Irisin

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Christos S Mantzoros - One of the best experts on this subject based on the ideXlab platform.

  • Irisin in metabolic diseases
    Endocrine, 2018
    Co-Authors: Stergios A Polyzos, Athanasios D Anastasilakis, Jannis Kountouras, Zoe Efstathiadou, Polyzois Makras, N Perakakis, Christos S Mantzoros
    Abstract:

    Irisin is a myokine/adipokine induced by the exercise in mice and humans, which is proposed to induce “browning” of white adipose tissue, its primary target, thus increasing thermogenesis and energy expenditure. Since its identification, Irisin has been linked to favorable effects on metabolic diseases, including obesity, type 2 diabetes mellitus (T2DM), lipid metabolism and cardiovascular disease (CVD), nonalcoholic fatty liver disease (NAFLD), polycystic ovary syndrome (PCOS), and metabolic bone diseases. Generally, despite the promising profile of Irisin in rodents, its effects on human are less recognized. Most, but not all studies show a positive association between Irisin and indices of adiposity. In T2DM, NAFLD, and CVD, most observational studies reported lower Irisin levels in patients than controls. Regarding metabolic bone diseases, Irisin is positively associated with bone mineral density and strength in athletes, and inversely associated with osteoporotic fractures in postmenopausal osteoporosis. In PCOS, data remain largely conflicting. Irisin does not seem to be further reduced when two metabolic diseases, e.g., T2DM and NAFLD, or obesity and NAFLD exist though more data are needed. Furthermore, it seems that diverse confounders may have affected the results of different clinical studies. Irisin remains an appealing molecule from a pathophysiological point of view and an appealing therapeutic target for metabolic diseases, albeit much research is still needed.

  • cord blood Irisin levels are positively correlated with birth weight in newborn infants
    Metabolism-clinical and Experimental, 2015
    Co-Authors: Kyoung Eun Joung, Christos S Mantzoros, Andreas Filippaios, Kyung Hee Park, Fadime Dincer, Helen Christou
    Abstract:

    Abstract Background Irisin is a novel myokine, secreted from skeletal muscle after exercise. Irisin mediates exercise-related energy expenditure by turning white adipose tissue (WAT) into brown adipose tissue (BAT). Thus, Irisin is considered as a potential biomarker for obesity and metabolic syndrome. Infants born small for gestational age (SGA) have increased risk for metabolic syndrome. However, the physiologic role of Irisin in neonates remains to be studied. Objective To evaluate the association of umbilical cord blood Irisin levels with gestational age and birth weight categories in neonates. Methods A cross-sectional study of 341 newborns, from 26 to 41 weeks’ gestation. We collected umbilical cord blood and analyzed plasma for Irisin by ELISA. Results Plasma Irisin levels were positively correlated with gestational age (r = 0.21, p  Conclusions Our results support the notion that Irisin may have a physiologic role in neonates. We speculate that decreased levels of Irisin in SGA infants may contribute to the development of catch-up growth and metabolic syndrome later in life.

  • Irisin in response to exercise in humans with and without metabolic syndrome
    The Journal of Clinical Endocrinology and Metabolism, 2015
    Co-Authors: Aikaterina Siopi, Vassilis Mougios, Christos S Mantzoros, Kyung Hee Park
    Abstract:

    Context: Irisin is a recently identified exercise-induced myokine. However, the circulating levels of Irisin in response to different types of exercise in subjects with metabolic syndrome are unknown. Objective: This study aimed to study the levels of Irisin in healthy males and subjects with metabolic syndrome at baseline and in response to exercise. Design: Each individual completed high-intensity interval exercise (HIIE), continuous moderate-intensity exercise (CME), and resistance exercise (RE) sessions in a random, crossover design. Percentage change in circulating Irisin levels was examined. Two different Irisin assays were used to compare the results of the RE study. Results: Circulating Irisin increased immediately after HIIE, CME, and RE and declined 1 hour later. The increase was greater in response to resistance compared with either high-intensity intermittent exercise or CME. Change in Irisin in response to exercise did not differ between individuals with and without metabolic syndrome. Conclu...

