Objective: To study the mechanism of Sijunzi decoction treating limb weakness in spleen Qi deficiency (SQD) based on the myonuclear domain (MND) theory. Methods: 40 male Sprague-Dawley rats were randomly divided into ...Objective: To study the mechanism of Sijunzi decoction treating limb weakness in spleen Qi deficiency (SQD) based on the myonuclear domain (MND) theory. Methods: 40 male Sprague-Dawley rats were randomly divided into the normal group, SQD model group (model group), SQD+ still water group (SW group) and SQD+ Sijunzi decoction group (CM group), 10 rats each group;Grip-Strength Meter was used to measure limb grip strength;transmission electron microscope was employed to observe the ultrastructural changes of the myofibers, Image Pro 6.0 was used to measure the myonuclear numbers, cross-section area (CSA) and then their ratios (the MND sizes) were calculated, immunofluorescence assay was chosen to test the expressions of paired box gene 7 (Pax7) and myogenic differentiation antigen (MyoD). Results: Compared with those in the normal group, limb grip strength was decreased, sarcomeres were abnormal, and all the myonuclear numbers, CSA and MND sizes were reduced, but the Pax7+ cell numbers were increased, significantly, in the model and SW groups;Compared with those in the model and SW groups, limb grip strength was increased, sarcomeres were basically normal, the myonuclear number and CSA were both greater, and the Pax7+ and MyoD+ cell numbers were both increased, significantly, in the CM group. Conclusion: Sijunzi decoction might increase the myonuclear number by activating the MSCs to treat limb weakness in SQD.展开更多
Skeletal muscle constitutes the largest tissue in fish and represents the primary edible portion.Given the substantial differences in muscle growth dynamics between fish and mammals,fish serve as a crucial and distinc...Skeletal muscle constitutes the largest tissue in fish and represents the primary edible portion.Given the substantial differences in muscle growth dynamics between fish and mammals,fish serve as a crucial and distinctive model organism for investigating the fundamental mechanisms of growth regulation in vertebrates.Myo-inositol(MI),originally discovered in muscle,plays significant biological roles in growth regulation,membrane biogenesis,and transmembrane signal transduction.However,to date,no studies have investigated how MI affects adult fish growth and muscle development.A total of 450 adult grass carp(Ctenopharyngodon idella)(704.84±0.91 g)were randomly divided into 6 treatments with 3 replicates of 25 fish each to receive dietary MI at 35.38(basal diet,deficient group),98.12,195.21,292.30,389.39,and 486.48 mg/kg.The trial period lasted for 8 weeks.Results indicated that compared with the 35.38 mg/kg MI group,all groups supplemented with MI improved the specific growth rate(SGR)and percent weight gain(PWG)of adult grass carp(P<0.05).Compared with the deficient group,the sodium-myo-inositol cotransporter 2(SMIT2)and MI content in the muscle of grass carp in the 292.30 to 486 mg/kg MI group were significantly elevated(P<0.05).Compared with the deficient group,the dietary MI levels of 195.21 to 486.48 mg/kg lead to increased myofiber mean diameters and the frequency of myofibers with a diameter>100 mm,while decreased myofiber diameters<60 mm(P<0.05).This implies that MI promotes muscle hypertrophy.The hypertrophic effect of MI was primarily ascribed to an increase in the number of myonuclear and enhanced protein synthesis,which is associated with the regulation of the skeletal muscle lysyl oxidase(LOX)and the protein kinase B(AKT)/target of rapamycin(TOR)/ribosomal protein S6 kinase 1(S6K1)signaling pathways.Additionally,MI inhibited the myostatin(MSTN)and the forkhead box O3(FoxO3)/muscle RING-finger protein-1(MuRF1)/muscle atrophy F-box(MAFbx)pathways,which are involved in muscle atrophy and protein degradation.Based on PWG,the appropriate MI requirement of adult grass carp was determined to be 301.30 mg/kg.This study offers a preliminary theoretical foundation for the potential mechanism by which MI promotes muscle hypertrophy in fish and furnishes a reference for the commercial feed formulation of adult grass carp.展开更多
Powerlifting regularly exposes athletes to extreme stimuli such as chronic heavy resistance training(HRT),and many powerlifters choose to augment their performance with anabolic-androgenic steroids(AAS).However,little...Powerlifting regularly exposes athletes to extreme stimuli such as chronic heavy resistance training(HRT),and many powerlifters choose to augment their performance with anabolic-androgenic steroids(AAS).However,little is known about the myocellular adaptations that occur from long-term HRT and AAS use,especially into middle age.We were presented with the unique opportunity to study muscle cells from an elite-level powerlifter(EPL;age 40 years)with≥30 years of HRT experience and≥15 years of AAS use.The purpose of this case study was to identify myocellular characteristics[myosin heavy chain(MHC)fiber type,fiber size,and myonuclear content]in EPL,as well as compare these data to existing litera-ture.The participant underwent a resting vastus lateralis muscle biopsy and single fibers were analyzed for MHC content via SDS-PAGE.A subset of fibers underwent MHC-specific imaging analysis via confocal microscopy to identify cell size(cross-sectional area,CSA)and myonuclear domain(MND)size.MHC fiber type distribution was 9% I,12% I/IIa,79% IIa,and 0% other isoforms.This pure MHC IIa(fast-twitch)fiber content was amongst the highest reported in the literature.Imaging analysis of MHC IIa fibers revealed a mean CSA of 4218±933μm^(2) and MND of 12,548±3181μm^(3).While the fast-twitch fiber CSA was comparable to values in previous literature,mean MND was smaller than has been reported in untrained men,implying greater capacity for growth and repair.These findings showcase the unique muscle cell structure of an elite powerlifter,extending the known physiological limits of human muscle size and strength.展开更多
文摘Objective: To study the mechanism of Sijunzi decoction treating limb weakness in spleen Qi deficiency (SQD) based on the myonuclear domain (MND) theory. Methods: 40 male Sprague-Dawley rats were randomly divided into the normal group, SQD model group (model group), SQD+ still water group (SW group) and SQD+ Sijunzi decoction group (CM group), 10 rats each group;Grip-Strength Meter was used to measure limb grip strength;transmission electron microscope was employed to observe the ultrastructural changes of the myofibers, Image Pro 6.0 was used to measure the myonuclear numbers, cross-section area (CSA) and then their ratios (the MND sizes) were calculated, immunofluorescence assay was chosen to test the expressions of paired box gene 7 (Pax7) and myogenic differentiation antigen (MyoD). Results: Compared with those in the normal group, limb grip strength was decreased, sarcomeres were abnormal, and all the myonuclear numbers, CSA and MND sizes were reduced, but the Pax7+ cell numbers were increased, significantly, in the model and SW groups;Compared with those in the model and SW groups, limb grip strength was increased, sarcomeres were basically normal, the myonuclear number and CSA were both greater, and the Pax7+ and MyoD+ cell numbers were both increased, significantly, in the CM group. Conclusion: Sijunzi decoction might increase the myonuclear number by activating the MSCs to treat limb weakness in SQD.
