Mitochondrial dysfunction in type 2 diabetes:A neglected path to skeletal muscle atrophy

Over the course of several decades,robust research has firmly established the significance of mitochondrial pathology as a central contributor to the onset of skeletal muscle atrophy in individuals with diabetes.However,the specific intricacies governing this process remain elusive.Extensive evidence highlights that individuals with diabetes regularly confront the severe consequences of skeletal muscle degradation.Deciphering the sophisticated mechanisms at the core of this pathology requires a thorough and meticulous exploration into the nuanced factors intricately associated with mitochondrial dysfunction.

Biology of Hippo signaling pathway:Skeletal muscle development and beyond

Global demand for farm animals and their meat products i.e.,pork,chicken and other livestock meat,is steadily incresing.With the ongoing life science research and the rapid development of biotechnology,it is a great opportunity to develop advanced molecular breeding markers to efficiently improve animal meat production traits.Hippo is an important study subject because of its crucial role in the regulation of organ size.In recent years,with the increase of research on Hippo signaling pathway,the integrative application of multi-omics technologies such as genomics,transcriptomics,proteomics,and metabolomics can help promote the in-depth involvement of Hippo signaling pathway in skeletal muscle development research.The Hippo signaling pathway plays a key role in many biological events,including cell division,cell migration,cell proliferation,cell differentiation,cell apoptosis,as well as cell adhesion,cell polarity,homeostasis,maintenance of the face of mechanical overload,etc.Its influence on the development of skeletal muscle has important research value for enhancing the efficiency of animal husbandry production.In this study,we traced the origin of the Hippo pathway,comprehensively sorted out all the functional factors found in the pathway,deeply analyzed the molecular mechanism of its function,and classified it from a novel perspective based on its main functional domain and mode of action.Our aim is to systematically explore its regulatory role throughout skeletal muscle development.We specifically focus on the Hippo signaling pathway in embryonic stem cell development,muscle satellite cell fate determination,myogenesis,skeletal muscle meat production and organ size regulation,muscle hypertrophy and atrophy,muscle fiber formation and its transformation between different types,and cardiomyocytes.The roles in proliferation and regeneration are methodically summarized and analyzed comprehensively.The summary and prospect of the Hippo signaling pathway within this article will provide ideas for further improving meat production and muscle deposition and developing new molecular breeding technologies for livestock and poultry,which will be helpful for the development of animal molecular breeding.

Catalpa bignonioides extract improves exercise performance through regulation of growth and metabolism in skeletal muscles

Objective:To evaluate the effects of Catalpa bignonioides fruit extract on the promotion of muscle growth and muscular capacity in vitro and in vivo.Methods:Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.Cell proliferation was assessed using a 5-bromo-2’-deoxyuridine(BrdU)assay kit.Western blot analysis was performed to determine the protein expressions of related factors.The effects of Catalpa bignonioides extract were investigated in mice using the treadmill exhaustion test and whole-limb grip strength assay.Chemical composition analysis was performed using high-performance liquid chromatography(HPLC).Results:Catalpa bignonioides extract increased the proliferation of C2C12 mouse myoblasts by activating the Akt/mTOR signaling pathway.It also induced metabolic changes,increasing the number of mitochondria and glucose metabolism by phosphorylating adenosine monophosphate-activated protein kinase.In an in vivo study,the extract-treated mice showed improved motor abilities,such as muscular endurance and grip strength.Additionally,HPLC analysis showed that vanillic acid may be the main component of the Catalpa bignonioides extract that enhanced muscle strength.Conclusions:Catalpa bignonioides improves exercise performance through regulation of growth and metabolism in skeletal muscles,suggesting its potential as an effective natural agent for improving muscular strength.

Micro RNA transcriptome of skeletal muscle during yak development reveals that miR-652 regulates myoblasts differentiation and survival by targeting ISL1

The growth and development of skeletal muscle also determine the meat production of yak, ultimately affecting the economic benefits. Hence, improving growth performance is a top priority in the yak industry. Skeletal muscle development is a complex process involving the regulation of several genes, including microRNAs(miRNAs). However,the transcription of miRNAs in yak skeletal muscle during prenatal to postnatal stages is unknown. We used small RNA sequencing(small RNA-Seq) to determine the global miRNAs of longissimus dorsi muscle from yak(the samples were collected from three fetuses and three adults). Totally 264 differently expressed miRNAs(|log2(fold change)|>1and P-value≤0.05) were detected between the two groups. Gene Ontology(GO) and Kyoto Encyclopedia of Genes and Genomes(KEGG) analysis showed that differently expressed miRNAs-targeted genes participated in pathways associated with muscle development, such as MAPK, PI3K-Akt, and Hippo signaling pathways, etc. MiR-652, which was up-regulated in the fetal group, was transfected into C2C12 myoblasts to examine its role. miR-652 promoted(P≤0.05)proliferation and differentiation, but inhibited(P≤0.001) apoptosis at early period. Furthermore, miR-652 reduced(P≤0.001) the proportion of C2C12 myoblasts in the G1 phase while increasing(P≤0.01) the proportion of cells in the S and G2 phases. Dual-luciferase reporter assays indicated that ISL1 served as a target of miR-652. In general, these findings expand our understanding of yak skeletal muscle miRNAs, and suggested that miR-652 probably regulated myogenesis by regulating ISL1.

