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.

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.

Effects of Astragalus membranaceus on Energy Metabolism and Expression of CNTF Protein in Skeletal Muscle of Exercise-induced Fatigue Rats

[Objectives]This study was conducted to investigate the effects of Astragalus membranaceus in different groups on energy metabolism and CNTF protein expression in skeletal muscle of exercise-induced fatigue rats.[Methods]Thirty-five clean male SD rats were randomly divided into a normal group,and low-,meddle-and high-dose groups of A.membranaceus aqueous solution,with 7 rats in each group.The low-dose,medium-dose and high-dose groups were given by gavage at 0.65,1.3 and 2.6 g/kg,respectively,while the normal group and the model group were given normal food and water.The weight of rats was observed.The contents of serum urea,lactate,muscle glycogen,liver glycogen and CNTF expression were detected.[Results]After modeling,compared with the normal group,the serum lactate and urea contents of rats in the model group significantly increased(P<0.01),while the muscle glycogen content(P<0.01)and liver glycogen content(P<0.05)of the skeletal muscle significantly decreased.Compared with the model group,the low-,meddle-and high-dose groups of A.membranaceus significantly reduced the levels of lactate and urea in serum(P<0.01),while the levels of muscle glycogen and liver glycogen in the skeletal muscle significantly increased(P<0.01,P<0.05).[Conclusions]This study provides a good research foundation for the treatment of exercise-induced fatigue using traditional Chinese herb A.membranaceus in modern clinical practice.

Effect of berberine on glucolipid metabolization in diabetic skeletal muscle and its mechanism

Aim To investigate the effect of berberine on damaged morphology and glucolipid metabolization in skeletal muscle of diabetic rat and the relationship between peroxisome proliferator-activated receptor （PPARs） α/γ/δ protein expression. Methods Type 2 diabetes mellitus rats were induced by an injection of 35 mg.kg^-1 streptozotocin （STZ） and a high-carbohydrate/ high-fat diet for 16 weeks. From week 17 to 32, diabetic rats were given low-, middle-, high-dose berberine （75, 150, 300 mg.kg^-1）, fenofibrate （100 mg.kg^-1） and rosiglitazone （4 mg.kg^-1） by oral administration, respectively. The skeletal muscle structure was observed with hematoxylin-eosin （HE） staining, glycogen and triglyceride contents were measured by spectrophotometry and PPAR α/γ/δ protein expressions were detected by immunohistochemistry. Results Fiber distribution remained normal in skeletal muscles of all the groups, middle-, high-dose berberine partly improved diabetic fibre atrophy, increased glycogen and decreased triglyceride levels in diabetic muscle （P〈 0.01）. Middle-, high-dose berberine and rosiglitazone all significantly reduced PPARy protein level in diabetic skeletal muscle （P 〈 0.01）; middle-, high-dose berberine and fenofibrate strikingly increased both PPARu and PPAR8 expression （P〈 0.01）. Conclusion Berberine modulates PPAR α/γ/δ protein expression in diabetic skeletal muscle which may contribute to ameliorate fibre damage and glucolipid metabolization.

Metabolism and regulation of FNDC 5 in skeletal muscle

Purpose： Fibronectin type III domain-containing protein 5 （FNDC5）, also known as irisin, is a myokine secreted from muscle in response to exercise and improves obesity and glucose homeostasis. However, the molecular mecha- nisms that regulate FNDC5 expression and the functional significance of FNDC5 in skeletal muscle remain un- known. In this study, we explored the possible pathways that induce FNDC5 expression and delineated its metabol- ic effects on skeletal muscle. Methods： C2C12 myotubes were treated with various concentrations of Sp-cAMP, forskolin, and ionomycin respectively for various durations. FNDC5 and related metabolic genes＇ expressions were measured by quantitative real-time polymerase chain reaction （qRT-PCR）. Cyclic AMP responsive element-binding protein （CREB） phosphorylation was measured by Western blot. Oxidative phosphorylation was quantified by oxy- gen consumption rate （OCR） measurement using XF-96 analyzer （Seahorse Bioscience）. The statistical signifi- cance was calculated by one-way analysis of variance （ANOVA）. Data were considered significant when P 〈 0.05. Results： We found that cAMP and forskolin dose and time dependently increased FNDC5 expression in C2C12 myotubes. A synergistic effect of forskolin and ionomycin on FNDC5 expression was also found. CREB phosphoryl- ation was elevated in myotubes simultaneously upon these treatments. C2C12 myotubes over expressing CREB dis- plays increased FNDC5 expression as well, suggesting CREB was a regulator of FNDC5 expression. Functionally, irisin treatment enhanced mitochondrial biogenesis of C2C12 myotubes through increasing peroxisome proliferator- activated receptor gamma coactivator-1α （PGC-1α）, nuclear respiratory factor 1 （NRF1） and mitochondrial tran-scription factor A （TFAM） expressions, leading to increase myotube mitochondrial respirations and ATP produc- tion. Conclusions Our observation indicates that irisin is a metabolic modulator of skeletal muscle, whose expres- sion is controlled by cAMP pathway and intracellular level of calcium.

