Preventing muscle wasting: pro-insulin C-peptide prevents loss in muscle mass in streptozotocin-diabetic rats

Texture analysis of T1- and T2-weighted images identifies myofiber atrophy and grip strength decline in streptozotocin-induced type 1 diabetic sarcopenia rats

BACKGROUND

Type 1 diabetes mellitus is associated with accelerated skeletal muscle aging and sarcopenia, a condition characterized by muscle mass and function loss. Early and noninvasive evaluation of muscle microstructural damage is critical for managing sarcopenia in diabetes. This study evaluated the potential of MRI texture analysis as a noninvasive imaging tool to assess myofiber size and grip strength alterations in a rat model of diabetic sarcopenia.

MATERIALS AND METHODS

Twenty SD rats were randomly and evenly allocated to the control (CON) and diabetic sarcopenia (DS) groups. Blood glucose, body weight, and forelimb grip strength were measured weekly. In the eighth week, axial T1WI and T2WI scans were performed to extract 16 texture features of the gastrocnemius muscle. The size of the fibers, including the cross-sectional area, perimeter, and minFeretDiam, was calculated from the HE-stained images. Differences between the two groups were analyzed via t tests or Mann‒Whitney U tests. Receiver operating characteristic (ROC) analysis was conducted to evaluate the diagnostic performance of MRI texture features. Associations between MRI texture features, grip strength, and myofiber size were assessed via Spearman correlation analysis.

RESULTS

The DS group presented significant reductions in body weight, grip strength, and myofiber size (p < 0.001). Seven texture features demonstrated high repeatability. Among them, T1WI_Entropy and T2WI_Entropy were significantly lower, whereas T1WI_Mean, T2WI_Mean, and T2WI_Variance were greater in the DS group than in the control group (p < 0.05 to p < 0.001). ROC analysis revealed that the MRI texture features performed well in differentiating the DS and CON groups (AUC 0.830 ~ 1.000). Strong correlations were found between MRI texture parameters and muscle strength and myofiber size.

CONCLUSION

Muscle texture analysis based on T1WI and T2WI effectively differentiated type 1 diabetic sarcopenic rats from normal controls and revealed strong associations with muscle strength and myofiber size. These findings indicate that MRI texture parameters serve as potential biomarkers for diagnosing muscle damage in type 1 diabetic sarcopenia patients, suggesting that MRI texture parameters are promising noninvasive tools for early detection and monitoring of myofiber atrophy in diabetic sarcopenia.

Advances in body composition and gender differences in susceptibility to frailty syndrome: Role of osteosarcopenic obesity

There is general consensus that an improper diet negatively impacts health and that nutrition is a primary tool for the prevention of non-communicable diseases. Unfortunately, the importance of studying body composition, which can reveal early predictors of gender-related diseases, is still not well understood in this context. Currently, individuals are still classified as obese based solely on their body mass index, without considering the amount of fat, its distribution, and the quantity of muscle and bone mass. In this regard, the body composition phenotype defined as "osteosarcopenic obesity" affects approximately 6-41 % of postmenopausal women, with prevalence increasing with age due to the hormonal and metabolic changes that occur during this period. This particular phenotype arises from the strong relationship between visceral fat, muscle, bone, and gut microbiota and predispose postmenopausal women to frailty. Frailty is a complex clinical phenomenon with significant care and economic implications for our society. Recent studies suggest that women have a higher prevalence of frailty syndrome and its individual components, such as osteoporosis, fractures and sarcopenia, compared to men. Here, we provide a comprehensive overview of recent advances regarding the impact of gender on body composition and frailty. Furthermore, we reflect on the crucial importance of personalized nutritional interventions, with a focus on reducing visceral fat, increasing protein intake and optimizing vitamin D levels. A review of the scientific literature on this topic highlights the importance of studying body composition for a personalized and gender-specific approach to nutrition and dietetics, in order to identify frailty syndrome early and establish personalized treatments. This new method of researching disease predictors could likely help clarify the controversial results of studies on vitamin D, calcium and proteins, translate into practical wellness promotion across diverse elderly populations.