  • The effect of Irisin on antioxidant system in liver.
    Free Radical Biology and Medicine, 2014
    Co-Authors: Saime Batirel, Perinur Bozaykut, Ergul Mutlu Altundag, Nesrin Kartal Ozer, Christos S Mantzoros
    Abstract:

    Abstract Nonalcoholic fatty liver disease (NAFLD) is a global health problem and lead to subacute liver failure, cirrhosis and/or hepatocellular carcinoma. An increased generation of reactive oxygen species (ROS) and antioxidant depletion is found in the liver of obese patients with NAFLD. Irisin is a recently identified exercise-induced myokine. It increases total energy consumption, reduces body weight, and insulin resistance. It was shown that Irisin levels were significantly lower in patients with NAFLD. The aim of the present study was to investigate the effect of Irisin on prooxidant-antioxidant balance in liver. In the first phase; AML12 liver cells were divided into 4 groups: control, hydrogen peroxide (H 2 O 2 )-treated, 10 nM Irisin-treated and 50 nM Irisin-treated groups. ROS accumulation in these groups was analyzed by FACS. In the second phase; to see if there is any protective role of Irisin on ROS production in the liver, AML12 liver cells were divided into 4 groups: control, H 2 O 2 -treated, H 2 O 2 +10 nM Irisin-treated and H 2 O 2 +50 nM-Irisin treated groups. After measuring ROS accumulation again in these groups, the levels of enzymes related with prooxidant-antioxidant balance via oxidative stress in liver were measured by western blotting. In H 2 O 2 treatment groups, ROS production was increased in AML12 liver cells, on the other hand in Irisin treatment groups ROS production was slightly changed. Irisin might be a potential target for metabolic diseases like NAFLD.

  • plasma Irisin levels progressively increase in response to increasing exercise workloads in young healthy active subjects
    European Journal of Endocrinology, 2014
    Co-Authors: Stella S Daskalopoulou, Andreas Filippaios, Alexandra B Cooke, Yessicahaydee Gomez, Andrew F Mutter, Ertirea Tesfamariam Mesfum, Christos S Mantzoros
    Abstract:

    Background: Irisin, a recently discovered myokine, has been shown to induce browning of white adipose tissue, enhancing energy expenditure and mediating some of the beneficial effects of exercise. We aimed to estimate the time frame of changes in Irisin levels after acute exercise and the effect of different exercise workloads and intensities on circulating Irisin levels immediately post-exercise. Methods: In a pilot study, four healthy subjects (22.5G1.7 years) underwent maximal workload exercise (maximal oxygen consumption, VO2 max) and blood was drawn at prespecified intervals to define the time frame of pre- and post-exercise Irisin changes over a 24-h period. In the main study, 35 healthy, non-smoking (23.0G3.3 years) men and women (nZ20/15) underwent three exercise protocols R48-h apart, in random order: i) maximal workload (VO2 max); ii) relative workload (70% of VO2 max/10 min); and iii) absolute workload (75 W/10 min). Blood was drawn immediately pre-exercise and 3 min post-exercise. Results: In the pilot study, Irisin levels increased by 35% 3 min post-exercise, then dropped and remained relatively constant. In the main study, Irisin levels post-exercise were significantly higher than those of pre-exercise after all workloads (all, P!0.001). Post-to-pre-exercise differences in Irisin levels were significantly different between workloads (PZ0.001), with the greatest increase by 34% following maximal workload (PZ0.004 vs relative and absolute). Conclusions: Circulating Irisin levels were acutely elevated in response to exercise, with a greater increase after maximal workload. These findings suggest that Irisin release could be a function of muscle energy demand. Future studies need to determine the underlying mechanisms of Irisin release and explore Irisin's therapeutic potential.

Haibo Song - One of the best experts on this subject based on the ideXlab platform.

