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Lan XQ, Deng CJ, Wang QQ, Zhao LM, Jiao BW, Xiang Y. The role of TGF-β signaling in muscle atrophy, sarcopenia and cancer cachexia. Gen Comp Endocrinol 2024; 353:114513. [PMID: 38604437 DOI: 10.1016/j.ygcen.2024.114513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 02/24/2024] [Accepted: 04/03/2024] [Indexed: 04/13/2024]
Abstract
Skeletal muscle, comprising a significant proportion (40 to 50 percent) of total body weight in humans, plays a critical role in maintaining normal physiological conditions. Muscle atrophy occurs when the rate of protein degradation exceeds protein synthesis. Sarcopenia refers to age-related muscle atrophy, while cachexia represents a more complex form of muscle wasting associated with various diseases such as cancer, heart failure, and AIDS. Recent research has highlighted the involvement of signaling pathways, including IGF1-Akt-mTOR, MuRF1-MAFbx, and FOXO, in regulating the delicate balance between muscle protein synthesis and breakdown. Myostatin, a member of the TGF-β superfamily, negatively regulates muscle growth and promotes muscle atrophy by activating Smad2 and Smad3. It also interacts with other signaling pathways in cachexia and sarcopenia. Inhibition of myostatin has emerged as a promising therapeutic approach for sarcopenia and cachexia. Additionally, other TGF-β family members, such as TGF-β1, activin A, and GDF11, have been implicated in the regulation of skeletal muscle mass. Furthermore, myostatin cooperates with these family members to impair muscle differentiation and contribute to muscle loss. This review provides an overview of the significance of myostatin and other TGF-β signaling pathway members in muscular dystrophy, sarcopenia, and cachexia. It also discusses potential novel therapeutic strategies targeting myostatin and TGF-β signaling for the treatment of muscle atrophy.
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Affiliation(s)
- Xin-Qiang Lan
- Metabolic Control and Aging Group, Human Aging Research Institute (HARI) and School of Life Science, Nanchang University, Nanchang 330031, Jiangxi, China
| | - Cheng-Jie Deng
- Department of Biochemistry and Molecular Biology, Faculty of Basic Medical Science, Kunming Medical University, Kunming 650500, Yunnan, China
| | - Qi-Quan Wang
- Metabolic Control and Aging Group, Human Aging Research Institute (HARI) and School of Life Science, Nanchang University, Nanchang 330031, Jiangxi, China
| | - Li-Min Zhao
- Senescence and Cancer Group, Human Aging Research Institute (HARI) and School of Life Science, Nanchang University, Nanchang 330031, Jiangxi, China
| | - Bao-Wei Jiao
- National Key Laboratory of Genetic Evolution & Animal Models, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650201, Yunnan, China
| | - Yang Xiang
- Metabolic Control and Aging Group, Human Aging Research Institute (HARI) and School of Life Science, Nanchang University, Nanchang 330031, Jiangxi, China.
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Bikker P, Jansman AJM. Review: Composition and utilisation of feed by monogastric animals in the context of circular food production systems. Animal 2023; 17 Suppl 3:100892. [PMID: 37479667 DOI: 10.1016/j.animal.2023.100892] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 06/15/2023] [Accepted: 06/16/2023] [Indexed: 07/23/2023] Open
Abstract
Food production has a major impact on environmental emissions, climate change and land-use. To reduce this impact, the circularity of future food production systems is expected to become increasingly important. In a circular food system, crop land is primarily used for plant-based food production, while low-opportunity cost feed materials (LCF), i.e. crop residues, co-products of the food industry, grass from marginal land and food waste form the basis of future, animal feeds. Animal diets thus contain much less cereals and soybean meal and include a higher proportion of diverse co-products, residues and novel human-inedible ingredients. These diets are characterised by a lower starch content, and a higher content of fibre, protein, fat, and phytate compared to present diets. In this review, possible consequences of the development towards a more circular food system for the type, volume and nutritional characteristics of feed materials and complete feeds are addressed and related research questions in the area of animal nutrition, physiology and metabolism are discussed. Additional attention is given to possible effects on intestinal health and gut functionality and to (bio)technological processing of LCF to improve their suitability for feeding farm animals, with a focus on the effects in pigs and poultry. It is concluded that an increased use of LCF may limit the use of presently used criteria for the efficiency of animal production and nutrient utilisation. Development of characteristics that reflect the efficacy and efficiency of the net contribution of animal production in a circular food system is required. Animal scientists can have an important role in the development of more circular food production systems by focussing on the optimal use of LCF in animal diets for the production of animal-source food, while minimising the use of human-edible food in animal feed.
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Affiliation(s)
- P Bikker
- Wageningen Livestock Research, Wageningen University & Research, PO Box 338, 6700 AH Wageningen, the Netherlands.
| | - A J M Jansman
- Wageningen Livestock Research, Wageningen University & Research, PO Box 338, 6700 AH Wageningen, the Netherlands
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Costa DM, Cruz-Filho JD, Vasconcelos ABS, Gomes-Santos JV, Reis LC, de Lucca W, Camargo EA, Lauton-Santos S, Zanon NM, Kettelhut ÍDC, Navegantes LC, Mecawi ADS, Badauê-Passos D, Lustrino D. Oxytocin induces anti-catabolic and anabolic effects on protein metabolism in the female rat oxidative skeletal muscle. Life Sci 2021; 279:119665. [PMID: 34087281 DOI: 10.1016/j.lfs.2021.119665] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/20/2021] [Accepted: 05/21/2021] [Indexed: 11/26/2022]
Abstract
AIMS Although it is well established that skeletal muscle contains oxytocin (OT) receptors and OT-knockout mice show premature development of sarcopenia, the role of OT in controlling skeletal muscle mass is still unknown. Therefore, the present work aimed to determine OT's effects on skeletal muscle protein metabolism. MAIN METHODS Total proteolysis, proteolytic system activities and protein synthesis were assessed in isolated soleus muscle from prepubertal female rats. Through in vivo experiments, rats received 3-day OT treatment (3UI.kg-1.day-1, i.p.) or saline, and muscles were harvested for mass-gain assessment. KEY FINDINGS In vitro OT receptor stimulation reduced total proteolysis, specifically through attenuation of the lysosomal and proteasomal proteolytic systems, and in parallel activated the Akt/FoxO1 signaling and suppressed atrogenes (e.g., MuRF-1 and atrogin-1) expression induced by motor denervation. On the other hand, the protein synthesis was not altered by in vitro treatment with the OT receptor-selective agonist. Although short-term OT treatment did not change the atrogene mRNA levels, the protein synthesis was stimulated, resulting in soleus mass gain, probably through an indirect effect. SIGNIFICANCE Taken together, these data show for the first time that OT directly inhibits the proteolytic activities of the lysosomal and proteasomal systems in rat oxidative skeletal muscle by suppressing atrogene expression via stimulation of Akt/FoxO signaling. Moreover, the data obtained from in vivo experiments suggest OT's ability to control rat oxidative skeletal muscle mass.
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Affiliation(s)
- Daniely Messias Costa
- Graduate Program in Physiological Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil; Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - João da Cruz-Filho
- Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - Alan Bruno Silva Vasconcelos
- Graduate Program in Physiological Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil; Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - João Victor Gomes-Santos
- Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - Luis Carlos Reis
- Department of Physiological Sciences, Center for Biological and Health Sciences, Rural Federal University of Rio de Janeiro, Seropédica, RJ, Brazil
| | - Waldecy de Lucca
- Department of Morphology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - Enilton Aparecido Camargo
- Graduate Program in Physiological Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil; Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - Sandra Lauton-Santos
- Graduate Program in Physiological Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil; Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - Neusa Maria Zanon
- Department of Physiology and Biochemistry & Immunology, Ribeirão Preto Medical School, São Paulo University, Ribeirão Preto, SP, Brazil
| | - Ísis do Carmo Kettelhut
- Department of Physiology and Biochemistry & Immunology, Ribeirão Preto Medical School, São Paulo University, Ribeirão Preto, SP, Brazil
| | - Luiz Carlos Navegantes
- Department of Physiology and Biochemistry & Immunology, Ribeirão Preto Medical School, São Paulo University, Ribeirão Preto, SP, Brazil
| | - André de Souza Mecawi
- Department of Biophysics, São Paulo Medical School, Federal University of São Paulo, São Paulo, SP, Brazil
| | - Daniel Badauê-Passos
- Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - Danilo Lustrino
- Graduate Program in Physiological Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil; Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil.
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Mayorga EJ, Ross JW, Keating AF, Rhoads RP, Baumgard LH. Biology of heat stress; the nexus between intestinal hyperpermeability and swine reproduction. Theriogenology 2020; 154:73-83. [PMID: 32531658 DOI: 10.1016/j.theriogenology.2020.05.023] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/15/2020] [Accepted: 05/17/2020] [Indexed: 02/06/2023]
Abstract
Unfavorable weather conditions are one of the largest constraints to maximizing farm animal productivity. Heat stress (HS), in particular, compromises almost every metric of profitability and this is especially apparent in the grow-finish and reproductive aspects of the swine industry. Suboptimal production during HS was traditionally thought to result from hypophagia. However, independent of inadequate nutrient consumption, HS affects a plethora of endocrine, physiological, metabolic, circulatory, and immunological variables. Whether these changes are homeorhetic strategies to survive the heat load or are pathological remains unclear, nor is it understood if they temporally occur by coincidence or if they are chronologically causal. However, mounting evidence suggest that the origin of the aforementioned changes lie at the gastrointestinal tract. Heat stress compromises intestinal barrier integrity, and increased appearance of luminal contents in circulation causes local and systemic inflammatory responses. The resulting immune activation is seemingly the epicenter to many, if not most of the negative consequences HS has on reproduction, growth, and lactation. Interestingly, thermoregulatory and production responses to HS are only marginally related. In other words, increased body temperature indices poorly predict decreases in productivity. Further, HS induced malnutrition is also a surprisingly inaccurate predictor of productivity. Thus, selecting animals with a "heat tolerant" phenotype based solely or separately on thermoregulatory capacity or production may not ultimately increase resilience. Describing the physiology and mechanisms that underpin how HS jeopardizes animal performance is critical for developing approaches to ameliorate current production issues and requisite for generating future strategies (genetic, managerial, nutritional, and pharmaceutical) aimed at optimizing animal well-being, and improving the sustainable production of high-quality protein for human consumption.
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Affiliation(s)
- E J Mayorga
- Department of Animal Science, Iowa State University, Ames, IA, 50011, USA
| | - J W Ross
- Department of Animal Science, Iowa State University, Ames, IA, 50011, USA
| | - A F Keating
- Department of Animal Science, Iowa State University, Ames, IA, 50011, USA
| | - R P Rhoads
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - L H Baumgard
- Department of Animal Science, Iowa State University, Ames, IA, 50011, USA.
