induced by NTRK1 knockdown. The results of in vitro analysis indicated that NTRK1 knockdown attenuated viability, NeuN expression, ATP production, mitochondrial membrane potential, and mitophagy, while enhancing apoptosis and ROS production in mouse hippocampal neurons. Conversely, pre-treatment with O304 and rapamycin abrogated the suppression of mitophagy and the promotion of neuronal damage induced upon NTRK1 silencing. Conclusively, NTRK1 knockdown induces mouse hippocampal neuronal damage through the suppression of mitophagy via inactivating the AMPK/ULK1/FUNDC1 pathway. This finding would provide insight leading to the development of novel strategies for the treatment of cognitive impairment induced due to hippocampal neuronal damage.