Functional imaging of skeletal muscle glucose metabolism by ¹⁸FDG PET to characterize insulin resistance in patients at high risk for coronary artery disease

Insulin resistance is associated with several coronary risk factors and is thought to play a critical role for the development of coronary artery disease. Insulin resistance has several causes, including an impaired skeletal muscle glucose utilization rate (SMGU), reduced peripheral blood flow, and altered fatty tissue metabolism, with SMGU being considered the most important. Nonetheless, insulin resistance has only been estimated by the glucose disposal rate (GDR) in previous studies. Methods: Skeletal muscle metabolic imaging with 18FDG and positron emission tomography (PET) was undertaken to measure SMGU during hyperinsulinemiceuglycemic clamping in 22 normotensive type-2 diabetics under no medications (T2- DM), 17 normotensive non-diabetic hypertriglyceridemics, 22 patients with hypertension, and 12 agematched controls. Whole body insulin resistance was assessed by the GDR during hyperinsulinemiceuglycemic insulin clamping. Results: The SMGU and GDR were significantly reduced in T2DM (32.1 ± 16.6 μmol/min/kg and 24.3 ± 13.0 μmol/min/kg, respectively), hypertriglyceridemics (36.5 ± 13.5 μmol/min/ kg and 22.7 ± 8.07 μmol/min/kg respectively) and patients with hypertension (35.4 ± 26.6 μmol/min/kg and 29.0 ± 9.90 μmol/min/kg, respectively) compared with controls (72.2 ± 44.1 μmol/min/kg and 43.0 ± 22.9 μmol/min/kg, p < 0.01, respectively). In all groups studied, SMGU was significantly correlated with GDR (r = 0.76, p < 0.01) and GDR (F = 13.9) was independently related to SMGU (r = 0.81, p < 0.01). Conclusion: Insulin resistance is significantly associated with SMGU to a similar degree among patients with T2DM, essential hypertension and hypertriglyceridemia. 18FDG PET functional imaging allows insulin resistance to be assessed.

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.

Human skeletal muscle perilipin 2 and 3 expression varies with insulin sensitivity

Background: Impaired insulin sensitivity may partly arise from a dysregulated lipid metabolism in human skeletal muscle. This study investigates the expression levels of perilipin 2, 3, and 5, and four key lipases in human skeletal muscle from the subjects that exhibit a range from normal to very low insulin sensitivity. Methods: 25 middle aged male participants were matched for lean body mass and recruited into three groups;type 2 diabetes patients (T2D), impaired glucose tolerance (IGT), and healthy sedentary controls (CON) according to their glucose tolerance and VO2peak. A muscle biopsy was obtained from vastus lateralis, and a two-step sequential euglycaemic-hyperinsulinaemic clamp was performed. Muscle samples were analyzed by Western blot for expression of perilipin 2, 3, 5, adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), endothelial lipase (EL) and lipoprotein lipase (LPL). Results: Perilipin 3 expression was higher in T2D compared to CON. Perilipin 2 expression was higher in CON than T2D. We observed no difference in expression of perili pin 5, ATGL, HSL, EL or LPL between the groups. Conclusions: In the present study the muscle perilipin 3 expression and perilipin 2 expression varied markedly with insulin sensitivity. This difference in perilipin expression may indicate that the lipid droplet function and thus storage and release of fatty acid-vary with insulin sensitivity.