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Przygodda F, Manfredi LH, Machado J, Gonçalves DAP, Zanon NM, Bonagamba LGH, Machado BH, Kettelhut ÍC, Navegantes LCC. Acute intermittent hypoxia in rats activates muscle proteolytic pathways through a gluccorticoid-dependent mechanism. J Appl Physiol (1985) 2016; 122:1114-1124. [PMID: 27932681 DOI: 10.1152/japplphysiol.00977.2015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 11/18/2016] [Accepted: 12/03/2016] [Indexed: 02/08/2023] Open
Abstract
Although it is well known that chronic hypoxia induces muscle wasting, the effects of intermittent hypoxia on skeletal muscle protein metabolism remain unclear. We hypothesized that acute intermittent hypoxia (AIH), a challenge that activates the hypothalamic-pituitary-adrenal axis, would alter muscle protein homeostasis through a glucocorticoid-dependent mechanism. Three-week-old rats were submitted to adrenalectomy (ADX) and exposed to 8 h of AIH (6% O2 for 40 s at 9-min intervals). Animals were euthanized, and the soleus and extensor digitorum longus (EDL) muscles were harvested and incubated in vitro for measurements of protein turnover. AIH increased plasma levels of corticosterone and induced insulin resistance as estimated by the insulin tolerance test and lower rates of muscle glucose oxidation and the HOMA index. In both soleus and EDL muscles, rates of overall proteolysis increased after AIH. This rise was accompanied by an increased proteolytic activities of the ubiquitin(Ub)-proteasome system (UPS) and lysosomal and Ca2+-dependent pathways. Furthermore, AIH increased Ub-protein conjugates and gene expression of atrogin-1 and MuRF-1, two key Ub-protein ligases involved in muscle atrophy. In parallel, AIH increased the mRNA expression of the autophagy-related genes LC3b and GABARAPl1. In vitro rates of protein synthesis in skeletal muscles did not differ between AIH and control rats. ADX completely blocked the insulin resistance in hypoxic rats and the AIH-induced activation of proteolytic pathways and atrogene expression in both soleus and EDL muscles. These results demonstrate that AIH induces insulin resistance in association with activation of the UPS, the autophagic-lysosomal process, and Ca2+-dependent proteolysis through a glucocorticoid-dependent mechanism.NEW & NOTEWORTHY Since hypoxia is a condition in which the body is deprived of adequate oxygen supply and muscle wasting is induced, the present work provides evidence linking hypoxia to proteolysis through a glucocorticoid-dependent mechanism. We show that the activation of proteolytic pathways, atrophy-related genes, and insulin resistance in rats exposed to acute intermittent hypoxia was abolished by surgical removal of adrenal gland. This finding will be helpful for understanding of the muscle wasting in hypoxemic conditions.
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Affiliation(s)
- Franciele Przygodda
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Leandro Henrique Manfredi
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.,Federal University of Fronteira Sul, Chapecó, Santa Catarina, Brazil
| | - Juliano Machado
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Dawit A P Gonçalves
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.,Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil; and
| | - Neusa M Zanon
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Leni G H Bonagamba
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Benedito H Machado
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Ísis C Kettelhut
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.,Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil; and
| | - Luiz C C Navegantes
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil;
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6
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Song F, Xu D, Mai K, Zhou H, Xu W, He G. Comparative Study on the Cellular and Systemic Nutrient Sensing and Intermediary Metabolism after Partial Replacement of Fishmeal by Meat and Bone Meal in the Diet of Turbot (Scophthalmus maximus L.). PLoS One 2016; 11:e0165708. [PMID: 27802317 PMCID: PMC5089717 DOI: 10.1371/journal.pone.0165708] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 10/17/2016] [Indexed: 01/16/2023] Open
Abstract
This study was designed to examine the cellular and systemic nutrient sensing mechanisms as well as the intermediary metabolism responses in turbot (Scophthalmus maximus L.) fed with fishmeal diet (FM diet), 45% of FM replaced by meat and bone meal diet (MBM diet) or MBM diet supplemented with essential amino acids to match the amino acid profile of FM diet (MBM+AA diet). During the one month feeding trial, feed intake was not affected by the different diets. However, MBM diet caused significant reduction of specific growth rate and nutrient retentions. Compared with the FM diet, MBM diet down-regulated target of rapamycin (TOR) and insulin-like growth factor (IGFs) signaling pathways, whereas up-regulated the amino acid response (AAR) signaling pathway. Moreover, MBM diet significantly decreased glucose and lipid anabolism, while increased muscle protein degradation and lipid catabolism in liver. MBM+AA diet had no effects on improvement of MBM diet deficiencies. Compared with fasted, re-feeding markedly activated the TOR signaling pathway, IGF signaling pathway and glucose, lipid metabolism, while significantly depressed the protein degradation signaling pathway. These results thus provided a comprehensive display of molecular responses and a better explanation of deficiencies generated after fishmeal replacement by other protein sources.
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Affiliation(s)
- Fei Song
- The Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture), Ocean University of China, Qingdao, 266003, China
- The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, 266003, China
| | - Dandan Xu
- The Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture), Ocean University of China, Qingdao, 266003, China
- The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, 266003, China
| | - Kangsen Mai
- The Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture), Ocean University of China, Qingdao, 266003, China
- The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, 266003, China
| | - Huihui Zhou
- The Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture), Ocean University of China, Qingdao, 266003, China
- The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, 266003, China
| | - Wei Xu
- The Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture), Ocean University of China, Qingdao, 266003, China
| | - Gen He
- The Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture), Ocean University of China, Qingdao, 266003, China
- The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, 266003, China
- * E-mail:
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Jin D, Sun J, Huang J, He Y, Yu A, Yu X, Yang Z. TNF-α reduces g0s2 expression and stimulates lipolysis through PPAR-γ inhibition in 3T3-L1 adipocytes. Cytokine 2014; 69:196-205. [PMID: 24993166 DOI: 10.1016/j.cyto.2014.06.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 05/22/2014] [Accepted: 06/04/2014] [Indexed: 01/04/2023]
Abstract
Tumor necrosis factor-α (TNF-α) is a multifunctional cytokine that acts as a mediator of obesity-linked insulin resistance (IR). It is commonly accepted that macrophage-derived TNF-α acts in a paracrine manner on adjacent adipocytes, induces lipolysis, which contributes to obesity-linked hyperglycemia. Several studies suggested that G0/G1 switch gene 2 (g0s2) was up-regulated during adipogenesis, and its protein could be degraded in response to TNF-α stimulation. The aim of the present work was to investigate the transcriptional regulation of g0s2 by TNF-α stimulation. In this study, 3T3-L1 pre-adipocytes were differentiated, and treated with TNF-α for 24h. The effects of TNF-α on lipolysis and lipase expression were then examined. Our results revealed that TNF-α exerted dose- and time-dependent lipolytic effects, which could be partially reversed by overexpression of g0s2 and peroxisome proliferator-activated receptor-γ (ppar-γ). In addition, TNF-α treatment significantly reduced the expression of adiponectin, ppar-γ, hormone-sensitive Lipase (hsl), adipose triglyceride lipase (atgl) as well as ATGL co-factors. Interestingly, TNF-α significantly decreased adiponectin and PPAR-γ protein levels, while treatment with the proteasomal inhibitor MG-132 maintained PPAR-γ levels. Degradation of PPAR-γ almost completely abolished the binding of PPAR-γ to the g0s2 promoter in adipocytes treated with TNF-α. We propose that proteasomal degradation of PPAR-γ and the reduction of g0s2 content are permissive for prolonged TNF-α induced lipolysis.
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Affiliation(s)
- Dan Jin
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China.
| | - Jun Sun
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Jing Huang
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Yiduo He
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - An Yu
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Xiaoling Yu
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Zaiqing Yang
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China.
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Taylor D, Vradenburg J, Smith L, Lovern M, McMurry S. Effects of anthropogenic and environmental stress on the corticosterone levels of wintering Northern Pintails (Anas acuta). CAN J ZOOL 2014. [DOI: 10.1139/cjz-2013-0105] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Winter-specific survival rates for female Northern Pintails (Anas acuta L., 1758; hereafter “Pintails”) at the Bosque del Apache National Wildlife Refuge were found in a previous study to be low relative to other wintering areas, raising concerns that tourism could be impacting the health of the population. Measurements of corticosterone levels enable the assessment and quantification of human-induced stressors that can ultimately affect fitness. We analyzed corticosterone concentrations and the relationship between body condition and maximum stress-induced corticosterone in areas with and without tourism access. Female Pintails were captured in winters of 2008–2009 and 2009–2010. The corticosterone response was similar between areas with and without tourism, but different between winters. In mid-January 2010, levels were 73% greater after 60 min compared with those in 2009. A greater stress response in mid-January 2010 may have been due to colder temperatures and arriving later and in poorer condition. Also in 2009–2010, there was a negative correlation between carcass fat and maximum corticosterone, possibly in response to colder temperatures, arriving in poorer condition, or a combination of both. Our study indicates that in mid- to late winter, activity of the hypothalamic–pituitary–adrenal axis may be higher during winters with comparatively greater environmental hardships, emphasizing the importance of carefully managing waterfowl during periods when they are most sensitive.
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Affiliation(s)
- D.P. Taylor
- U.S. Fish and Wildlife Service, Sequoyah National Wildlife Refuge, Route 1, Box 18-A, Vian, OK 74962, USA
| | - J.N. Vradenburg
- U.S. Fish and Wildlife Service, Bosque del Apache National Wildlife Refuge, P.O. Box 280, San Antonio, NM 88201, USA
| | - L.M. Smith
- Oklahoma State University, 501 Life Sciences West, Stillwater, OK 74078, USA
| | - M.B. Lovern
- Oklahoma State University, 501 Life Sciences West, Stillwater, OK 74078, USA
| | - S.T. McMurry
- Oklahoma State University, 501 Life Sciences West, Stillwater, OK 74078, USA
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Bhat M, Kalam R, Qadri SS, Madabushi S, Ismail A. Vitamin D deficiency-induced muscle wasting occurs through the ubiquitin proteasome pathway and is partially corrected by calcium in male rats. Endocrinology 2013; 154:4018-29. [PMID: 23928374 DOI: 10.1210/en.2013-1369] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Vitamin D deficiency leads to muscle wasting in both animals and humans. A vitamin D-deficient rat model was created using Sprague Dawley male rats. We studied the involvement of the ubiquitin proteasome and other proteolytic pathways in vitamin D deficiency-induced muscle atrophy. To delineate the effect of hypocalcemia that accompanies D deficiency, a group of deficient rats was supplemented with high calcium alone. Total protein degradation in muscle was assessed by release of tyrosine; proteasomal, lysosomal, and calpain enzyme activities were studied using specific substrates by fluorometry, and E2 enzyme expression was assessed by Western blot analysis. Muscle histology was done by myosin ATPase staining method, whereas 3-methylhistidine in the urine was estimated using HPLC. Muscle gene expression was measured by semiquantitative RT-PCR. Total protein degradation in muscle and the level of 3-methylhistidine in urine were increased in the deficient group compared with the control group. Proteasomal enzyme activities, expression of the E2 ubiquitin conjugating enzyme, and ubiquitin conjugates were increased in the deficient group compared with controls. On the other hand, lysosomal and calpain activities were not altered. Type II fiber area, a marker for muscle atrophy, was decreased in the deficient muscle compared with control muscle. Muscle atrophy marker genes and proteasomal subunit genes were up-regulated, whereas myogenic genes were down-regulated in D-deficient muscle. From the results it appears that the ubiquitin proteasome pathway is the major pathway involved in vitamin D deficiency-induced muscle protein degradation and that calcium supplementation alone in the absence of vitamin D partially corrects the changes.
