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Sepúlveda-Lara A, Sepúlveda P, Marzuca-Nassr GN. Resistance Exercise Training as a New Trend in Alzheimer's Disease Research: From Molecular Mechanisms to Prevention. Int J Mol Sci 2024; 25:7084. [PMID: 39000191 PMCID: PMC11241132 DOI: 10.3390/ijms25137084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 06/17/2024] [Accepted: 06/20/2024] [Indexed: 07/16/2024] Open
Abstract
Alzheimer's disease is a pathology characterized by the progressive loss of neuronal connections, which leads to gray matter atrophy in the brain. Alzheimer's disease is the most prevalent type of dementia and has been classified into two types, early onset, which has been associated with genetic factors, and late onset, which has been associated with environmental factors. One of the greatest challenges regarding Alzheimer's disease is the high economic cost involved, which is why the number of studies aimed at prevention and treatment have increased. One possible approach is the use of resistance exercise training, given that it has been shown to have neuroprotective effects associated with Alzheimer's disease, such as increasing cortical and hippocampal volume, improving neuroplasticity, and promoting cognitive function throughout the life cycle. However, how resistance exercise training specifically prevents or ameliorates Alzheimer's disease has not been fully characterized. Therefore, the aim of this review was to identify the molecular basis by which resistance exercise training could prevent or treat Alzheimer's disease.
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Affiliation(s)
- Alexis Sepúlveda-Lara
- Doctorado en Ciencias mención Biología Celular y Molecular Aplicada, Facultad de Ciencias Agropecuarias, Universidad de La Frontera, Temuco 4811230, Chile;
| | - Paulina Sepúlveda
- Departamento de Ciencias Preclínicas, Facultad de Medicina, Universidad de La Frontera, Temuco 4811230, Chile;
| | - Gabriel Nasri Marzuca-Nassr
- Departamento de Ciencias de la Rehabilitación, Facultad de Medicina, Universidad de la Frontera, Temuco 4811230, Chile
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Scervino MVM, Fortes MAS, Vitzel KF, de Souza DR, Murata GM, Santana GO, da Silva EB, Levada‐Pires AC, Kuwabara WMT, Loureiro TCA, Curi R. Autophagy signaling in hypertrophied muscles of diabetic and control rats. FEBS Open Bio 2023; 13:1709-1722. [PMID: 37470707 PMCID: PMC10476571 DOI: 10.1002/2211-5463.13677] [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: 12/21/2022] [Revised: 07/05/2023] [Accepted: 07/19/2023] [Indexed: 07/21/2023] Open
Abstract
Autophagy plays a vital role in cell homeostasis by eliminating nonfunctional components and promoting cell survival. Here, we examined the levels of autophagy signaling proteins after 7 days of overload hypertrophy in the extensor digitorum longus (EDL) and soleus muscles of control and diabetic rats. We compared control and 3-day streptozotocin-induced diabetic rats, an experimental model for type 1 diabetes mellitus (T1DM). EDL muscles showed increased levels of basal autophagy signaling proteins. The diabetic state did not affect the extent of overload-induced hypertrophy or the levels of autophagy signaling proteins (p-ULK1, Beclin-1, Atg5, Atg12-5, Atg7, Atg3, LC3-I and II, and p62) in either muscle. The p-ULK-1, Beclin-1, and p62 protein expression levels were higher in the EDL muscle than in the soleus before the hypertrophic stimulus. On the contrary, the soleus muscle exhibited increased autophagic signaling after overload-induced hypertrophy, with increases in Beclin-1, Atg5, Atg12-5, Atg7, Atg3, and LC3-I expression in the control and diabetic groups, in addition to p-ULK-1 in the control groups. After hypertrophy, Beclin-1 and Atg5 levels increased in the EDL muscle of both groups, while p-ULK1 and LC3-I increased in the control group. In conclusion, the baseline EDL muscle exhibited higher autophagy than the soleus muscle. Although TDM1 promotes skeletal muscle mass loss and strength reduction, it did not significantly alter the extent of overload-induced hypertrophy and autophagy signaling proteins in EDL and soleus muscles, with the two groups exhibiting different patterns of autophagy activation.