Berberine Inhibits Gluconeogenesis in Skeletal Muscles and Adipose Tissues in Streptozotocin-induced Diabetic Rats via LKB1-AMPK-TORC2 Signaling Pathway

The effect and potential molecular mechanisms of berberine on gluconeogenesis in skeletal muscles and adipose tissues were investigated.After adaptive feeding for one week,8 rats were randomly selected as the normal group and fed on a standard diet.The remaining 32 rats were fed on a high-fat diet and given an intravenous injection of streptozotocin(STZ)for 2 weeks to induce the diabetic models.The diabetic rat models were confirmed by oral glucose tolerance test(OGTT)and randomly divided into 4 groups(n=8 each),which were all fed on a high-fat diet.Berberine(3 g/kg per day)or metformin(183 mg/kg per day)was intragastrically administered to the diabetic rats for 12 weeks,serving as berberine group and metformin group respectively.5-aminoimidazole-4-carboxamide1-β-D-ribofuranoside[AICAR,an agonist of AMP-activated protein kinase(AMPK),0.5 mg/kg per day]was subcutaneously injected to the diabetic rats for 12 weeks,serving as AICAR group.The remaining 8 diabetic rats served as the model group,which was given a 0.5%carboxyl methylcellulose solution by oral gavage.Fasting serum insulin(FINS),OGTT as well as lipid parameters were tested by commercial kit.The protein levels of liver kinase B1(LKB1),AMPK,phosphorylated AMP-activated protein kinase(p-AMPK),transducer of regulated CREB activity 2(TORC2),phosphorylated transducer of regulated CREB activity 2(p-TORC2),phosphoenolpyruvate carboxykinase(PEPCK),and glucose-6-phosphatase(G6Pase)in skeletal muscles and adipose tissues were examined by Western blotting.The results showed that berberine significantly decreased the body weight,plasma glucose,insulin levels,and homeostatic model assessment for insulin resistance(HOMA-IR)of diabetic rats compared with those in the model group.Meanwhile,the serum total triglyceride(TG),total cholesterol(TC),and low-density lipoprotein cholesterol(LDL-C)levels were markedly decreased and high-density lipoprotein cholesterol(HDL-C)level was significantly increased after the treatment with berberine.In addition,we found that berberine significantly increased the expression of p-AMPK and LKB1,while decreasing the p-TORC2 levels in skeletal muscles and adipose tissues.Moreover,the expression of PEPCK and G6Pase was significantly down-regulated after the treatment with berberine compared to the model group.It was suggested that the mechanism by which berberine inhibited peripheral tissue gluconeogenesis may be attributed to the activation of the LKB1-AMPK-TORC2 signaling pathway.

Gene Expression Profile of Human Skeletal Muscle and Adipose Tissue of Chinese Han Patients with Type 2 Diabetes Mellitus

Objective To study the differential patterns of gene expression in skeletal muscle and adipose tissue between type 2 diabetes mellitus （T2DM） patients and healthy subjects using DNA microarray analysis, Methods T2DM patiens were divided into female group, young male group and old male group. DNA microarray analysis and quantitative real-time PCR were carried out to anaIyze the relation between gene expressions and T2DM. Results The mRNA expression of 298, 578, and 350 genes was changed in the skeletal muscle of diabetes mellitus patients compared with control subjects. The 1320, 1143, and 2847 genes were modified in adipose tissue of the three groups. Among the genes surveyed, the change of 25 and 39 gene transcripts in skeletal muscle and adipose tissue was ≥2 folds, These differentially expressed genes were classified into 15 categories according to their functions. Conclusion New genes are found and T2DM can be prevented or cured.