  • Irisin mediated protective effect on lps induced acute lung injury via suppressing inflammation and apoptosis of alveolar epithelial cells
    Biochemical and Biophysical Research Communications, 2017
    Co-Authors: Lei Shao, Di Meng, Fei Yang, Haibo Song, Dongqi Tang
    Abstract:

    Abstract It is considered that the essence of acute lung injury (ALI) is an excessive and uncontrolled inflammatory response in lung, of which mainly is attributed to the release of inflammatory mediators. Recent studies demonstrated that Irisin, which is a metabolism associated factor after physical exercise could suppression of inflammation by regulating cellular signaling pathways, however, the underlying molecular mechanism remains to be determined. The present study aimed to reveal the potential mechanism responsible for the anti-inflammatory effects of Irisin on LPS-induced acute lung injury in mice and in A549 cells. The results of histopathological changes showed that Irisin ameliorated the lung injury that was induced by LPS in time- and dose-dependent manner. QRT-PCR assays demonstrated that Irisin suppressed the production of IL-1β, IL-6, MCP-1 and TNF-α, and western blot assays demonstrated that Irisin suppressed apoptosis of ALI. The expression of caspase-3 and Bax were decreased and Bcl-2 was increased by Irisin administration. Further study was conducted on nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK) using pathways using western blots. The results showed that Irisin inhibited reduced LPS-induced activation of MAPK and NF-κB signaling. All results indicated that Irisin has protective effect on LPS-induced ALI in mice and in A549 cells. Thus, irisn related with physical exercise may be a potential therapy for the treatment of pulmonary inflammation.

  • Irisin induces angiogenesis in human umbilical vein endothelial cells in vitro and in zebrafish embryos in vivo via activation of the erk signaling pathway
    PLOS ONE, 2015
    Co-Authors: Fei Wu, Haibo Song, Yuan Zhang, Yuzhu Zhang, Fang Wang, Miao Jiang, Qian Mu, Wen Zhang, Liang Li, Huanjie Li
    Abstract:

    As a link between exercise and metabolism, Irisin is assumed to be involved in increased total body energy expenditure, reduced body weight, and increased insulin sensitivity. Although our recent evidence supported the contribution of Irisin to vascular endothelial cell (ECs) proliferation and apoptosis, further research of Irisin involvement in the angiogenesis of ECs was not conclusive. In the current study, it was found that Irisin promoted Human Umbilical Vein Endothelial Cell (HUVEC) angiogenesis via increasing migration and tube formation, and attenuated chemically-induced intersegmental vessel (ISV) angiogenic impairment in transgenic TG (fli1: GFP) zebrafish. It was further demonstrated that expression of matrix metalloproteinase (MMP) 2 and 9 were also up-regulated in endothelial cells. We also found that Irisin activated extracellular signal–related kinase (ERK) signaling pathways. Inhibition of ERK signaling by using U0126 decreased the pro-migration and pro-angiogenic effect of Irisin on HUVEC. Also, U0126 inhibited the elevated expression of MMP-2 and MMP-9 when they were treated with Irisin. In summary, these findings provided direct evidence that Irisin may play a pivotal role in maintaining endothelium homeostasis by promoting endothelial cell angiogenesis via the ERK signaling pathway.

  • Irisin promotes human umbilical vein endothelial cell proliferation through the erk signaling pathway and partly suppresses high glucose induced apoptosis
    PLOS ONE, 2014
    Co-Authors: Haibo Song, Fei Wu, Yuan Zhang, Yuzhu Zhang, Fang Wang, Miao Jiang, Zhongde Wang, M Zhang, Shiwu Li, Lijun Yang
    Abstract:

    Irisin is a newly discovered myokine that links exercise with metabolic homeostasis. It is involved in modest weight loss and improves glucose intolerance. However, the direct effects and mechanisms of Irisin on vascular endothelial cells (ECs) are not fully understood. In the current study, we demonstrated that Irisin promoted Human Umbilical Vein Endothelial Cell (HUVEC) proliferation. It was further demonstrated that this pro-proliferation effect was mediated by Irisin-induced activation of extracellular signal–related kinase (ERK) signaling pathways. Inhibition of ERK signaling with U0126 decreased the pro-proliferation effect of Irisin on HUVECs. It was also demonstrated that Irisin reduced high glucose-induced apoptosis by up-regulating Bcl-2 expression and down-regulating Bax, Caspase-9 and Caspase-3 expression. In summary, these results suggested that Irisin plays a novel role in sustaining endothelial homeostasis by promoting HUVEC proliferation via the ERK signaling pathway and protects the cell from high glucose-induced apoptosis by regulating Bcl-2,Bax and Caspase expression.

Fei Wu - One of the best experts on this subject based on the ideXlab platform.

