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Elefson SK, Stoll B, Davis TA, Fiorotto ML, El-Kadi SW, Genovese K, Thymann T, Sangild PT, Burrin DG. Adverse Metabolic Phenotypes in Parenterally Fed Neonatal Pigs Do Not Persist into Adolescence. J Nutr 2024; 154:638-647. [PMID: 38181968 PMCID: PMC10900187 DOI: 10.1016/j.tjnut.2023.12.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 12/18/2023] [Accepted: 12/28/2023] [Indexed: 01/07/2024] Open
Abstract
BACKGROUND Nutrition during fetal and neonatal life is an important determinant for the risk of adult-onset diseases, especially type 2 diabetes and obesity. OBJECTIVES We aimed to determine whether total parenteral nutrition (TPN) compared with enteral formula feeding [enteral nutrition (EN)] in term piglets during the first 2 wk after birth would increase the long-term (5-mo) development of metabolic syndrome phenotypes with adverse glucose homeostasis, fatty liver disease, and obesity. METHODS Neonatal female pigs were administered TPN (n = 12) or fed enterally with a liquid enteral milk-replacer formula (EN, n = 12) for 14 d. After transitioning TPN pigs to enteral feeding of liquid formula (days 15-26), both groups were adapted to a solid high-fat diet (30% of the total diet) and sucrose (20% of the total diet) diet (days 27-33), which was fed until the end of the study (140 d). Body composition was measured by dual-energy X-ray absorptiometry at 14, 45, and 140 d. Serum biochemistry and glucose-insulin values (after a fasting intravenous glucose tolerance test) were obtained at 140 d. Liver and muscle were analyzed for insulin receptor signaling and triglycerides. RESULTS Body weight was similar, but percent fat was higher, whereas percent lean and bone mineral density were lower in TPN than in EN pigs (P < 0.01) at 45 d of age but not at 140 d. At 140 d, there were no differences in serum markers of liver injury or lipidemia. Intravenous glucose tolerance test at 140 d showed a lower (P < 0.05) AUC for both glucose and insulin in TPN than in EN pigs, but the ratio of AUCs of insulin and glucose was not different between groups. CONCLUSIONS Administration of TPN during the neonatal period increased adipose deposition that transiently persisted in early adolescence when challenged with a high-fat diet but was not sustained or manifested as glucose intolerance.
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Affiliation(s)
- Sarah K Elefson
- USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States
| | - Barbara Stoll
- USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States
| | - Teresa A Davis
- USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States
| | - Marta L Fiorotto
- USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States
| | - Samer W El-Kadi
- School of Animal Sciences, Virginia Tech, Blacksburg, VA, United States
| | - Kenneth Genovese
- USDA Southern Plains Agricultural Research Center, College Station, TX, United States
| | - Thomas Thymann
- Department of Veterinary and Animal Science, University of Copenhagen, Copenhagen, Denmark
| | - Per T Sangild
- Department of Veterinary and Animal Science, University of Copenhagen, Copenhagen, Denmark
| | - Douglas G Burrin
- USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States.
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Zhou H, Shi X, Yu Y, Yang L, OuYang J, Bian Y, Liu Y, Li G. Puerarin Alleviates Oxidized Oil-Induced Oxidative Injury and Inflammation via Inhibition of the Nrf2/Keap1 and HMGB1/TLR4/MAPK Signaling Pathways: An Investigation in a Chicken Model. Mol Nutr Food Res 2023; 67:e2200663. [PMID: 37776050 DOI: 10.1002/mnfr.202200663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 05/29/2023] [Indexed: 10/01/2023]
Abstract
SCOPE Puerarin has possessed a wide range of pharmacological activities. However, little is known about the protective effects of puerarin on the oxidized oil-induced injury. Here, the antioxidant and anti-inflammatory effects of puerarin are described using a chicken model. METHODS AND RESULTS A total of 360 broilers are arranged in four treatments. Diets include two types of soybean oil (fresh or oxidized) and two levels of puerarin (0 or 750 mg kg-1 ). Results show that puerarin alleviates oxidized soybean oil-induced hepatic and thymic oxidative injury. This effect is observed by increasing the SOD activity and the expressions of Nrf2 signaling pathway-related genes and reducing the MDA content in the liver and thymus. Moreover, puerarin supplementation decreases the concentrations and mRNA levels of pro-inflammatory factors in the liver and thymus. The potential mechanism responsible for this is the decrease in the mRNA or protein levels of HMGB1, TLR4, MyD88, and p65 in the liver or thymus. Western blotting results indicate that puerarin also decreases the phosphorylation of JNK1/2, ERK1/2, and p38 in the liver and thymus. CONCLUSION This study demonstrates puerarin may be a potential nutrient supplement in the treatment of oxidized oil-induced damage, and the Nrf2/Keap1 and HMGB1/TLR4/MAPK signaling pathways might be its important target.
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Affiliation(s)
- Hua Zhou
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, P. R. China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, 330045, P. R. China
| | - Xuan Shi
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, P. R. China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, 330045, P. R. China
| | - Yingmei Yu
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, P. R. China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, 330045, P. R. China
| | - Lei Yang
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, P. R. China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, 330045, P. R. China
| | - Jingxin OuYang
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, P. R. China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, 330045, P. R. China
| | - Yinhao Bian
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, P. R. China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, 330045, P. R. China
| | - Yichun Liu
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, P. R. China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, 330045, P. R. China
| | - Guanhong Li
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, P. R. China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, 330045, P. R. China
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Zhou H, Yu Y, Shi X, Zou T, Yang L, OuYang J, Bian Y, Liu Y, Li G. Dietary puerarin supplementation improves immune function in the small intestines of oxidized oil-challenged broilers. Anim Sci J 2023; 94:e13895. [PMID: 38031207 DOI: 10.1111/asj.13895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 09/09/2023] [Accepted: 10/24/2023] [Indexed: 12/01/2023]
Abstract
Puerarin has possessed a wide range of pharmacological activities. However, little is known about the protective effects of puerarin on the oxidized oil-induced injury. Here, we describe the anti-inflammatory effects of puerarin in chickens. A total of 360 broilers were arranged in four treatments. Diets included two types of soybean oil (fresh or oxidized) and two levels of puerarin (0 or 750 mg/kg). Results showed that puerarin alleviated oxidized soybean oil-induced intestinal immune injury by decreasing the expressions of HSP and pro-inflammatory factor (P < 0.05) and enhancing the mRNA levels of anti-inflammatory factor and CATH-1 (P < 0.05) in broilers. Moreover, puerarin supplementation decreased the mRNA abundances of TLR4 and MyD88 (P < 0.05) and upregulated the expressions of A20 and SOCS-1 (P < 0.05) in the small intestine of oxidized soybean oil-challenged broilers. Collectively, this study demonstrates puerarin may be a potential nutrient supplement in the treatment of oxidized oil-induced damage in poultry.
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Affiliation(s)
- Hua Zhou
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, China
| | - Yingmei Yu
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, China
| | - Xuan Shi
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, China
| | - Tiande Zou
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, China
| | - Lei Yang
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, China
| | - Jingxin OuYang
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, China
| | - Yinhao Bian
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, China
| | - Yichun Liu
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, China
| | - Guanhong Li
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
- Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Nanchang, China
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Ong C, Lee JH, Leow MKS, Puthucheary ZA. A narrative review of skeletal muscle atrophy in critically ill children: pathogenesis and chronic sequelae. Transl Pediatr 2021; 10:2763-2777. [PMID: 34765499 PMCID: PMC8578782 DOI: 10.21037/tp-20-298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/18/2020] [Indexed: 11/10/2022] Open
Abstract
Muscle wasting is now recognized as a growing, debilitating problem in critically ill adults, resulting in long-term deficits in function and an impaired quality of life. Ultrasonography has demonstrated decreases in skeletal muscle size during pediatric critical illness, although variations exist. However, muscle protein turnover patterns during pediatric critical illness are unclear. Understanding muscle protein turnover during critical illness is important in guiding interventions to reduce muscle wasting. The aim of this review was to explore the possible protein synthesis and breakdown patterns in pediatric critical illness. Muscle protein turnover studies in critically ill children are lacking, with the exception of those with burn injuries. Children with burn injuries demonstrate an elevation in both muscle protein breakdown (MPB) and synthesis during critical illness. Extrapolations from animal models and whole-body protein turnover studies in children suggest that children may be more dependent on anabolic factors (e.g., nutrition and growth factors), and may experience greater muscle degradation in response to insults than adults. Yet, children, particularly the younger ones, are more responsive to anabolic agents, suggesting modifiable muscle wasting during critical illness. There is a lack of evidence for muscle wasting in critically ill children and its correlation with outcomes, possibly due to current available methods to study muscle protein turnover in children-most of which are invasive or tedious. In summary, children may experience muscle wasting during critical illness, which may be more reversible by the appropriate anabolic agents than adults. Age appears an important determinant of skeletal muscle turnover. Less invasive methods to study muscle protein turnover and associations with long-term outcome would strengthen the evidence for muscle wasting in critically ill children.
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Affiliation(s)
- Chengsi Ong
- Nutrition and Dietetics, KK Women's and Children's Hospital, Singapore, Singapore
| | - Jan Hau Lee
- Children's Intensive Care Unit, KK Women's Children's Hospital, Singapore, Singapore.,Duke-NUS Medical School, Singapore, Singapore
| | - Melvin K S Leow
- Duke-NUS Medical School, Singapore, Singapore.,Clinical Nutrition Research Center, Agency for Science, Technology and Research, Singapore, Singapore.,Department of Endocrinology, Tan Tock Seng Hospital, Singapore, Singapore.,Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Zudin A Puthucheary
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.,Adult Critical Care Unit, Royal London Hospital, London, UK
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Zhou H, Yu B, Sun J, Liu Z, Chen H, Ge L, Chen D. Short-chain fatty acids can improve lipid and glucose metabolism independently of the pig gut microbiota. J Anim Sci Biotechnol 2021; 12:61. [PMID: 33952344 PMCID: PMC8101156 DOI: 10.1186/s40104-021-00581-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 03/08/2021] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Previous studies have shown that exogenous short-chain fatty acids (SCFAs) introduction attenuated the body fat deposition in conventional mice and pigs. However, limited studies have evaluated the effects of exogenously introduced SCFAs on the lipid and glucose metabolism independently of the gut microbiota. This study was to investigate the effects of exogenous introduction of SCFAs on the lipid and glucose metabolism in a germ-free (GF) pig model. METHODS Twelve hysterectomy-derived newborn pigs were reared in six sterile isolators. All pigs were hand-fed with sterile milk powder for 21 d, then the sterile feed was introduced to pigs for another 21 d. In the second 21-d period, six pigs were orally administrated with 25 mL/kg sterile saline per day and considered as the GF group, while the other six pigs were orally administrated with 25 mL/kg SCFAs mixture (acetic, propionic, and butyric acids, 45, 15, and 11 mmol/L, respectively) per day and regarded as FA group. RESULTS Orally administrated with SCFAs tended to increase the adiponectin concentration in serum, enhance the CPT-1 activity in longissimus dorsi, and upregulate the ANGPTL4 mRNA expression level in colon (P < 0.10). Meanwhile, the mRNA abundances of ACC, FAS, and SREBP-1C in liver and CD36 in longissimus dorsi of the FA group were decreased (P < 0.05) compared with those in the GF group. Besides, the mRNA expression of PGC-1α in liver and LPL in longissimus dorsi tended to (P < 0.10) upregulate and downregulate respectively in the FA group. Moreover, oral administration of SCFAs tended to increase the protein level of GPR43 (P < 0.10) and decrease the protein level of ACC (P < 0.10) in liver. Also, oral administration of SCFAs upregulated the p-AMPK/AMPK ratio and the mRNA expressions of GLUT-2 and GYS2 in liver (P < 0.05). In addition, the metabolic pathway associated with the biosynthesis of unsaturated fatty acids was most significantly promoted (P < 0.05) by oral administration of SCFAs. CONCLUSIONS Exogenous introduction of SCFAs might attenuate the fat deposition and to some extent improve the glucose control in the pig model, which occurred independently of the gut microbiota.