Protective Effect of ATP on Skeletal Muscle Satellite Cells Damaged by H_2O_2

This study investigated the protective effect of ATP on skeletal muscle satellite cells damaged by H2O2 in neonatal rats and the possible mechanism. The skeletal muscle satellite cells were randomly divided into four groups： normal group, model group（cells treated with 0.1 mmol/L H2O2 for 50 s）, protection group（cells treated with 16, 8, 4, 2, 1, 0.5, or 0.25 mmol/L ATP for 24 h, and then with 0.1 mmol/L H2O2 for 50 s）, proliferation group（cells treated with 16, 8, 4, 2, 1, 0.5, or 0.25 mmol/L ATP for 24 h）. MTT assay, FITC＋PI＋DAPI fluorescent staining, Giemsa staining and immunofluorescence were performed to examine cell viability and apoptosis, and apoptosis-related proteins. The results showed that the survival rate of skeletal muscle satellite cells was decreased and the apoptosis rate was increased after H2O2 treatment（P〈0.01）. Different doses of ATP had different effects on skeletal muscle satellite cells damaged by H2O2： the survival rate of muscle satellite cells treated with ATP at 4, 2, or 1 mmol/L was increased. The protective effect was most profound on cells treated with 2 mmol/L ATP. Immunofluorescence showed that ATP could increase the number of Bcl-2-positive cells（P〈0.01） and decrease the number of the Bax-positive cells（P〈0.01）. It was concluded that ATP could protect skeletal muscle satellite cells against H2O2 damage in neonatal rats, which may be attributed to the up-regulation of the expression of Bcl-2 and down-regulation of Bax, resulting in the suppression of apoptosis.

Sulforaphane enhances Nrf2-mediated antioxidant responses of skeletal muscle induced by exhaustive exercise in HIIT mice

Nuclear factor erythroid-derived 2-like 2(Nrf2)is the master regulator of antioxidant defenses.High-intensity interval training(HIIT)has been proposed as a time-efficient training program and has become a substantial component of modern training program In the present study,we evaluated the effects of sulforaphane(SFN),a dietary isothiocyanate derived from cruciferous vegetables and a potent Nrf2 activator,on Nrf2-mediated antioxidant defense responses of skeletal muscle induced by exhaustive exercise in HIIT mice.Male C57 BL/6 J mice were randomly allocated into control group,HIIT group,and HIIT pretreated with SFN(HIIT+SFN)group.On the third day after completion of a 6-weeks HIIT protocol,an exhaustive treadmill test was conducted in all mice.Mice were intraperitoneally injected with SFN(HIIT+SFN group)or PBS(HIIT and control mice)4 times in 3 days prior to the exhaustive treadmill test.The results indicated that the 6-weeks HIIT protocol did not increase the antioxidative capacity of skeletal muscle during exhaustive exercise.Importantly,SFN treatment improved anti oxidative capacity of skeletal muscle in response to the acute exhaustive exercise by increasing mRNA and nucleoprotein expression of Nrf2 and these genes involved in antioxidant generation and decreasing blood creatine kinase(CK)and 4-hydroxy-2-nonenal(4-HNE)-modified protein levels in the HIIT mice.

Effects of DHRS3 in C2C12 Myoblast Differentiation and Mouse Skeletal Muscle Injury

Myoblast differentiation is an essential process during skeletal muscle development.C2C12 myoblast is a commonly used experimental model to study muscle cell differentiation in vitro.Dehydrogenase/reductase(SDR family)member 3(DHRS3)is a highly conserved member in short-chain alcohol dehydrogenase/reductase superfamily and has been shown to be involved in the metabolism of retinol.Previous experimental results showed that the expression of DHRS3 increased significantly during the differentiation of myoblasts differentiation.However,the effect of DHRS3 on mouse muscle cell differentiation was unclear.The objective of current study was to determine if DHRS3 affected muscle cell differentiation,and if DHRS3 was involved in muscle regeneration.Protein expression was determined by western blot and immunofluorescence analysis.The activation and inhibition of DHRS3 increased and decreased C2C12 myoblast differentiation respectively,which indicated that DHRS3 could affect C2C12 myoblast differentiation.DHRS3 expression was significantly changed during muscle regeneration,with the regeneration of muscle injury,the expression of DHRS3 tended to increase first and then decrease.It suggested that DHRS3 might be involved in muscle regeneration.In summary,this study confirmed the involvement of DHRS3 in C2C12 myoblast differentiation and mouse skeletal muscle regeneration and provided a theoretical basis for further elucidating the molecular mechanism of muscle development.