20(S)-ginsenoside Rg3 protects against diabetic muscle atrophy by promoting myoblastic differentiation and protecting mitochondrial function

BACKGROUND

High glucose levels are a primary cause of diabetes-associated cellular dysfunction and tissue damage. Muscles are the key insulin target organ and therefore, have a high level of sensitivity to hyperglycemia. Our previous study revealed that 20(S)-ginsenoside Rg3 (S-Rg3) is a monomer with a good myogenic differentiation effect in ginsenoside. Furthermore, it can alleviate dexamethasone-induced muscle atrophy by protecting mitochondrial function. However, whether S-Rg3 is effective for diabetic-induced muscle atrophy has not been reported.

PURPOSE

This study aimed to investigate the protective effect of S-Rg3 on diabetic-induced muscle atrophy.

METHODS

C2C12 myoblasts, Drosophila, and mice were used as model systems, and the protective effect of S-Rg3 on diabetes was evaluated by assessing the levels of glucose and lipids. Furthermore, H&E, toluidine blue, Giemsa, and immunofluorescence staining were performed to detect the effects of S-Rg3 on muscle atrophy and myogenic differentiation. Moreover, the effects of S-Rg3 on mitochondrial morphology and function were also evaluated by electron microscopy, flow cytometry, and Seahorse. In addition, the underlying pathways of S-Rg3 effects were detected by Western blot. The related inhibitors and gene mutations in Drosophila were used for validation.

RESULTS

The analysis of diabetic mice model fed with a high-fat diet (HFD) and high glucose (HG) revealed that in the injured C2C12 myoblasts, S-Rg3 treatment significantly reduced the levels of triglycerides and glucose. Furthermore, it promoted the differentiation of myoblasts and inhibited mitochondrial dysfunction. In the Drosophila HG and HFD diabetic model, S-Rg3 reduced triglyceride and trehalose levels, increased climbing distance values, promoted myoblasts differentiation, preserved mitochondrial function, and inhibited muscle atrophy. Mechanistically, the beneficial effects of S-Rg3 were at least partially associated with the phosphorylation of AMPK and FoxO3 together with the inhibition of Smad3 phosphorylation, this pathway was validated by the UAS-AMPKα-RNAi Drosophila model.

CONCLUSION

In summary, this study revealed mechanistic insights into how S-Rg3 protects against diabetes-associated muscle atrophy in cells, Drosophila, and mice.

Jie-Du-Tong-Luo formula protects C2C12 myotubes against high glucose and palmitic acid injury by activating the PI3K/Akt/PPARγ pathway in vitro

Introduction

In prior reports, Jie-Du-Tong-Luo (JDTL) was reported to help control insulin secretion and blood glucose in patients with diabetes, while also protecting liver and pancreatic islet cells against injury caused by exposure to high glucose (HG) levels. This study was thus developed to assess the effects of JDTL on HG and palmitic acid (PA)-induced muscle injury and to explore the mechanistic basis for these effects.

Methods

A model of muscle injury was established using mouse C2C12 myotubes treated with HG + PA. A proteomics approach was used to assess changes in protein levels following JDTL treatment, after which Western immunoblotting was employed to validate significantly affected pathways.

Results

JDTL was able to protect against HG + PA-induced muscle cell injury in this experimental system, altering lipid metabolism and inflammatory activity in these injured C2C12 myotubes. Western blotting suggested that JDTL is capable of activating PI3K/Akt/PPARγ signaling to control lipid metabolism without any corresponding impact on the inflammatory NF-κB pathway.

Conclusions

These data highlight the ability of JDTL to protect against HG + PA-induced injury to muscle cells, and suggest that the underlying basis for such efficacy is related to the PI3K/Akt/PPARγ pathway-mediated modulation of lipid metabolism.