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Affiliation(s)
- Maria V. M. Scervino
- Instituto de Ciências da Atividade Física e Esporte (ICAFE)Universidade Cruzeiro do SulSão PauloBrazil
- Departmento de Fisiologia e Biofísica, Instituto de Ciências BiomédicasUniversidade de São PauloBrazil
| | - Marco A. S. Fortes
- Departmento de Fisiologia e Biofísica, Instituto de Ciências BiomédicasUniversidade de São PauloBrazil
- Departmento de NutriçãoCentro Universitário AvantisBalneário CamburiúBrazil
| | - Kaio F. Vitzel
- School of Health Sciences, College of HealthMassey UniversityAucklandNew Zealand
| | - Diego R. de Souza
- Instituto de Ciências da Atividade Física e Esporte (ICAFE)Universidade Cruzeiro do SulSão PauloBrazil
- Departamento de Projetos de Pesquisa e EnsinoEscola de Educação Física da Polícia Militar do Estado de São PauloBrazil
| | - Gilson M. Murata
- Departmento de Fisiologia e Biofísica, Instituto de Ciências BiomédicasUniversidade de São PauloBrazil
| | - Giovanna O. Santana
- Instituto de Ciências da Atividade Física e Esporte (ICAFE)Universidade Cruzeiro do SulSão PauloBrazil
| | - Eliane B. da Silva
- Instituto de Ciências da Atividade Física e Esporte (ICAFE)Universidade Cruzeiro do SulSão PauloBrazil
| | - Adriana C. Levada‐Pires
- Instituto de Ciências da Atividade Física e Esporte (ICAFE)Universidade Cruzeiro do SulSão PauloBrazil
| | - Wilson M. T. Kuwabara
- Departmento de Fisiologia e Biofísica, Instituto de Ciências BiomédicasUniversidade de São PauloBrazil
| | - Tatiana C. A. Loureiro
- Departmento de Fisiologia e Biofísica, Instituto de Ciências BiomédicasUniversidade de São PauloBrazil
| | - Rui Curi
- Instituto de Ciências da Atividade Física e Esporte (ICAFE)Universidade Cruzeiro do SulSão PauloBrazil
- Departmento de Fisiologia e Biofísica, Instituto de Ciências BiomédicasUniversidade de São PauloBrazil
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Yang X, Wang L, Zhang L, Zhai X, Sheng X, Quan H, Lin H. Exercise mitigates Dapagliflozin-induced skeletal muscle atrophy in STZ-induced diabetic rats. Diabetol Metab Syndr 2023; 15:154. [PMID: 37438792 PMCID: PMC10337193 DOI: 10.1186/s13098-023-01130-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 07/01/2023] [Indexed: 07/14/2023] Open
Abstract
BACKGROUND Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are commonly used in the management of type 2 diabetes mellitus (T2DM) and have been found to worsen the reduction of skeletal muscle mass in individuals with T2DM. This study aims to examine the potential of exercise in mitigating the skeletal muscle atrophy induced by SGLT2i treatment. METHODS A rat model of T2DM (40 male Sprague-Dawley rats; T2DM induced by a combination of high-fat diet and streptozotocin) was used to examine the effects of six-week treatment with Dapagliflozin (DAPA, SGLT2i) in combination with either aerobic exercise (AE) or resistance training (RT) on skeletal muscle. T2DM-eligible rats were randomized into the T2DM control group (CON, n = 6), DAPA treatment group (DAPA, n = 6), DAPA combined with aerobic exercise intervention group (DAPA + AE, n = 6), and DAPA combined with resistance training intervention group (DAPA + RT, n = 6). To assess the morphological changes in skeletal muscle, myosin ATPase and HE staining were performed. mRNA expression levels of Atrogin-1, MuRF1, and Myostatin were determined using quantitative PCR. Furthermore, protein expression levels of AKT, p70S6K, mTOR, FoXO1/3A, NF-κB, and MuRF1 were examined through western blotting. RESULTS Both the administration of DAPA alone and the combined exercise intervention with DAPA resulted in significant reductions in blood glucose levels and body weight in rats. However, DAPA alone administration led to a decrease in skeletal muscle mass, whereas RT significantly increased skeletal muscle mass and muscle fiber cross-sectional area. The DAPA + RT group exhibited notable increases in both total protein levels and phosphorylation levels of AKT and p70S6K in skeletal muscle. Moreover, the DAPA, DAPA + AE, and DAPA + RT groups demonstrated downregulation of protein expression (FoXO1/3A) and mRNA levels (Atrogin-1, MuRF1, and Myostatin) associated with muscle atrophy. CONCLUSIONS Our findings provide support for the notion that dapagliflozin may induce skeletal muscle atrophy through mechanisms unrelated to protein metabolism impairment in skeletal muscle, as it does not hinder protein metabolic pathways while reduces muscle atrophy-related genes. Additionally, our observations reveal that RT proves more effective than AE in enhancing skeletal muscle mass and muscle fiber cross-sectional area in rats with T2DM by stimulating protein anabolism within the skeletal muscle.