Study the dynamic effects of exercise on IRS-2 content and tyrosine phosphorylation in skeletal muscle of rats

To explore the dynamic effects of exercise on IRS-2 protein content and tyrosine phosphorylation in DM rats,Sixty SD rats were divided into six groups: normal control group(NC)、diabetes mellitus group(DMC) and exercise group.The exercise groups exercised for different periods of time.The content and tyrosine phosphorylation of IRS-2 protein were measured by Western bolt analysis.Result showed that contents of IRS-2 protein in 60,120,180 min groups were enhanced up to 19.0%,22.4% and 17.2%(P<0.01) respectively,and the tyrosine phosphorylation of IRS-2 protein in 60,120,180 min group enhanced up to 43.1%,80.4% and 53%(P<0.01) respectively,compared with the DMC group.We concluded that that the contents and the tyrosine phosphorylation of IRS-2 protein had obvious time trait after exercise.

Yiqi Yangyin and Huatan Quyu granule can improve skeletal muscle energy metabolism in a type 2 diabetic rat model by promoting the AMPK/SIRT/PGC-1α signalling pathway

Objective:To investigate how Yiqi Yangyin and Huatan Quyu granule (YYHO) improves skeletal muscle insulin resistance in a type 2 diabetic rat model and to discover whether the molecular mechanism is related to the promotion of the AMPK/SIRT/PGC-1α signalling pathway.Methods:Rats were randomly divided into 4 groups:the normal group,the model group,the YYHQ granule group,and the pioglitazone group.The type 2 diabetic rat model was established by feeding a high-fat diet for 5 weeks along with a single intraperitoneal injection of 30 mg/kg streptozotocin (STZ).After modelling successfully,the appropriate drug was intragastrically administered to diabetic rats for 2 weeks,once per day.The YYHQ granule group was given a dose of 4.8 g/kg body weight per day,the pioglitazone group was given a dose of 1.35 mg/kg body weight per day.The doses for both groups were equivalent to the clinical equivalent dose based on a previous study.Other groups were gavaged with the same amount of saline water.Body weight,food intake,water intake,urine volume and grip strength were recorded weekly.The fasting blood glucose(FBG) was determined weekly using blood glucose test strips.The related glucose and lipid metabolism indexes,e.g.,fasting insulin (Fins),glycated haemoglobin (GHb),HOMA-IR,ISI,triglycerides (TG),total cholesterol (TC),high-density lipoprotein cholesterol (HDL-C),low-density lipoprotein cholesterol (LDL-C) and free fatty acid (FFA),were determined using biochemical method.The mRNA expression levels of adenosine monophosphate-activated protein kinase (AMPK),peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α),carnitine palmitoyl transterase-1 (CPT-1),Sirtuin 1 (SIRT1),and Sirtuin 3 (SIRT3) were assessed using quantitative real-time PCR (qRT-PCR).The protein expression levels of creatine kinase (CK),Ca2+ ATPase,α-Actin,AMPK,PGC-1α and CPT-1 were determined using enzyme-linked immunosorbent assay method (ELISA).Results:Body weight decreased significantly (P <.01),food intake,water intake and urine volume increased significantly (P <.01),and grip strength decreased significantly (P <.01) in the model group compared with the normal group.The levels of FBG,Fins,GHb and HOMA-IR increased significantly (P <.01),and the ISI decreased significantly (P <.01) in the model group.The levels of TG,TC,LDL-C and FFA increased significantly (P <.05 or P <.01),and the level of HDL-C decreased significantly (P <.05) in the model group.These changes were reversed after treatment with YYHQ granule or pioglitazone.Compared with the model group,the YYHQ granule and pioglitazone groups significantly improve body weight,water intake and urine volume (P <.05 or P <.01),however,both treatments had no significant effect on food intake (P >.05).The levels of FBG,Fins,GHb,HOMA-IR and ISI were improved significantly (P <.01) and the levels of TG,TC and LDL-C were improved significantly (P <.05 or P <.01),however,both treatments had no significant effect on the levels of HDL-C and FFA (P >.05).Further results indicated that YYHQ granule significantly decreased the mRNA expression of AMPK,PGC-1α,CPT-1,SIRT1 and SIRT3 in skeletal muscle (P <.01) and the pioglitazone group showed similar effects;moreover,the protein expression levels of CK,Ca2+ATPase,α-Actin,AMPK,PGC-1α and CPT-1 in skeletal muscle significantly decreased (P <.01),however,pioglitazone had no significant effect on CK and α-Actin (P >.05).Conclusion:The possible molecular mechanism of YYHQ granule improving skeletal muscle insulin resistance in a type 2 diabetic rat model may be related to the stimulation of energy metabolism in skeletal muscle via the AMPK/SIRT/PGC-1α signalling pathway.