  • Irisin induces angiogenesis in human umbilical vein endothelial cells in vitro and in zebrafish embryos in vivo via activation of the erk signaling pathway
    PLOS ONE, 2015
    Co-Authors: Fei Wu, Haibo Song, Yuan Zhang, Yuzhu Zhang, Fang Wang, Miao Jiang, Qian Mu, Wen Zhang, Liang Li, Huanjie Li
    Abstract:

    As a link between exercise and metabolism, Irisin is assumed to be involved in increased total body energy expenditure, reduced body weight, and increased insulin sensitivity. Although our recent evidence supported the contribution of Irisin to vascular endothelial cell (ECs) proliferation and apoptosis, further research of Irisin involvement in the angiogenesis of ECs was not conclusive. In the current study, it was found that Irisin promoted Human Umbilical Vein Endothelial Cell (HUVEC) angiogenesis via increasing migration and tube formation, and attenuated chemically-induced intersegmental vessel (ISV) angiogenic impairment in transgenic TG (fli1: GFP) zebrafish. It was further demonstrated that expression of matrix metalloproteinase (MMP) 2 and 9 were also up-regulated in endothelial cells. We also found that Irisin activated extracellular signal–related kinase (ERK) signaling pathways. Inhibition of ERK signaling by using U0126 decreased the pro-migration and pro-angiogenic effect of Irisin on HUVEC. Also, U0126 inhibited the elevated expression of MMP-2 and MMP-9 when they were treated with Irisin. In summary, these findings provided direct evidence that Irisin may play a pivotal role in maintaining endothelium homeostasis by promoting endothelial cell angiogenesis via the ERK signaling pathway.

  • Irisin promotes human umbilical vein endothelial cell proliferation through the erk signaling pathway and partly suppresses high glucose induced apoptosis
    PLOS ONE, 2014
    Co-Authors: Haibo Song, Fei Wu, Yuan Zhang, Yuzhu Zhang, Fang Wang, Miao Jiang, Zhongde Wang, M Zhang, Shiwu Li, Lijun Yang
    Abstract:

    Irisin is a newly discovered myokine that links exercise with metabolic homeostasis. It is involved in modest weight loss and improves glucose intolerance. However, the direct effects and mechanisms of Irisin on vascular endothelial cells (ECs) are not fully understood. In the current study, we demonstrated that Irisin promoted Human Umbilical Vein Endothelial Cell (HUVEC) proliferation. It was further demonstrated that this pro-proliferation effect was mediated by Irisin-induced activation of extracellular signal–related kinase (ERK) signaling pathways. Inhibition of ERK signaling with U0126 decreased the pro-proliferation effect of Irisin on HUVECs. It was also demonstrated that Irisin reduced high glucose-induced apoptosis by up-regulating Bcl-2 expression and down-regulating Bax, Caspase-9 and Caspase-3 expression. In summary, these results suggested that Irisin plays a novel role in sustaining endothelial homeostasis by promoting HUVEC proliferation via the ERK signaling pathway and protects the cell from high glucose-induced apoptosis by regulating Bcl-2,Bax and Caspase expression.

Kyung Hee Park - One of the best experts on this subject based on the ideXlab platform.

  • cord blood Irisin levels are positively correlated with birth weight in newborn infants
    Metabolism-clinical and Experimental, 2015
    Co-Authors: Kyoung Eun Joung, Christos S Mantzoros, Andreas Filippaios, Kyung Hee Park, Fadime Dincer, Helen Christou
    Abstract:

    Abstract Background Irisin is a novel myokine, secreted from skeletal muscle after exercise. Irisin mediates exercise-related energy expenditure by turning white adipose tissue (WAT) into brown adipose tissue (BAT). Thus, Irisin is considered as a potential biomarker for obesity and metabolic syndrome. Infants born small for gestational age (SGA) have increased risk for metabolic syndrome. However, the physiologic role of Irisin in neonates remains to be studied. Objective To evaluate the association of umbilical cord blood Irisin levels with gestational age and birth weight categories in neonates. Methods A cross-sectional study of 341 newborns, from 26 to 41 weeks’ gestation. We collected umbilical cord blood and analyzed plasma for Irisin by ELISA. Results Plasma Irisin levels were positively correlated with gestational age (r = 0.21, p  Conclusions Our results support the notion that Irisin may have a physiologic role in neonates. We speculate that decreased levels of Irisin in SGA infants may contribute to the development of catch-up growth and metabolic syndrome later in life.