Diabetes-induced muscle wasting: molecular mechanisms and promising therapeutic targets

Diabetes has become a serious public health crisis, presenting significant challenges to individuals worldwide. As the largest organ in the human body, skeletal muscle is a significant target of this chronic disease, yet muscle wasting as a complication of diabetes is still not fully understood and effective treatment methods have yet to be developed. Here, we discuss the targets involved in inducing muscle wasting under diabetic conditions, both validated targets and emerging targets. Diabetes-induced skeletal muscle wasting is known to involve changes in various signaling molecules and pathways, such as protein degradation pathways, protein synthesis pathways, mitochondrial function, and oxidative stress inflammation. Recent studies have shown that some of these present potential as promising therapeutic targets, including the neuregulin 1/epidermal growth factor receptor family, advanced glycation end-products, irisin, ferroptosis, growth differentiation factor 15 and more. This study's investigation and discussion of such pathways and their potential applications provides a theoretical basis for the development of clinical treatments for diabetes-induced muscle wasting and a foundation for continued focus on this disease.

Effects of C-Peptide on Dexamethasone-Induced In Vitro and In Vivo Models as a Potential Therapeutic Agent for Muscle Atrophy

This study aimed to investigate the effects of C-peptide on C2C12 myotubes and a mouse model. Both in vitro and in vivo experiments were conducted to elucidate the role of C-peptide in muscle atrophy. Various concentrations (0, 0.01, 0.1, 1, 10, and 100 nM) of C-peptide were used on the differentiated C2C12 myotubes with or without dexamethasone (DEX). C57BL/6J mice were administered with C-peptide and DEX for 8 days, followed by C-peptide treatment for 12 days. Compared to the DEX group, C-peptide increased the fusion and differentiation indices and suppressed atrophic factor expression in C2C12 myotubes. However, 100 nM C-peptide decreased the fusion and differentiation indices and increased atrophic factor expression regardless of DEX treatment. In C57BL/6J mice, DEX + C-peptide co-treatment significantly attenuated the body and muscle weight loss and improved the grip strength and cross-sectional area of the gastrocnemius (Gas) and quadriceps (Quad) muscles. C-peptide downregulated the mRNA and protein levels of muscle degradation-related markers, particularly Atrogin-1, in Gas and Quad muscles. This study underscores the potential of C-peptides in mitigating muscle weight reduction and preserving muscle function during muscle atrophy via molecular regulation. In addition, the work presents basic data for future studies on the effect of C-peptide on diabetic muscular dystrophy.

U-shaped association between plasma C-peptide and sarcopenia: A cross-sectional study of elderly Chinese patients with diabetes mellitus

Limited research exists regarding the relationship between fasting plasma C-peptide levels and sarcopenia. As a result, our study aimed to examine this association in elderly Chinese diabetic patients. This cross-sectional study included 288 elderly patients with diabetes mellitus from the Fourth People's Hospital in Guiyang who were enrolled prospectively between March 2020 and February 2023. The independent variable of interest was fasting plasma C-peptide, while the dependent variable was sarcopenia. Data on several covariates, including demographic factors, lifestyle habits, co-morbidities, anthropometric indicators, and laboratory indicators, were also collected. Of the 288 participants, 27.43% (79/288) had sarcopenia. After adjusting for potential confounding variables, we found a U-shaped association between fasting plasma C-peptide levels and sarcopenia, with inflection points identified at approximately 774 pmol/L and 939 mmol/L. Within the range of 50-744 pmol/L, each 100 pmol/L increase in CysC was associated with a 37% decrease in the odds of sarcopenia (odds ratio [OR], 0.63; 95% confidence interval [CI], 0.49 to 0.83; P < 0.001). Additionally, within the range of 939-1694 pmol/L, each 100 pmol/L increase in fasting plasma C-peptide was associated with a 76% increase in the odds of sarcopenia (odds ratio [OR], 1.76; 95% confidence interval [CI], 1.11 to 2.81; P = 0.017). Our study revealed a U-shaped association between fasting plasma C-peptide levels and the likelihood of sarcopenia, with lower risk in the range of 774-939 pmol/L. These findings may assist in the development of more effective prevention and treatment strategies for sarcopenia in elderly diabetic patients.