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Affiliation(s)
- Xudong Yang
- College of Physical Education and Health Sciences, Zhejiang Normal University, Jinhua, Zhejiang, China
- Exercise and Metabolism Research Center, Zhejiang Normal University, Jinhua, Zhejiang, China
| | - Lifeng Wang
- College of Physical Education and Health Sciences, Zhejiang Normal University, Jinhua, Zhejiang, China
- Exercise and Metabolism Research Center, Zhejiang Normal University, Jinhua, Zhejiang, China
| | - Liangzhi Zhang
- College of Physical Education and Health Sciences, Zhejiang Normal University, Jinhua, Zhejiang, China
- Exercise and Metabolism Research Center, Zhejiang Normal University, Jinhua, Zhejiang, China
| | - Xia Zhai
- Medical Molecular Biology Laboratory, School of Medicine, Jinhua Polytechnic, Jinhua, Zhejiang, China
| | - Xiusheng Sheng
- Medical Molecular Biology Laboratory, School of Medicine, Jinhua Polytechnic, Jinhua, Zhejiang, China
| | - Helong Quan
- Exercise and Metabolism Research Center, Zhejiang Normal University, Jinhua, Zhejiang, China.
- School of Sports Science and Physical Education, Research Center of Sports and Health Science, Northeast Normal University, 5268 Renmin Street, Changchun, Jilin, 130024, China.
| | - Hengjun Lin
- Department of Colorectal anal surgery, Jinhua people's hospital, 267 Danxi East Road, Jinhua, Zhejiang, 321007, China.
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Cao Q, Zhang X, Xie F, Li Y, Lin F. Long-noncoding RNA HOXA transcript at the distal tip ameliorates the insulin resistance and hepatic gluconeogenesis in mice with gestational diabetes mellitus via the microRNA-423-5p/wingless-type MMTV integration site family member 7A axis. Bioengineered 2022; 13:13224-13237. [PMID: 35642360 PMCID: PMC9275933 DOI: 10.1080/21655979.2022.2076982] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Long-noncoding RNA HOXA transcript at the distal tip (HOTTIP) has been probed to exert essential effects on diabetes progression, while its function in gestational diabetes mellitus (GDM) remains unclear. This study was committed to unravel the effects of HOTTIP on GDM progression via the microRNA (miR)-423-5p/wingless-type MMTV integration site family member 7A (WNT7A) axis. The GDM mouse model was established. HOTTIP, miR-423-5p and WNT7A levels in GDM mice were examined. The saline with dissolved various constructs altering HOTTIP, miR-423-5p and WNT7A expression was injected into GDM mice to detect the levels of GDM‐related biochemical indices, HOMA indices, liver gluconease: expression levels of phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphatase (G-6-Pase), glucose transporter 2 (GLUT2) and pathological changes of pancreatic tissues, and the apoptosis rate of pancreatic cells in GDM mice. The relations among HOTTIP, miR-423-5p and WNT7A were validated. HOTTIP and WNT7A levels were decreased while miR-423-5p was elevated in GDM mice. The enriched HOTTIP or silenced miR-423-5p alleviated the levels of GDM‐relatedbiochemical indices, enhanced the insulin homeostasis, elevated GLUT2 expression and decreased G-6-pase and PEPCK expression, mitigated the pathological changes of pancreatic tissues, and hindered the apoptosis of pancreatic cells. MiR-143-5p upregulation abrogated the effects of elevated HOTTIP on repressing GDM; whereas WNT7A deletion reversed the therapeutic effects of reduced miR-423-5p. HOTTIP sponged miR-423-5p that targeted WNT7A. HOTTIP ameliorates insulin resistance and hepatic gluconeogenesis in GDM mice via the modulation of the miR-423-5p/WNT7A axis. This study affords novel therapeutic modalities for GDM treatment.
