Lifelong treadmill training improves muscle function detected by a modified grip strength test during aging in BALB/c mice

GPNMB attenuates neuroinflammation and improves ischemic stroke via modulation of PI3K/Akt and p38 MAPK signaling pathways

BACKGROUND

Ischemic stroke is a leading cause of disability and mortality worldwide, with limited effective treatments. Neuroinflammation plays a crucial role in the progression of ischemic brain injury. Glycoprotein nonmetastatic melanoma protein B (GPNMB) has emerged as a potential regulator of inflammation, but its role and underlying mechanisms in ischemic stroke remain largely unknown.

METHODS

We investigated the expression profile, functional significance, and molecular pathways of GPNMB in ischemic stroke using a mouse model of middle cerebral artery occlusion (MCAO), transcriptome sequencing, and human serum samples. The effects of GPNMB knockdown on stroke outcomes, neuroinflammation, and neuronal damage were assessed in vivo. Bioinformatic analyses and experimental validation were performed to identify the downstream signaling pathways of GPNMB.

RESULTS

GPNMB was highly upregulated in the ischemic brain, with its expression peaking at 3-7 days post-MCAO. Serum GPNMB levels were elevated in ischemic stroke patients and correlated with stroke severity. GPNMB knockdown exacerbated stroke outcomes, neuroinflammation, and neuronal damage. Mechanistically, GPNMB positively modulated the PI3K/Akt/GSK3β pathway while negatively regulating p38 MAPK, JNK, and ERK activation. GPNMB knockdown enhanced the expression of NF-κB, a master transcriptional regulator of inflammation.

CONCLUSION

GPNMB is highly upregulated in the ischemic brain and confers neuroprotection against ischemic injury by modulating neuroinflammation via the PI3K/Akt and p38 MAPK signaling pathways.

pH-Responsive Persistent Luminescent Nanosystem with Sensitized NIR Imaging and Ratiometric Imaging Modes for Tumor Surgery Navigation

Owing to autofluorescence-free feature, persistent luminescent (PersL) nanoparticles (PLNPs) become potential materials for tumor surgical navigation. However, it is still challenging to enhance PersL intensity, contrast ratio, and imaging stability so as to meet clinical demand and avoid missed detection of microlesions. Herein, integrating a tumor microenvironment (TME)-responsive strategy, sensitization enhancement, and internal-standard ratiometric method, a dual-mode PersL imaging strategy is proposed: After loading pH-responsive fluorescent molecule Rh-ADM on PLNPs ZnGa2O4:Cr3+,Mn2+ (ZGCM-Rh8), the fluorescence resonance energy transfer (FRET) pathways between Cr3+ and Rh-ADM, as well as Mn2+ and Rh-ADM, could sensitize the NIR PersL emitted by Cr3+ and quench the green PersL from Mn2+ at acidic TME, respectively. As a result, ZGCM-Rh8 is endowed with WLED (white light LED)-excited NIR imaging mode and UV-excited ratiometric imaging mode. Under WLED, ZGCM-Rh8 realizes 4.5-fold PersL enhancement and 97.9 as the maximum tumor contrast after precise control of Rh-ADM contents, helping with the preoperative diagnosis of deep lesions. Under UV, ZGCM-Rh8 conducts ratiometric PersL imaging steadily, and the "NIR/Vis" ratios at the tumor keep larger than 110, succeeding in detecting out a 1.5 mm small lesion and serving thorough surgical elimination of H22 ectopic intramuscular tumor in balb/c mice. To our knowledge, ZGCM-Rh8 is the first to realize pH-responsive PersL sensitization and apply ratiometric PersL imaging technology to surgical navigation.

Safranal exerts a neuroprotective effect on Parkinson's disease with suppression of NLRP3 inflammation activation

BACKGROUND

Parkinson's disease (PD) is a common central nervous system neurodegenerative disease. Neuroinflammation is one of the significant neuropathological hallmarks. As a traditional Chinese medicine, Safranal exerts anti-inflammatory effects in various diseases, however, whether it plays a similar effect on PD is still unclear. The study was to investigate the effects and mechanism of Safranal on PD.

