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1.
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2.
Accumulation of intramuscular adipose tissue (IMAT) and development of fibrous tissues due to accumulation of collagen both affect meat quality such as tenderness, texture, and flavor. Thus, it is important for the production of high‐quality meat to regulate the amount of adipose and fibrous tissues in skeletal muscle. IMAT is comprised of adipocytes, while collagens included in fibrous tissues are mainly produced by activated fibroblasts. Both adipocytes and fibroblasts are differentiated from their common ancestors, called mesenchymal progenitor cells (MPC). We previously established rat MPC clone, 2G11 cells. As several reports implicated the plasticity of fibroblast differentiation, in the present study, using 2G11 cells, we asked whether myofibroblasts differentiated from MPC are capable of re‐gaining adipogenic potential in vitro. By treating with bFGF, their αSMA expression was reduced and adipogenic potential was restored partially. Furthermore, by lowering cell density together with bFGF treatment, 2G11 cell‐derived myofibroblasts lost αSMA expression and showed the highest adipogenic potential, and this was along with their morphological change from flattened‐ to spindle‐like shape, which is typically observed with MPC. These results indicated that MPC‐derived myofibroblasts could re‐acquire adipogenic potential, possibly mediated through returning to an undifferentiated MPC‐like state.  相似文献   

3.
The present study describes the isolation, cloning and characterization of adipogenic progenitor cells from rat skeletal muscle. Among the obtained 10 clones, the most highly adipogenic progenitor, 2G11 cells, were further characterized. In addition to their adipogenicity, 2G11 cells retain myogenic potential as revealed by formation of multinucleated myotubes when co‐cultured with myoblasts. 2G11 cells were resistant to an inhibitory effect of basic fibroblast growth factor on adipogenesis, while adipogenesis of widely used preadipogenic cell line, 3T3‐L1 cells, was suppressed almost completely by the same treatment. In vivo transplantation experiments revealed that 2G11 cells are able to possess both adipogenicity and myogenicity in vivo. These results indicate the presence of bipotent progenitor cells in rat skeletal muscle, and suggest that such cells may contribute to ectopic fat formation in skeletal muscle.  相似文献   

4.
To determine the effects of maternal nutrition on modifications of foetal development of the skeletal muscle and possible increase in the potential of skeletal muscle growth in cattle, gestating cows were either fed 190% NRC recommendations (overnourished; ON) or 100% NRC recommendation (control; CO). Interaction between maternal nutrition (MN) and the foetal sex (FS) was also investigated. Foetuses were necropsied at four different time points throughout gestation (139, 199, 241 and 268 days of gestation) to assess the mRNA expression of myogenic, adipogenic and fibrogenic markers in skeletal muscle. Phenotypic indicators of the development of skeletal muscle fibres, intramuscular lipogenesis and collagen development were also evaluated. Modifications in mRNA expression of skeletal muscle of foetuses were observed in function of MN and FS despite the lack of effect of MN and FS on foetal weight at necropsy. Maternal ON increased the mRNA expression of the myogenic marker Cadherin‐associated protein, beta 1 (CTNNB1) and adipogenic markers Peroxissome proliferator‐activated receptor gamma (PPARG) and Zinc finger protein 423 (ZNF423) at midgestation. However, no differences on foetal skeletal muscle development were observed between treatments at late gestation indicating that a compensatory development may have occurred on CO foetuses making the effect of MN on skeletal muscle development not significant at late gestation. Moreover, our data have shown an evidence of sexual dimorphism during foetal stage with a greater skeletal muscle development in male than in female foetuses. In conclusion, providing a higher nutritional level to pregnant cows changes the trajectory of the development of skeletal muscle during midgestation, but apparently does not change the potential of post‐natal growth of muscle mass of the offspring, as no differences in skeletal muscle development were observed in late gestation.  相似文献   