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Affiliation(s)
- Qianqian Cao
- Department of Gynecology and Obstetrics, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Xiaojie Zhang
- Department of Gynecology and Obstetrics, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Fengfeng Xie
- Department of Gynecology and Obstetrics, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yangping Li
- Department of Gynecology and Obstetrics, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Feng Lin
- Department of Gynecology and Obstetrics, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
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Yin L, Li N, Jia W, Wang N, Liang M, Yang X, Du G. Skeletal muscle atrophy: From mechanisms to treatments. Pharmacol Res 2021; 172:105807. [PMID: 34389456 DOI: 10.1016/j.phrs.2021.105807] [Citation(s) in RCA: 88] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/03/2021] [Accepted: 08/07/2021] [Indexed: 02/07/2023]
Abstract
Skeletal muscle is a crucial tissue for movement, gestural assistance, metabolic homeostasis, and thermogenesis. It makes up approximately 40% of the total body weight and 50% of total protein. However, several pathological abnormalities (e.g., chronic diseases, cancer, long-term infection, aging) can induce an imbalance in skeletal muscle protein synthesis and degradation, which triggers muscle wasting and even leads to atrophy. Skeletal muscle atrophy is characterized by weakening, shrinking, and decreasing muscle mass and fiber cross-sectional area at the histological level. It manifests as a reduction in force production, easy fatigue and decreased exercise capability, along with a lower quality of life. Mechanistically, there are several pathophysiological processes involved in skeletal muscle atrophy, including oxidative stress and inflammation, which then activate signal transduction, such as the ubiquitin proteasome system, autophagy lysosome system, and mTOR. Considering the great economic and social burden that muscle atrophy can inflict, effective prevention and treatment strategies are essential but still limited. Exercise is widely acknowledged as the most effective therapy for skeletal muscle atrophy; unfortunately, it is not applicable for all patients. Several active substances for skeletal muscle atrophy have been discovered and evaluated in clinical trials, however, they have not been marketed to date. Knowledge is being gained on the underlying mechanisms, highlighting more promising treatment strategies in the future. In this paper, the mechanisms and treatment strategies for skeletal muscle atrophy are briefly reviewed.
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Affiliation(s)
- Lin Yin
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Drug Target and Screening Research, Institute of Materia Medica of Peking Union Medical College, 1 Xian Nong Tan Street, Beijing 100050, PR China
| | - Na Li
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Drug Target and Screening Research, Institute of Materia Medica of Peking Union Medical College, 1 Xian Nong Tan Street, Beijing 100050, PR China
| | - Weihua Jia
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Drug Target and Screening Research, Institute of Materia Medica of Peking Union Medical College, 1 Xian Nong Tan Street, Beijing 100050, PR China
| | - Nuoqi Wang
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Drug Target and Screening Research, Institute of Materia Medica of Peking Union Medical College, 1 Xian Nong Tan Street, Beijing 100050, PR China
| | - Meidai Liang
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Drug Target and Screening Research, Institute of Materia Medica of Peking Union Medical College, 1 Xian Nong Tan Street, Beijing 100050, PR China
| | - Xiuying Yang
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Drug Target and Screening Research, Institute of Materia Medica of Peking Union Medical College, 1 Xian Nong Tan Street, Beijing 100050, PR China.
| | - Guanhua Du
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Drug Target and Screening Research, Institute of Materia Medica of Peking Union Medical College, 1 Xian Nong Tan Street, Beijing 100050, PR China.