METHODS

The PD mouse model was established by 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine MPTP firstly. Next, the degree of muscle stiffness, neuromuscular function, motor retardation and motor coordination ability were examined by observing and testing mouse movement behavior. Immunofluorescence staining was used to observe the expression of tyrosine hydroxylase (TH). The dopamine (DA) content of the striatum was detected by High-performance liquid chromatography (HPLC). The expression of TH and NLRP3 inflammasome-related markers NLRP3, IL-1β, and Capase-1 were detected by Real-time Polymerase Chain Reaction (qRT-PCR) and western blotting (WB) respectively.

RESULTS

Through behavioral testing, Parkinson's mouse showed a higher muscle stiffness and neuromuscular tension, a more motor retardation and activity disorders, together with a worse motor coordination compared with sham group. Simultaneously, DA content and TH expression in the striatum were decreased. However, after using Safranal treatment, the above pathological symptoms of Parkinson's mouse all improved compared with Safranal untreated group, the DA content and TH expression were also increased to varying degrees. Surprisingly, it observed a suppression of NLRP3 inflammation in the striatum of Parkinson's mouse.

CONCLUSIONS

Safranal played a neuroprotective effect on the Parkinson's disease and its mechanism was related to the inhibition of NLRP3 inflammasome activation.

Linalool, a Fragrance Compound in Plants, Protects Dopaminergic Neurons and Improves Motor Function and Skeletal Muscle Strength in Experimental Models of Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the gradual loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc), resulting in reduced dopamine levels in the striatum and eventual onset of motor symptoms. Linalool (3,7-dimethyl-1,6-octadien-3-ol) is a monoterpene in aromatic plants exhibiting antioxidant, antidepressant, and anti-anxiety properties. The objective of this study is to evaluate the neuroprotective impacts of linalool on dopaminergic SH-SY5Y cells, primary mesencephalic and cortical neurons treated with 1-methyl-4-phenylpyridinium ion (MPP+), as well as in PD-like mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Cell viability, α-tubulin staining, western blotting, immunohistochemistry and behavioral experiments were performed. In MPP+-treated SH-SY5Y cells, linalool increased cell viability, reduced neurite retraction, enhanced antioxidant defense by downregulation of apoptosis signaling (B-cell lymphoma 2 (Bcl-2), cleaved caspase-3 and poly ADP-ribose polymerase (PARP)) and phagocyte NADPH oxidase (gp91phox), as well as upregulation of neurotrophic signaling (brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF)) and nuclear factor-erythroid 2 related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway. In MPP+-treated primary mesencephalic neurons, linalool enhanced the expressions of tyrosine hydroxylase (TH), Sirtuin 1 (SirT1), and parkin. In MPP+-treated primary cortical neurons, linalool upregulated protein expression of SirT1, γ-Aminobutyric acid type A-α1 (GABAA-α1), and γ-Aminobutyric acid type B (GABAB). In PD-like mice, linalool attenuated the loss of dopamine neurons in SNpc. Linalool improved the motor and nonmotor behavioral deficits and muscle strength of PD-like mice. These findings suggest that linalool potentially protects dopaminergic neurons and improves the impairment symptoms of PD.

Environmental Enrichment Improves Motor Function and Muscle Transcriptome of Aged Mice