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Affiliation(s)
- Hua Zhou
- Key Laboratory of Animal Disease-Resistance Nutrition, Chengdu, 611130 Sichuan China
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu, 611130 Sichuan China
| | - Bing Yu
- Key Laboratory of Animal Disease-Resistance Nutrition, Chengdu, 611130 Sichuan China
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu, 611130 Sichuan China
| | - Jing Sun
- Key Laboratory of Pig Industry Sciences, Rongchang, 402460 Chongqing China
- Chongqing Academy of Animal Sciences, Rongchang, 402460 Chongqing China
| | - Zuohua Liu
- Key Laboratory of Pig Industry Sciences, Rongchang, 402460 Chongqing China
- Chongqing Academy of Animal Sciences, Rongchang, 402460 Chongqing China
| | - Hong Chen
- College of Food Science, Sichuan Agricultural University, Ya’an, 625014 Sichuan China
| | - Liangpeng Ge
- Key Laboratory of Pig Industry Sciences, Rongchang, 402460 Chongqing China
- Chongqing Academy of Animal Sciences, Rongchang, 402460 Chongqing China
| | - Daiwen Chen
- Key Laboratory of Animal Disease-Resistance Nutrition, Chengdu, 611130 Sichuan China
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu, 611130 Sichuan China
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Skeletal Muscle Changes, Function, and Health-Related Quality of Life in Survivors of Pediatric Critical Illness. Crit Care Med 2021; 49:1547-1557. [PMID: 33861558 DOI: 10.1097/ccm.0000000000004970] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To describe functional and skeletal muscle changes observed during pediatric critical illness and recovery and their association with health-related quality of life. DESIGN Prospective cohort study. SETTING Single multidisciplinary PICU. PATIENTS Children with greater than or equal to 1 organ dysfunction, expected PICU stay greater than or equal to 48 hours, expected survival to discharge, and without progressive neuromuscular disease or malignancies were followed from admission to approximately 6.7 months postdischarge. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Functional status was measured using the Functional Status Scale score and Pediatric Evaluation of Disability Inventory-Computer Adaptive Test. Patient and parental health-related quality of life were measured using the Pediatric Quality of Life Inventory and Short Form-36 questionnaires, respectively. Quadriceps muscle size, echogenicity, and fat thickness were measured using ultrasonography during PICU stay, at hospital discharge, and follow-up. Factors affecting change in muscle were explored. Associations between functional, muscle, and health-related quality of life changes were compared using regression analysis. Seventy-three survivors were recruited, of which 44 completed follow-ups. Functional impairment persisted in four of 44 (9.1%) at 6.7 months (interquartile range, 6-7.7 mo) after discharge. Muscle size decreased during PICU stay and was associated with inadequate energy intake (adjusted β, 0.15; 95% CI, 0.02-0.28; p = 0.030). No change in echogenicity or fat thickness was observed. Muscle growth postdischarge correlated with mobility function scores (adjusted β, 0.05; 95% CI, 0.01-0.09; p = 0.046). Improvements in mobility scores were associated with improved physical health-related quality of life at follow-up (adjusted β, 1.02; 95% CI, 0.23-1.81; p = 0.013). Child physical health-related quality of life at hospital discharge was associated with parental physical health-related quality of life (adjusted β, 0.09; 95% CI, 0.01-0.17; p = 0.027). CONCLUSIONS Muscle decreased in critically ill children, which was associated with energy inadequacy and impaired muscle growth postdischarge. Muscle changes correlated with change in mobility, which was associated with child health-related quality of life. Mobility, child health-related quality of life, and parental health-related quality of life appeared to be interlinked.
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Rudar M, Naberhuis JK, Suryawan A, Nguyen HV, Stoll B, Style CC, Verla MA, Olutoye OO, Burrin DG, Fiorotto ML, Davis TA. Prematurity blunts the insulin- and amino acid-induced stimulation of translation initiation and protein synthesis in skeletal muscle of neonatal pigs. Am J Physiol Endocrinol Metab 2021; 320:E551-E565. [PMID: 33427053 PMCID: PMC7988778 DOI: 10.1152/ajpendo.00203.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Extrauterine growth restriction in premature infants is largely attributed to reduced lean mass accretion and is associated with long-term morbidities. Previously, we demonstrated that prematurity blunts the feeding-induced stimulation of translation initiation signaling and protein synthesis in skeletal muscle of neonatal pigs. The objective of the current study was to determine whether the blunted feeding response is mediated by reduced responsiveness to insulin, amino acids, or both. Pigs delivered by cesarean section preterm (PT; 103 days, n = 25) or at term (T; 112 days, n = 26) were subject to euinsulinemic-euaminoacidemic-euglycemic (FAST), hyperinsulinemic-euaminoacidemic-euglycemic (INS), or euinsulinemic-hyperaminoacidemic-euglycemic (AA) clamps four days after delivery. Indices of mechanistic target of rapamycin complex 1 (mTORC1) signaling and fractional protein synthesis rates were measured after 2 h. Although longissimus dorsi (LD) muscle protein synthesis increased in response to both INS and AA, the increase was 28% lower in PT than in T. Upstream of mTORC1, Akt phosphorylation, an index of insulin signaling, was increased with INS but was 40% less in PT than in T. The abundances of mTOR·RagA and mTOR·RagC, indices of amino acid signaling, increased with AA but were 25% less in PT than in T. Downstream of mTORC1, eIF4E·eIF4G abundance was increased by both INS and AA but attenuated by prematurity. These results suggest that preterm birth blunts both insulin- and amino acid-induced activation of mTORC1 and protein synthesis in skeletal muscle, thereby limiting the anabolic response to feeding. This anabolic resistance likely contributes to the high prevalence of extrauterine growth restriction in prematurity.NEW & NOTEWORTHY Extrauterine growth faltering is a major complication of premature birth, but the underlying cause is poorly understood. Our results demonstrate that preterm birth blunts both the insulin-and amino acid-induced activation of mTORC1-dependent translation initiation and protein synthesis in skeletal muscle, thereby limiting the anabolic response to feeding. This anabolic resistance likely contributes to the reduced accretion of lean mass and extrauterine growth restriction of premature infants.
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Affiliation(s)
- Marko Rudar
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
- Department of Animal Sciences, Auburn University, Auburn, Alabama
| | - Jane K Naberhuis
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Agus Suryawan
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Hanh V Nguyen
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Barbara Stoll
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Candace C Style
- Division of Pediatric Surgery, Michael E. DeBakey Department of Surgery, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas
| | - Mariatu A Verla
- Division of Pediatric Surgery, Michael E. DeBakey Department of Surgery, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas
| | - Oluyinka O Olutoye
- Division of Pediatric Surgery, Michael E. DeBakey Department of Surgery, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas
| | - Douglas G Burrin
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Marta L Fiorotto
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Teresa A Davis
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
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Naberhuis JK, Suryawan A, Nguyen HV, Hernandez-Garcia A, Cruz SM, Lau PE, Olutoye OO, Stoll B, Burrin DG, Fiorotto ML, Davis TA. Prematurity blunts the feeding-induced stimulation of translation initiation signaling and protein synthesis in muscle of neonatal piglets. Am J Physiol Endocrinol Metab 2019; 317:E839-E851. [PMID: 31503514 PMCID: PMC6879862 DOI: 10.1152/ajpendo.00151.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [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
Postnatal growth of lean mass is commonly blunted in preterm infants and may contribute to short- and long-term morbidities. To determine whether preterm birth alters the protein anabolic response to feeding, piglets were delivered at term or preterm, and fractional protein synthesis rates (Ks) were measured at 3 days of age while fasted or after an enteral meal. Activation of signaling pathways that regulate protein synthesis and degradation were determined. Relative body weight gain was lower in preterm than in term. Gestational age at birth (GAB) did not alter fasting plasma glucose or insulin, but when fed, plasma insulin and glucose rose more slowly, and reached peak value later, in preterm than in term. Feeding increased Ks in longissimus dorsi (LD) and gastrocnemius muscles, heart, pancreas, and kidney in both GAB groups, but the response was blunted in preterm. In diaphragm, lung, jejunum, and brain, feeding increased Ks regardless of GAB. Liver Ks was greater in preterm than term and increased with feeding regardless of GAB. In all tissues, changes in 4EBP1, S6K1, and PKB phosphorylation paralleled changes in Ks. In LD, eIF4E·eIF4G complex formation, phosphorylation of TSC2, mTOR, and rpS6, and association of mammalian target of rapamycin (mTOR1) complex with RagA, RagC, and Rheb were increased by feeding and blunted by prematurity. There were no differences among groups in LD protein degradation markers. Our results demonstrate that preterm birth reduces weight gain and the protein synthetic response to feeding in muscle, pancreas, and kidney, and this is associated with blunted insulin- and/or amino acid-induced translation initiation signaling.
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Affiliation(s)
- Jane K Naberhuis
- United States Department of Agriculture, Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Agus Suryawan
- United States Department of Agriculture, Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Hanh V Nguyen
- United States Department of Agriculture, Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Adriana Hernandez-Garcia
- United States Department of Agriculture, Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Stephanie M Cruz
- Division of Pediatric Surgery, Michael E. DeBakey Department of Surgery, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas
| | - Patricio E Lau
- Division of Pediatric Surgery, Michael E. DeBakey Department of Surgery, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas
| | - Oluyinka O Olutoye
- Division of Pediatric Surgery, Michael E. DeBakey Department of Surgery, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas
| | - Barbara Stoll
- United States Department of Agriculture, Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Douglas G Burrin
- United States Department of Agriculture, Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Marta L Fiorotto
- United States Department of Agriculture, Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Teresa A Davis
- United States Department of Agriculture, Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
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Diao H, Jiao AR, Yu B, Mao XB, Chen DW. Gastric infusion of short-chain fatty acids can improve intestinal barrier function in weaned piglets. GENES AND NUTRITION 2019; 14:4. [PMID: 30761185 PMCID: PMC6359775 DOI: 10.1186/s12263-019-0626-x] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 01/08/2019] [Indexed: 12/21/2022]
Abstract
Background The present study was conducted to investigate the effects of gastric infusion of short-chain fatty acids (SCFA) on gut barrier function in a pig model. In this study, 21 DLY barrows with an average initial body weight of (8.31 ± 0.72) kg were randomly allotted into three treatments: (1) control, (2) infusing low SCFA, S1, (3) infusing high SCFA, S2. The experimental period lasted for 7 days. Results Gastric infusion of SCFA increased the concentrations of SCFA in serum and digesta, and enhanced the mRNA and protein abundances of SCFA receptors in pig intestine (P < 0.05). Moreover, gastric infusion of SCFA led to alteration of intestinal morphology, elevation of intestinal development-related gene abundances, and decrease of apoptotic cell percentage, as well as reduction of pro-apoptosis gene and protein abundances (P < 0.05). Besides, the jejunal SLC7A1 and ileal DMT1 mRNA abundances in the SCFA infusion groups were higher than those in the control group (P < 0.05). Additionally, gastric infusion of SCFA increased the mRNA abundances of Occludin and Claudin-1 in the duodenum and ileum, enhanced Lactobacillus spp counts in the ileal digesta, decreased the mRNA and protein abundances of IL-1β in the colon, and reduced Escherichia coli count in the ileal digesta (P < 0.05). Conclusions These data indicated that gastric infusion of SCFA, especially high SCFA concentration, may be beneficial to gut development of piglets via improving gut morphology, decreasing apoptotic cell percentage, and maintaining intestinal barrier function. Electronic supplementary material The online version of this article (10.1186/s12263-019-0626-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- H Diao
- 1Institute of Animal Nutrition, Sichuan Agricultural University, Xinkang Road 46#, Ya'an, 625014 Sichuan Province People's Republic of China.,Animal Breeding and Genetics key Laboratory of Sichuan Province, Sichuan Academy of Animal Science, Chengdu, Sichuan Province People's Republic of China
| | - A R Jiao
- 1Institute of Animal Nutrition, Sichuan Agricultural University, Xinkang Road 46#, Ya'an, 625014 Sichuan Province People's Republic of China
| | - B Yu
- 1Institute of Animal Nutrition, Sichuan Agricultural University, Xinkang Road 46#, Ya'an, 625014 Sichuan Province People's Republic of China
| | - X B Mao
- 1Institute of Animal Nutrition, Sichuan Agricultural University, Xinkang Road 46#, Ya'an, 625014 Sichuan Province People's Republic of China
| | - D W Chen
- 1Institute of Animal Nutrition, Sichuan Agricultural University, Xinkang Road 46#, Ya'an, 625014 Sichuan Province People's Republic of China
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10
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Rudar M, Fiorotto ML, Davis TA. Regulation of Muscle Growth in Early Postnatal Life in a Swine Model. Annu Rev Anim Biosci 2018; 7:309-335. [PMID: 30388025 DOI: 10.1146/annurev-animal-020518-115130] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Skeletal muscle growth during the early postnatal period is rapid in the pig and dependent on the capacity of muscle to respond to anabolic and catabolic stimuli. Muscle mass is driven by the balance between protein synthesis and degradation. Among these processes, muscle protein synthesis in the piglet is exceptionally sensitive to the feeding-induced postprandial changes in insulin and amino acids, whereas muscle protein degradation is affected only during specific catabolic states. The developmental decline in the response of muscle to feeding is associated with changes in the signaling pathways located upstream and downstream of the mechanistic target of rapamycin protein complex. Additionally, muscle growth is supported by an accretion of nuclei derived from satellite cells. Activated satellite cells undergo proliferation, differentiation, and fusion with adjacent growing muscle fibers. Enhancing early muscle growth through modifying protein synthesis, degradation, and satellite cell activity is key to maximizing performance, productivity, and lifelong pig health.