5.
Satellite cells, resident myogenic stem cells found in postnatal skeletal muscle, are most abundant during early postnatal development and sharply decline in frequency thereafter to adult levels in mice and rats. Therefore, postnatal changes in satellite cell mitotic activities are important aspects for further understanding a muscle growth strategy. In large meat‐production animals, however, the traditional in vivo proliferation assay may be less realistic because it requires intra‐peritoneal (ip) injection of huge dosage of mutagenic nucleosides, 3H‐labeled thymidine or bromodeoxyuridine (BrdU), at each age‐time of sacrifice. We report in the present pilot study using rats that in vivo proliferation activity of satellite cells can be evaluated by an in vitro BrdU‐incorporation assay in early cultures. Briefly, satellite cells were prepared from upper hind‐limb and back muscles and maintained for 24 h with imposing by BrdU addition for the last 2 h, followed by the regular immunocytochemistry for determining BrdU‐incorporated cell percentage. This in vitro assay demonstrated a rapid decrease in proliferating satellite cell frequency to the adult level during about 3‐month period after birth, and yielded a high correlation to the measurements by the in vivo BrdU ip‐injection method during the postnatal period examined from day‐2 to month‐11. The in vitro proliferation assay may be further adaptable for large domestic animals by the combination with a muscle biopsy technique that enables age‐interval sampling from the same growing animals.  相似文献   

6.
We have shown in vitro that mechanical stretch triggers activation of quiescent satellite cells of skeletal muscle to enter the cell cycle through an intracellular cascade of events including nitric oxide (NO) synthesis that results in the release of hepatocyte growth factor (HGF) from its extracellular association and its subsequent presentation to signaling receptors. In order to explore the activation mechanism in vivo, stretch experiments were conducted in the living animal using our suspension model developed. This system used the weight of the hind portion of rats to stretch the inside muscles of the left hind limb suspended for a period of 0.5–2.0 h. At the end of the stretch period, the rats received an intraperitoneal injection of bromodeoxyuridine followed by immunocytochemistry for its incorporation as an index of satellite cell activation in vivo. Depending on the period of stretch, bromodeoxyuridine labeling was increased significantly over the contralateral unstretched leg or control muscle from untreated rats. A stretched muscle extract prepared from the 2 h stretched tissue by incubating it in PBS, showed the active form of HGF as revealed by immunoblotting and it could stimulate the activation of unstretched satellite cells. Also, administering NO synthase inhibitor L‐NAME prior to muscle stretch abolished the stretch activation of satellite cells. Therefore, the results from these experiments demonstrate that stretching muscle triggers NO synthesis and HGF release, which could activate satellite cells in vivo.  相似文献   

7.
Successful regeneration and remodeling of neuromuscular junctions are critical for restoring functional capacities and properties of skeletal muscle after damage, and axon‐guidance molecules may be involved in the signaling that regulates such restoration. Recently, we found that early‐differentiated satellite cells up‐regulate a secreted neural chemorepellent Sema3A upon in vivo muscle‐crush injury. The study also revealed that Sema3A expression is up‐regulated in primary satellite‐cell cultures in response to hepatocyte growth factor (HGF) and basic fibroblast growth factor (FGF2) and is prevented by transforming growth factor (TGF)‐β2, 3. In order to verify the physiological significance of this regulation in vitro, the present study was designed to estimate the time‐course of extracellular HGF, FGF2 and TGF‐β3 concentrations after crush‐injury of Gastrocnemius muscle in the rat lower hind‐limb, using a combination of a non‐homogenization/non‐spin extraction of extracellular wound fluids and enhanced chemiluminescence–Western blotting analyses. Results clearly demonstrated that active HGF and FGF2 are prevalent in 2–8 days post‐crush, whereas active TGF‐β3 increases after 12 days, providing a better understanding of the time‐coordinated levels of HGF, FGF2 and TGF‐β3 that drive regulation of Sema3A expression during regenerative intramuscular moto‐neuritogenesis.  相似文献   