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Affiliation(s)
- Mehrajuddin Bhat
- PhD, Department of Endocrinology & Metabolism, National Institute of Nutrition, Jamai Osmania, PO, Tarnaka, Hyderabad, India 500007.
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Leucine modulates the effect of Walker factor, a proteolysis-inducing factor-like protein from Walker tumours, on gene expression and cellular activity in C2C12 myotubes. Cytokine 2013; 64:343-50. [DOI: 10.1016/j.cyto.2013.05.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 05/15/2013] [Accepted: 05/17/2013] [Indexed: 01/26/2023]
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11
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Cornelius JM, Boswell T, Jenni-Eiermann S, Breuner CW, Ramenofsky M. Contributions of endocrinology to the migration life history of birds. Gen Comp Endocrinol 2013; 190:47-60. [PMID: 23602795 DOI: 10.1016/j.ygcen.2013.03.027] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Revised: 03/24/2013] [Accepted: 03/25/2013] [Indexed: 11/29/2022]
Abstract
Migration is a key life cycle stage in nearly 2000 species of birds and is a greatly appreciated phenomenon in both cultural and academic arenas. Despite a long research tradition concerning many aspects of migration, investigations of hormonal contributions to migratory physiology and behavior are more limited and represent a comparatively young research field. We review advances in our understanding of the hormonal mechanisms of migration with particular emphasis on the sub-stages of the migration life history: development, departure, flight and arrival. These sub-stages vary widely in their behavioral, ecological and physiological contexts and, as such, should be given appropriate individual consideration.
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Affiliation(s)
- J M Cornelius
- Department of Neurobiology, Physiology and Behavior, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA.
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Manfredi LH, Zanon NM, Garófalo MA, Navegantes LCC, Kettelhut IC. Effect of short-term cold exposure on skeletal muscle protein breakdown in rats. J Appl Physiol (1985) 2013; 115:1496-505. [PMID: 23908317 DOI: 10.1152/japplphysiol.00474.2013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Although it is well established that carbohydrate and lipid metabolism are profoundly altered by cold stress, the effects of short-term cold exposure on protein metabolism in skeletal muscle are still poorly understood. Because cold acclimation requires that an organism adjust its metabolic flux, and muscle amino acids may be an important energy source for heat production, we hypothesize that muscle proteolysis is increased and protein synthesis is decreased under such a stress condition. Herein, cold exposure for 24 h decreased rates of protein synthesis and increased overall proteolysis in both soleus and extensor digitorum longus (EDL) muscles, but it did not affect muscle weight. An increase in proteolysis was accompanied by hyperactivity of the ubiquitin-proteasome system (UPS) in both soleus and EDL, and Ca(2+)-dependent proteolysis in EDL. Furthermore, muscles of rats exposed to cold showed increased mRNA and protein levels of atrogin-1 and muscle RING finger enzyme-1 (MuRF1). Additionally, cold stress reduced phosphorylation of Akt and Forkhead box class O1 (FoxO1), a well-known effect that increases FoxO translocation to the nucleus and leads to activation of proteolysis. Plasma insulin levels were lower, whereas catecholamines, corticosterone, and thyroid hormones were higher in cold-exposed rats compared with control rats. The present data provide the first direct evidence that short-term cold exposure for 24 h decreases rates of protein synthesis and increases the UPS and Ca(2+)-dependent proteolytic processes, and increases expression of atrogin-1 and MuRF1 in skeletal muscles of young rats. The activation of atrophy induced by acute cold stress seems to be mediated at least in part through the inactivation of Akt/FoxO signaling and activation of AMP-activated protein kinase.
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Affiliation(s)
- L H Manfredi
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
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13
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Aragon AA, Schoenfeld BJ. Nutrient timing revisited: is there a post-exercise anabolic window? J Int Soc Sports Nutr 2013; 10:5. [PMID: 23360586 PMCID: PMC3577439 DOI: 10.1186/1550-2783-10-5] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 01/25/2013] [Indexed: 12/19/2022] Open
Abstract
Nutrient timing is a popular nutritional strategy that involves the consumption of combinations of nutrients--primarily protein and carbohydrate--in and around an exercise session. Some have claimed that this approach can produce dramatic improvements in body composition. It has even been postulated that the timing of nutritional consumption may be more important than the absolute daily intake of nutrients. The post-exercise period is widely considered the most critical part of nutrient timing. Theoretically, consuming the proper ratio of nutrients during this time not only initiates the rebuilding of damaged muscle tissue and restoration of energy reserves, but it does so in a supercompensated fashion that enhances both body composition and exercise performance. Several researchers have made reference to an anabolic “window of opportunity” whereby a limited time exists after training to optimize training-related muscular adaptations. However, the importance - and even the existence - of a post-exercise ‘window’ can vary according to a number of factors. Not only is nutrient timing research open to question in terms of applicability, but recent evidence has directly challenged the classical view of the relevance of post-exercise nutritional intake with respect to anabolism. Therefore, the purpose of this paper will be twofold: 1) to review the existing literature on the effects of nutrient timing with respect to post-exercise muscular adaptations, and; 2) to draw relevant conclusions that allow practical, evidence-based nutritional recommendations to be made for maximizing the anabolic response to exercise.
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Grizard J, Dardevet D, Papet I, Mosoni L, Mirand PP, Attaix D, Tauveron I, Bonin D, Arnal M. Nutrient regulation of skeletal muscle protein metabolism in animals. The involvement of hormones and substrates. Nutr Res Rev 2012; 8:67-91. [PMID: 19094280 DOI: 10.1079/nrr19950007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- J Grizard
- Laboratoire d'Etude du Métabolisme Azoté, Institut National de la Recherche Agronomique, Centre de Clermont-Ferrand - Theix, Centre de Recherche en Nutrition Humaine d'Auvergne, 63122 Saint-Genès-Champanelle, France
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Bailey AN, Hocker AD, Vermillion BR, Smolkowski K, Shah SN, Jewett BA, Dreyer HC. MAFbx, MuRF1, and the stress-activated protein kinases are upregulated in muscle cells during total knee arthroplasty. Am J Physiol Regul Integr Comp Physiol 2012; 303:R376-86. [PMID: 22761181 DOI: 10.1152/ajpregu.00146.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Total knee arthroplasty (TKA) is the most common and a cost-effective surgical remediation for older adults with long-standing osteoarthritis. In parallel with the expanding population of older adults, the number of TKAs performed annually is projected to be 3.48 million by 2030. During this surgery, a tourniquet is used to stop blood flow to the operative leg. However, the molecular pathways that are affected by tourniquet use during TKA continue to be elucidated. We hypothesized that components of the catabolic FoxO3a (i.e., MuRF1, MAFbx, and Bnip3) pathway, as well as the cellular stress pathways [i.e., stress-activated protein kinase (SAPK)/JNK and MAPKs], are upregulated during TKA. The purpose of this study was to measure changes in transcripts and proteins involved in muscle cell catabolic and stress-activated pathways. We obtained muscle biopsies from subjects, 70 ± 1.3 yr, during TKA, from the vastus lateralis at baseline (before tourniquet inflation), during maximal ischemia (just before tourniquet release), and during reperfusion. Total tourniquet time was 43 ± 2 min and reperfusion time was 16 ± 1. Significant increases in FoxO3a downstream targets, MAFbx and MuRF1, were present for mRNA levels during ischemia (MAFbx, P = 0.04; MuRF1, P = 0.04), and protein expression during ischemia (MAFbx, P = 0.002; MuRF1, P = 0.001) and reperfusion (MuRF1, P = 0.002). Additionally, stress-activated JNK gene expression (P = 0.01) and protein were elevated during ischemia (P = 0.001). The results of this study support our hypothesis that protein degradation pathways are stimulated during TKA. Muscle protein catabolism is likely to play a role in the rapid loss of muscle volume measured within 2 wk of this surgery.
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Affiliation(s)
- Ashley N Bailey
- Department of Human Physiology, University of Oregon, Eugene, 97403-1240, USA
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16
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Drew MD, Schafer TC, Zijlstra RT. Glycemic index of starch affects nitrogen retention in grower pigs1. J Anim Sci 2012; 90:1233-41. [DOI: 10.2527/jas.2010-3458] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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Staples AW, Burd NA, West DWD, Currie KD, Atherton PJ, Moore DR, Rennie MJ, Macdonald MJ, Baker SK, Phillips SM. Carbohydrate does not augment exercise-induced protein accretion versus protein alone. Med Sci Sports Exerc 2011; 43:1154-61. [PMID: 21131864 DOI: 10.1249/mss.0b013e31820751cb] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
PURPOSE We tested the thesis that CHO and protein coingestion would augment muscle protein synthesis (MPS) and inhibit muscle protein breakdown (MPB) at rest and after resistance exercise. METHODS Nine men (age=23.0±1.9 yr, body mass index=24.2±2.1 kg·m) performed two unilateral knee extension trials (four sets×8-12 repetitions to failure) followed by consumption of 25 g of whey protein (PRO) or 25 g of whey protein plus 50 g of maltodextrin (PRO+CARB). Muscle biopsies and stable isotope methodology were used to measure MPS and MPB. RESULTS The areas under the glucose and insulin curves were 17.5-fold (P<0.05) and 5-fold (P<0.05) greater, respectively, for PRO+CARB than for PRO. Exercise increased MPS and MPB (both P<0.05), but there were no differences between PRO and PRO+CARB in the rested or exercised legs. Phosphorylation of Akt was greater in the PRO+CARB than in the PRO trial (P<0.05); phosphorylations of Akt (P=0.05) and acetyl coA carboxylase-β (P<0.05) were greater after exercise than at rest. The concurrent ingestion of 50 g of CHO with 25 g of protein did not stimulate mixed MPS or inhibit MPB more than 25 g of protein alone either at rest or after resistance exercise. CONCLUSIONS Our data suggest that insulin is not additive or synergistic to rates of MPS or MPB when CHO is coingested with a dose of protein that maximally stimulates rates of MPS.