Defective maintenance of intracellular Ca^(2+) homeostasis is linked to increased muscle fatigability in the MG29 null mice

Mitsugumin 29 (MG29) is a transmembrane protein that is normally found in the triad junction of skeletal muscle. Our previous studies have shown that targeted deletion of mg29 from the skeletal muscle resulted in abnormality of the triad junction structure, and also increased susceptibility to muscle fatigue. To elucidate the basis of these effects, we investigated the properties of Ca2+-uptake and -release in toxin-skinned Extensor Digitorium Longus (EDL) muscle fibers from control and mg29 knockout mice. Compared with the control muscle, submaximal Ca2+-uptake into the sarcoplasmic reticulum (SR) was slower and the storage of Ca2+ inside the SR was less in the mutant muscle, due to increased leakage process of Ca2+ movement across the SR. The leakage pathway is associated with the increased sensitivity of Ca2+/caffeine -induced Ca2+ release to myoplasmic Ca2+. Therefore, the increased fatigability of mutant EDL muscles can result from a combination of a slowing of Ca2+ uptake, modification of Ca2+-induced Ca2+ release (CICR), and a reduction in total SR Ca2+ content.

Relationship of Intracellular Free Ca^(2+) Concentration and Calcium-activated Chloride Channels of Pulmonary Artery Smooth Muscle Cells in Rats under Hypoxic Conditions

To investigate the relationship between intracellular free Ca^2＋ concentration （[Ca^2＋ ]i ） and calcium-activated chloride （Clca） channels of pulmonary artery smooth muscle cells （PASMCs） in rats under acute and chronic hypoxic conditions, acute hypoxia-induced contraction was observed in rat pulmonary artery by using routine blood vascular perfusion in vitro. The fluorescence Ca^2＋ indicator Fura-2/AM was used to observe [Ca^2＋ ]i of rat PASMCs under normal and chronic hypoxic condition. The effect of Clca channels on PASMCs proliferation was assessed by MTT assay. The Clca channel blockers niflumic acid （NFA） and indaryloxyacetic acid （IAA-94） exerted inhibitory effects on acute hypoxia-evoked contractions in the pulmonary artery. Under chronic hypoxic condition, [Ca^2＋ ]i was increased. Under normoxic condition, [Ca^2＋ If was （123.634-18.98） nmol/ L, and in hypoxic condition, [Ca^2＋]i wag （281. 754-16.48） nmol/L （P〈0. 01）. Under normoxic condition, [Ca^2＋ ]i showed no significant change and no effect on Clca channels was observed （P〉 0. 05）. Chronic hypoxia increased [Ca^2＋ ]i which opened Clca channels. The NFA and IAA-94 blocked the channels and decreased [Ca^2＋ ]i from （281.75± 16.48） nmot/L to （117.66 ±15.36） nmol/L （P〈0.01）. MTT assay showed that under chronic hypoxic condition NFA and IAA-94 decreased the value of absorbency （A value） from 0. 459±0. 058 to 0. 224±0. 025 （P〈0. 01）. Hypoxia increased [Ca^2＋ ]i which opened Cl~ channels and had a positive-feedback in [Ca^2＋ ]i. This may play an important role in hypoxic pulmonary hypertension. Under chronic hypoxic condition, Clca channel may play a part in the regulation of proliferation of PASMCs.

Effects of Atractylodes Macrocephala on the Cytomembrane Ca^(2+)-activated K^+ Currents in Cells of Human Pregnant Myometrial Smooth Muscles

The study examined the inhibitory effect of Atractylodes macrocephala （AM） on the uterine contraction during premature delivery and explored its electrophysiological mechanism by studying the effects of AM on the Ca^2＋-activated K^＋ currents of pregnant human myometrial smooth muscle cells with or without the treatment with intedeukin-6. Single cells were acutely isolated from pregnant human myometrial smooth muscles. Whole-cell Ca^2＋-activated K^＋ currents were recorded by using an Axopatchl-D amplifier. The cells were divided into three groups： group A in which AM was added into perfusate, group B, in which interleukin-6 was added into perfusate） and group C in which AM was added into perfusate after addition of interleukin-6. IL-6 10 ng/mL inhibited BKca by 36.9%±13.7% as compared with control （P〈0.01）. AM at 2 mg/mL raised BKca by 36.7%±22.6% or 45.2%±13.7% with or without the treatment of IL-6, respectively （P〈0.01）. It is concluded that AM was able to enhance the BKca of pregnant human myometrial smooth muscle cells treated or untreated with interleukin-6 and its effect on the BKca IL-treated cells was stronger that its effect on BKca of untreated cells. Our results suggested that AM can help to maintain the membrane potentials and the resting status of pregnant human myometrial smooth muscle cells.