Measurement of lumbar muscle glucose utilization rate can be as useful in estimating skeletal muscle insulin resistance as that of thigh muscle

Background: Skeletal muscle glucose utilization (SMGU) can be accessed by positron emission tomography (PET) and18F-FDG to characterize insulin resistance. The quantity of skeletal muscle in the lumbar is sufficient to indicate that SMGU in the lumbar (SMGU- lumbar) can be measured with18F-FDG PET of the chest instead of obtaining thigh muscle SMGU (SMGU-thigh). This would reduce PET scan time to avoid thigh muscle PET scan. This study was aimed to compare SMGU-lumbar and thigh muscle SMGU under insulin clamping to identify the validity of measurements of SMGU in the lumbar for studies of insulin resistance. Methods: Thirty-three patients underwent sequential dynamic18F-FDG PET of both the thoracic (37 min) and thigh region (22 min) during hyperinsulinemic euglycemic insulin clamping. Both SMGU-lumbar and SMGU-thigh were calculated by Patlak graphical analysis. Whole body insulin resistance was assessed by a whole body glucose disposal rate during hyperinsulinemic euglycemic insulin clamping. Input function was obtained from the time activity curve of the descending aorta and venous blood sampling as previously validated. Results: SMGU-thigh (0.0506 ± 0.0334 μmol/min/g) was comparable to SMGU-lumbar (0.0497 ± 0.0255 μmol/min/g). The Bland-Altman method of difference plot analysis showed a significant correlationship between SMGU- thigh and SMGU-lumbar (r = 0.506, p = 0.0028). There were seen very good significant correlationship between whole body glucose utilization rate in both thigh (r = 0.737, p = 0.0001) and lumbar (r = 0.772, p = 0.0001). Conclusion: These results support the validity of measuring SMGU-lumbar to estimate insulin resistance during PET imaging of the chest.

Skeletal muscle and whole body insulin resistance but not cardiac muscle insulin resistance could be improved by troglitazone therapy within 12 weeks in type-2 diabetes

Background: Existence of myocardial insulin resistance (IR) has been reported in type II diabetics (T2- DM) and coronary artery disease (CAD). Improvement in heart and skeletal muscle IR after thiazolidinedione’s therapy was reported in T2DM and CAD. However effects of troglitazone therapy (TRO) on myocardial IR remain uncertain. To clarify heart and skeletal muscle and whole body IR in T2DM without CAD by TRO to clarify whether TRO would provide different results. Methods: We analyzed data on 15 T2DM patients who underwent dynamic PET with 18F-FDG under insulin clamping before and during TRO (200 mg/day) and 17 controls. Results: Whole body glucose disposal rate (WBGR mg/min/kg) in T2DM before TRO (3.41 ± 1.72) was significantly lower than in controls (9.76 ± 2.97, p < 0.01) as was the skeletal muscle glucose utilization rate (SMGU mg/min/kg);T2DM (0.367 ± 0.217) vs. controls (1.34 ± 0.613, p < 0.01) and myocardial glucose utilization rate (MGU mg/min/kg;T2DM 5.86 ± 2.03 vs. controls 7.34 ± 1.80, p < 0.05). WBGR in T2DM during TRO (5.17 ± 2.75, p < 0.05) was significantly higher than that before TRO, as was the SMGU (0.782 ± 0.20, p < 0.05). The MGU in T2DM during TRO (6.59 ± 0.72) was comparable with that before TRO. Conclusion: Myocardial IR response to TRO differed from that in skeletal muscle and the whole body in T2DM without CAD.

Adiponectin and lipid metabolism in skeletal muscle

White adipose tissue(WAT)is a key energy depot in humans and most animals.Traditionally,it is believed that WAT passively accumulates triglycerides or releases fatty acids to accommodate systemic energy meta bolism.However,recent studies have demonstrated that WAT also actively participates in energy metabolism mainly through its secretion of cytokines and hormones.Therefore,at this time,WAT is recognized as an endocrine organ.Adiponectin is one of the key adipocyte-derived hormones that regulate systemic or tissue lipid and glucose meta bolism.In contrast to most other adipocyte-derived hormones,adiponectin increases insulin sensitivity and improves lipid and glucose metabolism.Although the insulin-sensitizing function of adiponectin has been well established,recent studies have demonstrated that adiponectin also regulates metabolism through pathways independent of insulin signaling.Due to the massive tissue mass of skeletal muscle,lipid uptake and subsequent fatty acid oxidation in skeletal muscle have a big impact on maintaining systemic energy homeostasis.Furthermore,adiponectin gene expression is regulated by energy intake.Therefore,adiponectin serves as a coordinator of energy balance amongst WAT,skeletal muscle and other tissues.We summarize the regulatory effects of adiponectin on lipid and glucose metabolism in skeletal muscle.Future research directions have also been proposed.