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Affiliation(s)
- Aaron W Staples
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
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Bergantin LB, Figueiredo LB, Godinho RO. The lumbrical muscle: a novel in situ system to evaluate adult skeletal muscle proteolysis and anticatabolic drugs for therapeutic purposes. J Appl Physiol (1985) 2011; 111:1710-8. [PMID: 21921242 DOI: 10.1152/japplphysiol.00586.2011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The molecular regulation of skeletal muscle proteolysis and the pharmacological screening of anticatabolic drugs have been addressed by measuring tyrosine release from prepubertal rat skeletal muscles, which are thin enough to allow adequate in vitro diffusion of oxygen and substrates. However, the use of muscle at accelerated prepubertal growth has limited the analysis of adult muscle proteolysis or that associated with aging and neurodegenerative diseases. Here we established the adult rat lumbrical muscle (4/hindpaw; 8/rat) as a new in situ experimental model for dynamic measurement of skeletal muscle proteolysis. By incubating lumbrical muscles attached to their individual metatarsal bones in Tyrode solution, we showed that the muscle proteolysis rate of adult and aged rats (3-4 to 24 mo old) is 45-25% of that in prepubertal animals (1 mo old), which makes questionable the usual extrapolation of proteolysis from prepubertal to adult/senile muscles. While acute mechanical injury or 1- to 7-day denervation increased tyrosine release from adult lumbrical muscle by up to 60%, it was reduced by 20-28% after 2-h incubation with β-adrenoceptor agonists, forskolin or phosphodiesterase inhibitor IBMX. Using inhibitors of 26S-proteasome (MG132), lysosome (methylamine), or calpain (E64/leupeptin) systems, we showed that ubiquitin-proteasome is accountable for 40-50% of total lumbrical proteolysis of adult, middle-aged, and aged rats. In conclusion, the lumbrical model allows the analysis of muscle proteolysis rate from prepubertal to senile rats. By permitting eight simultaneous matched measurements per rat, the new model improves similar protocols performed in paired extensor digitorum longus (EDL) muscles from prepubertal rats, optimizing the pharmacological screening of drugs for anticatabolic purposes.
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Affiliation(s)
- Leandro Bueno Bergantin
- Div. of Cellular Pharmacology, Dept. of Pharmacology, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Três de maio, 100, São Paulo, SP, Brazil
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19
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Kozlowski CP, Ricklefs RE. The effects of brood size on growth and steroid hormone concentrations in nestling eastern bluebirds (Sialia sialis). Gen Comp Endocrinol 2011; 173:447-53. [PMID: 21819987 DOI: 10.1016/j.ygcen.2011.07.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 07/14/2011] [Accepted: 07/16/2011] [Indexed: 11/28/2022]
Abstract
Birds in multi-nestling broods often experience reduced growth and elevated nutritional and social stress as a result of competition for parental resources. While responses are often species-specific, experimentally increasing brood size has been shown to decrease growth and increase production of both testosterone and corticosterone in nestling passerines. To investigate the relationship between brood size, growth, and steroid hormone production in eastern bluebirds, we cross-fostered nestlings to small, medium, and large broods. Body mass, skeletal size, serum testosterone, and baseline serum corticosterone concentration were measured prior to fledging. Bluebird nestlings raised in large broods weighed less than nestlings in small and medium-sized broods and secreted elevated concentrations of testosterone. Nestling corticosterone concentrations did not vary in response to brood size or body condition, but concentrations were higher in males compared to females. Our results suggest that nestling bluebirds experiencing nutritional and social stress increase testosterone production. Elevated concentrations may enhance begging and competitive abilities in smaller young. Higher concentrations of corticosterone in males may be related to sex-biased provisioning. Further experimental work is needed to ascertain the effects of elevated testosterone concentrations in nestling bluebirds, as well as the causes and consequences of elevated corticosterone for male nestlings.
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Affiliation(s)
- Corinne P Kozlowski
- Saint Louis Zoo, Research Department, 1 Government Drive, St. Louis, MO 63110, USA.
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20
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Lira EC, Gonçalves DA, Parreiras-E-Silva LT, Zanon NM, Kettelhut IC, Navegantes LC. Phosphodiesterase-4 inhibition reduces proteolysis and atrogenes expression in rat skeletal muscles. Muscle Nerve 2011; 44:371-81. [DOI: 10.1002/mus.22066] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Wang J, Salem M, Qi N, Kenney PB, Rexroad CE, Yao J. Molecular characterization of the MuRF genes in rainbow trout: Potential role in muscle degradation. Comp Biochem Physiol B Biochem Mol Biol 2010; 158:208-15. [PMID: 21145412 DOI: 10.1016/j.cbpb.2010.11.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 11/23/2010] [Accepted: 11/23/2010] [Indexed: 12/31/2022]
Abstract
Muscle growth is determined primarily by the balance between protein synthesis and degradation. When rates of protein synthesis are similar between individuals, protein degradation is critical in explaining differences in growth efficiency. Studies in mammals showed that muscle atrophy results from increased protein breakdown, and is associated with activation of the ubiquitin proteasome pathway, including induction of the muscle-specific ubiquitin protein ligase, MuRF1. Animals lacking MuRF1 are resistant to muscle atrophy. In fish, little is known about the role of the proteasome/MuRF pathway in muscle degradation. The objectives of this study were to: 1) clone and characterize MuRF genes in rainbow trout; and 2) determine expression of MuRF genes in association with starvation- and vitellogenesis-induced muscle atrophy in rainbow trout. We have identified full-length cDNA sequences for three MuRF genes (MuRF1, MuRF2, and MuRF3). These genes encode proteins with typical MuRF structural domains, including a RING-finger, a B-box and a Leucine-rich coiled-coil domain. RT-PCR analysis showed that MuRF genes are predominantly expressed in muscle and heart tissues. Real time PCR analysis revealed that expression of all MuRF genes is up-regulated during starvation and MuRF3 is up-regulated in vitellogenesis-associated muscle degradation. These results suggest that MuRF genes have an important role in fish muscle protein degradation. Further studies are warranted to assess the potential use of MuRF genes as tools to monitor fish muscle growth and degradation.
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Affiliation(s)
- Jiannan Wang
- Laboratory of Animal Biotechnology and Genomics, Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, WV 26506, USA
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22
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Abstract
This short review outlines the physiology of glucagon in vivo, with an emphasis on its neural control, the author's area of interest. Glucagon is secreted from alpha cells, which are a minority of the pancreatic islet. Anatomically, they are down stream from the majority islet beta cells. Beta-cell secretory products restrain glucagon secretion. Activation of the autonomic nerves, which innervate the islet, increases glucagon secretion. Glucagon is secreted into the portal vein and thus has its major physiologic action at the liver to break down glycogen. Glucagon thereby maintains hepatic glucose production during fasting and increases hepatic glucose production during stress, including the clinically important stress of hypoglycemia. Three different mechanisms proposed to stimulate glucagon secreted during hypoglycemia are discussed: (1) a stimulatory effect of low glucose directly on the alpha cell, (2) withdrawal of an inhibitory effect of adjacent beta cells, and (3) a stimulatory effect of autonomic activation. In type 1 diabetes (T1DM), increased glucagon secretion contributes to the elevated ketones and acidosis present in diabetic ketoacidosis (DKA). It also contributes to the hyperglycemia seen with or without DKA. The glucagon response to insulin-induced hypoglycemia is impaired soon after the development of T1DM. The mediators of this impairment include loss of beta cells and loss of sympathetic nerves from the autoimmune diabetic islet.
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Chotechuang N, Azzout-Marniche D, Bos C, Chaumontet C, Gaudichon C, Tomé D. Down-regulation of the ubiquitin-proteasome proteolysis system by amino acids and insulin involves the adenosine monophosphate-activated protein kinase and mammalian target of rapamycin pathways in rat hepatocytes. Amino Acids 2010; 41:457-68. [PMID: 20957397 DOI: 10.1007/s00726-010-0765-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 09/28/2010] [Indexed: 12/01/2022]
Abstract
The purpose of this work was to examine whether changes in dietary protein levels could elicit differential responses of tissue proteolysis and the pathway involved in this response. In rats fed with a high protein diet (55%) for 14 days, the liver was the main organ where adaptations occurred, characterized by an increased protein pool and a strong, meal-induced inhibition of the protein breakdown rate when compared to the normal protein diet (14%). This was associated with a decrease in the key-proteins involved in expression of the ubiquitin-proteasome and autophagy pathway gene and a reduction in the level of hepatic ubiquitinated protein. In hepatocytes, we demonstrated that the increase in amino acid (AA) levels was sufficient to down-regulate the ubiquitin proteasome pathway, but this inhibition was more potent in the presence of insulin. Interestingly, AICAR, an adenosine monophosphate-activated protein kinase (AMPK) activator, reversed the inhibition of protein ubiquination induced by insulin at high AA concentrations. Rapamycin, an mammalian target of rapamycin (mTOR) inhibitor, reversed the inhibition of protein ubiquination induced by a rise in insulin levels with both high and low AA concentrations. Moreover, in both low and high AA concentrations in the presence of insulin, AICAR decreased the mTOR phosphorylation, and in the presence of both AICAR and rapamycin, AICAR reversed the effects of rapamycin. These results demonstrate that the inhibition of AMPK and the activation of mTOR transduction pathways, are required for the down-regulation of protein ubiquitination in response to high amino acid and insulin concentrations.
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Affiliation(s)
- Nattida Chotechuang
- CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, AgroParisTech, 16 rue Claude, 75005, Paris, France
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Kozlowski CP, Mauck RA, O'Reilly KM, Philipsborn J, Ricklefs RE. Changes in plasma hormone levels correlate with fledging in nestling Leach's storm-petrels. Gen Comp Endocrinol 2010; 169:91-7. [PMID: 20688060 DOI: 10.1016/j.ygcen.2010.07.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Revised: 07/27/2010] [Accepted: 07/28/2010] [Indexed: 11/26/2022]
Abstract
Leach's storm-petrels accumulate large amounts of body mass throughout the nestling period. Approximately 4days before fledging, nestlings weigh 50-100% more than adults. In order to shed this excess mass, nestlings engage in behavioral anorexia, and leave the burrow when they are light enough to fly. During this prefledging period, we measured several plasma hormones (corticosterone, thyroxine, and testosterone) to determine whether the behavioral changes associated with fledging are correlated with endocrine changes. In several species, including petrels, corticosterone levels are known to increase near fledging. Reduced food consumption has been shown to elevate corticosterone levels and decrease thyroxine levels in nestling birds. In nestling storm-petrels, levels of both corticosterone and thyroxine increased. Storm-petrels were found to secrete measurable levels of testosterone, but levels did not change during the prefledging period. Increased corticosterone levels might be part of an endocrine signal that initiates changes in feeding behavior, or may result from reduced food intake. Elevated thyroxine levels may be related to metabolic changes involved in mass loss. Future experimental work is needed to ascertain whether the described endocrine changes are responsible for, or result from, prefledging changes in petrel feeding behavior.
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Affiliation(s)
- Corinne P Kozlowski
- Research Department, Saint Louis Zoo, 1 Government Drive, St Louis, MO 63110, USA.