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Affiliation(s)
- Marko Rudar
- USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030, USA; , ,
| | - Marta L Fiorotto
- USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030, USA; , ,
| | - Teresa A Davis
- USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030, USA; , ,
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11
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El-Kadi SW, Boutry C, Suryawan A, Gazzaneo MC, Orellana RA, Srivastava N, Nguyen HV, Kimball SR, Fiorotto ML, Davis TA. Intermittent bolus feeding promotes greater lean growth than continuous feeding in a neonatal piglet model. Am J Clin Nutr 2018; 108:830-841. [PMID: 30239549 PMCID: PMC6186212 DOI: 10.1093/ajcn/nqy133] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 05/18/2018] [Indexed: 12/21/2022] Open
Abstract
Background Orogastric tube feeding is indicated in neonates with an impaired ability to ingest food normally and can be administered with an intermittent bolus or continuous feeding schedule. Objectives The objectives were to 1) compare the long-term effect of continuous with intermittent feeding on growth using the newborn pig as a model, 2) determine whether feeding frequency alters lean tissue and fat mass gain, and 3) identify the signaling mechanisms by which protein deposition is controlled in skeletal muscle in response to feeding frequency. Design Neonatal pigs were fed the same amount of a balanced formula by orogastric tube either as an intermittent bolus meal every 4 h (INT) or as a continuous infusion (CON). Body composition was assessed at the start and end of the study by dual-energy X-ray absorptiometry, and hormone and substrate profiles, muscle mass, protein synthesis, and indexes of nutrient and insulin signaling were measured after 21 d. Results Body weight, lean mass, spine length, and skeletal muscle mass were greater in the INT group than in the CON group. Skeletal muscle fractional protein synthesis rates were greater in the INT group after a meal than in the CON group and were associated with higher circulating branched-chain amino acid and insulin concentrations. Skeletal muscle protein kinase B (PKB) and ribosomal protein S6 kinase phosphorylation and eukaryotic initiation factor (eIF) 4E-eIF4G complex formation were higher, whereas eIF2α phosphorylation was lower in the INT group than in the CON group, indicating enhanced activation of insulin and amino acid signaling to translation initiation. Conclusions These results suggest that when neonates are fed the same amounts of nutrients as intermittent meals rather than continuously there is greater lean growth. This response can be ascribed, in part, to the pulsatile pattern of amino acids, insulin, or both induced by INT, which enables the responsiveness of anabolic pathways to feeding to be sustained chronically in skeletal muscle.
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Affiliation(s)
- Samer W El-Kadi
- USDA–Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX,Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA
| | - Claire Boutry
- USDA–Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Agus Suryawan
- USDA–Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Maria C Gazzaneo
- USDA–Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Renán A Orellana
- USDA–Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Neeraj Srivastava
- USDA–Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Hanh V Nguyen
- USDA–Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Scot R Kimball
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA
| | - Marta L Fiorotto
- USDA–Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Teresa A Davis
- USDA–Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX,Address correspondence to TAD (e-mail: )
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12
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Winkel SM, Trenhaile-Grannemann MD, Van Sambeek DM, Miller PS, Salcedo J, Barile D, Burkey TE. Effects of energy restriction during gilt development on milk nutrient profile, milk oligosaccharides, and progeny biomarkers. J Anim Sci 2018; 96:3077-3088. [PMID: 29860339 DOI: 10.1093/jas/sky212] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 05/29/2018] [Indexed: 11/12/2022] Open
Abstract
An ongoing study at the University of Nebraska-Lincoln (which included 14 batches of gilts; n = 90 gilts/batch) demonstrated that energy restriction during the developmental period of a gilt increases longevity and may also have beneficial effects on progeny health and growth, particularly, parity 1 progeny. Therefore, we hypothesized that energy restriction during gilt development may affect milk nutrient profile, milk oligosaccharides (OS), and postnatal progeny biomarkers. During the development period, batch 14 gilts (n = 128, 8 gilts/pen) were fed 3 dietary treatments including the following: 1) Control diet formulated to NRC (2012) specifications (CTL); 2) Restricted (20% energy restriction via addition of 40% soy hulls; RESTR); and 3) CTL diet plus addition of crystalline amino acids equivalent to the SID Lys:ME of the RESTR diet (CTL+). All diets were fed ad libitum and applied in a 3-phase feeding regimen during gilt development (days 123 to 230 of age). Average daily feed intake was used to estimate daily metabolizable energy intake (Mcal/d) during each phase (Phase 1: 10.13, 6.97, 9.95; Phase 2: 11.25, 8.05, 10.94; and Phase 3: 9.47, 7.95,11.07) for CTL, RESTR, and CTL+, respectively. After 230 d of age, gilts were bred and fed a common diet. Milk samples were collected from batch 14 gilts (n = 7 per treatment) on days 0 and 14 postfarrowing for compositional analysis of N, CP, dry matter (DM), GE, insulin, and OS. Piglet blood samples (n = 6 piglets/gilt) were obtained on days 1 and 15 postfarrowing for quantification of glucagon-like peptide-2 (GLP-2) and insulin. No effects of developmental diet were observed for milk N, CP, DM, or GE; however, N, CP, DM, and insulin were increased (P < 0.05) on day 1 compared with day 14. A total of 61 different milk OS were identified. Milk OS profile was significantly different for neutral and acidic OS (P < 0.05) on day 0, but there were no significant differences on day 14. For piglet GLP-2, a treatment by day interaction was observed (P < 0.009); specifically, on day 1 GLP concentrations were greater (P < 0.001) in CTL+ compared with RESTR (6.73 vs. 1.21 ng/mL). For serum insulin, a treatment by day interaction was observed (P < 0.01); specifically, insulin in RESTR progeny was greater (P < 0.03) than CTL on day 1. In conclusion, nutritional management of the developing gilt may affect milk nutrient composition, milk OS profile, and piglet serum biomarkers.
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Affiliation(s)
- Shana M Winkel
- Department of Animal Science, University of Nebraska, Lincoln, NE
| | | | | | - Phillip S Miller
- Department of Animal Science, University of Nebraska, Lincoln, NE
| | - Jaime Salcedo
- Department of Food Science and Technology, University of California, Davis, CA
| | - Daniela Barile
- Department of Food Science and Technology, University of California, Davis, CA
| | - Thomas E Burkey
- Department of Animal Science, University of Nebraska, Lincoln, NE
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13
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Suryawan A, Davis TA. Amino Acid- and Insulin-Induced Activation of mTORC1 in Neonatal Piglet Skeletal Muscle Involves Sestin2-GATOR2, Rag A/C-mTOR, and RHEB-mTOR Complex Formation. J Nutr 2018; 148:825-833. [PMID: 29796625 PMCID: PMC6669959 DOI: 10.1093/jn/nxy044] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 02/14/2018] [Indexed: 12/18/2022] Open
Abstract
Background Feeding stimulates protein synthesis in skeletal muscle of neonates and this response is regulated through activation of mechanistic target of rapamycin complex 1 (mTORC1). The identity of signaling components that regulate mTORC1 activation in neonatal muscle has not been fully elucidated. Objective We investigated the independent effects of the rise in amino acids (AAs) and insulin after a meal on the abundance and activation of potential regulators of mTORC1 in muscle and whether the responses are modified by development. Methods Overnight-fasted 6- and 26-d-old pigs were infused for 2 h with saline (control group) or with a balanced AA mixture (AA group) or insulin (INS group) to achieve fed levels while insulin or AAs, respectively, and glucose were maintained at fasting levels. Muscles were analyzed for potential mTORC1 regulatory mechanisms and results were analyzed by 2-factor ANOVA followed by Tukey's post hoc test. Results The abundances of DEP domain-containing mTOR-interacting protein (DEPTOR), growth factor receptor bound protein 10 (GRB10), and regulated in development and DNA damage response 2 (REDD2) were lower (65%, 73%, and 53%, respectively; P < 0.05) and late endosomal/lysosomal adaptor, MAPK and mTOR activator 1/2 (LAMTOR1/2), vacuolar H+-ATPase (V-ATPase), and Sestrin2 were higher (94%, 141%, 145%, and 127%, respectively; P < 0.05) in 6- than in 26-d-old pigs. Both AA and INS groups increased phosphorylation of GRB10 (P < 0.05) compared with control in 26- but not in 6-d-old pigs. Formation of Ras-related GTP-binding protein A (RagA)-mTOR, RagC-mTOR, and Ras homolog enriched in brain (RHEB)-mTOR complexes was increased (P < 0.05) and Sestrin2-GTPase activating protein activity towards Rags 2 (GATOR2) complex was decreased (P < 0.05) by both AA and INS groups and these responses were greater (P < 0.05) in 6- than in 26-d-old pigs. Conclusion The results suggest that formation of RagA-mTOR, RagC-mTOR, RHEB-mTOR, and Sestrin2-GATOR2 complexes may be involved in the AA- and INS-induced activation of mTORC1 in skeletal muscle of neonates after a meal and that enhanced activation of the mTORC1 signaling pathway in neonatal muscle is in part due to regulation by DEPTOR, GRB10, REDD2, LAMTOR1/2, V-ATPase, and Sestrin2.
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Affiliation(s)
- Agus Suryawan
- US Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Teresa A Davis
- US Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX,Address correspondence to TAD (e-mail: )
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14
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Manjarín R, Columbus DA, Solis J, Hernandez-García AD, Suryawan A, Nguyen HV, McGuckin MM, Jimenez RT, Fiorotto ML, Davis TA. Short- and long-term effects of leucine and branched-chain amino acid supplementation of a protein- and energy-reduced diet on muscle protein metabolism in neonatal pigs. Amino Acids 2018; 50:943-959. [PMID: 29728917 DOI: 10.1007/s00726-018-2572-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 04/19/2018] [Indexed: 12/15/2022]
Abstract
The objective of this study was to determine if enteral leucine or branched-chain amino acid (BCAA) supplementation increases muscle protein synthesis in neonates who consume less than their protein and energy requirements, and whether this increase is mediated via the upregulation of the mechanistic target of rapamycin complex 1 (mTORC1) pathway or the decrease in muscle protein degradation signaling. Neonatal pigs were fed milk replacement diets containing reduced energy and protein (R), R supplemented with BCAA (RBCAA), R supplemented with leucine (RL), or complete protein and energy (CON) at 4-h intervals for 9 (n = 24) or 21 days (n = 22). On days 9 and 21, post-prandial plasma amino acids and insulin were measured at intervals for 4 h; muscle protein synthesis rate and activation of mTOR-related proteins were determined at 120 min post-feeding in muscle. For all parameters measured, the effects of diet were not different between day 9 or day 21. Compared to CON and R, plasma leucine and BCAA were higher (P ≤ 0.01) in RL- and RBCAA-fed pigs, respectively. Body weight gain, protein synthesis, and activation of S6 kinase (S6K1), 4E-binding protein (4EBP1), and eukaryotic initiation factor 4 complex (eIF4E·eIF4G) were decreased in RBCAA, RL, and R relative to CON (P < 0.01). RBCAA and RL upregulated (P ≤ 0.01) S6K1, 4EBP1, and eIF4E·eIF4G compared to R. In conclusion, when protein and energy are restricted, both leucine and BCAA supplementation increase mTOR activation, but do not enhance skeletal muscle protein synthesis and muscle growth in neonatal pigs.
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Affiliation(s)
- Rodrigo Manjarín
- Department of Pediatrics, U.S. Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, 1100 Bates Street, Suite 9070, Houston, TX, 77030, USA.,Animal Science Department, California Polytechnic State University, San Luis Obispo, CA, 93407, USA
| | - Daniel A Columbus
- Department of Pediatrics, U.S. Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, 1100 Bates Street, Suite 9070, Houston, TX, 77030, USA.,Prairie Swine Centre, Inc., Saskatoon, SK, S7H 5N9, Canada
| | - Jessica Solis
- Department of Pediatrics, U.S. Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, 1100 Bates Street, Suite 9070, Houston, TX, 77030, USA
| | - Adriana D Hernandez-García
- Department of Pediatrics, U.S. Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, 1100 Bates Street, Suite 9070, Houston, TX, 77030, USA
| | - Agus Suryawan
- Department of Pediatrics, U.S. Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, 1100 Bates Street, Suite 9070, Houston, TX, 77030, USA
| | - Hanh V Nguyen
- Department of Pediatrics, U.S. Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, 1100 Bates Street, Suite 9070, Houston, TX, 77030, USA
| | - Molly M McGuckin
- Animal Science Department, California Polytechnic State University, San Luis Obispo, CA, 93407, USA
| | - Rafael T Jimenez
- Animal Science Department, California Polytechnic State University, San Luis Obispo, CA, 93407, USA
| | - Marta L Fiorotto
- Department of Pediatrics, U.S. Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, 1100 Bates Street, Suite 9070, Houston, TX, 77030, USA
| | - Teresa A Davis
- Department of Pediatrics, U.S. Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, 1100 Bates Street, Suite 9070, Houston, TX, 77030, USA.