Aging results in the progressive decline of muscle strength. Interventions to maintain muscle strength may mitigate the age-related loss of physical function, thus maximizing health span. The work on environmental enrichment (EE), an experimental paradigm recapitulating aspects of an active lifestyle, has revealed EE-induced metabolic benefits mediated by a brain-fat axis across the lifespan of mice. EE initiated at 18-month of age shows a trend toward an increased mean lifespan. While previous work described EE's influences on the aging dynamics of several central-peripheral processes, its influence on muscle remained understudied. Here, the impact of EE is investigated on motor function, neuromuscular physiology, and the skeletal muscle transcriptome. EE is initiated in 20-month-old mice for a five-month period. EE mice exhibit greater relative lean mass that is associated with improved mobility and hindlimb grip strength. Transcriptomic profiling of muscle tissue reveals an EE-associated enrichment of gene expression within several metabolic pathways related to oxidative phosphorylation and the TCA cycle. Many mitochondrial-related genes-several of which participate in the electron transport chain-are upregulated. Stress-responsive signaling pathways are downregulated because of EE. The results suggest that EE improves motor function-possibly through preservation of mitochondrial function-even late in life.

pH-Responsive Plasmon-Enhanced Persistent Luminescent ZnGa2O4:Cr3+ Nanopomegranate for Tumor Imaging

Noble metal compositing is a promising method to enhance radiance intensity of persistent luminescent (PersL) nanoparticles (NPs) via surface plasmon resonance (SPR) for better tumor imaging, but it rarely unites with the pH-response strategy due to the challenge of realizing rigorous pH-responsive spatial distance control as a "button switch" of SPR. Here, ZnGa2O4:Cr3+ (ZGC) NPs as "pomegranate seeds" are cladded with sodium alginate to form nanoclusters (ZGC-SA), subsequently coated with carboxyl-rich polymers to acquire "pomegranate rind" (ZSPB) and finally decorated with 10 nm gold NPs (AuNPs) on the surface to obtain nanopomegranate structure (ZSPB@AuNPs). Though without deliberate distance control, there are plenty of "seeds" inside ZSPB@AuNPs fortunately at appropriate positions, which could be plasmon-enhanced by AuNPs. Furthermore, triggered by carboxyl protonation in subacid tumor, ZSPB@AuNPs aggregate and subsequently facilitate such plasmon enhancement effect, resulting in 4.4-fold PersL promotion at pH 5.5 (tumor microenvironment, TME) over pH 7.4 and in a maximum "tumor to normal tissue ratio" of PersL imaging signals of 125.9. Under surgical navigation of ZSPB@AuNPs, intramuscular tumors of mice could be resected without residue signals left. This nanopomegranate achieves TME pH-responsive plasmon-enhanced PersL for the first time and broadens the way for designing plasmon-enhanced PersL nanosystems.

SEPSIS LEADS TO IMPAIRED MITOCHONDRIAL CALCIUM UPTAKE AND SKELETAL MUSCLE WEAKNESS BY REDUCING THE MICU1:MCU PROTEIN RATIO

Purpose: Intensive care unit-acquired weakness (ICUAW) is a severe neuromuscular complication that frequently occurs in patients with sepsis. The precise molecular pathophysiology of mitochondrial calcium uptake 1 (MICU1) and mitochondrial calcium uniporter (MCU) in ICUAW has not been fully elucidated. Here, we speculate that ICUAW is associated with MICU1:MCU protein ratio-mediated mitochondrial calcium ([Ca 2+ ] m ) uptake dysfunction. Methods: Cecal ligation and perforation (CLP) was performed on C57BL/6J mice to induce sepsis. Sham-operated animals were used as controls. Lipopolysaccharide (LPS) (5 μg/mL) was used to induce inflammation in differentiated C2C12 myoblasts. Compound muscle action potential (CMAP) was detected using a biological signal acquisition system. Grip strength was measured using a grip-strength meter. Skeletal muscle inflammatory factors were detected using ELISA kits. The cross-sectional area (CSA) of the tibialis anterior (TA) muscle was detected by hematoxylin and eosin staining. Cytosolic calcium ([Ca 2+ ] c ) levels were measured using Fluo-4 AM. Adeno-associated virus (AAV) was injected into TA muscles for 4 weeks to overexpress MICU1 prophylactically. A lentivirus was used to infect C2C12 cells to increase MICU1 expression prophylactically. Findings: The results suggest that sepsis induces [Ca 2+ ] m uptake disorder by reducing the MICU1:MCU protein ratio, resulting in skeletal muscle weakness and muscle fiber atrophy. However, MICU1 prophylactic overexpression reversed these effects by increasing the MICU1:MCU protein ratio. Conclusions: ICUAW is associated with impaired [Ca 2+ ] m uptake caused by a decreased MICU1:MCU protein ratio. MICU1 overexpression improves sepsis-induced skeletal muscle weakness and atrophy by ameliorating the [Ca 2+ ] m uptake disorder.