AKG/OXGR1 promotes skeletal muscle blood flow and metabolism by relaxing vascular smooth muscle

In response to contraction during exercise,skeletal muscle growth and metabolism are dynamically regulated by nerve action,blood flow,and metabolic feedback.α-Ketoglutarate(AKG),a bioactive intermediate in the tricarboxylic acid cycle released during exercise,has been shown to promote skeletal muscle hypertrophy.However,the underlying mechanism of AKG in regulating skeletal muscle development and metabolism is still less known.2-Oxoglutarate receptor 1(OXGR1),the endogenous AKG receptor,is found to be distributed in the vascular smooth muscle(VSM)of skeletal muscles.OXGR1 knockout results in skeletal muscle atrophy,accompanied by decreased expression of myosin heavy chain I(MyHC I),capillary density,and endurance exercise capacity.Furthermore,the study found that dietary AKG supplementation increased mice endurance exercise distance,MyHC I/MyHC IIb ratio,arteriole,and capillary densities in skeletal muscle.Meanwhile,acute AKG administration gradually increased the blood flow in the lower limbs.Further,by using OXGR1 global knockout and OXGR1 VSM-specific(MYH11-Cre×OXGR1-FloxP)knockdown models,we found that OXGR1 in VSM is essential for AKG-induced improvement of skeletal muscle performances.According to the in vitro study,AKG expanded the cell area in VSM with a decreased intracellular pH by OXGR1.Our results demonstrated a novel role of AKG/OXGR1 in VSM of skeletal muscle to regulate blood flow and then enhance slow muscle fiber conversion and capillarization.These findings provide a theoretical basis for the AKG/OXGR1 signaling pathway to maintain human muscle function and improve meat production and livestock and poultry meat quality.

低温对民猪骨骼肌线粒体能量代谢基因的影响

为了探究低温环境下民猪肌肉组织内与线粒体能量代谢相关基因的变化情况,以解析民猪抗寒特性的遗传机制。将9头体质量相近的母猪随机分成3组,每组3头,在冬季将其中2组置于室外半敞篷舍内饲养,分别处理3 d(急性低温处理组)和58 d(慢性低温处理组),1组置于常规舍内饲养,作为对照组。以背肌为试验材料,采用PCR array方法,对90个与线粒体能量代谢相关基因的表达水平进行检测。结果表明,与对照组相比,急性低温处理组基因的表达水平差异不显著,但慢性低温处理显著改变 ATP5H、 ATP5L、 ATP6V1G3、 COX5A、 COX7A2、 COX7A2L、 NDUFS4、 SDHB、 UQCRQ和 GADD45B基因的表达水平,尤其是 GADD45B,达到了极显著水平(P<0.01),这些基因均为编码OXPHOS系统亚基基因,推测慢性低温诱导了背肌ATP的生成。对 GADD45B基因进一步分析发现,该基因在哺乳动物中高度保守,基本符合分子进化规律,表达具有明显的组织特异性。急性低温处理对民猪背肌内ATP的生成影响不显著,但慢性低温处理诱导ATP的生成,以维持体温恒定。

短链脂肪酸干预老年大鼠肌少症的作用及机制

背景:研究显示短链脂肪酸是一种潜在的骨骼肌能量代谢调节物,但具体机制尚不明确。目的:探索短链脂肪酸对老年肌少症的作用及可能的相关机制。方法:将SD大鼠随机分为对照组、肌少症组、肌少症+短链脂肪酸组,后2组大鼠采用摘除大鼠卵巢、1周后按体质量5 mg/kg皮下注射地塞米松、连续7 d给药的方案建立老年肌少症大鼠模型;对照组大鼠打开腹腔找到卵巢但不摘除,随即缝合腹腔。肌少症+短链脂肪酸组大鼠造模术后给予含有150 mmol/L短链脂肪酸的饮用水(乙酸钠600 mg/kg、丙酸钠200 mg/kg、丁酸钠200 mg/kg),对照组及肌少症组大鼠给予等量的生理盐水,1次/d,连续4周。造模结束后测量大鼠双侧腓肠肌质量和体质量计算腓肠肌指数,评估造模是否成功。于造模成功后0,1,2,4周测量大鼠的摄食量、体质量及抓力;苏木精-伊红染色观察腓肠肌形态学改变;Western blot法检测腓肠肌中p-AMPK、p-ULK1蛋白的表达。结果与结论:与对照组比较,肌少症组大鼠摄食量、体质量及抓力均显著降低(P<0.05),腓肠肌的湿质量显著降低(P<0.05),腓肠肌中p-AMPK和p-ULK1蛋白表达均显著降低(P<0.05);与肌少症组相比,肌少症+短链脂肪酸组大鼠摄食量、体质量、抓力、腓肠肌的湿质量及腓肠肌中p-AMPK和p-ULK1的蛋白表达显著增加(P<0.05)。结果提示,短链脂肪酸可改善老年肌少症的症状,可能与骨骼肌中AMPK和ULK1蛋白水平增高有关。