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Nemoto A, Goyagi T. Tail suspension is useful as a sarcopenia model in rats. Lab Anim Res 2021; 37:7. [PMID: 33441192 PMCID: PMC7805154 DOI: 10.1186/s42826-020-00083-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/29/2020] [Indexed: 12/21/2022] Open
Abstract
Background Sarcopenia promotes skeletal muscle atrophy and exhibits a high mortality rate. Its elucidation is of the highest clinical importance, but an animal experimental model remains controversial. In this study, we investigated a simple method for studying sarcopenia in rats. Results Muscle atrophy was investigated in 24-week-old, male, tail-suspended (TS), Sprague Dawley and spontaneously hypertensive rats (SHR). Age-matched SD rats were used as a control group. The skeletal muscle mass weight, muscle contraction, whole body tension (WBT), cross-sectional area (CSA), and Muscle RING finger-1 (MuRF-1) were assessed. Enzyme-linked immunosorbent assay was used to evaluate the MuRF-1 levels. Two muscles, the extensor digitorum longus and soleus muscles, were selected for representing fast and slow muscles, respectively. All data, except CSA, were analyzed by a one-way analysis of variance, whereas CSA was analyzed using the Kruskal-Wallis test. Muscle mass weight, muscle contraction, WBT, and CSA were significantly lower in the SHR (n = 7) and TS (n = 7) groups than in the control group, whereas MuRF-1 expression was dominant. Conclusions TS and SHR presented sarcopenic phenotypes in terms of muscle mass, muscle contraction and CSA. TS is a useful technique for providing muscle mass atrophy and weakness in an experimental model of sarcopenia in rats.
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Affiliation(s)
- Akira Nemoto
- Department of Anesthesia and Intensive Care Medicine, Akita University Graduate School of Medicine, 1-1-1, Hondo, Akita, 010-0843, Japan
| | - Toru Goyagi
- Department of Anesthesia and Intensive Care Medicine, Akita University Graduate School of Medicine, 1-1-1, Hondo, Akita, 010-0843, Japan.
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de Souza DR, Vasconcelos DAAD, Murata GM, Fortes MAS, Marzuca-Nassr GN, Levada-Pires AC, Vitzel KF, Abreu P, Scervino MVM, Hirabara SM, Curi R, Pithon-Curi TC. Glutamine supplementation versus functional overload in extensor digitorum longus muscle hypertrophy. PHARMANUTRITION 2020. [DOI: 10.1016/j.phanu.2020.100236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Abstract
Sarcopenia as a progressive and generalized skeletal muscle disorder that is associated with an increased likelihood of adverse outcomes, including falls, fractures, physical disability, and mortality. On the other hand, an age-related decline in muscle strength prior to the reduction of muscle mass, is proposed to be "dynapenia". Sarcopenia and dynapenia have recently been recognized as a diabetic complications in type 2 diabetes. We firstly indicated that sarcopenia was frequently observed in 16.6% of patients with type 1 diabetes aged even over 40 years. Additionally, we recently reported that the prevalence rate of dynapenia was higher than sarcopenia in patients with type 2 diabetes. Chronic hyperglycemia accelerates accumulation of advanced glycation end products (AGEs), which causes diabetic vascular complications through oxidative stress and chronic inflammation. We also demonstrated that skin autofluorescence (AF) as a marker of AGEs, was the independent determinant for skeletal muscle mass and strength in patients with type 2 diabetes and muscle strength in type 1 diabetes. Therefore, the early diagnosis of muscle weakness is essential for patients with diabetes and sustained good glycemic control with exercise and dietary intervention might be beneficial to prevent the progression of muscle weakness in these patients.
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Marzuca-Nassr GN, Vitzel KF, Murata GM, Márquez JL, Curi R. Experimental Model of HindLimb Suspension-Induced Skeletal Muscle Atrophy in Rodents. Methods Mol Biol 2019; 1916:167-176. [PMID: 30535694 DOI: 10.1007/978-1-4939-8994-2_16] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Due to the difficulty of performing research protocols that reproduce human skeletal muscle disuse conditions, an experimental animal model of "hindlimb suspension" (or hindlimb unloading) was developed. This method was created in the 1970s and utilizes rats and mice to mimic space flight and bed rest in humans. It provides an alternative to investigate mechanisms associated with skeletal muscle mass loss and interventions designed to attenuate atrophy induced by hindlimb unloading. The mentioned protocol also allows investigating quality of bones and changes in several physiological parameters such as blood pressure, heart rate, plasma or tissue lipid composition, and glycemia.