Effects of ethanol on the tonicity of corporal tissue and the intracellular Ca^2＋ concentration of human corporal smooth muscle cells

Heavy alcohol consumption is associated with an increased risk of erectile dysfunction （ED）; however, the acute effects of ethanol （EtOH） on penile tissue are not fully understood. We sought to investigate the effects of EtOH on corporal tissue tonicity, as well as the intracellular Ca^2＋ concentration （[Ca^2＋]i） and potassium channel activity of corporal smooth muscle. Strips of corpus cavernosum （CC） from rabbits were mounted in organ baths for isometric tension studies. Electrical field stimulation （EFS） was applied to strips precontracted with 10 μmol L^-1 phenylephrine as a control. EtOH was then added to the organ bath and incubated before EFS. The [Ca^2＋]i levels were monitored by the ratio of fura-2 fluorescence intensities using the fura-2 loading method. Single-channel and whole-cell currents were recorded by the conventional patch-clamp technique in short-term cultured smooth muscle cells from human CC tissue. The corpus cavernosal relaxant response of EFS was decreased in proportion to the concentration of EtOH. EtOH induced a sustained increase in [Ca^2＋]i in a dose-dependent manner, Extracellular application of EtOH significantly increased whole-cell K^＋ currents in a concentration-dependent manner （P 〈 0.05）. EtOH also increased the open probability in cell-attached patches; however, in inside-out patches, the application of EtOH to the intracellular aspect of the patches induced slight inhibition of Ca^2＋-activated potassium channel （KCa） activity. EtOH caused a dose-dependent increase in cavemosal tension by alterations to [Ca^2＋]i. Although EtOH did not affect KCa channels directly, it increased the channel activity by increasing [Ca^2＋]i. The increased corpus cavemosal tone caused by EtOH might be one of the mechanisms of ED after heavy drinking.

Effect of Hypoxia on Ca^(2+) Concentration in Broiler's Cardiac Muscle Cells

The purpose of this research was to study the effect of hypoxia on the Ca^2＋ concentration in broiler＇s cardiac muscle cells （CMCs）. The concentration of Ca^2＋ in the CMC was observed using a laser scanning confocal microscope （LSCM）. The results showed that hypoxia could significantly increase intracellular Ca^2＋（normal oxygen, 99.3 ＋_ 13.1; hypoxia, 129.4 ＋_ 24.3, P 〈 0.01） in CMCs. The Ca^2＋ antagonist （nifedipine, verapamil） could significantly restrain the Ca^2＋ influx across the cell membrane of CMC treated by hypoxia （CMC： hypoxia ＋ verapamil, 100.9± 28.2; hypoxia ＋ nifedipine, 107.6± 27.7; P 〈 0.01）. The results showed hypoxia could increase intracellular Ca^2＋ concentration of CMC, and the Ca^2＋ antagonist could restrain the Ca^2＋ influx across the cell membrane of CMC treated by hypoxia.

2型糖尿病患者骨骼肌厚度和弹性变化及其影响因素

目的观察2型糖尿病患者骨骼肌厚度和弹性变化及其影响因素。方法前瞻性招募62例2型糖尿病患者(T2DM组)及60名健康成年人(HC组),以剪切波弹性成像(SWE)技术检测其放松及收缩状态下腹直肌和腓肠肌最大杨氏模量(E_(max)),比较组间2种状态下骨骼肌厚度及弹性模量,并采用多重线性回归分析影响腹直肌和腓肠肌弹性模量的因素。结果组间放松及收缩状态下腹直肌和腓肠肌厚度差异均无统计学意义(P均>0.05);T2DM组放松及收缩状态下腹直肌及腓肠肌Emax均低于HC组(P均<0.05)。多重线性回归分析显示,T2DM组放松及收缩状态下腹直肌及腓肠肌弹性模量均随病程、空腹血糖(FBG)及糖化血红蛋白(HbA1c)而呈线性降低(P均<0.05)。结论2型糖尿病患者骨骼肌弹性模量降低,且随病程、FBG及HbA1c而呈线性下降。