有氧运动对2型糖尿病大鼠糖脂代谢、骨骼肌炎症和自噬的影响

背景:肥胖及其导致的慢性低度炎症是诱发2型糖尿病的重要危险因素,这种炎症反应还将进一步累及骨骼肌,导致骨骼肌的分解代谢和自噬通量增加;有氧运动作为防治2型糖尿病的主流运动方式,对2型糖尿病骨骼肌也可能具有一定的保护作用。目的:探究有氧运动对2型糖尿病大鼠糖脂代谢、骨骼肌炎症和骨骼肌自噬的影响和调节机制。方法:通过8周高脂饲养联合链脲佐菌素注射建立2型糖尿病大鼠模型,将实验大鼠分为普通对照组、普通运动组、糖尿病对照组和糖尿病运动组,分别在4周有氧运动(跑速16 m/min,60 min/d,5 d/周)前后采用全自动生化分析仪检测各组大鼠血糖、血清高密度脂蛋白、低密度脂蛋白和三酰甘油水平,酶联免疫吸附法检测血清胰岛素水平,计算胰岛素抵抗指数和葡萄糖代谢曲线下面积;在4周有氧运动后采用酶联免疫吸附法测定比目鱼肌中白细胞介素6和肿瘤坏死因子α水平,免疫印迹法测定比目鱼肌中叉头框蛋白O3(forkhead box protein O3,FoxO3)、LC3和p62的蛋白表达水平。结果与结论:①与普通对照组相比,糖尿病对照组大鼠的糖耐量曲线下面积和胰岛素抵抗指数均显著升高(P<0.001,P=0.025),有氧运动能显著降低普通运动组(P<0.001,P=0.038)和糖尿病运动组(P<0.001,P=0.004)的糖耐量曲线下面积和胰岛素抵抗指数。②与普通对照组相比,糖尿病对照组大鼠的血清高密度脂蛋白水平显著降低(P=0.030)、低密度脂蛋白和三酰甘油水平显著升高(P=0.027,P=0.014),有氧运动能显著降低普通运动组的三酰甘油、低密度脂蛋白水平(P=0.019,P=0.008)以及糖尿病运动组的三酰甘油水平(P=0.022)。③与普通对照组相比,糖尿病对照组大鼠比目鱼肌的白细胞介素6和肿瘤坏死因子α水平均显著升高(P<0.001,P=0.007),有氧运动能显著降低糖尿病运动组的肿瘤坏死因子α水平(P=0.017)。④与普通对照组相比,糖尿病对照组大鼠比目鱼肌的LC3-Ⅱ/LC3-Ⅰ比值显著升高,有氧运动能显著提高普通运动组的LC3-Ⅱ/LC3-Ⅰ比值(P<0.001),降低糖尿病运动组的LC3-Ⅱ/LC3-Ⅰ比值、FoxO3和p62蛋白表达水平(P=0.026,P=0.050,P=0.048)。⑤结果表明,高脂饲养联合链脲佐菌素注射建立的2型糖尿病模型具有明显糖脂代谢障碍,同时累及并导致骨骼肌炎症反应和自噬过度激活;有氧运动可以改善2型糖尿病糖脂代谢,降低骨骼肌局部炎症并抑制骨骼肌自噬,从而对骨骼肌起到保护作用。