基金supported by the National Natural Science Foundation of China(U21A20266,U23A20250)the earmarked fund for CARS(CARS-45)the National Key R&D Programof China(2023YFD2400600)and Key R&D Projects in Sichuan Province(2024YFNH0016).
文摘Skeletal muscle constitutes the largest tissue in fish and represents the primary edible portion.Given the substantial differences in muscle growth dynamics between fish and mammals,fish serve as a crucial and distinctive model organism for investigating the fundamental mechanisms of growth regulation in vertebrates.Myo-inositol(MI),originally discovered in muscle,plays significant biological roles in growth regulation,membrane biogenesis,and transmembrane signal transduction.However,to date,no studies have investigated how MI affects adult fish growth and muscle development.A total of 450 adult grass carp(Ctenopharyngodon idella)(704.84±0.91 g)were randomly divided into 6 treatments with 3 replicates of 25 fish each to receive dietary MI at 35.38(basal diet,deficient group),98.12,195.21,292.30,389.39,and 486.48 mg/kg.The trial period lasted for 8 weeks.Results indicated that compared with the 35.38 mg/kg MI group,all groups supplemented with MI improved the specific growth rate(SGR)and percent weight gain(PWG)of adult grass carp(P<0.05).Compared with the deficient group,the sodium-myo-inositol cotransporter 2(SMIT2)and MI content in the muscle of grass carp in the 292.30 to 486 mg/kg MI group were significantly elevated(P<0.05).Compared with the deficient group,the dietary MI levels of 195.21 to 486.48 mg/kg lead to increased myofiber mean diameters and the frequency of myofibers with a diameter>100 mm,while decreased myofiber diameters<60 mm(P<0.05).This implies that MI promotes muscle hypertrophy.The hypertrophic effect of MI was primarily ascribed to an increase in the number of myonuclear and enhanced protein synthesis,which is associated with the regulation of the skeletal muscle lysyl oxidase(LOX)and the protein kinase B(AKT)/target of rapamycin(TOR)/ribosomal protein S6 kinase 1(S6K1)signaling pathways.Additionally,MI inhibited the myostatin(MSTN)and the forkhead box O3(FoxO3)/muscle RING-finger protein-1(MuRF1)/muscle atrophy F-box(MAFbx)pathways,which are involved in muscle atrophy and protein degradation.Based on PWG,the appropriate MI requirement of adult grass carp was determined to be 301.30 mg/kg.This study offers a preliminary theoretical foundation for the potential mechanism by which MI promotes muscle hypertrophy in fish and furnishes a reference for the commercial feed formulation of adult grass carp.
文摘Powerlifting regularly exposes athletes to extreme stimuli such as chronic heavy resistance training(HRT),and many powerlifters choose to augment their performance with anabolic-androgenic steroids(AAS).However,little is known about the myocellular adaptations that occur from long-term HRT and AAS use,especially into middle age.We were presented with the unique opportunity to study muscle cells from an elite-level powerlifter(EPL;age 40 years)with≥30 years of HRT experience and≥15 years of AAS use.The purpose of this case study was to identify myocellular characteristics[myosin heavy chain(MHC)fiber type,fiber size,and myonuclear content]in EPL,as well as compare these data to existing litera-ture.The participant underwent a resting vastus lateralis muscle biopsy and single fibers were analyzed for MHC content via SDS-PAGE.A subset of fibers underwent MHC-specific imaging analysis via confocal microscopy to identify cell size(cross-sectional area,CSA)and myonuclear domain(MND)size.MHC fiber type distribution was 9% I,12% I/IIa,79% IIa,and 0% other isoforms.This pure MHC IIa(fast-twitch)fiber content was amongst the highest reported in the literature.Imaging analysis of MHC IIa fibers revealed a mean CSA of 4218±933μm^(2) and MND of 12,548±3181μm^(3).While the fast-twitch fiber CSA was comparable to values in previous literature,mean MND was smaller than has been reported in untrained men,implying greater capacity for growth and repair.These findings showcase the unique muscle cell structure of an elite powerlifter,extending the known physiological limits of human muscle size and strength.