运动联合益生菌干预2型糖尿病大鼠糖脂代谢、氧化应激及骨骼肌卫星细胞成肌分化水平的变化

目的观察运动联合益生菌干预2型糖尿病大鼠糖脂代谢、氧化应激及骨骼肌卫星细胞表达的影响。方法8周龄SPF级SD雄性大鼠60只,随机选择10只大鼠为正常对照组(NC组),造模组大鼠腹腔注射链脲佐菌素,建立2型糖尿病大鼠模型,随机分为模型组(TN组)、运动+糖尿病组(YTN组)、益生菌+糖尿病组(GTN组)、运动+益生菌+糖尿病组(YGTN组),6周的递增负荷有氧跑台运动(第1周跑台速度为15 m/min,持续30 min;第2周跑台速度为15 m/min,持续60 min;第3~6周跑台速度为19.3 m/min,运动时间持续60 min,持续训练到第6周,每周5 d);GTN组和YGTN组在训练前1 h灌胃10.0 mL/(kg·d)的Lactibiane Iki益生菌溶液(浓度为10~7 CFU/mL)。最后,测定大鼠糖脂代谢指标、氧化应激指标及骨骼肌卫星细胞蛋白的表达。结果(1)TN组、YTN组、GTN组和YGTN组大鼠空腹血糖(fasting plasma glucose,FBG)、血清胰岛素(fasting serum insulin,FINS)、糖化血红蛋白(hemoglobin A1c,HBA1C)和胰岛素抵抗指数(homeostasis model assessment-insulin resistance index,HOMA-IR)水平均高于NC组(P<0.01),其中,YGTN组大鼠FBG水平均低于TN组、YTN组、GTN组(P<0.05);YTN组、GTN组和YGTN组大鼠血清FINS水平均与TN组比较均有所下降(P<0.01);YGTN组大鼠血清HBA1C水平均低于TN组、YTN组和GTN组水平(P<0.01);YGTN组大鼠HOMA-IR指数与TN组、YTN组和GTN组比较下降较显著(P<0.01)。结果表明有氧运动联合益生菌干预组大鼠FBG、FINS、HBA1C和HOMA-IR含量下降较明显。(2)TN组大鼠血清总胆固醇(total cholesterol,T-CHO)、甘油三酯(triglyceride,TG)、低密度脂蛋白胆固醇(low density lipoprotein cholesterol,LDL)和游离脂肪酸(free fatty acid,FFA)水平均高于NC组(P<0.05),YGTN组大鼠血清T-CHO、TG、LDL和FFA水平均低于TN组(P<0.05),基本上恢复到NC组的水平。TN组大鼠血清高密度脂蛋白胆固醇(high density lipoprotein cholesterol,HDL)水平低于NC组(P<0.05),YGTN组大鼠血清HDL水平高于TN组(P<0.05),基本上恢复到NC组水平。结果表明有氧运动联合益生菌干预糖尿病大鼠,可降低糖尿病大鼠血清T-CHO、TG、LDL、FFA含量,提高HDL水平较明显。(3)TN组大鼠血清丙二醛(malondialdehyde,MDA)和游离8-异前列腺素F2α(8-iso-prostaglandin F2α,8-isoPGF2α)水平均高于NC组(P<0.05或P<0.01),YGTN组大鼠血清MDA和8-isoPGF2α水平均低于TN组(P<0.05或P<0.01);TN组大鼠血清过氧化氢酶(catalase,CAT)、超氧化物歧化酶(superoxide dismutase,SOD)、谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)和总抗氧化能力(total antioxidant capacity,T-AOC)水平均低于NC组(P<0.01),YGTN组大鼠血清CAT、SOD、GSH-Px和T-AOC水平均高于NC组(P<0.01),但基本上恢复到NC组的水平。(4)TN组大鼠骨骼肌卫星细胞配对盒基因7(paired box gene 7,Pax7)、成肌分化因子(myogenic determination gene,MyoD)、肌细胞生成素(myogenin,MyoG)和生肌因子5(myogenic factor 5,Myf5)蛋白表达均低于NC组(P<0.05或P<0.01),YGTN组大鼠骨骼肌Pax7、MyoD、MyoG和Myf5蛋白表达均高于TN组(P<0.05或P<0.01);基本上恢复到NC组水平。TN组大鼠骨骼肌生成抑制素(myostatin,MSTN)蛋白表达高于NC组(P<0.05),YGTN组大鼠骨骼肌MSTN蛋白表达低于TN组(P<0.05),基本上恢复到NC组水平。结论益生菌和有氧运动具有减轻胰岛素抵抗,改善血脂和氧化激的作用,在改善2型糖尿病大鼠血糖和胰岛素水平具有协同作用。此外,有氧运动联合益生菌干预促进了肌细胞的分化,可能对防止T2DM引起肌肉质量的流失和力量下降以及肌肉组织的并发症发挥一定的作用。