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Brand C, Horovitz-Fried M, Inbar A, Tamar-Brutman-Barazani, Brodie C, Sampson SR. Insulin stimulation of PKCδ triggers its rapid degradation via the ubiquitin-proteasome pathway. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:1265-75. [PMID: 20708645 DOI: 10.1016/j.bbamcr.2010.07.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 07/15/2010] [Accepted: 07/26/2010] [Indexed: 01/20/2023]
Abstract
Insulin rapidly upregulates protein levels of PKCδ in classical insulin target tissues skeletal muscle and liver. Insulin induces both a rapid increase in de novo synthesis of PKCδ protein. In this study we examined the possibility that insulin may also inhibit degradation of PKCδ. Experiments were performed on L6 skeletal muscle myoblasts or myotubes in culture. Phorbol ester (PMA)- and insulin-induced degradation of PKCδ were abrogated by proteasome inhibition. Both PMA and insulin induced ubiquitination of PKCδ, but not of that PKCα or PKCε and increased proteasome activity within 5 min. We examined the role of tyrosine phosphorylation of PKCδ in targeting PKCδ for degradation by the ubiquitin-proteasome pathway. Transfection of cells with PKCδY(311)F, which is not phosphorylated, resulted in abolition of insulin-induced ubiquitination of PKCδ and increase in proteasome activity. We conclude that insulin induces degradation of PKCδ via the ubiquitin-proteasome system, and that this effect requires phosphorylation on specific tyrosine residues for targeting PKCδ for degradation by the ubiquitin-proteasome pathway. These studies provide additional evidence for unique effects of insulin on regulation of PKCδ protein levels.
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Affiliation(s)
- Chagit Brand
- The Faculty of Life Science, Bar-Ilan University, Ramat-Gan, Israel
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26
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Glucose metabolism in burn patients: The role of insulin and other endocrine hormones. Burns 2010; 36:599-605. [DOI: 10.1016/j.burns.2009.11.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 07/24/2009] [Accepted: 11/11/2009] [Indexed: 01/08/2023]
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Corbel HÃ, Geiger S, Groscolas R. Preparing to fledge: the adrenocortical and metabolic responses to stress in king penguin chicks. Funct Ecol 2010. [DOI: 10.1111/j.1365-2435.2009.01619.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Jenni-Eiermann S, Hasselquist D, Lindström A, Koolhaas A, Piersma T. Are birds stressed during long-term flights? A wind-tunnel study on circulating corticosterone in the red knot. Gen Comp Endocrinol 2009; 164:101-6. [PMID: 19481083 DOI: 10.1016/j.ygcen.2009.05.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Revised: 02/16/2009] [Accepted: 05/19/2009] [Indexed: 10/20/2022]
Abstract
During endurance flight most birds do not feed and have to rely on their body reserves. Fat and protein is catabolised to meet the high energetic demands. Even though the hormonal regulation of migration is complex and not yet fully understood, the adrenocortical hormone corticosterone crystallizes to play a major role in controlling physiological traits in migratory birds during flight. However, results from field studies are partially equivocal, not least because data from birds during endurance flight are hard to get and present mostly a momentary shot. A wind-tunnel experiment offered the possibility to measure repeatedly under controlled conditions the effect of long flights on the stress hormone corticosterone. In a long-distance migrating shorebird, the red knot Calidris canutus, we measured plasma concentrations of corticosterone within 3 min and after a restraint time of 30 min directly after 2h and 10h non-stop flights, respectively, and during rest. Baseline corticosterone levels were unchanged directly after the flights, indicating that endurance flight did not affect corticosterone levels. The adrenocortical response to restraint showed the typical rise in birds during rest, while birds after a 2 or 10h flight substantially decreased plasma corticosterone concentrations. We suggest that the negative adrenocortical response to restraint after flight is part of the mechanism to reduce the proteolytic effect of corticosterone to save muscle protein and to avoid muscle damaging effects.
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Molina GE, Rocco GF, Fontana KE. Desempenho da potência anaeróbia em atletas de elite do mountain bike submetidos à suplementação aguda com creatina. REV BRAS MED ESPORTE 2009. [DOI: 10.1590/s1517-86922009000600011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Com o objetivo de investigar os efeitos da suplementação aguda com creatina no desempenho da potência anaeróbia de atletas de elite do mountain bike, 20 atletas em período básico do macrociclo de treinamento foram distribuídos aleatoriamente (duplo-cego) em dois grupos: placebo (PLA, n = 10) e creatina (CRE, n = 10). Foram avaliados quanto à composição corporal (pesagem hidrostática) e potência anaeróbia (teste de Wingate - TW) antes (PRÉ) e depois (PÓS) de sete dias de suplementação. A creatina ou maltodextrina foi usada em três doses diárias de 0,3g/kg de massa corporal diluídos em meio líquido adoçado. Não foram observadas diferenças significativas nas variáveis morfológicas após sete dias de suplementação (PRÉ x PÓS), e os grupos não diferiram apesar da variação percentual (Δ%) contrária (positiva para o grupo CRE e negativa para o PLA). A potência anaeróbia pico (PP) e o instante da potência pico (IPP) aumentaram e o índice de fadiga diminuiu do PRÉ para o PÓS-testes no grupo CRE, enquanto que o grupo PLA não apresentou diferenças significantes. A PP apresentou forte tendência em ser maior e o IPP foi maior no grupo CRE comparado com o PLA. Conclui-se que existem evidências de que a suplementação com creatina (0,3g/kg) em curto prazo (sete dias) pode retardar o IPP (CRE 3,0 ± 0,5/3,6 ± 0,8 Δ%= 20%) no teste de Wingate em atletas de elite do mountain bike, sugerindo que a suplementação com creatina pode melhorar o desempenho físico quanto à potência anaeróbia durante o trabalho de alta intensidade e curta duração.
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Rose AJ, Richter EA. Regulatory mechanisms of skeletal muscle protein turnover during exercise. J Appl Physiol (1985) 2009; 106:1702-11. [DOI: 10.1152/japplphysiol.91375.2008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Skeletal muscle protein turnover is a relatively slow metabolic process that is altered by various physiological stimuli such as feeding, fasting, and exercise. During exercise, catabolism of amino acids contributes very little to ATP turnover in working muscle. With regard to protein turnover, there are now consistent data from tracer studies in rodents and humans showing that global protein synthesis is blunted in working skeletal muscle. Whether there is altered skeletal muscle protein breakdown during exercise remains unclear. The blunting of protein synthesis is believed to be mediated by suppressed mRNA translation initiation and elongation steps involving, but not limited to, changes in eukaryotic initiation factor 4E binding protein 1 and eukaryotic elongation factor 2 phosphorylation (eEF2), respectively. Evidence is provided that upstream signaling to translation factors is mediated by signaling downstream of changes in intracellular Ca2+ and energy turnover. In particular, a signaling cascade involving Ca2+/calmodulin-eEF2 kinase-eEF2 is implicated. The possible functional significance of altered protein turnover in working skeletal muscle during exercise is discussed. Further work with available and new techniques will undoubtedly reveal the functional significance and signaling mechanisms behind changes in skeletal muscle protein turnover during exercise.
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Wang Z, Zhao C, Moya R, Davies JD. A novel role for CD4+ T cells in the control of cachexia. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2008; 181:4676-84. [PMID: 18802070 PMCID: PMC4664528 DOI: 10.4049/jimmunol.181.7.4676] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cachexia is the dramatic weight loss and muscle atrophy seen in chronic disease states, including autoimmunity, cancer, and infection, and is often associated with lymphopenia. We have previously shown that CD4(+) T cells that express the lowest density of CD44 (CD4(+)CD44(v.low)) are significantly reduced in diabetic NOD mice that are cachexic compared with diabetic mice that are not cachexic. Using this model, and a model of cancer cachexia, we test the hypothesis that CD4(+)CD44(v.low) cells play an active role in protecting the host from cachexia. CD4(+)CD44(v.low) cells, but not CD4(+) cells depleted of CD44(v.low) cells, delay the onset of wasting when infused into either diabetic or prediabetic NOD recipients. However, no significant effect on the severity of diabetes was detected. In a model of cancer cachexia, they significantly reduce muscle atrophy, and inhibit muscle protein loss and DNA loss, even when given after the onset of cachexia. Protection from wasting and muscle atrophy by CD4(+)CD44(v.low) cells is associated with protection from lymphopenia. These data suggest, for the first time, a role for an immune cell subset in protection from cachexia, and further suggest that the mechanism of protection is independent of protection from autoimmunity.
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Affiliation(s)
| | | | | | - Joanna D. Davies
- Address correspondence and reprint requests to Dr. Joanna D. Davies, Torrey Pines Institute for Molecular Studies, 3550 General Atomics Court, San Diego, CA 92121. address:
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Contrin LM, Lobo SM, Navegantes LC, Orrico SP, Queiroz MM, Cury PM, Lira EC, Carta A, Yamamoto AE, Vincent JL. Tyrosine: a possible marker of severe intestinal injury during ischemia. J Surg Res 2008; 155:268-72. [PMID: 19505700 DOI: 10.1016/j.jss.2008.06.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 05/12/2008] [Accepted: 06/06/2008] [Indexed: 11/28/2022]
Abstract
BACKGROUND Long periods of ischemia can cause organ injury and dysfunction. The protein degradation occurring in the muscular layer and in the mucosa of the intestinal wall during ischemia may release amino acids into the intestinal lumen or into the circulation. The small intestine, like skeletal muscle, cannot synthesize or degrade tyrosine. Thus, the tyrosine concentration released from the gut mucosa reflects the balance between protein synthesis and degradation. We aimed to determine whether tyrosine can be used as a marker of intestinal injury during ischemia. METHODS In 19 anesthetized rabbits, an ultrasonic flow probe was placed around the superior mesenteric artery to estimate blood flow. A segment from the ileum was isolated using two multilumen catheters with inflated balloons to create a closed segment for perfusion. Animals were allocated into three groups: a sham group without intervention (group I); a group submitted to superior mesenteric artery ligation only (group II); and a group submitted to 1 h of SMA clamping followed by 1 h of reperfusion (group III). Concentrations of lactate and tyrosine (fluorometry) were determined in the serum and the gut luminal perfusate. RESULTS Gut luminal perfusate tyrosine concentrations increased significantly in group II (from 10 +/- 8 to 93 +/- 63 mm/mL at 2 h) and were significantly higher than in group I (26 +/- 24 mm/mL) and group III (11 +/- 13 mm/mL) (P < 0.05 for all). CONCLUSION Tyrosine is released from cells into the lumen during severe intestinal ischemia. Regional measurements of tyrosine levels may be a useful indicator of severe intestinal villus compromise.
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Affiliation(s)
- Ligia M Contrin
- Intensive Care Unit, Hospital de Base-Faculdade de Medicina, São José do Rio Preto, Brazil
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Corbel H, Groscolas R. A role for corticosterone and food restriction in the fledging of nestling White storks. Horm Behav 2008; 53:557-66. [PMID: 18313056 DOI: 10.1016/j.yhbeh.2007.12.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 12/05/2007] [Accepted: 12/21/2007] [Indexed: 10/22/2022]
Abstract
Fledging is a critical period in the life of a bird, notably because at this stage under-development and lack of experience in searching for food may impair survival. The behavioral changes that accompany nest departure are therefore expected to be finely tuned to body condition and growth by endocrine processes. This study examines the possible involvement of corticosterone (CORT) in the stimulation of fledging in White storks through measurement of the changes in its plasma levels in relation to growth, nutritional status and the hatching rank of nestlings. For the first time in nest-bound chicks, we show that fledging is preceded by a marked and progressive 4 fold increase in baseline plasma CORT levels concomitant with an increase in locomotor activity (wing flapping) at the nest. Data on changes in body size, body mass, plasma metabolites and feeding frequency support the view that the increase in plasma CORT was induced by food restriction rather than being endogenously programmed. The timing and intensity of plasma CORT increase was dependent on the hatching rank within a brood, this increase being blunted in the less developed chicks possibly to avoid the impairment of final wing growth. These results show that an increase in plasma CORT as a result of food restriction and through the stimulation of locomotor activity is involved in the control of fledging in White storks. Moreover the CORT increase is adjusted to the hatching rank-related growth status of nestlings.
