Effects of repeated lengthening contractions on skeletal muscle adaptations in female rats

Willems, Mark E. T.; Miller, Gerald R.; Stauber, F.D.; Stauber, William T.

doi:10.1007/s12576-009-0078-y

Cited by 6 publications

(5 citation statements)

References 38 publications

(41 reference statements)

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“…Several studies have examined the effects of cyclical loading and repeated muscle strains on extracellular matrix content, including collagen [7], [8], [17], [22], [24], [25], [26], [27], [28], [29]. There is also data concerning the influence of physical exercise, mechanical loading andcyclical loading on CTGF and TGFB1 production in musculoskeletal tissues.…”

Section: Discussionmentioning

confidence: 99%

“…Stauber and colleagues have shown that repeated muscle strains at fast velocities (lengthening contractions stimulated electrically) resulted in fibrotic myopathy with increased collagen content, collagen cross-links and non-contractile tissues, while repeated strains at low velocities did not [25], [26], [27], [28]. Factors and mechanisms of repetitive strain-induced fibrosis in tissues are still under investigation, but appear to involve CTGF and transforming growth factor beta-1 (TGFB1) [29], [30], [31], [32], [33].…”

Section: Introductionmentioning

confidence: 99%

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Performance of Repetitive Tasks Induces Decreased Grip Strength and Increased Fibrogenic Proteins in Skeletal Muscle: Role of Force and Inflammation

et al. 2012

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BackgroundThis study elucidates exposure-response relationships between performance of repetitive tasks, grip strength declines, and fibrogenic-related protein changes in muscles, and their link to inflammation. Specifically, we examined forearm flexor digitorum muscles for changes in connective tissue growth factor (CTGF; a matrix protein associated with fibrosis), collagen type I (Col1; a matrix component), and transforming growth factor beta 1 (TGFB1; an upstream modulator of CTGF and collagen), in rats performing one of two repetitive tasks, with or without anti-inflammatory drugs.Methodology/ResultsTo examine the roles of force versus repetition, rats performed either a high repetition negligible force food retrieval task (HRNF), or a high repetition high force handle-pulling task (HRHF), for up to 9 weeks, with results compared to trained only (TR-NF or TR-HF) and normal control rats. Grip strength declined with both tasks, with the greatest declines in 9-week HRHF rats. Quantitative PCR (qPCR) analyses of HRNF muscles showed increased expression of Col1 in weeks 3–9, and CTGF in weeks 6 and 9. Immunohistochemistry confirmed PCR results, and also showed greater increases of CTGF and collagen matrix in 9-week HRHF rats than 9-week HRNF rats. ELISA, and immunohistochemistry revealed greater increases of TGFB1 in TR-HF and 6-week HRHF, compared to 6-week HRNF rats. To examine the role of inflammation, results from 6-week HRHF rats were compared to rats receiving ibuprofen or anti-TNF-α treatment in HRHF weeks 4–6. Both treatments attenuated HRHF-induced increases in CTGF and fibrosis by 6 weeks of task performance. Ibuprofen attenuated TGFB1 increases and grip strength declines, matching our prior results with anti-TNFα.Conclusions/SignificancePerformance of highly repetitive tasks was associated with force-dependent declines in grip strength and increased fibrogenic-related proteins in flexor digitorum muscles. These changes were attenuated, at least short-term, by anti-inflammatory treatments.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Performance of Repetitive Tasks Induces Decreased Grip Strength and Increased Fibrogenic Proteins in Skeletal Muscle: Role of Force and Inflammation

et al. 2012

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“…The measurement of muscle mass can be confounded by a number of factors including intramuscular fat, which can be influenced by specific genetic factors during growth (33), and connective tissue, which can be affected by physical activity (34). Myofibrillar protein content accurately reflects the pool of functional proteins that account for the ability of muscles to perform work (35).…”

Section: Discussionmentioning

confidence: 99%

Increased rat neonatal activity influences adult cytokine levels and relative muscle mass.

Buchowicz

Nance

et al. 2010

Pediatric Research

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Little is known about the effect of physical activity in early life on subsequent growth and regulation of inflammation. We previously reported that exposure of muscles in growing rats to IL-6 results in decreased muscle growth apparently due to a state of resistance to growth factors such IGF-I and that running exercise could ameliorate this growth defect. Herein we hypothesized that increased activity, for a brief period during neonatal life, would pattern the adult rat towards a less inflammatory phenotype. Neonatal rats were induced to move about their cage for brief periods from day 5 to day 15 postpartum. Additional groups were undisturbed controls (CON) and handled (HAND). Sub-groups of rats were sampled at 30 and 65 days of age. Relative to CON and HAND, neonatal exercise (EX) results in decreased circulating levels of TNFα, IL-6 and IL-1β in adulthood, primarily in male rats. In addition, adult male EX rats had lower body mass and increased skeletal muscle mass suggesting a leaner phenotype. The results of this study suggest that moderate increases in activity early in life can influence the adult toward a more healthy phenotype with regard to inflammatory mediators and relative muscle mass.