8.
Skeletal muscle fiber is largely classified into two types: type 1 (slow‐twitch) and type 2 (fast‐twitch) fibers. Meat quality and composition of fiber types are thought to be closely related. Previous research showed that overexpression of constitutively active peroxisome proliferator‐activated receptor (PPAR)δ, a nuclear receptor present in skeletal muscle, increased type 1 fibers in mice. In this study, we found that hexane extracts of Yamabushitake mushroom (Hericium erinaceus) showed PPARδ agonistic activity in vitro. Eight‐week‐old C57BL/6J mice were fed a diet supplemented with 5% (w/w) freeze‐dried Yamabushitake mushroom for 24 hr. After the treatment period, the extensor digitorum longus (EDL) muscles were excised. The Yamabushitake‐supplemented diet up‐regulated the PPARδ target genes Pdk4 and Ucp3 in mouse skeletal muscles in vivo. Furthermore, feeding the Yamabushitake‐supplemented diet to mice for 8 weeks resulted in a significant increase in muscle endurance. These results indicate that Yamabushitake mushroom contains PPARδ agonistic ligands and that dietary intake of Yamabushitake mushroom could activate PPARδ in skeletal muscle of mice. Unexpectedly, we observed no significant alterations in composition of muscle fiber types between the mice fed control and Yamabushitake‐supplemented diets.  相似文献   

9.
Regenerative mechanisms that regulate intramuscular motor innervation. including configuration of the neuromuscular connections are thought to reside in the spatiotemporal expression of axon‐guidance molecules. Our previous studies proposed a heretofore unexplored role of satellite cells as a key source of a secreted neural chemorepellent semaphorin 3A (Sema3A) expression. In order to verify this concept, there is still a critical need to provide direct evidence to show the up‐regulation of Sema3A protein in satellite cells in vivo upon muscle injury. The present study employed a Sema3A/MyoD double‐immunohistochemical staining for cryo‐sections prepared from cardiotoxin injected gastrocnemius muscle of adult mouse lower hind‐limb. Results clearly demonstrated that Sema3A expression was up‐regulated in myogenic differentiation‐positive satellite cells at 4–12 days post‐injury period, the time that corresponds to the cell differentiation phase characterized by increasing myogenin messenger RNA expression. This direct proof encourages a possible implication of satellite cells in the spatiotemporal regulation of extracellular Sema3A concentrations, which potentially ensures coordinating a delay in neurite sprouting and re‐attachment of motoneuron terminals onto damaged muscle fibers early in muscle regeneration in synchrony with recovery of muscle‐fiber integrity.  相似文献   

10.
Satellite cells attached to skeletal muscle fibers play a crucial role in skeletal muscle regeneration. During regeneration, the satellite cells proliferate, migrate to the damaged region, and fuse to each other. Although it is important to determine the cellular mechanisms controlling myoblast behavior, their regulators are not well understood. In this study, we evaluated the roles of Fbxw7 in primary myoblasts and determined its potential as a therapeutic target for muscle disease. We originally found that Fbxw7β, one of the E3 ubiquitin ligase Fbxw7 subtypes, negatively regulates differentiation, proliferation and migration of myoblasts and satellite cells on muscle fiber. However, these phenomena were not observed in myoblasts expressing a dominant‐negative, F‐box deleted Fbxw7β, mutant. Our results suggest that myoblast differentiation potential and muscle regeneration can be regulated by Fbxw7β.  相似文献   

11.
To investigate the effect of basic fibroblast growth factor (bFGF) on the proliferation of bovine skeletal muscle satellite cells,bovine skeletal muscle satellite cells were isolated and cultured in the medium with bFGF,the growth and differentiation state of muscle satellite cells were observed,and the growth curve and EDU cell proliferation assay were conducted.The results showed that cell morphology of bovine skeletal muscle satellite cells cultured in medium containing bFGF was better and proliferation rate was significantly higher than that in control group (P<0.05).The results indicated that bFGF could promote proliferation of bovine skeletal muscle satellite cells efficiently in growth medium and differential medium.Our study established an efficient method to culture bovine skeletal muscle satellite cells,which could provide reference for studying and using of skeletal muscle satellite cells.  相似文献   