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Affiliation(s)
- Hélène Corbel
- Institut Pluridisciplinaire Hubert Curien, Département d'Ecologie, Physiologie et Ethologie, UMR 7178 CNRS-ULP, 23 rue Becquerel, 67087, Strasbourg Cedex 02, France
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Corbel H, Morlon F, Groscolas R. Is fledging in king penguin chicks related to changes in metabolic or endocrinal status? Gen Comp Endocrinol 2008; 155:804-13. [PMID: 18155218 DOI: 10.1016/j.ygcen.2007.11.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2007] [Revised: 11/06/2007] [Accepted: 11/07/2007] [Indexed: 11/19/2022]
Abstract
This study examines the possibility that metabolic or endocrinal factors initiate fledging in the king penguin, a semi-altricial seabird species breeding a single chick on the ground. Chick fledging (departure to sea) occurred 5d after completion of the molt. It was preceded by a 16d fasting period and by a 7-fold increase in locomotor activity. From the measurement of the plasma concentration of metabolites and of glucagon and insulin, pre-fledging king penguin chicks were found to adapt to fasting in a classical way, i.e. by sparing body protein and mobilizing fat stores. At fledging, chicks were in phase II of fasting and their departure to sea was not stimulated by reaching critical energy depletion (phase III), in contrast to that which has been reported in breeding-fasting adults. The plasma level of corticosterone remained unchanged throughout the whole pre-fledging period, providing no support for a role of this stress-hormone in the facilitation of fledging. Thus, king penguin fledglings did not appear to be environmentally or nutritionally stressed. The plasma levels of thyroid hormones were elevated during the pre-fledging molt, in accordance with their key role in molt control in adult penguins. These levels declined by the time of the molt end, the plasma level of T4 thereafter being directly related to the time left before fledging. These results do not support the view that chronically elevated levels of thyroid hormones are required for the energy-demanding transition between being ashore and in cold water, but they suggest that the maintenance of high T4 levels may delay fledging.
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Affiliation(s)
- Hélène Corbel
- Institut Pluridisciplinaire Hubert Curien, Département d'Ecologie, Physiologie et Ethologie, UMR 7178 CNRS-ULP, 23 rue Becquerel, 67087 Strasbourg Cedex 02, France.
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Lira EC, Graca FA, Goncalves DAP, Zanon NM, Baviera AM, Strindberg L, Lönnroth P, Migliorini RH, Kettelhut IC, Navegantes LCC. Cyclic adenosine monophosphate-phosphodiesterase inhibitors reduce skeletal muscle protein catabolism in septic rats. Shock 2007; 27:687-94. [PMID: 17505310 DOI: 10.1097/shk.0b013e31802e43a6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We have previously shown that catecholamines exert an inhibitory effect on muscle protein degradation through a pathway involving the cyclic adenosine monophosphate (cAMP) cascade in normal rats. In the present work, we investigated in vivo and in vitro effects of cAMP-phosphodiesterase inhibitors on protein metabolism in skeletal muscle from rats submitted to a model of acute sepsis. The in vivo muscle protein metabolism was evaluated indirectly by measurements of the tyrosine interstitial concentration using microdialysis. Muscle blood flow (MBF) was monitored by ethanol perfusion technique. Sepsis was induced by cecal ligation and puncture and resulted in lactate acidosis, hypotension, and reduction in MBF (-30%; P < 0.05). Three-hour septic rats showed an increase in muscle interstitial tyrosine concentration (approximately 150%), in arterial plasma tyrosine levels (approximately 50%), and in interstitial-arterial tyrosine concentration difference (approximately 200%; P < 0.05). Pentoxifylline (50 mg/kg of body weight, i.v.) infusion during 1 h after cecal ligation and puncture prevented the tumor necrosis factor alpha increase and significantly reduced by 50% (P < 0.05) the interstitial-arterial tyrosine difference concentration. In situ perfusion with isobutylmethylxanthine (IBMX; 10(-3) M) reduced by 40% (P < 0.05) the muscle interstitial tyrosine in both sham-operated and septic rats. Neither pentoxifylline nor IBMX altered MBF. The addition of IBMX (10(-3) M) to the incubation medium increased (P < 0.05) muscle cAMP levels and reduced proteolysis in both groups. The in vitro addition of H89, a protein kinase A inhibitor, completely blocked the antiproteolytic effect of IBMX. The data show that activation of cAMP-dependent pathways and protein kinase A reduces muscle protein catabolism during basal and septic state.
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Contarteze RVL, Manchado FDB, Gobatto CA, Mello MARD. Biomarcadores de estresse em ratos exercitados por natação em intensidades igual e superior à máxima fase estável de lactato. REV BRAS MED ESPORTE 2007. [DOI: 10.1590/s1517-86922007000300008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
INTRODUÇÃO: O estresse alcançado durante exercício agudo/crônico é relevante, pois altos índices de estresse podem prejudicar o bem-estar dos animais. As concentrações dos hormônios adrenocorticotrófico (ACTH) e corticosterona, bem como as concentrações de ácido ascórbico e colesterol das glândulas adrenais são importantes biomarcadores de estresse. OBJETIVO: Analisar a sensibilidade de diferentes biomarcadores de estresse em ratos durante exercício agudo de natação em diferentes intensidades. MÉTODO: Ratos (18) adaptados à natação foram submetidos a três testes de 25 minutos suportando cargas 5,0; 5,5 e 6,0% do peso corporal (PC), para obtenção da máxima fase estável de lactato (MFEL). Em seguida, os animais foram divididos em dois grupos: M (n = 9), sacrificado após 25 minutos de exercício na intensidade de MFEL e S (n = 9), sacrificado após exercício exaustivo, em intensidade 25% superior a MFEL. Para comparações, um grupo controle C (n = 10) foi sacrificado em repouso. RESULTADOS: As concentrações séricas de ACTH e corticosterona foram superiores após exercício em ambas as intensidades comparadas com o grupo controle (P < 0,05). As concentrações de ACTH e corticosterona do grupo S foram, ainda, maiores do que as do grupo M (P < 0,05). As concentrações de colesterol e ácido ascórbico na adrenal dos grupos exercitados (M e S) foram inferiores às do grupo controle (P < 0,05). Não houve diferença das concentrações de ácido ascórbico e colesterol da adrenal quando comparadas as duas intensidades de exercício (M e S) (P < 0,05). CONCLUSÃO: Todos os biomarcadores do eixo HHA apontaram alterações no nível de estresse de ratos submetidos a exercício agudo de natação; as concentrações séricas de ACTH e corticosterona mostraram-se mais sensíveis a pequenas alterações na intensidade do exercício.
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López-Oliva ME, Agis-Torres A, Muñoz-Martínez E. The modulator effect of GH on skeletal muscle lysosomal enzymes is dietary protein dependent. Growth Horm IGF Res 2007; 17:137-148. [PMID: 17307005 DOI: 10.1016/j.ghir.2006.12.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Revised: 12/14/2006] [Accepted: 12/22/2006] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The purpose of this work is to determine whether changes in dietary protein level could alter the modulator effect that GH has on the muscle lysosomal system by influencing the hydrolytic activities of cathepsin D, acid RNase and DNase II and the participation of these enzymes in muscle growth. DESIGN BALB/c female mice were fed a diet containing 20% (HP) or 12% (MP) protein ad libitum and were treated with either saline (s) or rhGH (GH) (74 ng/g) for 29 days. Body weight and feed intake were recorded daily. At 25, 30, 35, 40, 45 and 50 days of age, five mice from each group were slaughtered and nucleic acids and protein concentrations and cathepsin D, acid RNase and DNase II activities in gastrocnemius muscle were analysed. Correlation coefficients were used to analyse the links between the activity of each enzyme with its substrate. RESULTS GH-treatment induced a depletion-recovery response in muscle growth through a compensatory mechanism. Changes in protein content, DNA and RNA concentrations were related to changes in lysosomal enzyme activities. Muscle cathepsin D activity in saline mice fell as the dietary protein concentration increased. GH-treatment reversed this effect by enhancing the proteolytic activity in muscle of well-fed mice and inhibiting it in mice fed a 12% protein diet. This inversion appears to be related to the different mechanism elicited by GH-treatment on skeletal muscle protein growth in each dietary group. An opposite trend was observed in muscle acid nuclease activities. Acid RNase and DNase II increased according to the dietary protein concentration, since a 12% protein diet induced a lower catabolism, especially on muscle DNA of saline mice. In contrast, GH-treatment decreased acid RNase and DNase II activities, but only in mice fed a 20% protein diet, perhaps leading to spare muscle RNA for protein synthesis, as well as to the inhibition of DNA degradation during catch-up growth. A lower dietary protein concentration appeared to reverse the GH protective effect on nucleic acids. CONCLUSIONS GH seems to act as a dietary protein-dependent modulator of the skeletal muscle lysosomal enzyme activity. These lysosomal enzymes play a role during muscle growth in GH-treated post-weaning mice by modifying muscle protein and DNA and RNA degradation.
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Affiliation(s)
- M E López-Oliva
- Sección Departamental de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain.
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Madihally SV, Pantelogianis A, Toner M. Antiproteolytic Action of Orally Delivered Insulin Using pH-Responsive Hydrogels in a Rat Burn Model. J Surg Res 2006; 135:187-94. [PMID: 16616764 DOI: 10.1016/j.jss.2006.01.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2005] [Revised: 01/10/2006] [Accepted: 01/23/2006] [Indexed: 11/22/2022]
Abstract
Subcutaneously delivered small doses of insulin has shown beneficial effects on burn injury-induced muscle wasting and wound healing. To improve the method of insulin treatment for clinical settings, this study investigated the effect of insulin delivered orally using pH-responsive poly(methacrylic-g-ethylene glycol) (P(MAA-g-EG)) hydrogels in a 20% total burn surface area rat burn injury model. P(MAA-g-EG) were synthesized in-house and insulin release characteristics were performed in vitro. Young rats weighing 80-150 g were subjected to 15-20% total body surface area burn injury and treated with insulin-containing hydrogels enclosed in gelatin capsules for 3 days. The dosage was adjusted to match 0.25 U (day 1), 0.5U (day 2), and 1.0 U (day 3) per 100 grams of body weight. All animals were housed in metabolic cages and their physical activity, body weight, food consumption, water uptake, circulating glucose levels, and urinary tyrosine content were monitored for 4 to 15 days after burn. Results show that the orally delivered insulin restored the body weight of burned rats and influenced wound healing, similar to subcutaneous delivery. Measured glucose levels showed significantly less perturbation, suggesting the possibility of increasing the dosage. In conclusion, muscle wasting can be significantly inhibited by the oral administration of insulin using pH-responsive hydrogels.