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15
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Paddon-Jones D, Coss-Bu JA, Morris CR, Phillips SM, Wernerman J. Variation in Protein Origin and Utilization: Research and Clinical Application. Nutr Clin Pract 2017; 32:48S-57S. [PMID: 28388379 DOI: 10.1177/0884533617691244] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Muscle health can be rapidly compromised in clinical environments. Modifiable strategies to preserve metabolic homeostasis in adult patient populations include physical activity and pharmacologic support; however, optimizing dietary practices, or more specifically protein intake, is a necessary prerequisite for any other treatment strategy to be fully effective. Simply increasing protein intake is a well-intentioned but often unfocused strategy to protect muscle health in an intensive care setting. Protein quality is a frequently overlooked factor with the potential to differentially influence health outcomes. Quality can be assessed by a variety of techniques, with digestible indispensable amino acid score being the current and most comprehensive technique endorsed by the Food and Agriculture Organization. In practical terms, animal-based proteins are consistently scored higher in quality compared with incomplete proteins, regardless of the assessment method. Consequently, choosing parenteral and/or enteral feeding options that contain high-quality proteins, rich in the branched-chain amino acid leucine, may help establish a dietary framework with the potential to support clinical practice and improve health outcomes in critically ill patients.
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Affiliation(s)
- Douglas Paddon-Jones
- 1 Department of Nutrition and Metabolism, The University of Texas Medical Branch, Galveston, Texas, USA
| | - Jorge A Coss-Bu
- 2 Pediatrics Critical Care, Baylor College of Medicine, Houston, Texas, USA
| | - Claudia R Morris
- 3 Division of Pediatric Emergency Medicine, Emory School of Medicine, Atlanta, Georgia, USA
| | - Stuart M Phillips
- 4 Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Jan Wernerman
- 5 Department of Clinical Science, Karolinska University, Solna, Sweden
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16
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Insulin modulates energy and substrate sensing and protein catabolism induced by chronic peritonitis in skeletal muscle of neonatal pigs. Pediatr Res 2016; 80:744-752. [PMID: 27508897 PMCID: PMC5746053 DOI: 10.1038/pr.2016.129] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 04/26/2016] [Indexed: 11/08/2022]
Abstract
BACKGROUND Acute infection promotes skeletal muscle wasting and insulin resistance, but the effect of insulin on energy and substrate sensing in skeletal muscle of chronically infected neonates has not been studied. METHODS Eighteen 2-d-old pigs underwent cecal ligation and puncture (CLP) or sham surgery (CON) to induce a chronic infection for 5 d. On d 5, pancreatic-substrate clamps were performed to attain fasting or fed insulin levels but to maintain glucose and amino acids in the fasting range. Total fractional protein synthesis rates (Ks), translational control mechanisms, and energy sensing and degradation signal activation were measured in longissimus dorsi muscle. RESULTS In fasting conditions, CLP reduced Ks and sirtuin 1 (SIRT1) and increased AMP-activated protein kinase α (AMPKα) activation and muscle RING-finger protein-1 (MuRF1). Insulin treatment increased Ks and mitochondrial protein synthesis, enhanced translation activation, and reduced SIRT1 in CON. In contrast, in CLP, insulin treatment increased Ks, protein kinase B (PKB) and Forkhead box O1 phosphorylation, antagonized AMPK activation, and decreased peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α), MuRF1, and SIRT1. CONCLUSION Energy and substrate sensing in skeletal muscle by the PKB-AMPK-SIRT1-PGC-1α axis is impacted by chronic infection in neonatal pigs and can be modulated by insulin.
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17
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Hernandez-García AD, Columbus DA, Manjarín R, Nguyen HV, Suryawan A, Orellana RA, Davis TA. Leucine supplementation stimulates protein synthesis and reduces degradation signal activation in muscle of newborn pigs during acute endotoxemia. Am J Physiol Endocrinol Metab 2016; 311:E791-E801. [PMID: 27624100 PMCID: PMC5241557 DOI: 10.1152/ajpendo.00217.2016] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 09/06/2016] [Indexed: 11/22/2022]
Abstract
Sepsis disrupts skeletal muscle proteostasis and mitigates the anabolic response to leucine (Leu) in muscle of mature animals. We have shown that Leu stimulates muscle protein synthesis (PS) in healthy neonatal piglets. To determine if supplemental Leu can stimulate PS and reduce protein degradation (PD) signaling in neonatal muscle during endotoxemia, overnight-fasted neonatal pigs were infused for 8 h with LPS or saline while plasma amino acids, glucose, and insulin were maintained at fasting levels during pancreatic-substrate clamps. Leu or saline was infused during the last hour. Markers of PS and PD were determined in skeletal muscle. Compared with controls, Leu increased PS in longissimus dorsi (LD), gastrocnemius, and soleus muscles. LPS decreased PS in these three muscles by 36%, 28%, and 38%, but Leu antagonized that reduction by increasing PS by 84%, 81%, and 83%, respectively, when supplemented to LPS. Leu increased eukaryotic translation initiation factor (eIF)3b-raptor interactions, eIF4E-binding protein-1, and S6 kinase 1 phosphorylation as well as eIF4E·eIF4G complex formation in LD, gastrocnemius, and soleus muscles of control and LPS-treated pigs. In LD muscle, LPS increased the light chain (LC)3-II-to-LC3 ratio and muscle-specific RING finger (MuRF-1) abundance but not atrogin-1 abundance or AMP-activated protein kinase-α phosphorylation. Leu supplementation to LPS-treated pigs reduced the LC3-II-to-LC3 ratio, MuRF-1 abundance, and AMP-activated protein kinase-α phosphorylation compared with LPS alone. In conclusion, parenteral Leu supplementation attenuates the LPS-induced reduction in PS by stimulating mammalian target of rapamycin complex 1-dependent translation and may reduce PD by attenuating autophagy-lysosome and MuRF-1 signaling in neonatal skeletal muscle.
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Affiliation(s)
- Adriana D Hernandez-García
- Children's Nutrition Research Center, United States Department of Agriculture/Agricultural Research Service, Houston, Texas; and Critical Care Section, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Daniel A Columbus
- Children's Nutrition Research Center, United States Department of Agriculture/Agricultural Research Service, Houston, Texas; and
| | - Rodrigo Manjarín
- Children's Nutrition Research Center, United States Department of Agriculture/Agricultural Research Service, Houston, Texas; and
| | - Hanh V Nguyen
- Children's Nutrition Research Center, United States Department of Agriculture/Agricultural Research Service, Houston, Texas; and
| | - Agus Suryawan
- Children's Nutrition Research Center, United States Department of Agriculture/Agricultural Research Service, Houston, Texas; and
| | - Renán A Orellana
- Children's Nutrition Research Center, United States Department of Agriculture/Agricultural Research Service, Houston, Texas; and Critical Care Section, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Teresa A Davis
- Children's Nutrition Research Center, United States Department of Agriculture/Agricultural Research Service, Houston, Texas; and
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18
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Hernandez-García A, Manjarín R, Suryawan A, Nguyen HV, Davis TA, Orellana RA. Amino acids, independent of insulin, attenuate skeletal muscle autophagy in neonatal pigs during endotoxemia. Pediatr Res 2016; 80:448-51. [PMID: 27064245 PMCID: PMC4996682 DOI: 10.1038/pr.2016.83] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 01/28/2016] [Indexed: 02/03/2023]
Abstract
BACKGROUND Sepsis induces loss of skeletal muscle mass by activating the ubiquitin proteasome (UPS) and autophagy systems. Although muscle protein synthesis in healthy neonatal piglets is responsive to amino acids (AA) stimulation, it is not known if AA can prevent the activation of muscle protein degradation induced by sepsis. We hypothesize that AA attenuate the sepsis-induced activation of UPS and autophagy in neonates. METHODS Newborn pigs were infused for 8 h with liposaccharide (LPS) (0 and 10 μg·kg(-1)·h(-1)), while circulating glucose and insulin were maintained at fasting levels; circulating AA were clamped at fasting or fed levels. Markers of protein degradation and AA transporters in longissimus dorsi (LD) were examined. RESULTS Fasting AA increased muscle microtubule-associated protein light 1 chain 3 II (LC3-II) abundance in LPS compared to control, while fed AA levels decreased LC3-II abundance in both LPS and controls. There was no effect of AA supplementation on activated protein kinase (AMP), forkhead box O1 and O4 phosphorylation, nor on sodium-coupled neutral AA transporter 2 and light chain AA transporter 1, muscle RING-finger protein-1 and muscle Atrophy F-Box/Atrogin-1 abundance. CONCLUSION These findings suggest that supplementation of AA antagonize autophagy signal activation in skeletal muscle of neonates during endotoxemia.
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Affiliation(s)
- Adriana Hernandez-García
- U.S. Department of Agriculture/Agricultural Research Service, Children´s Nutrition Research Center, Houston, TX 77030,Critical Care Section, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Rodrigo Manjarín
- U.S. Department of Agriculture/Agricultural Research Service, Children´s Nutrition Research Center, Houston, TX 77030
| | - Agus Suryawan
- U.S. Department of Agriculture/Agricultural Research Service, Children´s Nutrition Research Center, Houston, TX 77030
| | - Hanh V. Nguyen
- U.S. Department of Agriculture/Agricultural Research Service, Children´s Nutrition Research Center, Houston, TX 77030
| | - Teresa A. Davis
- U.S. Department of Agriculture/Agricultural Research Service, Children´s Nutrition Research Center, Houston, TX 77030
| | - Renán A. Orellana
- U.S. Department of Agriculture/Agricultural Research Service, Children´s Nutrition Research Center, Houston, TX 77030,Critical Care Section, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030,Corresponding Author: Renán A. Orellana, USDA/ARS Children's Nutrition Research Center, 1100 Bates Street, Suite 9070, Houston, Texas, USA 77030, Tel: (832) 826-6230 Fax: (832) 825-6229,
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Manjarín R, Columbus DA, Suryawan A, Nguyen HV, Hernandez-García AD, Hoang NM, Fiorotto ML, Davis T. Leucine supplementation of a chronically restricted protein and energy diet enhances mTOR pathway activation but not muscle protein synthesis in neonatal pigs. Amino Acids 2016; 48:257-267. [PMID: 26334346 PMCID: PMC4713246 DOI: 10.1007/s00726-015-2078-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 08/18/2015] [Indexed: 12/15/2022]
Abstract
Suboptimal nutrient intake represents a limiting factor for growth and long-term survival of low-birth weight infants. The objective of this study was to determine if in neonates who can consume only 70 % of their protein and energy requirements for 8 days, enteral leucine supplementation will upregulate the mammalian target of rapamycin (mTOR) pathway in skeletal muscle, leading to an increase in protein synthesis and muscle anabolism. Nineteen 4-day-old piglets were fed by gastric tube 1 of 3 diets, containing (kg body weight(-1) · day(-1)) 16 g protein and 190 kcal (CON), 10.9 g protein and 132 kcal (R), or 10.8 g protein + 0.2 % leucine and 136 kcal (RL) at 4-h intervals for 8 days. On day 8, plasma AA and insulin levels were measured during 6 post-feeding intervals, and muscle protein synthesis rate and mTOR signaling proteins were determined at 120 min post-feeding. At 120 min, leucine was highest in RL (P < 0.001), whereas insulin, isoleucine and valine were lower in RL and R compared to CON (P < 0.001). Compared to RL and R, the CON diet increased (P < 0.01) body weight, protein synthesis, phosphorylation of S6 kinase (p-S6K1) and 4E-binding protein (p-4EBP1), and activation of eukaryotic initiation factor 4 complex (eIF4E · eIF4G). RL increased (P ≤ 0.01) p-S6K1, p-4EBP1 and eIF4E · eIF4G compared to R. In conclusion, when protein and energy intakes are restricted for 8 days, leucine supplementation increases muscle mTOR activation, but does not improve body weight gain or enhance skeletal muscle protein synthesis in neonatal pigs.