  • Irisin in response to exercise in humans with and without metabolic syndrome
    The Journal of Clinical Endocrinology and Metabolism, 2015
    Co-Authors: Aikaterina Siopi, Vassilis Mougios, Christos S Mantzoros, Kyung Hee Park
    Abstract:

    Context: Irisin is a recently identified exercise-induced myokine. However, the circulating levels of Irisin in response to different types of exercise in subjects with metabolic syndrome are unknown. Objective: This study aimed to study the levels of Irisin in healthy males and subjects with metabolic syndrome at baseline and in response to exercise. Design: Each individual completed high-intensity interval exercise (HIIE), continuous moderate-intensity exercise (CME), and resistance exercise (RE) sessions in a random, crossover design. Percentage change in circulating Irisin levels was examined. Two different Irisin assays were used to compare the results of the RE study. Results: Circulating Irisin increased immediately after HIIE, CME, and RE and declined 1 hour later. The increase was greater in response to resistance compared with either high-intensity intermittent exercise or CME. Change in Irisin in response to exercise did not differ between individuals with and without metabolic syndrome. Conclu...

  • exercise induced Irisin secretion is independent of age or fitness level and increased Irisin may directly modulate muscle metabolism through ampk activation
    The Journal of Clinical Endocrinology and Metabolism, 2014
    Co-Authors: Vassilis Mougios, Athanasios Kabasakalis, Aikaterina Siopi, Ioannis G Fatouros, Ioannis I Douroudos, Andreas Filippaios, Grigorios Panagiotou, Kyung Hee Park, Christos S Mantzoros
    Abstract:

    CONTEXT: Irisin has been proposed to be a myokine mediating the effect of exercise on adipocyte browning. The physiology of Irisin in humans is not completely understood. OBJECTIVE: To study the physiology of Irisin in healthy individuals with different age and fitness levels and to explore the direct effects of Irisin on muscle metabolism. DESIGN, SETTING, AND SUBJECTS: Treadmill exercise studies were conducted to measure circulating Irisin at baseline and in response to exercise among old and young, physically active and sedentary individuals. Also, high- and moderate-intensity swimming was performed in adolescent men and women to study the effect of exercise intensity and the time course of Irisin induction by acute bouts of exercise. Human myotubes were treated with recombinant Irisin, and the effect on gene expression, cell signaling, and metabolism was examined. RESULTS: Baseline circulating Irisin was lower in old (vs young) and physically active (vs sedentary) subjects. Despite differences in basal levels, the percentage increase of Irisin by acute bouts of exercise was not related to age or fitness level. The time course study revealed that circulating Irisin increased immediately after high-intensity interval exercise and declined 1 hour thereafter. In vitro experiments showed that Irisin facilitates glucose and lipid metabolism in human muscle through AMP kinase phosphorylation. CONCLUSIONS: Despite the differences in basal Irisin levels, exercise-induced Irisin secretion is independent of age or fitness level. Increased Irisin can directly modulate muscle metabolism through AMP kinase activation.

  • exercise induced Irisin secretion is independent of age or fitness level and increased Irisin may directly modulate muscle metabolism through ampk activation
    The Journal of Clinical Endocrinology and Metabolism, 2014
    Co-Authors: Vassilis Mougios, Athanasios Kabasakalis, Aikaterina Siopi, Ioannis G Fatouros, Ioannis I Douroudos, Andreas Filippaios, Grigorios Panagiotou, Kyung Hee Park, Christos S Mantzoros
    Abstract:

    Context: Irisin has been proposed to be a myokine mediating the effect of exercise on adipocyte browning. The physiology of Irisin in humans is not completely understood. Objective: To study the physiology of Irisin in healthy individuals with different age and fitness levels and to explore the direct effects of Irisin on muscle metabolism. Design, Setting, and Subjects: Treadmill exercise studies were conducted to measure circulating Irisin at baseline and in response to exercise among old and young, physically active and sedentary individuals. Also, high- and moderate-intensity swimming was performed in adolescent men and women to study the effect of exercise intensity and the time course of Irisin induction by acute bouts of exercise. Human myotubes were treated with recombinant Irisin, and the effect on gene expression, cell signaling, and metabolism was examined. Results: Baseline circulating Irisin was lower in old (vs young) and physically active (vs sedentary) subjects. Despite differences in basa...