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Bird SP, Tarpenning KM, Marino FE. Liquid carbohydrate/essential amino acid ingestion during a short-term bout of resistance exercise suppresses myofibrillar protein degradation. Metabolism 2006; 55:570-7. [PMID: 16631431 DOI: 10.1016/j.metabol.2005.11.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Accepted: 11/15/2005] [Indexed: 10/24/2022]
Abstract
A number of physiological events including the level of contractile activity, nutrient status, and hormonal action influence the magnitude of exercise-induced skeletal muscle growth. However, it is not the independent action of a single mechanism, but the complex interaction between events that enhance the long-term adaptations to resistance training. The purpose of the present investigation was to examine the influence of liquid carbohydrate (CHO) and essential amino acid (EAA) ingestion during resistance exercise and modification of the immediate hormonal response on myofibrillar protein degradation as assessed by 3-methylhistidine (3-MH) excretion. After a 4-hour fast, 32 untrained young men (18-29 years) performed a single bout of resistance exercise (complete body; 3 setsx10 repetitions at 75% of 1-repetition maximum; 1-minute rest between sets), during which they consumed a 6% CHO (n=8) solution, a 6-g EAA (n=8) mixture, a combined CHO+EAA (n=8) supplement, or placebo (PLA; n=8) beverage. Resistance exercise performed in conjunction with CHO and CHO+EAA ingestion resulted in significantly elevated (P<.001) glucose and insulin concentrations above baseline, whereas EAA ingestion only increased the postexercise insulin response (P<.05). Time matched at 60 minutes, the PLA group exhibited a peak cortisol increase of 105% (P<.001) with no significant change in glucose or insulin concentrations. Conversely, the CHO and CHO+EAA groups displayed a decrease in cortisol levels of 11% and 7%, respectively. Coinciding with these hormonal response patterns were significant differences in myofibrillar protein degradation. Ingestion of the EAA and CHO treatments attenuated 3-MH excretion 48 hours after the exercise bout. Moreover, this response was synergistically potentiated when the 2 treatments were combined, with CHO+EAA ingestion resulting in a 27% reduction (P<.01) in 3-MH excretion. In contrast, the PLA group displayed a 56% increase (P<.01) in 3-MH excretion. These data demonstrate that not only does CHO and EAA ingestion during the exercise bout suppress exercise-induced cortisol release; the stimulatory effect of resistance exercise on myofibrillar protein degradation can be attenuated, most dramatically when the treatments are combined (CHO+EAA). Through an "anticatabolic effect," this altered balance may better favor the conservation of myofibrillar protein.
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Affiliation(s)
- Stephen P Bird
- School of Human Movement Studies, Charles Sturt University, Bathurst, NSW 2795, Australia.
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Bird SP, Tarpenning KM, Marino FE. Independent and combined effects of liquid carbohydrate/essential amino acid ingestion on hormonal and muscular adaptations following resistance training in untrained men. Eur J Appl Physiol 2006; 97:225-38. [PMID: 16456674 DOI: 10.1007/s00421-005-0127-z] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Accepted: 12/15/2005] [Indexed: 11/27/2022]
Abstract
This investigation examined chronic alteration of the acute hormonal response associated with liquid carbohydrate (CHO) and/or essential amino acid (EAA) ingestion on hormonal and muscular adaptations following resistance training. Thirty-two untrained young men performed 12 weeks of resistance training twice a week, consuming ~675 ml of either, a 6% CHO solution, 6 g EAA mixture, combined CHO + EAA supplement or placebo (PLA). Blood samples were obtained pre- and post-exercise (week 0, 4, 8, and 12), for determination of glucose, insulin, and cortisol. 3-Methylhistidine excretion and muscle fibre cross-sectional area (fCSA) were determined pre- and post-training. Post-exercise cortisol increased (P<0.05) during each training phase for PLA. No change was displayed by EAA; CHO and CHO + EAA demonstrated post-exercise decreases (P<0.05). All groups displayed reduced pre-exercise cortisol at week 12 compared to week 0 (P<0.05). Post-exercise insulin concentrations showed no change for PLA; increases were observed for the treatment groups (P<0.05), which remained greater for CHO and CHO + EAA (P<0.001) than PLA. EAA and CHO ingestion attenuated 3-methylhistidine excretion 48 h following the exercise bout. CHO + EAA resulted in a 26% decrease (P<0.01), while PLA displayed a 52% increase (P<0.01). fCSA increased across groups for type I, IIa, and IIb fibres (P<0.05), with CHO + EAA displaying the greatest gains in fCSA relative to PLA (P<0.05). These data indicate that CHO + EAA ingestion enhances muscle anabolism following resistance training to a greater extent than either CHO or EAA consumed independently. The synergistic effect of CHO + EAA ingestion maximises the anabolic response presumably by attenuating the post-exercise rise in protein degradation.
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MESH Headings
- Adaptation, Physiological/drug effects
- Adult
- Amino Acids, Essential/administration & dosage
- Amino Acids, Essential/pharmacology
- Blood Glucose/metabolism
- Body Composition/physiology
- Dietary Carbohydrates/administration & dosage
- Dietary Carbohydrates/pharmacology
- Double-Blind Method
- Exercise/physiology
- Hormones/blood
- Humans
- Hydrocortisone/blood
- Insulin/blood
- Male
- Methylhistidines/urine
- Muscle Fibers, Fast-Twitch/cytology
- Muscle Fibers, Fast-Twitch/drug effects
- Muscle Fibers, Fast-Twitch/physiology
- Muscle Fibers, Slow-Twitch/cytology
- Muscle Fibers, Slow-Twitch/drug effects
- Muscle Fibers, Slow-Twitch/physiology
- Muscle, Skeletal/cytology
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/physiology
- Time Factors
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Affiliation(s)
- Stephen P Bird
- School of Human Movement Studies, Charles Sturt University, Allen House 2.13, Bathurst, NSW, Australia.
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Nakashima K, Yamazaki M, Abe H. Effects of serum deprivation on expression of proteolytic-related genes in chick myotube cultures. Biosci Biotechnol Biochem 2005; 69:623-7. [PMID: 15784993 DOI: 10.1271/bbb.69.623] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We previously reported that serum deprivation stimulates myofibrillar proteolysis in chick myotubes. In the present study, we examined the effect of serum deprivation on expression of the proteolytic-related genes (ubiquitin, proteasome, calpains, and cathepsin B) by real-time PCR of cDNA in chick myotubes. Myotubes were incubated with serum-free medium for 24 h. Ubiquitin and proteasome subunits (C1 and C2) and calpains (m-, mu-, and p94/calpain-3) but not cathepsin B mRNA expression were increased by serum deprivation. These results indicate that serum deprivation stimulates ubiquitin-proteasome and calpain proteolytic pathways, resulting in an increase in myofibrillar proteolysis in chick myotubes.
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Affiliation(s)
- Kazuki Nakashima
- Nutrient Function Laboratory, Department of Animal Physiology and Nutrition, National Institute of Livestock and Grassland Science, Ikenodai, Tsukuba, Ibaraki, Japan.
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Navegantes LCC, Resano NMZ, Baviera AM, Migliorini RH, Kettelhut IC. CL 316,243, a selective β3-adrenergic agonist, inhibits protein breakdown in rat skeletal muscle. Pflugers Arch 2005; 451:617-24. [PMID: 16091956 DOI: 10.1007/s00424-005-1496-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Revised: 07/01/2005] [Accepted: 07/14/2005] [Indexed: 10/25/2022]
Abstract
The in vitro effect of CL 316,243 (CL), a selective beta3-adrenoceptor agonist in the rate of overall proteolysis, the activity of proteolytic systems (lysosomal, Ca2+-dependent, ATP-dependent, and ATP-independent) and in the process of protein synthesis was investigated in rat skeletal muscles. The rate of overall proteolysis in soleus muscle from rats incubated with CL (10(-4) and 10(-5) M) or epinephrine (10(-5) M) was significantly decreased. In vitro rates of maximal activity of Ca2+-dependent proteolysis in soleus muscles were decreased by about 41% in the presence of 10(-5) M CL. No change was observed in the activities of the lysosomal, ATP-dependent or ATP-independent proteolytic systems. The anti-proteolytic effect of CL or epinephrine was partially prevented by 10(-5) M SR 59230A, a selective beta3-adrenoceptor antagonist. The increase of proteolysis induced by food deprivation in soleus was abolished by in vitro addition of 10(-5) M CL. No change in proteolysis was observed in extensor digitorum longus (EDL) muscles incubated with any concentration of the beta3-adrenoceptor agonist tested. Rates of protein synthesis were not affected by 10(-4) M CL neither in soleus nor EDL. The data suggest that a beta3-adrenoceptor-mediated inhibition of Ca2+-dependent proteolysis participates of the antiproteolytic effect of catecholamines in oxidative muscles.
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Affiliation(s)
- Luiz Carlos C Navegantes
- Department of Physiology, Biochemistry and Immunology, School of Medicine, University of São Paulo, 14049-900, Ribeirão Preto, São Paulo, Brazil
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Lynch GS. Novel therapies for sarcopenia: ameliorating age-related changes in skeletal muscle. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.12.1.11] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Veronese ELG, Esmeraldino LE, Trombone APF, Santana AE, Bechara GH, Kettelhut I, Cintra ACO, Giglio JR, Sampaio SV. Inhibition of the myotoxic activity of Bothrops jararacussu venom and its two major myotoxins, BthTX-I and BthTX-II, by the aqueous extract of Tabernaemontana catharinensis A. DC. (Apocynaceae). PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2005; 12:123-130. [PMID: 15693719 DOI: 10.1016/j.phymed.2003.07.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Partial neutralization of the myotoxic effect of Bothrops jararacussu venom (BV) and two of its myotoxins [bothropstoxin-I (BthTX-I), catalytically inactive, and II (BthTX-II), showing low PLA2 activity], by the lyophilized aqueous extract of Tabernaemontana catharinensis (AE), was studied in rat isolated soleus muscle preparations (in vitro) and through i.m. injection in the gastrocnemius muscle (in vivo) by determination of creatine kinase (CK) activity and histopathological analysis. Incubation of soleus muscle for 1 h with BV or toxins (20 microg/ml) plus AE (400 microg/ml) added immediately after BV, BthTX-I or BthTX-II reduced CK levels by 53%, 37% and 56%, respectively. The myonecrotic effects of BV (20 microg/ml) upon soleus muscle was reduced 24%, 35% and 36% when AE (400 microg/ml) was added 1 h after BV and CK was evaluated 30 min, 1 and 2 h later, respectively. For BthTX-I these values were 46%, 48% and 47%, while for BthTX-II no inhibitory effect was detected. Histological analysis of soleus muscle after incubation with AE (400 microg/ml, 1 h) did not reveal any change in muscle fibers, but severe necrosis induced by BV or toxins (20 microg/ml) was clearly in evidence, and decreased significantly when soleus muscle was protected by AE. This protection was also observed when AE was administered 1 h after BV or BthTX-I, but not after BthTX-II. AE did not inhibit the catalytic PLA2 activity of BthTX-II or BV and did not change the PAGE pattern of BV, BthTX-I or BthTX-II. In vivo assays were performed in 100-g rats and maximal CK release was attained at a dose of 100 microg of BV, 3 h after injection. AE was not effective when injected 20 s after BV or toxins. However, injecting BV or toxins (100 microg), which were pre-incubated with AE (2 mg) caused an inhibition of 57%, 59% and 51%, respectively, with zero time pre-incubation, but was less effective with 1 h pre-incubation. This plant represents a potential source of promising myotoxin inhibitors.