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Affiliation(s)
- Rodrigo Manjarín
- U.S. Department of Agriculture/Agricultural Research Service (USDA/ARS), Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Daniel A. Columbus
- U.S. Department of Agriculture/Agricultural Research Service (USDA/ARS), Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Agus Suryawan
- U.S. Department of Agriculture/Agricultural Research Service (USDA/ARS), Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Hanh V. Nguyen
- U.S. Department of Agriculture/Agricultural Research Service (USDA/ARS), Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Adriana D. Hernandez-García
- U.S. Department of Agriculture/Agricultural Research Service (USDA/ARS), Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Nguyet-Minh Hoang
- U.S. Department of Agriculture/Agricultural Research Service (USDA/ARS), Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Marta L. Fiorotto
- U.S. Department of Agriculture/Agricultural Research Service (USDA/ARS), Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Teresa Davis
- U.S. Department of Agriculture/Agricultural Research Service (USDA/ARS), Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
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Wang P, Drackley J, Stamey-Lanier J, Keisler D, Loor J. Effects of level of nutrient intake and age on mammalian target of rapamycin, insulin, and insulin-like growth factor-1 gene network expression in skeletal muscle of young Holstein calves. J Dairy Sci 2014; 97:383-91. [DOI: 10.3168/jds.2013-7042] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 09/15/2013] [Indexed: 11/19/2022]
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Chen W, Tangara M, Xu J, Peng J. Developmental transition of pectoralis muscle from atrophy in late-term duck embryos to hypertrophy in neonates. Exp Physiol 2012; 97:861-72. [PMID: 22787243 DOI: 10.1113/expphysiol.2011.01083.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Unlike the mammalian fetus, whose growth is supported by the sustained provision of maternal nutrients, poultry embryos undergo development in a relatively closed space, and the yolk sac serves as the sole nutrient supply for embryonic development throughout the whole incubation period. To increase our understanding of the muscle developmental patterns in the final stage of incubation and early days posthatching, we used late-term duck embryos and newly hatched ducklings as animal models. Pectoralis muscle samples were collected at 22 days (22E) of incubation, 25 days (25E) of incubation, hatching and day 7 posthatching. The pectoralis muscle mass, muscle fibre bundles and myofibre cross-sectional area showed a marked reduction from 22E to hatching, but they increased dramatically by day 7 posthatching. The mRNA expression of Atrogin-1, a key mediator of the ubiquitin system responsible for protein degradation, increased dramatically with the age of late-term duck embryos, but it decreased by day 7 and reached a very low level. The extent of mRNA expression of FoxO1, one of the transcription factors of the Atrogin-1 gene, exhibited a transient increase at 25E and then decreased from hatching to day 7. The phosphorylated p70 ribosomal protein S6 kinase 1 (S6K1)/S6K1 ratio exhibited a dramatic reduction from 22E to hatching (P < 0.05) and then increased by day 7. The results of the present study indicated that there was a developmental transition of pectoralis muscle from atrophy in late-term duck embryos to hypertrophy in neonates.
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Affiliation(s)
- Wei Chen
- Department of Animal Nutrition and Feed Science, Huazhong Agricultural University, Wuhan, China
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Orellana RA, Wilson FA, Gazzaneo MC, Suryawan A, Davis TA, Nguyen HV. Sepsis and development impede muscle protein synthesis in neonatal pigs by different ribosomal mechanisms. Pediatr Res 2011; 69:473-8. [PMID: 21364490 PMCID: PMC3090498 DOI: 10.1203/pdr.0b013e3182176da1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In muscle, sepsis reduces protein synthesis (MPS) by restraining translation in neonates and adults. Even though protein accretion decreases with development as neonatal MPS rapidly declines by maturation, the changes imposed by development on the sepsis-associated decrease in MPS have not been described. Pigs at 7 and 26 d of age were infused for 8 h with lipopolysaccharide (LPS, endotoxin, 0 and 10 μg · kg⁻¹ · h⁻¹). Fractional MPS rates and translation eukaryotic initiation factor (eIF) activation in muscle were examined (n = 5-7/group). The LPS-induced decrease in MPS was associated with reduced ribosomal and translational efficiency, whereas the age-induced decrease in MPS occurred by decreasing ribosome number. Abundances of mammalian target of rapamycin (mTOR) and S6 decreased, and that of the repressor eIF4E · 4E-binding protein 1 (4EBP1) association increased in 26-d-old pigs--compared with 7-d-old pigs. LPS decreased the abundance of the active eIF4E ·eIF4G association and the phosphorylation of eIF4G across ages, whereas the abundance of eIF4G declined and eIF2α phosphorylation increased with age. Therefore, when lacking anabolic stimulation, the decrease in MPS induced by LPS is associated with reduced ribosomal efficiency and decreased eIF4E ·eIF4G assembly, whereas that induced by development involves reduced ribosomal number, translation factor abundance, and increased eIF2α phosphorylation.
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Affiliation(s)
- Renán A Orellana
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA.
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Urschel KL, Escobar J, McCutcheon LJ, Geor RJ. Effect of feeding a high-protein diet following an 18-hour period of feed withholding on mammalian target of rapamycin-dependent signaling in skeletal muscle of mature horses. Am J Vet Res 2011; 72:248-55. [DOI: 10.2460/ajvr.72.2.248] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Suryawan A, Davis TA. The abundance and activation of mTORC1 regulators in skeletal muscle of neonatal pigs are modulated by insulin, amino acids, and age. J Appl Physiol (1985) 2010; 109:1448-54. [PMID: 20724570 DOI: 10.1152/japplphysiol.00428.2010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Mammalian target of rapamycin complex 1 (mTORC1) signaling is crucial for the regulation of protein synthesis. Most of known mTORC1 regulators have been isolated and characterized using cell culture systems, and the physiological roles of these regulators have not been fully tested in vivo. Previously we demonstrated that the insulin (INS) and amino acid (AA)-induced activation of mTORC1 is developmentally regulated in skeletal muscle (Suryawan A et al. Am J Physiol Endocrinol Metab 293: E1597-E1605, 2007). The present study aimed to characterize in more detail the effects of the postprandial rise in INS and AA on the activation and abundance of mTORC1 regulators in muscle and how this is modified by development. Overnight fasted 6- and 26-day-old pigs were studied during 1) euinsulinemic-euglycemic-euaminoacidemic conditions (control), 2) euinsulinemic-euglycemic-hyperaminoacidemic clamps (AA), and 3) hyperinsulinemic-euglycemic-euaminoacidemic clamps (INS). INS, but not AA, enhanced the PRAS40 phosphorylation, and this effect was greater in 6- than in 26-day old pigs. Phospholipase D1 (PLD1) abundance and phosphorylation, and the association of PLD1 with Ras homolog enriched in brain (Rheb), were greater in the younger pigs. Neither INS, AA, nor age altered the abundance of Rheb, vacuolar protein sorting 34 (Vps34), or FK506-binding protein 38 (FKBP38). Although INS and AA had no effect, the abundance of ras-related GTP binding B (RagB) and the association of RagB with Raptor were greater in 6- than in 26-day-old pigs. Neither INS, AA, nor age altered AMPK-induced phosphorylation of Raptor. Our results suggest that the enhanced activation of mTORC1 in muscle of neonatal pigs is in part due to regulation by PRAS40, PLD1, and the Rag GTPases.
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Affiliation(s)
- Agus Suryawan
- United States Department of Agriculture/Agriculture Research Service Children's Nutrition Research Center, Department of Paediatrics, Baylor College of Medicine, Houston, TX 77030, USA
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Abstract
The stage of development between birth and weaning in mammals is a period of very rapid growth that is crucial for the long-term well-being of the animal. The rate of protein deposition in neonatal animals is very high because dietary protein is efficiently utilized to increase body protein mass. Our studies in neonatal pigs have shown that this high efficiency of protein deposition is largely due to the marked increase in protein synthesis after feeding, and this response is particularly profound in the skeletal muscle. The enhanced stimulation of muscle protein synthesis in neonates after feeding is independently mediated by the rise in insulin and amino acids and this response declines with age. Intracellular signaling components that respond to the postprandial rise in amino acids and insulin have been identified and their activation has been shown to be elevated in skeletal muscle of neonatal pigs after a meal and to decrease with development. The enhanced activation of these components in the amino acid and insulin signaling pathways in neonatal muscle contributes to the high rate of muscle protein synthesis and rapid gain in skeletal muscle mass in newborn pigs, which are essential determinants of efficient growth during development.
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Wilson FA, Suryawan A, Orellana RA, Kimball SR, Gazzaneo MC, Nguyen HV, Fiorotto ML, Davis TA. Feeding rapidly stimulates protein synthesis in skeletal muscle of neonatal pigs by enhancing translation initiation. J Nutr 2009; 139:1873-80. [PMID: 19692527 PMCID: PMC2744610 DOI: 10.3945/jn.109.106781] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Food consumption increases protein synthesis in most tissues by promoting translation initiation, and in the neonate, this increase is greatest in skeletal muscle. In this study, we aimed to identify the currently unknown time course of changes in the rate of protein synthesis and the activation of factors involved in translation in neonatal muscle after a meal. After overnight food deprivation, 36 5- to 7-d-old piglets were administered a nutritionally complete bolus i.g. meal and were killed immediately before or 30, 60, 90, 120, or 240 min later. The increase in skeletal muscle protein synthesis peaked 30 min after the meal and this was sustained through 120 min, returning to baseline thereafter. The relative proportion of polysomes to nonpolysomes was higher only after 30 min. Protein kinase B phosphorylation peaked 30 min after feeding and returned to baseline by 90 min. The phosphorylation of mammalian target of rapamycin, eukaryotic initiation factor (eIF) 4E binding protein (4E-BP1), ribosomal protein S6, and eIF4G was increased within 30 min of feeding and persisted through 120 min, but all had returned to baseline by 240 min. The association of 4E-BP1.eIF4E was reduced and eIF4E.eIF4G increased 30 min after receiving a meal, remaining so for 120 min, before returning to baseline at 240 min. Thus, in neonates, food consumption rapidly increased skeletal muscle protein synthesis by enhancing translation initiation and this increase was sustained for at least 120 min after the meal but returned to baseline by 240 min after the feeding.
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Affiliation(s)
- Fiona A. Wilson
- USDA/Agriculture Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030 and Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033
| | - Agus Suryawan
- USDA/Agriculture Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030 and Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033
| | - Renán A. Orellana
- USDA/Agriculture Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030 and Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033
| | - Scot R. Kimball
- USDA/Agriculture Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030 and Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033
| | - Maria C. Gazzaneo
- USDA/Agriculture Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030 and Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033
| | - Hanh V. Nguyen
- USDA/Agriculture Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030 and Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033
| | - Marta L. Fiorotto
- USDA/Agriculture Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030 and Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033
| | - Teresa A. Davis
- USDA/Agriculture Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030 and Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033
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The effect of the protein level in a pre-starter diet on the post-hatch performance and activation of ribosomal protein S6 kinase in muscle of neonatal broilers. Br J Nutr 2009; 103:206-11. [DOI: 10.1017/s0007114509991735] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The cytoplasmic serine/threonine ribosomal protein S6 kinase (S6K1) plays a critical role in controlling protein translation. There is evidence that amino acids regulate S6K1 and protein synthesis in avian species, but the effect of dietary protein level on the activation of S6K1 in neonatal chicks is unknown. Therefore, the aim of the present experiment was to investigate the effect of different protein levels, supplied during the first 5 d post-hatch, on body growth, breast muscle development and on the activation of S6K1 and its downstream target, the S6, in neonatal chicks. Chicks were fed a pre-starter diet during the first 5 d post-hatch containing low (19·6 % crude protein (CP); LP), medium (23·1 % CP; MP) or high (26·7 % CP) levels (HP) of protein. Weight gain of chicks fed the HP diet was higher (P < 0·05) compared with those fed the LP diet during day (d)3–d5 and the numerical advantage of this group was maintained from d2 to d7. On d2 and d3, greater levels of S6K1 and S6 phosphorylation and/or activity were observed in chicks receiving the HP diet compared with LP and MP diets, without differences between results of the latter two dietary treatments. In conclusion, the present results suggest that early protein nutrition impacts the development of broiler chicks.