超声造影在2型糖尿病患者骨骼肌微循环病变评估中的应用

目的通过超声造影(contrast-enhanced ultrasound,CEUS)评估小腿三头肌的微循环灌注情况,探讨CEUS在2型糖尿病(type 2 diabetes mellitus,T2DM)微血管病变评估中的应用价值。方法收集2020年8月至2023年1月在温州医科大学附属第二医院内分泌科住院治疗的T2DM患者51例,分为单纯T2DM组(n=15)、T2DM微循环病变组(n=36),记录每位患者的糖化血红蛋白(hemoglobin A1c,HbA1c)和胰岛素抵抗指数(homeostatic model assessment for insulin resistance,HOMA-IR)。CEUS观察小腿三头肌的造影情况,获取定量造影指标区域增强强度(enhanced intensity,PI-BI)和区域达峰时间(regional peak time,TTP-AT),并进行组间对比分析。结果T2DM微变组的HbA1c及HOMA-IR高于单纯T2DM组(P<0.05)。T2DM微变组腓肠肌内侧头(musculi gastrocnemii,MG)、腓肠肌外侧头(laterale musculi gastrocnemi,LG)、比目鱼肌(soleus,SOL)及交界区的TTP-AT均长于单纯T2DM组(P<0.05)。两组SOL的TTP-AT均为最长,LG次之,MG最短(P<0.05)。T2DM微变组MG的PI-BI高于SOL(P<0.05)。小腿三头肌交界区的TTP-AT与HbA1c、HOMA-IR之间均呈正相关(P<0.05)。结论CEUS小腿三头肌TTP-AT是评估T2DM患者微血管病变的新指标。

基于Nrf2调控Pink1/Parkin介导的线粒体自噬在老年肌肉减少症骨骼肌纤维化中的作用及机制研究

目的探讨线粒体自噬在老年肌肉减少症模型小鼠中的作用,并进一步探讨其作用机制。方法选取13.5个月龄SPF级雄性C57BL/6J小鼠13只分为老龄鼠组(O组,n=6)、老龄鼠+核转录因子红系2相关因子2(Nrf2)激动剂组(O+SFN组,n=7),另3月龄SPF级雄性C57BL/6小鼠8只作为青年鼠组(Y组)。O组按体重0.1 mL/10 g给予0.1%DMSO溶液,每周3次,O+SFN组按体重0.1 mL/10 g给予1%SFN溶液,每周3次,Y组给予等体积的0.1%DMSO溶液,各组持续10周。干预10周后,检测各组小鼠的体重、腓肠肌/体重比、抓力、腓肠肌细胞活性氧水平、腓肠肌细胞线粒体膜电位和腓肠肌细胞线粒体DNA(mtDNA)拷贝数;天狼星红染色观察各组小鼠腓肠肌组织纤维化情况;蛋白质印迹法检测腓肠肌组织中纤维化相关蛋白collagen 1、collagen 3和fibronectin及自噬相关蛋白Nrf2、PINK1、Parkin、LC3、BNIP3和FUNDC1的相对表达。结果干预10周后,O组和O+SFN组小鼠体重均高于Y组,腓肠肌/体重比均显著低于Y组,差异均有统计学意义(P<0.05);O+SFN组小鼠的体重及腓肠肌/体重比值均显著高于O组,差异均有统计学意义(P<0.05)。干预10周后,O组和O+SFN组小鼠抓力均低于Y组,而O+SFN组小鼠抓力显著高于O组,差异均有统计学意义(P<0.05)。干预10周后,O组和O+SFN组小鼠的活性氧含量和线粒体膜电位均显著高于Y组,mtDNA拷贝数显著低于Y组,差异均有统计学意义(P<0.05);O+SFN组小鼠的活性氧含量和线粒体膜电位低于O组,mtDNA拷贝数高于O组,差异均有统计学意义(P<0.05)。天狼星红染色观察可见,O组和O+SFN组小鼠的胶原纤维的比例显著高于Y组,O+SFN组的胶原纤维比例低于O组。干预10周后,O组和O+SFN组小鼠腓肠肌组织中collagen 1、collagen 3和fibronectin蛋白的相对表达均显著高于Y组,而Nrf2、BNIP3、FUNDC1、PINK1和Parkin蛋白的相对表达均显著低于Y组,差异均有统计学意义(P<0.05);O+SFN组小鼠腓肠肌组织中collagen 1、collagen 3和fibronectin蛋白的相对表达均低于O组,而Nrf2、BNIP3、FUNDC1、PINK1和Parkin蛋白的相对表达均高于O组,差异均有统计学意义(P<0.05)。结论骨骼肌纤维化是老年肌肉减少症发生发展的重要机制之一,激活Nrf2可上调PINK1/Parkin信号通路而对线粒体自噬发挥保护作用,进而抑制骨骼肌纤维化,缓解肌肉减少症,可作为临床防治老年肌肉减少症的新思路和新切入点。