Alterations in mitochondrial biogenesis and respiratory activity, inflammation of the senescence-associated secretory phenotype, and lipolysis in the perirenal fat and liver of rats following lifelong exercise and detraining

The primary aims of this study were to determine the effects of lifelong exercise and detraining on age-related alterations in mitochondrial function, inflammation associated with senescence-associated secretory phenotype (SASP), and lipolysis in the perirenal fat and liver of rats. Female Sprague-Dawley rats were randomly assigned to four groups: young control (n = 12), old control (n = 12), detraining (n = 12), and lifelong exercise (n = 12). We then investigated mitochondrial function, SASP-associated inflammation, and lipolysis in the perirenal fat and liver using qRT-PCR and western blotting to assess the expression of AKT, hypoxia-inducible factor 1α (HIF-1α), nuclear factor-kappa B (NF-κB), c-jun kinase (JNK), and p38 mitogen-activated protein kinase (p38MAPK). In the tissues of both the perirenal fat and liver, lifelong exercise significantly improved mitochondrial function, SASP-associated inflammation, and lipolysis. Meanwhile, pathways associated with inflammatory regulation were inhibited, predominantly via the activation of phosphorylated-AKT (p-AKT) and suppression of HIF-1α in both tissues, and via JNK in the perirenal fat and p38MAPK in the liver. Furthermore, detraining activated NF-κB expression in both tissues and induced the upregulation of serum high-sensitivity C-reactive protein (hsCRP) levels. Collectively, lifelong exercise was found to exert beneficial effects by ameliorating age-related alterations in mitochondrial function, SASP-associated inflammation, and lipolysis in perirenal fat and liver tissues, potentially inhibiting inflammation via the JNK and p38 MAPK pathways, respectively, as well as the HIF-1α and AKT pathways in both tissues. In contrast, detraining induced high levels of circulating hsCRP by activating the NF-κB signaling pathway in both tissues.

Autonomous climbing: An effective exercise mode with beneficial outcomes of aerobic exercise and resistance training

AIMS

To assess the effects of three specific exercise training modes, aerobic exercise (A), resistance training (R) and autonomous climbing (AC), aimed at proposing a cross-training method, on improving the physical, molecular and metabolic characteristics of mice without many side effects.

MATERIALS AND METHODS

Seven-week-old male mice were randomly divided into four groups: control (C), aerobic exercise (A), resistance training (R), and autonomous climbing (AC) groups. Physical changes in mice were tracked and analysed to explore the similarities and differences of these three exercise modes. Histochemistry, quantitative real-time PCR (RT-PCR), western blot (WB) and metabolomics analysis were performed to identify the underlying relationships among the three training modes.

KEY FINDINGS

Mice in the AC group showed better body weight control, glucose and energy homeostasis. Molecular markers of myogenesis, hypertrophy, antidegradation and mitochondrial function were highly expressed in the muscle of mice after autonomous climbing. The serum metabolomics landscape and enriched pathway comparison indicated that the aerobic oxidation pathway (pentose phosphate pathway, galactose metabolism and fatty acid degradation) and amino acid metabolism pathway (tyrosine, arginine and proline metabolism) were significantly enriched in group AC, suggesting an increased muscle mitochondrial function and protein balance ability of mice after autonomous climbing.

SIGNIFICANCE

We propose a new exercise mode, autonomous climbing, as a convenient but effective training method that combines the beneficial effects of aerobic exercise and resistance training.