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Abstract
PURPOSE OF REVIEW This review reports recent findings on the multiple factors that regulate skeletal muscle growth in neonates. RECENT FINDINGS Skeletal muscle is the fastest growing protein mass in neonates. The high rate of neonatal muscle growth is due to accelerated rates of protein synthesis accompanied by the rapid accumulation of muscle nuclei. Feeding profoundly stimulates muscle protein synthesis in neonates and the response decreases with age. The feeding-induced stimulation of muscle protein synthesis is modulated by enhanced sensitivity to the postprandial rise in insulin and amino acids. Insulin and amino acid signaling components have been identified that are involved in the feeding-induced stimulation of protein synthesis in neonatal muscle. The enhanced activation of these signaling components in skeletal muscle of the neonate contributes to the high rate of muscle protein synthesis and rapid gain in muscle protein mass in neonates. SUMMARY Recent findings suggest that the immature muscle has a heightened capacity to activate signaling cascades that promote translation initiation in response to the postprandial rise in insulin and amino acids thereby enabling their efficient utilization for muscle growth. This capacity is further supported by enhanced satellite cell proliferation, but how these two processes are linked remains to be established.
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Affiliation(s)
- Teresa A Davis
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA.
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Suryawan A, Jeyapalan AS, Orellana RA, Wilson FA, Nguyen HV, Davis TA. Leucine stimulates protein synthesis in skeletal muscle of neonatal pigs by enhancing mTORC1 activation. Am J Physiol Endocrinol Metab 2008; 295:E868-75. [PMID: 18682538 PMCID: PMC2575905 DOI: 10.1152/ajpendo.90314.2008] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Skeletal muscle in the neonate grows at a rapid rate due in part to an enhanced sensitivity to the postprandial rise in amino acids, particularly leucine. To elucidate the molecular mechanism by which leucine stimulates protein synthesis in neonatal muscle, overnight-fasted 7-day-old piglets were treated with rapamycin [an inhibitor of mammalian target of rapamycin (mTOR) complex (mTORC)1] for 1 h and then infused with leucine for 1 h. Fractional rates of protein synthesis and activation of signaling components that lead to mRNA translation were determined in skeletal muscle. Rapamycin completely blocked leucine-induced muscle protein synthesis. Rapamycin markedly reduced raptor-mTOR association, an indicator of mTORC1 activation. Rapamycin blocked the leucine-induced phosphorylation of mTOR, S6 kinase 1 (S6K1), and eukaryotic initiation factor (eIF)4E-binding protein-1 (4E-BP1) and formation of the eIF4E.eIF4G complex and increased eIF4E.4E-BP1 complex abundance. Rapamycin had no effect on the association of mTOR with rictor, a crucial component for mTORC2 activation, or G protein beta-subunit-like protein (GbetaL), a component of mTORC1 and mTORC2. Neither leucine nor rapamycin affected the phosphorylation of AMP-activated protein kinase (AMPK), PKB, or tuberous sclerosis complex (TSC)2, signaling components that reside upstream of mTOR. Eukaryotic elongation factor (eEF)2 phosphorylation was not affected by leucine or rapamycin, although current dogma indicates that eEF2 phosphorylation is mTOR dependent. Together, these in vivo data suggest that leucine stimulates muscle protein synthesis in neonates by enhancing mTORC1 activation and its downstream effectors.
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Affiliation(s)
- Agus Suryawan
- United States Department of Agriculture/Agriculture Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA
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Thivierge MC, Bush JA, Suryawan A, Nguyen HV, Orellana RA, Burrin DG, Jahoor F, Davis TA. Positive net movements of amino acids in the hindlimb after overnight food deprivation contribute to sustaining the elevated anabolism of neonatal pigs. J Appl Physiol (1985) 2008; 105:1959-66. [PMID: 18801965 DOI: 10.1152/japplphysiol.90352.2008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During the neonatal period, high protein breakdown rate is a metabolic process inherent to elevated rates of protein accretion in skeletal muscle. To determine the relationship between hindlimb net movements of essential and nonessential amino acids in the regulation of hindlimb protein breakdown during an overnight fasting-feeding cycle, we infused overnight-food-deprived 10- and 28-day-old piglets with [1-(13)C]phenylalanine and [ring-(2)H(4)]tyrosine over 7 h (during 3 h of fasting and then during 4 h of feeding). Extraction rates for aspartate and glutamate after an overnight fast were 15% and 51% in the 10-day-old compared with 6% and 25% in the 28-day-old (P < 0.05) piglets, suggesting an altered requirement for precursors of amino acids to shuttle nitrogen to the liver as early life progresses. This occurred simultaneously with marginal positive hindlimb net balance of essential amino acids after an overnight fast, with negative net release of many nonessential amino acids, such as alanine, asparagine, glutamine, glycine, and proline. This suggests that newborn muscle does not undergo significant protein mobilization after a short period of fasting in support of an elevated rate of protein accretion. Furthermore, tyrosine efflux from hindlimb breakdown between overnight fasting and feeding periods was not different in the 10-day-old piglets, for which tyrosine was limiting, but when tyrosine supply balanced requirements in the 28-day-old piglet, hindlimb efflux was increased (P = 0.01). The results of the present study indicate that proteolysis and net movements of amino acids are coordinated mechanisms that sustain the elevated rate of net protein accretion during overnight feeding-fasting cycles in the neonate.
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Affiliation(s)
- M Carole Thivierge
- Rowett Institute of Nutrition and Health, Greenburn Rd., Bucksburn, Aberdeen AB21 9SB, UK.
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Abstract
Newborn humans and animals grow at very rapid rates because they use the protein that they eat very efficiency to increase body protein mass. This high efficiency of protein deposition in neonates is largely due to their ability to markedly increase the amount of protein synthesized in their muscles when they eat. This enhanced stimulation of muscle protein synthesis after eating is mediated by the rise in the hormone, insulin, and the rise in amino acids, which are the building blocks of protein. Intracellular signaling components that respond to insulin and amino acids have been identified and these have been shown to be involved in the feeding-induced stimulation of protein synthesis in skeletal muscle of the neonate. The enhanced activation of these intracellular signaling components in neonatal muscle contributes to the high rate of muscle protein synthesis and rapid gain in skeletal muscle mass in newborns.
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Suryawan A, Orellana RA, Nguyen HV, Jeyapalan AS, Fleming JR, Davis TA. Activation by insulin and amino acids of signaling components leading to translation initiation in skeletal muscle of neonatal pigs is developmentally regulated. Am J Physiol Endocrinol Metab 2007; 293:E1597-605. [PMID: 17878222 PMCID: PMC2714663 DOI: 10.1152/ajpendo.00307.2007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Insulin and amino acids act independently to stimulate protein synthesis in skeletal muscle of neonatal pigs, and the responses decrease with development. The purpose of this study was to compare the separate effects of fed levels of INS and AA on the activation of signaling components leading to translation initiation and how these responses change with development. Overnight-fasted 6- (n = 4/group) and 26-day-old (n = 6/ group) pigs were studied during 1) euinsulinemic-euglycemiceuaminoacidemic conditions (controls), 2) euinsulinemic-euglycemichyperaminoacidemic clamps (AA), and 3) hyperinsulinemic-euglycemic-euaminoacidemic clamps (INS). INS, but not AA, increased the phosphorylation of protein kinase B (PKB) and tuberous sclerosis 2 (TSC2). Both INS and AA increased protein synthesis and the phosphorylation of mammalian target of rapamycin (mTOR), ribosomal protein S6 kinase-1, and eukaryotic initiation factor (eIF)4E-binding protein 1 (4E-BP1), and these responses were higher in 6-day-old compared with 26-day-old pigs. Both INS and AA decreased the binding of 4E-BP1 to eIF4E and increased eIF4E binding to eIF4G; these effects were greater in 6-day-old than in 26-day-old pigs. Neither INS nor AA altered the composition of mTORC1 (raptor, mTOR, and GbetaL) or mTORC2 (rictor, mTOR, and GbetaL) complexes. Furthermore, neither INS, AA, nor age had any effect on the abundance of Rheb and the phosphorylation of AMP-activated protein kinase and eukaryotic elongation factor 2. Our results suggest that the activation by insulin and amino acids of signaling components leading to translation initiation is developmentally regulated and parallels the developmental decline in protein synthesis in skeletal muscle of neonatal pigs.
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Affiliation(s)
- Agus Suryawan
- USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, 1100 Bates St., Houston, TX 77030, USA
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Davis TA, Suryawan A, Orellana RA, Nguyen HV, Fiorotto ML. Postnatal ontogeny of skeletal muscle protein synthesis in pigs. J Anim Sci 2007; 86:E13-8. [PMID: 17785597 PMCID: PMC2640319 DOI: 10.2527/jas.2007-0419] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The neonatal period is characterized by rapid growth and elevated rates of synthesis and accretion of skeletal muscle proteins. The fractional rate of muscle protein synthesis is very high at birth and declines rapidly with age. The elevated capacity for muscle protein synthesis in the neonatal pig is driven by the high ribosome content and, together with an increased efficiency of the translation process, promotes accelerated protein synthesis rates. Feeding profoundly stimulates muscle protein synthesis in neonatal pigs and the response decreases with age. The feeding-induced stimulation of muscle protein synthesis is modulated by an enhanced sensitivity to the postprandial increase in insulin and amino acids. The developmental decline in the response to insulin and amino acids parallels a marked decrease in the feeding-induced activation of translation initiation factors that regulate the binding of mRNA to the 40S ribosomal complex. The abundance and activation of many known positive regulators of the nutrient- and insulin-signaling pathways that are involved in translation initiation are high, whereas those of many negative regulators are low in skeletal muscle of younger pigs. Thus, the activation and(or) abundance of the positive regulators, such as the insulin receptor, insulin receptor-substrate-1, phosphoinositide-3 kinase, phosphoinositide-dependent kinase-1, protein kinase B, mammalian target of rapamycin, raptor, ribosomal protein S6 kinase-1, eukaryotic initiation factor (eIF) 4E-binding protein 1, and eIF4E associated with eIF4G, are greater in 7-d-old pigs than in 26-d-old pigs. The activation of negative regulators, including protein tyrosine phosphatase-1B, phosphatase and tensin homologue deleted on chromosome 10, protein phosphatase 2A, and tuberous sclerosis complex 1/2, are lower in 7-d-old pigs than in 26-d-old pigs. Thus, the developmental decline in the stimulation of skeletal muscle protein synthesis by insulin and amino acids is due in part to the developmentally related decrease in the activation of the signaling pathways that lead to translation initiation.
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Affiliation(s)
- T A Davis
- United States Department of Agriculture, Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston TX 77030, USA.
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Bergeron K, Julien P, Davis TA, Myre A, Thivierge MC. Long-chain n-3 fatty acids enhance neonatal insulin-regulated protein metabolism in piglets by differentially altering muscle lipid composition. J Lipid Res 2007; 48:2396-410. [PMID: 17673528 PMCID: PMC2668875 DOI: 10.1194/jlr.m700166-jlr200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
This study investigated the role of long-chain n-3 polyunsaturated fatty acids (LCn-3PUFAs) of muscle phospholipids in the regulation of neonatal metabolism. Twenty-eight piglets were weaned at 2 days of age and raised on one of two milk formulas that consisted of either a control formula supplying 0% or a formula containing 3.5% LCn-3PUFAs until 10 or 28 days of age. There was a developmental decline in the insulin sensitivity of amino acid disposal in control pigs during the first month of life, with a slope of -2.24 micromol.kg(-1).h(-1) (P = 0.01) per unit of insulin increment, as assessed using hyperinsulinemic-euglycemic-euaminoacidemic clamps. LCn-3PUFA feeding blunted this developmental decline, resulting in differing insulin sensitivities (P < 0.001). When protein metabolism was assessed under parenteral feeding-induced hyperinsulinemia, LCn-3PUFAs reduced by 16% whole body oxidative losses of amino acids (from 238 to 231 micromol.kg(-1).h(-1); P = 0.06), allowing 41% more amino acids to accrete into body proteins (from 90 to 127 micromol.kg(-1).h(-1); P = 0.06). The fractional synthetic rate of muscle mixed proteins remained unaltered by the LCn-3PUFA feeding. However, LCn-3PUFAs retarded a developmental increase in the essential-to-nonessential amino acid ratio of the muscle intracellular free pool (P = 0.05). Overall, alterations in metabolism were concomitant with a preferential incorporation of LCn-3PUFAs into muscle total membrane phospholipids (P < 0.001), in contrast to intramuscular triglycerides. These results underscore the potential role of LCn-3PUFAs as regulators of different aspects of protein metabolism in the neonate.