  • circulating Irisin in relation to insulin resistance and the metabolic syndrome
    The Journal of Clinical Endocrinology and Metabolism, 2013
    Co-Authors: Kyung Hee Park, Kyoung Eun Joung, Mary Brinkoetter, Lesya Zaichenko, Bindiya Thakkar, Ayse Sahinefe, Michael A Tsoukas, Eleni Geladari
    Abstract:

    Context: Irisin, a recently identified hormone, has been proposed to regulate energy homeostasis and obesity in mice. Whether Irisin levels are associated with risk of the metabolic syndrome (MetS), cardiometabolic variables, and cardiovascular disease (CVD) risk in humans remains unknown. Objective: Our objective was to assess the associations between baseline serum Irisin levels and MetS, cardiometabolic variables, and CVD risk. Design, Setting, and Subjects: We conducted a comparative cross-sectional evaluation of baseline circulating levels of the novel hormone Irisin and the established adipokine adiponectin with MetS, cardiometabolic variables, and CVD risk in a sample of 151 subjects. Results: Baseline Irisin levels were significantly higher in subjects with MetS than in subjects without MetS. Irisin was associated negatively with adiponectin (r = −0.4, P < .001) and positively with body mass index (r = 0.22, P = .008), systolic (r = 0.17, P = .04) and diastolic (r = 0.27, P = .001) blood pressure,...

Vassilis Mougios - One of the best experts on this subject based on the ideXlab platform.

  • Irisin in response to exercise in humans with and without metabolic syndrome
    The Journal of Clinical Endocrinology and Metabolism, 2015
    Co-Authors: Aikaterina Siopi, Vassilis Mougios, Christos S Mantzoros, Kyung Hee Park
    Abstract:

    Context: Irisin is a recently identified exercise-induced myokine. However, the circulating levels of Irisin in response to different types of exercise in subjects with metabolic syndrome are unknown. Objective: This study aimed to study the levels of Irisin in healthy males and subjects with metabolic syndrome at baseline and in response to exercise. Design: Each individual completed high-intensity interval exercise (HIIE), continuous moderate-intensity exercise (CME), and resistance exercise (RE) sessions in a random, crossover design. Percentage change in circulating Irisin levels was examined. Two different Irisin assays were used to compare the results of the RE study. Results: Circulating Irisin increased immediately after HIIE, CME, and RE and declined 1 hour later. The increase was greater in response to resistance compared with either high-intensity intermittent exercise or CME. Change in Irisin in response to exercise did not differ between individuals with and without metabolic syndrome. Conclu...

  • exercise induced Irisin secretion is independent of age or fitness level and increased Irisin may directly modulate muscle metabolism through ampk activation
    The Journal of Clinical Endocrinology and Metabolism, 2014
    Co-Authors: Vassilis Mougios, Athanasios Kabasakalis, Aikaterina Siopi, Ioannis G Fatouros, Ioannis I Douroudos, Andreas Filippaios, Grigorios Panagiotou, Kyung Hee Park, Christos S Mantzoros
    Abstract:

    CONTEXT: Irisin has been proposed to be a myokine mediating the effect of exercise on adipocyte browning. The physiology of Irisin in humans is not completely understood. OBJECTIVE: To study the physiology of Irisin in healthy individuals with different age and fitness levels and to explore the direct effects of Irisin on muscle metabolism. DESIGN, SETTING, AND SUBJECTS: Treadmill exercise studies were conducted to measure circulating Irisin at baseline and in response to exercise among old and young, physically active and sedentary individuals. Also, high- and moderate-intensity swimming was performed in adolescent men and women to study the effect of exercise intensity and the time course of Irisin induction by acute bouts of exercise. Human myotubes were treated with recombinant Irisin, and the effect on gene expression, cell signaling, and metabolism was examined. RESULTS: Baseline circulating Irisin was lower in old (vs young) and physically active (vs sedentary) subjects. Despite differences in basal levels, the percentage increase of Irisin by acute bouts of exercise was not related to age or fitness level. The time course study revealed that circulating Irisin increased immediately after high-intensity interval exercise and declined 1 hour thereafter. In vitro experiments showed that Irisin facilitates glucose and lipid metabolism in human muscle through AMP kinase phosphorylation. CONCLUSIONS: Despite the differences in basal Irisin levels, exercise-induced Irisin secretion is independent of age or fitness level. Increased Irisin can directly modulate muscle metabolism through AMP kinase activation.