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Affiliation(s)
| | - Kaio Fernando Vitzel
- School of Health Sciences, College of Health, Massey University, Auckland, New Zealand
| | | | - José Luis Márquez
- Faculty of Medical Sciences, School of Kinesiology, Universidad de Santiago de Chile, Santiago, Chile
| | - Rui Curi
- Interdisciplinary Post-Graduate Program in Health Sciences, Cruzeiro do Sul University, Sao Paulo, Brazil
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Wang C, Deng Y, Yue Y, Chen W, Zhang Y, Shi G, Wu Z. Glutamine Enhances the Hypoglycemic Effect of Insulin in L6 Cells via Phosphatidylinositol-3-Kinase (PI3K)/Protein Kinase B (AKT)/Glucose Transporter 4 (GLUT4) Signaling Pathway. Med Sci Monit 2018; 24:1241-1250. [PMID: 29491345 PMCID: PMC5842660 DOI: 10.12659/msm.909011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Background Diabetes mellitus (DM) is characterized by a decreased blood level of glutamine (Gln), which may contribute to the disturbance in the effect of insulin on skeletal muscle. Therefore, it is crucial to study how to improve the effect of insulin on skeletal muscle by increasing Gln. In the present study, we investigated the effect of Gln on the hypoglycemic action of insulin in skeletal muscle L6 cells at high glucose levels through the insulin signaling pathway and glycogen synthesis pathway. Material/Methods The L6 cells were cultured in and stimulated by Gln and insulin. The glutamine analogue, L-Gamma-Glutamyl-p-nitroanilide (GPNA), was used for verifying the effect of Gln. The expression of insulin signaling molecules, including phosphatidylinositol-3-kinase (PI3K), 3-phosphoinositide-dependent protein kinase-1 (PDK1), protein kinase B (AKT), protein kinase C zeta (PKCζ), and glucose transporter 4 (GLUT4), were detected by real-time PCR and Western blot analysis, GLUT4 translocation was observed by immunofluorescence staining, glycogen synthase kinase (GSK) was analyzed by Western blotting, and glucose uptake was measured by glucose oxidase method (GOD). Results The results demonstrated that Gln combined with insulin remarkably up-regulated PI3K and PDK1 and also increased AKT and PKCζ phosphorylation. The present study shows that Gln enhanced the impact of insulin on GLUT4 and its translocation. The results of glucose uptake and GSK phosphorylation further confirmed the hypoglycemic effect of Gln accompanied with insulin. The hypoglycemic effect of Gln was reversed by GPNA. Conclusions These findings suggest that Gln enhances the hypoglycemic role of insulin through the PI3K/AKT/GLUT4 signaling pathway and glycogen synthesis pathway.
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Affiliation(s)
- Caijuan Wang
- Tianjin Key Laboratory of Metabolic Diseases, Tianjin Metabolic Diseases Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China (mainland)
| | - Yujiao Deng
- Tianjin Key Laboratory of Metabolic Diseases, Tianjin Metabolic Diseases Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China (mainland)
| | - Yenan Yue
- Tianjin Key Laboratory of Metabolic Diseases, Tianjin Metabolic Diseases Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China (mainland)
| | - Wenting Chen
- Tianjin Key Laboratory of Metabolic Diseases, Tianjin Metabolic Diseases Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China (mainland)
| | - Yu Zhang
- Tianjin Key Laboratory of Metabolic Diseases, Tianjin Metabolic Diseases Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China (mainland)
| | - Guifang Shi
- Tianjin Key Laboratory of Metabolic Diseases, Tianjin Metabolic Diseases Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China (mainland)
| | - Zhongming Wu
- Tianjin Key Laboratory of Metabolic Diseases, Tianjin Metabolic Diseases Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China (mainland)
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