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Affiliation(s)
- E L G Veronese
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Avenida do Café, s/n, Bairro Monte Alegre, 14040-903 Ribeirão Preto, SP, Brazil
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Affiliation(s)
- Simon R Platt
- Centre for Small Animal Studies, The Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU, United Kingdom.
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Franch HA, Raissi S, Wang X, Zheng B, Bailey JL, Price SR. Acidosis impairs insulin receptor substrate-1-associated phosphoinositide 3-kinase signaling in muscle cells: consequences on proteolysis. Am J Physiol Renal Physiol 2004; 287:F700-6. [PMID: 15161606 DOI: 10.1152/ajprenal.00440.2003] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic acidosis is a stimulus for proteolysis in muscle in vivo, but the mechanism of this response is unknown. We tested the hypothesis that acidosis or TNF-alpha, a cytokine whose production increases in acidosis, regulates proteolysis by inhibiting insulin signaling through phosphoinositide 3-kinase (PI3K). In cultured L6 myotubes, acidified (pH 7.1) media did not accelerate the basal protein degradation rate, but it inhibited insulin's ability to suppress proteolysis. Insulin receptor substrate-1 (IRS-1)-associated PI3K activity was not altered in cells acidified for 10 min but was strongly inhibited in cells incubated at pH 7.1 for 24 h. Phosphorylation of Akt was also suppressed by acidification for 24 h. Acidification did not induce changes in IRS-1 abundance, insulin-stimulated IRS-1 tyrosine phosphorylation, or the amount of PI3K p85 regulatory subunit. In contrast to acidification, TNF-alpha suppressed proteolysis in the presence or absence of insulin but had no effect on IRS-1-associated PI3K activity. To establish that the PI3K pathway can regulate protein degradation in muscle, we measured proteolysis in cells after inhibition of PI3K activity with LY-294002 or infection with an adenovirus encoding a dominant negative PI3K p85alpha-subunit. Both approaches inhibited insulin-induced suppression of proteolysis to a degree similar to that seen with acidification. We conclude that acidosis accelerates protein degradation by impairing insulin signaling through PI3K in muscle cells.
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Affiliation(s)
- Harold A Franch
- Renal Divisioin, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA.
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Gore DC, Wolf SE, Sanford AP, Herndon DN, Wolfe RR. Extremity hyperinsulinemia stimulates muscle protein synthesis in severely injured patients. Am J Physiol Endocrinol Metab 2004; 286:E529-34. [PMID: 14665444 DOI: 10.1152/ajpendo.00258.2003] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insulin has a well-recognized anabolic effect on muscle protein, yet critically ill, severely injured patients are often considered "resistant" to the action of insulin. The purpose of this study was to assess the in vivo effects of hyperinsulinemia on human skeletal muscle in severely injured patients. To accomplish this goal, 14 patients with burns encompassing >40% of their body surface area underwent metabolic evaluation utilizing isotopic dilution of phenylalanine, femoral artery and vein blood sampling, and sequential muscle biopsies of the leg. After baseline metabolic measurements were taken, insulin was infused into the femoral artery at 0.45 mIU.min(-1).100 ml leg volume(-1) to create a local hyperinsulinemia but with minimal systemic perturbations. Insulin administration increased femoral venous concentration of insulin (P < 0.01) but with only a 4% (insignificant) decrease in the arterial glucose concentration and a 7% (insignificant) decrease in the arterial concentration of phenylalanine. Extremity hyperinsulinemia significantly increased leg blood flow (P < 0.05) and the rate of muscle protein synthesis (P < 0.05). Neither the rate of muscle protein breakdown nor the rate of transmembrane transport of phenylalanine was significantly altered with extremity hyperinsulinemia. In conclusion, this study demonstrates that insulin directly stimulates muscle protein synthesis in severely injured patients.
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Affiliation(s)
- Dennis C Gore
- The University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1172, USA.
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Ketelhut DFJ, de Mello MH, Veronese ELG, Esmeraldino LE, Murakami MT, Arni RK, Giglio JR, Cintra ACO, Sampaio SV. Isolation, characterization and biological activity of acidic phospholipase A2 isoforms from Bothrops jararacussu snake venom. Biochimie 2003; 85:983-91. [PMID: 14644553 DOI: 10.1016/j.biochi.2003.09.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Acidic phospholipase A(2) (PLA(2)) isoforms in snake venoms, particularly those from Bothrops jararacussu, have not been characterized. This article reports the isolation and partial biochemical, functional and structural characterization of four acidic PLA(2)s (designated SIIISPIIA, SIIISPIIB, SIIISPIIIA and SIIISPIIIB) from this venom. The single chain purified proteins contained 122 amino acid residues and seven disulfide bonds with approximate molecular masses of 15 kDa and isoelectric points of 5.3. The respective N-terminal sequences were: SIIISPIIA-SLWQFGKMIDYVMGEEGAKS; SIIISPIIB-SLWQFGKMIFYTGKNEPVLS; SIIISPIIIA-SLWQFGKMILYVMGGEGVKQ and SIIISPIIIB-SLWQFGKMIFYEMTGEGVL. Crystals of the acidic protein SIIISPIIB diffracted beyond 1.8 A resolution. These crystals are monoclinic with unit cell dimensions of a = 40.1 A, b = 54.2 A and c = 90.7 A. The crystal structure has been refined to a crystallographic residual of 16.1% (R(free) = 22.9%). Specific catalytic activity (U/mg) of the isolated acidic PLA(2)s were SIIISPIIA = 290.3 U/mg; SIIISPIIB = 279.0 U/mg; SIIISPIIIA = 270.7 U/mg and SIIISPIIIB = 96.5 U/mg. Although their myotoxic activity was low, SIIISPIIA, SIIISPIIB and SIIISPIIIA showed significant anticoagulant activity. However, there was no indirect hemolytic activity. SIIISPIIIB revealed no anticoagulant, but presented indirect hemolytic activity. With the exception of SIIISPIIB, which inhibited platelet aggregation, all the others were capable of inducing time-independent edema. Chemical modification with 4-bromophenacyl bromide did not inhibit the induction of edema, but did suppress other activities.
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Affiliation(s)
- D F J Ketelhut
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Avenida do Café, s/n, Bairro Monte Alegre, 14040-903, SP Ribeirão Preto, Brazil
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Ma K, Mallidis C, Bhasin S, Mahabadi V, Artaza J, Gonzalez-Cadavid N, Arias J, Salehian B. Glucocorticoid-induced skeletal muscle atrophy is associated with upregulation of myostatin gene expression. Am J Physiol Endocrinol Metab 2003; 285:E363-71. [PMID: 12721153 DOI: 10.1152/ajpendo.00487.2002] [Citation(s) in RCA: 272] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mechanisms by which excessive glucocorticoids cause muscular atrophy remain unclear. We previously demonstrated that dexamethasone increases the expression of myostatin, a negative regulator of skeletal muscle mass, in vitro. In the present study, we tested the hypothesis that dexamethasone-induced muscle loss is associated with increased myostatin expression in vivo. Daily administration (60, 600, 1,200 micro g/kg body wt) of dexamethasone for 5 days resulted in rapid, dose-dependent loss of body weight (-4.0, -13.4, -17.2%, respectively, P < 0.05 for each comparison), and muscle atrophy (6.3, 15.0, 16.6% below controls, respectively). These changes were associated with dose-dependent, marked induction of intramuscular myostatin mRNA (66.3, 450, 527.6% increase above controls, P < 0.05 for each comparison) and protein expression (0.0, 260.5, 318.4% increase above controls, P < 0.05). We found that the effect of dexamethasone on body weight and muscle loss and upregulation of intramuscular myostatin expression was time dependent. When dexamethasone treatment (600 micro g. kg-1. day-1) was extended from 5 to 10 days, the rate of body weight loss was markedly reduced to approximately 2% within this extended period. The concentrations of intramuscular myosin heavy chain type II in dexamethasone-treated rats were significantly lower (-43% after 5-day treatment, -14% after 10-day treatment) than their respective corresponding controls. The intramuscular myostatin concentration in rats treated with dexamethasone for 10 days returned to basal level. Concurrent treatment with RU-486 blocked dexamethasone-induced myostatin expression and significantly attenuated body loss and muscle atrophy. We propose that dexamethasone-induced muscle loss is mediated, at least in part, by the upregulation of myostatin expression through a glucocorticoid receptor-mediated pathway.
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Affiliation(s)
- Kun Ma
- Division of Endocrinology, Metabolism, and Molecular Medicine, Charles R. Drew University of Medicine and Science, Los Angeles, CA 90059, USA.
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Madibally SV, Solomon V, Mitchell RN, Van De Water L, Yarmush ML, Toner M. Influence of insulin therapy on burn wound healing in rats. J Surg Res 2003; 109:92-100. [PMID: 12643849 DOI: 10.1016/s0022-4804(02)00036-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Insulin is proposed as a therapy for suppressing muscle wasting after burn trauma although the long-term effects of this therapy on wound healing are not yet known. The present study was designed to investigate the effect of systemically administered insulin therapy on burn wound healing. MATERIALS AND METHODS Young rats weighing 80-150 g were subjected to 15-20% total body surface area burn injury on their shaved dorsum. The insulin dosage was increased over the first 3 days in each rat from 0.25 U (Day 1), 0.5 U (Day 2), and 1.0 U (Day 3) per 100 g body wt. The rats were euthanized at the fourth or fifteenth day postinjury. Skin sections were analyzed by histochemistry and quantitative polarization microscopy. RESULTS Histology showed a decreased number of inflammatory cells and increased vasodilation in the insulin-treated animals at Day 4 relative to untreated rats; at Day 15 there was increased reepithelialization. Quantitative analysis using polarization microscopy and picrosirius red staining showed an increased collagen deposition in wounds by Day 4 in insulin-treated rats relative to untreated burn controls. CONCLUSION These results indicate that insulin induces accelerated wound healing associated with diminished inflammation and increased collagen deposition.
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Affiliation(s)
- Sundararajan V Madibally
- Shriners Burns Hospital, Surgical Services and the Center for Engineering in Medicine, Massachusetts General Hospital, and Harvard Medical School, Boston, Massachusetts 02114, USA
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