12.
为研究碱性成纤维细胞生长因子(basic fibroblast growth factor,bFGF)对牛骨骼肌卫星细胞增殖的影响,试验对牛骨骼肌卫星细胞进行体外分离培养,在生长培养基和分化培养基中分别添加bFGF,观察细胞生长及分化情况,绘制细胞生长曲线,并进行EDU细胞增殖检测试验。结果显示,添加了bFGF培养基的细胞生长状态较对照组良好,细胞增殖速度快,细胞增殖率显著高于对照组(P<0.05),说明bFGF对牛骨骼肌卫星细胞在生长培养基和分化培养基中增殖都具有良好的促进作用。本研究建立了一种高效的牛骨骼肌卫星细胞培养方案,为骨骼肌卫星细胞的研究利用提供参考。  相似文献   

13.
Objective To describe in vivo corneal confocal microscopy of horses with fungal keratitis and correlate findings with clinical, histopathological, and microbiological evaluations of clinical cases and an ex vivo experimental equine fungal keratitis model. Animals studied A total of 12 horses with naturally‐acquired fungal keratitis and ex vivo equine corneas experimentally infected with clinical fungal isolates. Procedures Horses with naturally‐acquired fungal keratitis were examined with a modified Heidelberg Retina Tomograph II and Rostock Cornea Module. Confocal microscopy images of clinical isolates of Aspergillus fumigatus, Fusarium solani, and Candida albicans were obtained by examination of in vitro cultures and experimentally infected ex vivo equine corneas. Results Non‐specific in vivo corneal confocal microscopic findings in horses with fungal keratitis included leukocyte infiltrates, activated keratocytes, anterior stromal dendritic cell infiltrates, and vascularization. Linear, branching, hyper‐reflective structures that were 2–6 μm in width and 200 to >400 μm in length were detected in all horses with filamentous fungal keratitis. Round to oval hyper‐reflective structures that were 2–8 μm in diameter were detected in a horse with yeast fungal keratitis. The in vivo confocal microscopic appearance of the organisms was consistent with fungal morphologies observed during examination of in vitro cultures and infected ex vivo equine corneas. Conclusions In vivo corneal confocal microscopy is a rapid and non‐invasive method of diagnosing fungal keratitis in the horse. This imaging technique is useful for both ulcerative and non‐ulcerative fungal keratitis, and is particularly advantageous for confirming the presence of fungi in deep corneal stromal lesions.  相似文献   

14.
The possible relationship between myofiber type composition and adipose tissue development in skeletal muscle in vivo has been suggested. Recent evidence indicated that satellite cells are multipotent cells that can undergo not only myogenic, but also adipogenic differentiation. In the present study, rat satellite cells were isolated from soleus, back, extensor digitorum longus, tibialis anterior and quadriceps muscles, and their adipogenic potentials were compared by culturing them under adipogenic conditions in vitro. Cells from soleus muscle exhibited the highest adipogenic potential as judged from Oil Red-staining and immunocytochemical C/EBPalpha-staining. The adipogenic potential of satellite cells was positively correlated with type I myofiber distribution in the corresponding muscle of origin. These results demonstrated that the adipogenic potential of satellite cells differs according to the muscle of origin and suggested that its possible correlation to type I myofiber distribution may account for preferential adipose tissue development in slow oxidative muscles.  相似文献   