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“…In fact, TA and GA muscles are located in the anterior and posterior hindlimb compartment, respectively, and were thus immobilized in a lengthened and shortened position, respectively. Connective tissue thickening that prevailed during immobilization (49) was greater when lengthening was applied (37).…”

mentioning

confidence: 99%

The worsening of tibialis anterior muscle atrophy during recovery post-immobilization correlates with enhanced connective tissue area, proteolysis, and apoptosis

Slimani

Micol

Amat

et al. 2012

American Journal of Physiology-Endocrinology and Metabolism

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A, Combaret L. The worsening of tibialis anterior muscle atrophy during recovery post-immobilization correlates with enhanced connective tissue area, proteolysis, and apoptosis. Am J Physiol Endocrinol Metab 303: E1335-E1347, 2012. First published October 2, 2012; doi:10.1152/ajpendo.00379.2012.-Sustained muscle wasting due to immobilization leads to weakening and severe metabolic consequences. The mechanisms responsible for muscle recovery after immobilization are poorly defined. Muscle atrophy induced by immobilization worsened in the lengthened tibialis anterior (TA) muscle but not in the shortened gastrocnemius muscle. Here, we investigated some mechanisms responsible for this differential response. Adult rats were subjected to unilateral hindlimb casting for 8 days (I8). Casts were removed at I8, and animals were allowed to recover for 10 days (R1 to R10). The worsening of TA atrophy following immobilization occurred immediately after cast removal at R1 and was sustained until R10. This atrophy correlated with a decrease in type IIb myosin heavy chain (MyHC) isoform and an increase in type IIx, IIa, and I isoforms, with muscle connective tissue thickening, and with increased collagen (Col) I mRNA levels. Increased Col XII, Col IV, and Col XVIII mRNA levels during TA immobilization normalized at R6. Sustained enhanced peptidase activities of the proteasome and apoptosome activity contributed to the catabolic response during the studied recovery period. Finally, increased nuclear apoptosis prevailed only in the connective tissue compartment of the TA. Altogether, the worsening of the TA atrophy pending immediate reloading reflects a major remodeling of its fiber type properties and alterations in the structure/ composition of the extracellular compartment that may influence its elasticity/stiffness. The data suggest that sustained enhanced ubiquitin-proteasome-dependent proteolysis and apoptosis are important for these adaptations and provide some rationale for explaining the atrophy of reloaded muscles pending immobilization in a lengthened position.ubiquitin-proteasome proteolysis; caspase 9; extracellular matrix remodeling; reloading; matrix metalloproteases SKELETAL MUSCLE IS THE MAJOR RESERVOIR of body proteins. Sustained muscle wasting due to immobilization leads to weakening and severe metabolic consequences, which impacts health care costs. This wasting has been investigated thoroughly and results from an imbalance between protein synthesis and breakdown rates but also between apoptotic and regeneration processes (12,17,35,46,47). By contrast, the mechanisms responsible for muscle recovery after remobilization are poorly defined.The ubiquitin (Ub)-proteasome system (UPS) is involved in the breakdown of the major contractile proteins in catabolic conditions. Briefly, in this pathway a poly-Ub chain is covalently attached to the substrate by the Ub conjugation machinery, and the targeted protein is then recognized and degraded by the 26S proteasome (4). This pathway is activated after immobilization or ...

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Effects of repeated lengthening contractions on skeletal muscle adaptations in female rats

Cited by 6 publications

References 38 publications

Performance of Repetitive Tasks Induces Decreased Grip Strength and Increased Fibrogenic Proteins in Skeletal Muscle: Role of Force and Inflammation

Performance of Repetitive Tasks Induces Decreased Grip Strength and Increased Fibrogenic Proteins in Skeletal Muscle: Role of Force and Inflammation

Increased rat neonatal activity influences adult cytokine levels and relative muscle mass.

The worsening of tibialis anterior muscle atrophy during recovery post-immobilization correlates with enhanced connective tissue area, proteolysis, and apoptosis

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