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Affiliation(s)
- Karen Bergeron
- Department of Animal Science, Faculty of Food Sciences and Agriculture, Laval University, Québec, Québec G1K 7P4, Canada
- Institute of Nutraceuticals and Functional Foods, Faculty of Food Sciences and Agriculture, Laval University, Québec, Québec G1K 7P4, Canada
| | - Pierre Julien
- Lipid Research Center, Laval University Hospital Center, Québec, Québec G1V 4G2, Canada
| | - Teresa A. Davis
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Alexandre Myre
- Department of Animal Science, Faculty of Food Sciences and Agriculture, Laval University, Québec, Québec G1K 7P4, Canada
- Institute of Nutraceuticals and Functional Foods, Faculty of Food Sciences and Agriculture, Laval University, Québec, Québec G1K 7P4, Canada
| | - M. Carole Thivierge
- Department of Animal Science, Faculty of Food Sciences and Agriculture, Laval University, Québec, Québec G1K 7P4, Canada
- Institute of Nutraceuticals and Functional Foods, Faculty of Food Sciences and Agriculture, Laval University, Québec, Québec G1K 7P4, Canada
- Rowett Research Institute, Bucksburn, Aberdeen AB21 9SB, UK
- To whom correspondence should be addressed. e-mail:
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Mayes MA, Laforest MF, Guillemette C, Gilchrist RB, Richard FJ. Adenosine 5'-monophosphate kinase-activated protein kinase (PRKA) activators delay meiotic resumption in porcine oocytes. Biol Reprod 2006; 76:589-97. [PMID: 17167165 DOI: 10.1095/biolreprod.106.057828] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Adenosine monophosphate-activated kinase (PRKA) is a serine/threonine kinase that functions as a metabolic switch in a number of physiological functions. The present study was undertaken to assess the role of this kinase in nuclear maturation of porcine oocytes. RT-PCR and immunoblotting revealed the expression of the PRKAA1 subunit in granulosa cells, cumulus-oocyte complexes (COC), and denuded oocytes (DO). Porcine COC and DO contained transcripts that corresponded to the expected sizes of the designed primers for PRKAB1 and PRKAG1. The PRKAA2 subunit was detected in granulosa cells and COC, whereas the PRKAG3 subunit was not detected in granulosa cells, COC or DO, whereas it was detected in the heart. The PRKAA1 protein was detected in granulosa cells, COC, DO, and zona pellucida (ZP). In the presence of the pharmacological activator of PRKA 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranosyl 5'-monophosphate (ZMP), COC were transiently maintained in meiotic arrest in a fully reversible manner. This inhibitory effect was not observed in DO. Other known PRKA activators, 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR) and metformin, also blocked meiotic resumption in COC. In contrast to mouse oocytes, in which PRKA activators reverse the inhibitory effect of PDE3 inhibitors, this combination still blocked meiotic resumption in porcine COC. These results demonstrate that the meiotic resumption of porcine COC is transiently blocked by PRKA activators in a dose-dependent manner, and that this effect is dependent on PRKA activity in cumulus cells. The present study describes a new role for PRKA in regulating meiotic resumption in COC and strongly suggests that cumulus cells play an essential role in the control of porcine oocyte maturation through the PRKA metabolic switch.
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Affiliation(s)
- Mario A Mayes
- Centre de Recherche en Biologie de la Reproduction, Département des Sciences Animales, Faculté des Sciences de l'Agriculture et d'Alimentation, Université Laval, Québec, Canada G1K 7P4
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Suryawan A, Escobar J, Frank JW, Nguyen HV, Davis TA. Developmental regulation of the activation of signaling components leading to translation initiation in skeletal muscle of neonatal pigs. Am J Physiol Endocrinol Metab 2006; 291:E849-59. [PMID: 16757550 DOI: 10.1152/ajpendo.00069.2006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The rapid growth of neonates is driven by high rates of skeletal muscle protein synthesis. This high rate of protein synthesis, which is induced by feeding, declines with development. Overnight-fasted 7- and 26-day-old pigs either remained fasted or were refed, and the abundance and phosphorylation of growth factor- and nutrient-induced signaling components that regulate mRNA translation initiation were measured in skeletal muscle and liver. In muscle, but not liver, the activation of inhibitors of protein synthesis, phosphatase and tensin homolog deleted on chromosome 10, protein phosphatase 2A, and tuberous sclerosis complex 1/2 increased with age. Serine/threonine phosphorylation of the insulin receptor and insulin receptor substrate-1, which downregulates insulin signaling, and the activation of AMP-activated protein kinase, an inhibitor of protein synthesis, were unaffected by age and feeding in muscle and liver. Activation of positive regulators of protein synthesis, mammalian target of rapamycin (mTOR), ribosomal protein S6 kinase 1 (S6K1), and eIF4E-binding protein-1 (4E-BP1) decreased with age in muscle but not liver. Feeding enhanced mTOR, S6K1, and 4E-BP1 activation in muscle, and this response decreased with age. In liver, activation of S6K1 and 4E-BP1, but not mTOR, was increased by feeding but was unaffected by age. Raptor abundance and the association between raptor and mTOR were greater in 7- than in 26-day-old pigs. The results suggest that the developmental decline in skeletal muscle protein synthesis is due in part to developmental regulation of the activation of growth factor and nutrient-signaling components.
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Affiliation(s)
- Agus Suryawan
- United States Department of Agriculture/Agriculture Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates St., Houston, TX 77030, USA
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Suryawan A, Frank JW, Nguyen HV, Davis TA. Expression of the TGF-beta family of ligands is developmentally regulated in skeletal muscle of neonatal rats. Pediatr Res 2006; 59:175-9. [PMID: 16439574 DOI: 10.1203/01.pdr.0000196718.47935.6e] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
To dissect the possible role of the transforming growth factor-beta (TGF-beta) family in the regulation of skeletal muscle growth during the early postnatal period, the protein abundances of the TGF-beta family and their correlation with protein synthesis were determined in skeletal muscle of neonatal rats. To obtain direct evidence of the role of these growth factors in the regulation of protein synthesis, the TGF-beta inhibitor, follistatin, was infused into 10-d-old rats for 11 d and protein synthesis and phosphorylation of S6 kinase 1 (S6K1) and ribosomal protein (rpS6) were measured. TGF-beta2 abundance and protein synthesis in muscle decreased with development and were positively correlated. The abundances of bone morphogenetic protein 2 (BMP-2), BMP-7, and myostatin increased with development and were negatively correlated with protein synthesis. The abundances of BMP-2 and BMP-7 were positively correlated with BMP receptor IA (BMP-RIA) abundance. Activin A abundance was positively correlated with follistatin abundance and activin receptor IIB (Act-RIIB) abundance. Infusion of follistatin increased muscle protein synthesis and S6K1 and rpS6 phosphorylation. The results provide indirect and direct evidence of TGF-beta family involvement in the regulation of muscle protein synthesis during the neonatal period.
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Affiliation(s)
- Agus Suryawan
- Department of Pediatrics, USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX 77030, USA.
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Suryawan A, Davis TA. Developmental regulation of protein kinase B activation is isoform specific in skeletal muscle of neonatal pigs. Pediatr Res 2005; 58:719-24. [PMID: 16189199 DOI: 10.1203/01.pdr.0000180536.51032.ab] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The postprandial activation of the insulin signaling pathway that leads to translation initiation is enhanced in skeletal muscle of the neonate and decreases with development in parallel with the developmental decline in muscle protein synthesis. Our previous study showed that the activity of protein kinase B (PKB), a major insulin signaling component, was higher in 7- than in 26-d-old pigs. To examine the molecular mechanisms involved, we determined PKB isoform abundance and phosphorylation state, the abundance of its kinases, and PKB's association with its kinases. The abundances of total PKB, PKBalpha, and PKBgamma were higher in muscle of 7- than in 26-d-old pigs whereas PKBbeta abundance was similar in the two age groups. PKB phosphorylation at Thr308 was higher in 7- than in 26-d-old pigs but PKB phosphorylation at Ser473 was similar in both age groups. The association of PKB with 3'-phosphoinositide-dependent kinase-1 (PDK-1), a kinase that phosphorylates PKB at Thr308, and PDK-1 abundance were higher in 7- than in 26-d-old pigs. Moreover, PDK-1 phosphorylation at Ser-241, a site that is crucial for PDK-1 activation, was higher in 7- than in 26-d-old pigs. However, the association of PKB with integrin-linked kinase (ILK), a kinase that potentially phosphorylates PKB at Ser473, and ILK abundance were similar in both age groups. The result suggests that the developmental change in PKB activation is isoform specific and involves regulation by PDK-1.
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Affiliation(s)
- Agus Suryawan
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA
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Chapter 2 Regulation of skeletal muscle protein metabolism in growing animals. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s1877-1823(09)70009-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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O'Connor PMJ, Kimball SR, Suryawan A, Bush JA, Nguyen HV, Jefferson LS, Davis TA. Regulation of neonatal liver protein synthesis by insulin and amino acids in pigs. Am J Physiol Endocrinol Metab 2004; 286:E994-E1003. [PMID: 14761876 DOI: 10.1152/ajpendo.00391.2003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The high efficiency of protein deposition during the neonatal period is driven by high rates of protein synthesis, which are maximally stimulated after feeding. Infusion of amino acids, but not insulin, reproduces the feeding-induced stimulation of liver protein synthesis. To determine whether amino acid-stimulated liver protein synthesis is independent of insulin in neonates, and to examine the role of amino acids and insulin in the regulation of translation initiation in neonatal liver, we performed pancreatic glucose-amino acid clamps in overnight-fasted 7-day-old pigs. Pigs (n = 9-12/group) were infused with insulin at 0, 10, 22, and 110 ng.kg(-0.66).min(-1) to achieve 0, 2, 6, and 30 microU/ml insulin, respectively. At each insulin dose, amino acids were maintained at fasting or fed levels or, in conjunction with the highest insulin dose, allowed to fall to below fasting levels. Insulin had no effect on the fractional rate of protein synthesis in liver. Amino acids increased fractional protein synthesis rates in liver at each dose of insulin, including the 0 microU/ml dose. There was a dose-response effect of amino acids on liver protein synthesis. Amino acids and insulin increased protein S6 kinase and 4E-binding protein 1 (4E-BP1) phosphorylation; however, only amino acids decreased formation of the inactive 4E-BPI.eukaryotic initiation factor-4E (eIF4E) complex. The results suggest that amino acids regulate liver protein synthesis in the neonate by modulating the availability of eIF4E for 48S ribosomal complex formation and that this response does not require insulin.
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Affiliation(s)
- Pamela M J O'Connor
- United States Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates St., Suite 9064, Houston, TX 77030, USA
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Nakamura J, Okamura N, Kawakami Y. Augmentation of lipolysis in adipocytes from fed rats, but not from starved rats, by inhibition of rolipram-sensitive phosphodiesterase 4. Arch Biochem Biophys 2004; 425:106-14. [PMID: 15081899 DOI: 10.1016/j.abb.2004.02.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2004] [Revised: 02/26/2004] [Indexed: 11/28/2022]
Abstract
The sensitivity of adipocytes to lipolytic agents is increased after starvation. In this study, we found that LY294002, an inhibitor of phosphatidylinositol-3 kinase (PI3K), in the concentration of more than 50 microM potentiates lipolysis induced by adenosine deaminase in adipocytes from fed rats (f-adipocytes), but not from starved rats (s-adipocytes). It also enhanced the sensitivity to lipolytic action of isoproterenol in f-adipocytes much more than s-adipocytes. The target of LY294002 may be an anti-lipolytic regulator expressed in response to food intake. Since another PI3K inhibitor, wortmannin, or a phosphodiesterase 3 (PDE3) inhibitor, cilostamide, failed to cause any specific effect to f-adipocytes, the PI3K-PDE3B pathway cannot be a target of LY294002. We found that LY294002 inhibits efficiently the cytoplasmic PDE activity of adipocytes. Rolipram, a specific inhibitor of PDE4, also inhibited the cytoplasmic PDE and caused a preferential increase of lipolysis in f-adipocytes. LY294002 blunted the actions of rolipram on lipolysis and the PDE activity. LY294002 accelerated protein kinase A activation. These data suggest that the rolipram-sensitive PDE4 is an anti-lipolytic enzyme expressed according to food intake. LY294002 may potentiate lipolysis through inhibition of the PDE4.
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Affiliation(s)
- Jiro Nakamura
- Institute of Clinical Medicine, University of Tsukuba, Tsukuba-shi, Ibaraki-ken 305-8577, Japan.
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Abstract
PURPOSE OF REVIEW This review reports recent findings on the effect of enterally fed protein and amino acids on metabolism, function, and clinical outcome, particularly during the neonatal period. RECENT FINDINGS Splanchnic tissues metabolize significant proportions of some enteral amino acids and this likely contributes to the higher requirement for these amino acids when they are provided enterally versus parenterally. Splanchnic tissues are particularly key in the provision of nutrition to preterm infants, who possess an exceedingly high protein anabolic drive, but limited tolerance to aggressive enteral feeding. The protein anabolic response to specific proteins is influenced by the rate of digestion and the pattern of feeding, as well as the amino acid composition of the proteins. The post-prandial rise in amino acids and insulin stimulates neonatal tissue protein synthesis by modulation of the nutrient and insulin signaling pathways that lead to translation initiation. A flurry of investigations into the metabolic response and clinical impact of individual amino acids suggests that leucine, glutamine, and arginine, in particular, have specific roles in regulating protein synthesis and immune function. SUMMARY Recent findings suggest that enteral nutrition support that provides an optimum combination of proteins and amino acids can have a beneficial impact on the clinical outcome of patients.