  • exercise induced Irisin secretion is independent of age or fitness level and increased Irisin may directly modulate muscle metabolism through ampk activation
    The Journal of Clinical Endocrinology and Metabolism, 2014
    Co-Authors: Vassilis Mougios, Athanasios Kabasakalis, Aikaterina Siopi, Ioannis G Fatouros, Ioannis I Douroudos, Andreas Filippaios, Grigorios Panagiotou, Kyung Hee Park, Christos S Mantzoros
    Abstract:

    Context: Irisin has been proposed to be a myokine mediating the effect of exercise on adipocyte browning. The physiology of Irisin in humans is not completely understood. Objective: To study the physiology of Irisin in healthy individuals with different age and fitness levels and to explore the direct effects of Irisin on muscle metabolism. Design, Setting, and Subjects: Treadmill exercise studies were conducted to measure circulating Irisin at baseline and in response to exercise among old and young, physically active and sedentary individuals. Also, high- and moderate-intensity swimming was performed in adolescent men and women to study the effect of exercise intensity and the time course of Irisin induction by acute bouts of exercise. Human myotubes were treated with recombinant Irisin, and the effect on gene expression, cell signaling, and metabolism was examined. Results: Baseline circulating Irisin was lower in old (vs young) and physically active (vs sedentary) subjects. Despite differences in basa...

  • Irisin in response to acute and chronic whole body vibration exercise in humans
    Metabolism-clinical and Experimental, 2014
    Co-Authors: Vassilis Mougios, Athanasios Skraparlis, Athanasios Kabasakalis, Christos S Mantzoros
    Abstract:

    Abstract Objective Irisin is a recently identified myokine, suggested to mediate the beneficial effects of exercise by inducing browning of white adipocytes and thus increasing energy expenditure. In humans, the regulation of Irisin by exercise is not completely understood. We investigated the effect of acute and chronic whole-body vibration exercise, a moderate-intensity exercise that resembles shivering, on circulating Irisin levels in young healthy subjects. Materials/Methods Healthy untrained females participated in a 6-week program of whole-body vibration exercise training. Blood was drawn before and immediately after an acute bout of exercise at baseline (week 0) and after 6 weeks of training. Results The resting Irisin levels were not different at baseline (week 0) and after 6 weeks of training. At both 0 and 6 weeks of training, an acute bout of vibration exercise significantly elevated circulating Irisin levels by 9.5% and 18.1%, respectively ( p  = 0.05 for the percent change of Irisin levels). Conclusions Acute bouts of whole-body vibration exercise are effective in increasing circulating Irisin levels but chronic training does not change levels of baseline Irisin levels in humans.

  • Irisin in response to acute and chronic whole-body vibration exercise in humans
    Metabolism: Clinical and Experimental, 2014
    Co-Authors: Joo Young Huh, Athanasios Skraparlis, Athanasios Kabasakalis, Vassilis Mougios, Christos S Mantzoros
    Abstract:

    Objective Irisin is a recently identified myokine, suggested to mediate the beneficial effects of exercise by inducing browning of white adipocytes and thus increasing energy expenditure. In humans, the regulation of Irisin by exercise is not completely understood. We investigated the effect of acute and chronic whole-body vibration exercise, a moderate-intensity exercise that resembles shivering, on circulating Irisin levels in young healthy subjects. Materials/Methods Healthy untrained females participated in a 6-week program of whole-body vibration exercise training. Blood was drawn before and immediately after an acute bout of exercise at baseline (week 0) and after 6 weeks of training. Results The resting Irisin levels were not different at baseline (week 0) and after 6 weeks of training. At both 0 and 6 weeks of training, an acute bout of vibration exercise significantly elevated circulating Irisin levels by 9.5% and 18.1%, respectively (p = 0.05 for the percent change of Irisin levels). Conclusions Acute bouts of whole-body vibration exercise are effective in increasing circulating Irisin levels but chronic training does not change levels of baseline Irisin levels in humans. © 2014 Elsevier Inc.