长时间血清饥饿胁迫对猪骨骼肌卫星细胞代谢和自噬的影响

为了探究长时间、不同程度饥饿胁迫条件对原代猪骨骼肌卫星细胞(SMSCs)代谢和自噬的影响,本试验通过控制SMSCs培养体系中血清浓度以形成不同程度饥饿胁迫,其中20%血清培养浓度为正常对照组,15%、10%、5%和0%血清培养浓度为试验组。细胞培养96 h后,通过流式细胞术检测各组细胞凋亡率、线粒体膜电位和活性氧(ROS)水平,通过ATP检测试剂盒测定细胞内ATP水平,通过Western blot检测各组细胞蛋白中自噬标志蛋白LC3b、p62以及AMPK-mTOR自噬信号通路中p-AMPK/AMPK和p-mTOR/mTOR蛋白的表达。结果显示,与20%血清组相比,0%血清和5%血清细胞凋亡率极显著上调(P<0.01),10%血清组细胞凋亡率显著上调(P<0.05);各试验组线粒体膜电位均极显著下降(P<0.01),ROS水平和ATP水平均极显著上调(P<0.01);细胞中LC3b蛋白的相对表达量随血清浓度降低而升高,p62蛋白的相对表达量随血清浓度降低而降低;p-mTOR/mTOR比值随血清浓度降低而降低,p-AMPK/AMPK比值随血清浓度降低而升高。结果表明,通过长期减少SMSCs培养体系中血清浓度,可以促进细胞代谢加快和凋亡发生,并且通过AMPK/mTOR信号通路激发细胞发生自噬,上述变化的程度与血清减少的程度呈正相关。本试验为后续探索不同程度饥饿胁迫对动物肌肉发育影响的研究提供理论依据。

细胞外囊泡在少肌性肥胖中的作用及机制

背景:细胞外囊泡可通过参与细胞间通讯调节胰岛素抵抗和抑制炎症反应,同时可以修复骨骼肌,促进骨骼肌再生,有望成为少肌性肥胖的新型治疗方式。目的:探讨细胞外囊泡的生物发生、生物学功能及其与少肌性肥胖的关系,综述当前有关细胞外囊泡在少肌性肥胖的发病机制、诊断和治疗中的最新进展。方法:由第一作者应用计算机在PubMed、Embase和中国知网数据库检索涉及细胞外囊泡在少肌性肥胖中的相关研究,检索关键词为“extracellular vesicle,exosome,sarcopenic obesity,obese sarcopenia,skeletal muscle regeneration,skeletal muscle mass regulation”和“细胞外囊泡、外泌体、少肌性肥胖、肥胖肌少症、骨骼肌再生、骨骼肌质量调节”,检索时间为2022年6-11月,经过筛选后纳入87篇文献进行综述分析。结果与结论:①细胞外囊泡是细胞双向通讯的重要媒介,可通过自分泌、旁分泌和内分泌的方式参与正常生理和病理过程的调节。②少肌性肥胖是复杂的多因素疾病,细胞外囊泡主要通过调节骨骼肌炎症反应和肌细胞平衡稳态参与少肌性疾病的发生发展。③脂肪和骨骼肌分泌的细胞因子通过细胞外囊泡包裹而释放到细胞外循环并发生相互作用,促进骨骼肌胰岛素抵抗和脂肪生成,是少肌性肥胖中骨骼肌发生萎缩的主要病理生理学。④细胞外囊泡不仅通过提供特定的致病标志物促进少肌性肥胖的疾病发展进程,也是少肌性肥胖中具有价值的诊断指标。⑤由于运动期间骨骼肌释放细胞外囊泡增强了新陈代谢反应,促进骨骼肌再生,因此细胞外囊泡可以作为少肌性肥胖的治疗靶点,而且还可通过装载药物有效提高药物的生物利用度的方式,治疗少肌性肥胖。

Maternal supplementation with mulberry-leaf flavonoids improves the development of skeletal muscle in the offspring of chickens