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Affiliation(s)
- Douglas G Burrin
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA
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O'Connor PMJ, Kimball SR, Suryawan A, Bush JA, Nguyen HV, Jefferson LS, Davis TA. Regulation of translation initiation by insulin and amino acids in skeletal muscle of neonatal pigs. Am J Physiol Endocrinol Metab 2003; 285:E40-53. [PMID: 12637260 DOI: 10.1152/ajpendo.00563.2002] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Previous studies have shown that intravenous infusion of insulin and/or amino acids reproduces the feeding-induced stimulation of muscle protein synthesis in neonates and that insulin and amino acids act independently to produce this effect. The goal of the present study was to delineate the regulatory roles of insulin and amino acids on muscle protein synthesis in neonates by examining translational control mechanisms, specifically the eukaryotic translation initiation factors (eIFs), which enable coupling of initiator methionyl-tRNAi and mRNA to the 40S ribosomal subunit. Insulin secretion was blocked by somatostatin in fasted 7-day-old pigs (n = 8-12/group), insulin was infused to achieve plasma levels of approximately 0, 2, 6, and 30 microU/ml, and amino acids were clamped at fasting or fed levels or, at the high insulin dose, below fasting. Both insulin and amino acids increased the phosphorylation of ribosomal protein S6 kinase (S6K1) and the eIF4E-binding protein (4E-BP1), decreased the binding of 4E-BP1 to eIF4E, increased eIF4E binding to eIF4G, and increased fractional protein synthesis rates but did not affect eIF2B activity. In the absence of insulin, amino acids had no effect on these translation initiation factors but increased the protein synthesis rates. Raising insulin from below fasting to fasting levels generally did not alter translation initiation factor activity but raised protein synthesis rates. The phosphorylation of S6K1 and 4E-BP1 and the amount of 4E-BP1 bound to eIF4E and eIF4E bound to eIF4G were correlated with insulin level, amino acid level, and protein synthesis rate. Thus insulin and amino acids regulate muscle protein synthesis in skeletal muscle of neonates by modulating the availability of eIF4E for 48S ribosomal complex assembly, although other processes also must be involved.
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Affiliation(s)
- Pamela M J O'Connor
- United States Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030, USA
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Shen W, Wisniowski P, Ahmed L, Boyle DW, Denne SC, Liechty EA. Protein anabolic effects of insulin and IGF-I in the ovine fetus. Am J Physiol Endocrinol Metab 2003; 284:E748-56. [PMID: 12488244 DOI: 10.1152/ajpendo.00399.2002] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We determined the effect of insulin and/or recombinant human (rh)IGF-I infusion on ovine fetal phenylalanine kinetics, protein synthesis, and phenylalanine accretion. The chronically catheterized fetal lamb model was used at 130 days gestation. All studies were performed while fetal glucose and amino acid concentrations were held constant. Experimental infusates were 1). saline, 2). rhIGF-I plus a replacement dose of insulin (40 nmol), 3). insulin (890 mIU/h), and 4). IGF-I plus insulin (40 nmol IGF-I/h and 890 mIU insulin/h). Both hormones increased glucose and amino acid utilization, with insulin having a greater effect. The major effect on phenylalanine kinetics was a pronounced fall in phenylalanine hydroxylation, again with insulin having the greatest effect. Whole body protein breakdown was not significantly altered by either hormone; whole body protein synthesis was significantly increased during the combined infusion. Protein accretion was increased by both hormones, with the greatest increase during combined infusion. The fractional synthetic rate (FSR) of circulating albumin was increased by IGF-I but not by insulin. Both hormones significantly increased skeletal muscle FSR without a synergistic effect. The anabolic effects of insulin and IGF-I were more pronounced in these studies than in previous studies where amino acid concentrations were not maintained. The present data also suggest that insulin and IGF-I promote fetal growth through distinct, organ-specific mechanisms.
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Affiliation(s)
- Weihua Shen
- Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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Suryawan A, Davis TA. Protein-tyrosine-phosphatase 1B activation is regulated developmentally in muscle of neonatal pigs. Am J Physiol Endocrinol Metab 2003; 284:E47-54. [PMID: 12388170 DOI: 10.1152/ajpendo.00210.2002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The high activity of the insulin-signaling pathway contributes to the enhanced feeding-induced stimulation of translation initiation in skeletal muscle of neonatal pigs. Protein-tyrosine-phosphatase 1B (PTP1B) is a negative regulator of the tyrosine phosphorylation of the insulin receptor (IR) and insulin receptor substrate 1 (IRS-1). The activity of PTP1B is determined mainly by its association with IR and Grb2. We examined the level of PTP1B activity, PTP1B protein abundance, PTP1B tyrosine phosphorylation, and the association of PTP1B with IR and Grb2 in skeletal muscle and liver of fasted and fed 7- and 26-day-old pigs. PTP1B activity in skeletal muscle was lower (P < 0.05) in 7- compared with 26-day-old pigs but in liver was similar in the two age groups. PTP1B abundances were similar in muscle but lower (P < 0.05) in liver of 7- compared with 26-day-old pigs. PTP1B tyrosine phosphorylation in muscle was lower (P < 0.05) in 7- than in 26-day-old pigs. The associations of PTP1B with IR and with Grb2 were lower (P < 0.05) at 7 than at 26 days of age in muscle, but there were no age effects in liver. Finally, in both age groups, fasting did not have any effect on these parameters. These results indicate that basal PTP1B activation is developmentally regulated in skeletal muscle of neonatal pigs, consistent with the developmental changes in the activation of the insulin-signaling pathway reported previously. Reduced PTP1B activation in neonatal muscle likely contributes to the enhanced insulin sensitivity of skeletal muscle in neonatal pigs.
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Affiliation(s)
- Agus Suryawan
- United States Department of Agriculture/Agriculture Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA
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Davis TA, Fiorotto ML, Burrin DG, Vann RC, Reeds PJ, Nguyen HV, Beckett PR, Bush JA. Acute IGF-I infusion stimulates protein synthesis in skeletal muscle and other tissues of neonatal pigs. Am J Physiol Endocrinol Metab 2002; 283:E638-47. [PMID: 12217880 DOI: 10.1152/ajpendo.00081.2002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Studies have shown that protein synthesis in skeletal muscle of neonatal pigs is uniquely sensitive to a physiological rise in both insulin and amino acids. Protein synthesis in cardiac muscle, skin, and spleen is responsive to insulin but not amino acid stimulation, whereas in the liver, protein synthesis responds to amino acids but not insulin. To determine the response of protein synthesis to insulin-like growth factor I (IGF-I) in this model, overnight-fasted 7- and 26-day-old pigs were infused with IGF-I (0, 20, or 50 microg. kg(-1). h(-1)) to achieve levels within the physiological range, while amino acids and glucose were clamped at fasting levels. Because IGF-I infusion lowers circulating insulin levels, an additional group of high-dose IGF-I-infused pigs was also provided replacement insulin (10 ng. kg(-0.66). min(-1)). Tissue protein synthesis was measured using a flooding dose of L-[4-(3)H]phenylalanine. In 7-day-old pigs, low-dose IGF-I increased protein synthesis by 25-60% in various skeletal muscles as well as in cardiac muscle (+38%), skin (+24%), and spleen (+32%). The higher dose of IGF-I elicited no further increase in protein synthesis above that found with the low IGF-I dose. Insulin replacement did not alter the response of protein synthesis to IGF-I in any tissue. The IGF-I-induced increases in tissue protein synthesis decreased with development. IGF-I infusion, with or without insulin replacement, had no effect on protein synthesis in liver, jejunum, pancreas, or kidney. Thus the magnitude, tissue specificity, and developmental change in the response of protein synthesis to acute physiological increases in plasma IGF-I are similar to those previously observed for insulin. This study provides in vivo data indicating that circulating IGF-I and insulin act on the same signaling components to stimulate protein synthesis and that this response is highly sensitive to stimulation in skeletal muscle of the neonate.
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Affiliation(s)
- Teresa A Davis
- United States Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA.
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Davis TA, Fiorotto ML, Burrin DG, Reeds PJ, Nguyen HV, Beckett PR, Vann RC, O'Connor PMJ. Stimulation of protein synthesis by both insulin and amino acids is unique to skeletal muscle in neonatal pigs. Am J Physiol Endocrinol Metab 2002; 282:E880-90. [PMID: 11882508 DOI: 10.1152/ajpendo.00517.2001] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In neonatal pigs, the feeding-induced stimulation of protein synthesis in skeletal muscle, but not liver, can be reproduced by insulin infusion when essential amino acids and glucose are maintained at fasting levels. In the present study, 7- and 26-day-old pigs were studied during 1) fasting, 2) hyperinsulinemic-euglycemic-euaminoacidemic clamps, 3) euinsulinemic-euglycemic-hyperaminoacidemic clamps, and 4) hyperinsulinemic-euglycemic-hyperaminoacidemic clamps. Amino acids were clamped using a new amino acid mixture enriched in nonessential amino acids. Tissue protein synthesis was measured using a flooding dose of L-[4-(3)H]phenylalanine. In 7-day-old pigs, insulin infusion alone increased protein synthesis in various skeletal muscles (from +35 to +64%), with equivalent contribution of myofibrillar and sarcoplasmic proteins, as well as cardiac muscle (+50%), skin (+34%), and spleen (+26%). Amino acid infusion alone increased protein synthesis in skeletal muscles (from +28 to +50%), also with equivalent contribution of myofibrillar and sarcoplasmic proteins, as well as liver (+27%), pancreas (+28%), and kidney (+10%). An elevation of both insulin and amino acids did not have an additive effect. Similar qualitative results were obtained in 26-day-old pigs, but the magnitude of the stimulation of protein synthesis by insulin and/or amino acids was lower. The results suggest that, in the neonate, the stimulation of protein synthesis by feeding is mediated by either amino acids or insulin in most tissues; however, the feeding-induced stimulation of protein synthesis in skeletal muscle is uniquely regulated by both insulin and amino acids.
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Affiliation(s)
- Teresa A Davis
- United States Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, and Endocrinology and Metabolism Section, Baylor College of Medicine, Houston, Texas 77030, USA.
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Kimball SR, Farrell PA, Nguyen HV, Jefferson LS, Davis TA. Developmental decline in components of signal transduction pathways regulating protein synthesis in pig muscle. Am J Physiol Endocrinol Metab 2002; 282:E585-92. [PMID: 11832361 DOI: 10.1152/ajpendo.00269.2001] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Our previous studies showed that the feeding-induced stimulation of protein synthesis in skeletal muscle of neonatal pigs is accompanied by enhanced phosphorylation of the eukaryotic initiation factor (eIF)4E-binding protein (4E-BP1) and the ribosomal protein S6 kinase (S6K1). These effects of feeding are substantially reduced with development. The goal of the present investigation was to delineate the basis for the reduced responsiveness to feeding observed in the older animals. In these studies, the content and activity of protein kinases located upstream of S6K1 and 4E-BP1 in signal transduction pathways activated by amino acids, insulin, and insulin-like growth factor I were examined in 7- and 26-day-old pigs that were either fasted overnight or fed porcine milk after an overnight fast. Feeding stimulated phosphatidylinositol (PI) 3-kinase activity to the same extent in muscle of 7- and 26-day-old pigs, suggesting that PI 3-kinase is not limiting in muscle of older animals. In contrast, protein kinase B (PKB) activity was significantly less in muscle from 26- vs. 7-day-old pigs, regardless of nutritional status, suggesting that its activity is regulated by mechanisms distinct from PI 3-kinase. In part, the reduced PKB responsiveness can be attributed to a developmental decline in PKB content. Likewise, muscle content of the protein kinase termed mammalian target of rapamycin (mTOR) in 26-day-old pigs was <25% of that in 7-day-old animals. Finally, in agreement with our earlier work showing that S6K1 phosphorylation is reduced in older animals, S6K1 activity was stimulated to a lesser extent in 26- compared with 7-day-old pigs. Overall, the results suggest that the blunted protein synthetic response observed in 26- vs. 7-day-old neonatal pigs is due in part to decreased content and/or activity of signaling components downstream of PI 3-kinase, e.g., PKB, mTOR, and S6K1.
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Affiliation(s)
- Scot R Kimball
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA.
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