15.
Schmid, V.B., Seewald, W., Lees, P., King, J.N. In vitro and ex vivo inhibition of COX isoforms by robenacoxib in the cat: a comparative study. J. vet. Pharmacol. Therap. 33 , 444–452. Robenacoxib is a novel nonsteroidal anti‐inflammatory drug (NSAID) developed for use in companion animals. Whole blood assays were used to characterize in the cat the pharmacodynamics of robenacoxib for inhibition of the cyclooxygenase (COX) isoforms, COX‐1 and COX‐2, in comparison with other NSAIDs. Based on in vitro IC50COX‐1:IC50COX‐2 ratios, robenacoxib was COX‐2 selective (ratio = 32.2), diclofenac (ratio = 3.9) and meloxicam (ratio = 2.7) were only weakly COX‐2 preferential, and ketoprofen (ratio = 0.049) was COX‐1 selective. In an in vivo pharmacokinetic ex vivo pharmacodynamic study, after both p.o. (1–2 mg/kg) and subcutaneous (2 mg/kg) dosing, robenacoxib achieved peak blood concentrations rapidly (Tmax = 1 h for both administration routes) and was cleared from blood relatively rapidly (mean residence time was 1.70 h after p.o. and 1.79 h after subcutaneous dosing). In ex vivo COX isoform inhibition assays, orally (1–2 mg/kg) or subcutaneously (2 mg/kg) administered robenacoxib significantly inhibited COX‐2, with a relatively short duration of action in the central compartment, and had no effect on COX‐1. Therefore robenacoxib was COX‐2 selective and spared COX‐1 in vivo. In contrast, meloxicam (0.3 mg/kg via subcutaneous injection) inhibited both COX‐1 and COX‐2 isoforms significantly for at least 24 h, indicating nonselectivity in vivo.  相似文献   

16.
The aims of the present study were to establish a culture system for goat skeletal muscle stem cells and to examine their myogenic and adipogenic properties in vitro. Cells were isolated from the skeletal muscle of the Shiba goat and cultured in vitro. Most of the cells were positive for myogenic markers, such as Pax7, MyoD, and desmin, and immunocytochemistry revealed they differentiated to form myotubes expressing myosin heavy chain, indicating they were highly myogenic. Myogenic differentiation was strongly suppressed by the addition of basic fibroblast growth factor, while proliferation was unaffected. When the cells were cultured in adipogenic differentiation medium, some of the cells differentiated into mature adipocytes that stained with Oil Red-O. These cells were immunocytochemically positive for adipogenic markers, including peroxisome proliferator-activated receptor-gamma (PPAR gamma) and CCAAT/enhancer-binding protein-alpha (C/EBP alpha). These results clearly demonstrate the presence of both myogenic and adipogenic stem cells in goat skeletal muscle.  相似文献   

17.
To clarify muscle type‐specific effect of myostatin on myogenic regulatory factors (MRFs), we examined mRNA expression of MRFs in five skeletal muscles of normal (NM) and myostatin‐deficient double‐muscled (DM) adult Japanese Shorthorn cattle by quantitative reverse‐transcribed PCR. Among the four MRFs, namely, Myf5, MyoD, myogenin, and MRF4, MyoD expression was different among the muscles of the DM cattle (P < 0.01) but not of the NM cattle. Meanwhile, MyoD expression was significantly elevated only in masseter (MS) muscle in the DM cattle due to the myostatin deficiency (P < 0.05). Myf5 and MRF4 expression in semitendinosus (ST) was higher in the DM than in the NM cattle (P < 0.05). According to analysis of myosin heavy chain (MyHC) isoform expression, more MyHC‐2x and ‐2a and less ‐slow isoforms were expressed in the longissimus and ST muscles compared to the MS muscle in both cattle (P < 0.05), but no significant difference in MyHC expression was observed between the NM and DM cattle. Taken together, myostatin has influences on Myf5 and MRF4 expression in faster‐type muscles and on MyoD expression in slower‐type muscles, suggesting a possible muscle type‐specific effect of myostatin in skeletal muscle growth and maintenance.  相似文献   