The development of skeletal muscle is a crucial factor in determining the meat yield and economic benefits of broiler production.Recent research has shown that mulberry leaves and their extracts can be used to significantly improve the growth performance of livestock and poultry.The present study aims to elucidate the mechanisms involved in the regulation of skeletal muscle development in broiler offspring by dietary mulberry-leaf flavonoids(MLF)supplementation from the perspective of maternal effect theory.A total of 270 Qiling broiler breeder hens were randomly assigned to 3 treatments with different doses of MLF(0,30,60 mg/kg)for 8 weeks before collecting their fertilized eggs.The chicken offspring at 13 and 19 d of embryonic stage,and from 1 to 28 d old after hatching were included in this study.The results showed that maternal supplementation increased the breast muscle weight and body weight of the offspring at the embryo and chick stages(P<0.05).This was followed by increased cross-sectional area of pectoral muscle fibres at 14 d(P<0.05).Further determination revealed a tendency towards increased serum levels of insulin-like growth factor 1(IGF-1)(P=0.092)and muscle fibre count(P=0.167)at 1 d post-hatching following maternal MLF treatment,while serum uric acid(UA)was decreased at 14 d after hatching(P<0.05).Moreover,maternal MLF supplementation significantly up-regulated the mRNA expression of the myogenic regulatory factor Myf5 in skeletal muscle at the both embryonic and growth stages(P<0.05).The relative abundance of the downstream protein of BMPR2,Smad1 and p-Smad1/5/9 in the TGFβsignalling pathway was significantly increased by maternal MLF treatment.Meanwhile,the increased expression of the target protein p-mTOR in the breast muscle of the offspring chicks is in accordance with the improved growth rate of the breast and the body.In conclusion,maternal MLF supplementation can promote muscle protein metabolism and muscle fibre development of chick embryos through upregulation of Myf5 expression and BMP/p-Smad1/5/9 axis,thereby improving growth performance of slow growing broiler.

降糖方对糖耐量异常大鼠糖脂代谢及骨骼肌组织IκB-α和NF-κBp65的影响

目的:探讨降糖方对糖耐量异常大鼠糖脂代谢及骨骼肌组织κB抑制蛋白α(IκB-α)、核转录因子肽p65(NF-κBp65)的影响。方法:SD大鼠随机分为正常组、模型组、盐酸二甲双胍组、降糖方低、高剂量组,采用高脂饮食喂养4周,链脲佐菌素(STZ)腹膜内注射建立糖耐量异常大鼠模型,治疗8周后,观察骨骼肌组织病理变化,测定空腹血糖(FPG)、血清胰岛素(FINS)、胰岛素抵抗指数(HOMA-IR)、甘油三酯(TG)、总胆固醇(TC)、低密度脂蛋白(LDL-C)、骨骼肌组织IκB-α mRNA、NF-κBp65 mRNA水平、骨骼肌组织白细胞介素-4(IL-4)、白细胞介素-12(IL-12)、肿瘤坏死因子-α(TNF-α)蛋白水平。结果:正常组大鼠骨骼肌组织结构正常,模型组骨骼肌排列紊乱、肌纤维断裂、可见明显炎症细胞浸润;盐酸二甲双胍及降糖方干预后,骨骼肌炎症细胞浸润减少,肌纤维排列趋于整齐。模型组大鼠FPG、FINS、HOMA-IR水平、血清TG、TC、LDL-C水平、骨骼肌IκB-α mRNA、NF-κBp65 mRNA和蛋白水平、骨骼肌组织IL-4、IL-12、TNF-α蛋白水平高于对照组(P<0.01);盐酸二甲双胍组、降糖方低、高剂量组大鼠FPG、FINS、HOMA-IR水平,血清TG、TC、LDL-C水平,骨骼肌IκB-α mRNA、NF-κBp65 mRNA和蛋白水平、骨骼肌组织IL-4、IL-12、TNF-α蛋白表达水平低于模型组(P<0.01)。结论:降糖方对糖耐量异常大鼠糖脂代谢具有明显改善作用,其机制可能与降糖方抑制骨骼肌IκB-α mRNA、NF-κBp65 mRNA和蛋白的表达有关。

重复离心运动防治代谢性疾病研究进展

通过梳理重复性离心运动(eccentric exercise,ECC)与代谢性疾病防治相关研究,厘清重复性ECC在代谢性疾病防治中的应用成果、适应机制以及应用风险防范。ECC初期,一次不适应的ECC诱发的骨骼肌超微结构损伤和暂时性胰岛素抵抗是机体的代偿性保护机制;重复性ECC可实现在相对较低心血管负担下进行高负荷肌肉运动,在人体代谢、骨骼肌质量与功能、身体成分、心血管功能、炎症、日常生活自理能力、运动依从性等方面产生有益影响,是心血管系统、呼吸系统、运动能力等受限的代谢性疾病患者及其风险人群有效且相对安全可行的理想运动方式。这一代谢性疾病防治效应是机体各系统产生适应的结果。未来研究需进一步针对代谢性疾病患者及其风险人群探究更高依从性且功效更大化的ECC干预方案,并深入探索其机制。