18.
The value‐added products in livestock industry is one of the key issues in order to maximize the revenue and to create a new business model. Numerous studies have suggested application of herbal plants as feed additives to increase health, productivity, and/or high‐quality product in livestock. In this study, the first experiment was designed to develop in vitro evaluation system by using primary chicken myoblast (pCM) cells isolated from pectoralis major of 10‐day‐old male embryos. Subsequently, to evaluate effects of Korean Danggui Angelica gigas Nakai (AGN), we optimized the concentration of AGN root extract for treatment of primary pCM cells. After the treatment of AGN root extract, we compared proliferation and differentiation capacity, and also examined the gene expression. In the second experiment, the next generation sequencing analysis was performed to compare the different patterns of the global gene expression in pCM cells treated with AGN extract. Three up‐regulated (pancreas beta cells, fatty acid metabolism and glycolysis) and one down‐regulated (adipogenesis) gene sets were characterized suggesting that the AGN extract affected the metabolic pathways for the utilization of fat and glucose in chicken muscle cells. Furthermore, we validated the expression patterns of the up‐regulated genes (GCLC, PTPN6, ISL1, SLC25A13, TGFBI, and YWHAH) in the AGN‐treated pCM cells by quantitative RT‐PCR. These results demonstrated that the treatment of AGN extract decreased proliferation and differentiation of pCM cells, and affected the metabolic pathways of glucose and fatty acids. Moreover, AGN extract derived from byproducts such as stem and leaf also showed the reduced proliferation patterns on AGN‐treated pCM cells. Taken together, pCM cell‐based in vitro assay system could be primarily and efficiently applied for evaluating the biofunctional efficacy of various feed additive candidates.  相似文献   

19.
Chicks (Gallus gallus domesticus) show considerable growth of skeletal muscle during the neonatal period. The in vivo gene transfer method is useful for studying gene function and can be employed to elucidate the molecular mechanisms of skeletal muscle growth in chicks. We evaluated the following conditions for gene transfer to the skeletal muscle of neonatal chicks by electroporation: (i) voltage; (ii) age of the chick; (iii) plasmid DNA injected amount; and (iv) duration of gene expression. The results obtained from this study indicate that the most efficient gene transfer condition was as follows: 75 µg of plasmid DNA encoding β‐galactosidase was injected into the gastrocnemius muscle of chicks at 4 days of age electroporated at 50 V/cm. In addition, peak transferred gene expression was observed from 3 days to 5 days after electroporation. Our results provide optimal electroporation conditions for elucidating the gene function related to skeletal muscle growth and development in neonatal chicks.  相似文献   

20.
Reasons for performing study: Post operative ileus (POI) in horses is a severe complication after colic surgery. A commonly used prokinetic drug is lidocaine, which has been shown to have stimulatory effects on intestinal motility. The cellular mechanisms through which lidocaine affects smooth muscle activity are not yet known. Objectives: To examine the effects of lidocaine on smooth muscle in vitro and identify mechanisms by which it may affect the contractility of intestinal smooth muscle. Hypothesis: Ischaemia and reperfusion associated with intestinal strangulation can cause smooth muscle injury. Consequently, muscle cell functionality and contractile performance is decreased. Lidocaine can improve basic cell functions and thereby muscle cell contractility especially in ischaemia‐reperfusion‐challenged smooth muscle. Methods: To examine the effects of lidocaine on smooth muscle function directly, isometric force performance was measured in vitro in noninjured and in vivo ischaemia‐reperfusion injured smooth muscle tissues. Dose‐dependent response of lidocaine was measured in both samples. To assess membrane permeability as a marker of basic cell function, release of creatine kinase (CK) was measured by in vitro incubations. Results: Lidocaine‐stimulated contractility of ischaemia‐reperfusion injured smooth muscle was more pronounced than that of noninjured smooth muscle. A 3‐phasic dose‐dependency was observed with an initial recovery of contractility especially in ischaemia‐reperfusion injured smooth muscle followed by a plateau phase where contractility was maintained over a broad concentration range. CK release was decreased by lidocaine. Conclusion: Lidocaine may improve smooth muscle contractility and basic cell function by cellular repair mechanisms which are still unknown. Improving contractility of smooth muscle after ischaemia‐reperfusion injury is essential in recovery of propulsive intestinal motility. Potential relevance: Characterisation of the cellular mechanisms of effects of lidocaine, especially on ischaemia‐reperfusion injured smooth muscle, may lead to improved treatment strategies for horses with POI.  相似文献   

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