Excessive alcohol consumption is a leading cause of death and disability globally and can lead to diseases such as alcoholic skeletal myopathy. Skeletal muscle is the largest organ in the human body and functions to regulate whole-body energy homeostasis. Additionally, skeletal muscle can function as an endocrine organ via secretion of myokines. Two myokines, myonectin and irisin, present a wide range of effects upon metabolism, inflammation, and tissue survival- signaling. We hypothesized that chronic alcohol consumption will result in reduced circulating myonectin and irisin levels. Mice were fed an ethanol-containing or control diet for 10 days or 6 weeks. Tissues and serum were collected from mice and immunoblotting was used to quantify myonectin and irisin levels. Our data demonstrated that neither a 10 day nor 6-week ethanol diet was effective in altering myonectin levels, whereas irisin was undetectable. Therefore, we conclude that these myokines are not affected by alcohol consumption.

No / Skeletal muscle has long been established as a highly multifunctional organ, playing a vital role in locomotion, whole-body metabolic and energy homeostasis, and thermoregulation. More recently, emergent evidence has highlighted a potent secretory role for muscle, producing and releasing “myokine” molecules that act in autocrine, paracrine, or endocrine fashion to govern muscle physiology and regulate whole-body homeostasis via multi-tissue cross talk mechanisms. Myokines represent promising therapeutic targets in health and disease, with their discovery, measurement, and functional importance being a hotbed of research across numerous physiological contexts. Here, we provide an overview of myokines and summarize current understanding of their biological role(s). We also outline primary approaches for myokine analysis, including detailed methodology for performing omics-driven myokine prediction, while further appraising both method-specific and general technical considerations to provide an evidence-based approach for designing and conducting myokine experiments.

La Neuréguline 1 (NRG1) est une cytokine appartenant à la famille des facteurs decroissance. Pouvant être libéré par la contraction musculaire, elle fut récemment décritecomme une myokine. Au-delà de son rôle dans les processus de croissance et de maturation,la NRG1 favorise la régulation du métabolisme du glucose in vitro. L’objectif de ce travailétait d’étudier l’influence des pathologies métaboliques et de l’entrainement sur la voie dela NRG1 ainsi que son rôle physiologique dans la régulation du métabolisme énergétique.Nos résultats ont montré que la voie de la NRG1 n’était pas modifiée chez des rats rendusobèses par un régime enrichi lipides et en glucides. A l’inverse, l’entrainement en endurancecouplé à un régime équilibré favorise l’activation de la voie de la NRG1 dans le musclesquelettique de rats obèses. En effet, une période d’entrainement de huit semaines associéà un régime équilibré permet le clivage de la NRG1 et l’activation de son récepteur ErbB4dans le muscle gastrocnémien de rats obèses via l’activation de la métalloprotéase ADAM17.De plus, un traitement en chronique ou en aigu favorise la captation du glucose chez lasouris obèse et diabétique (db/db). Les mécanismes sous-tendant ce phénomèneimpliquerait l’activation du récepteur ErbB3 et l’activation des protéines FOXO1 et Akt dansle foie. Cependant, le traitement à la NRG1 ne modifie la dépense énergétique, la prisealimentaire et la composition alimentaire des souris db/db. Ainsi, il apparait que la NRG1pourrait jouer un rôle important dans la régulation du métabolisme glucidique in vivo chezen condition de pathologies métaboliques et que l’entrainement pourrait activer cette voiedans le muscle squelettique. / Neuregulin 1 (NRG1) is a cytokine that belongs to the epidermal growth factors family. NRG1can be released during exercise and can be define as a myokine. Initially studied for its rolein growth and maturation, NRG1 can also regulate glucose homeostasis in vitro. Thus, theaim of this work was to investigate the effect of training and metabolic disorders on NRG1pathway and its role in energy metabolism. Results showed that NRG1 pathway was notaltered in skeletal muscle of obese rats. Conversely, endurance training combined with awell-balanced diet improved NRG1 pathway activation in skeletal muscle of obese. Indeed, 8weeks of training and diet increased the cleavage of NRG1 and the activation of its receptorErbB4 through the activation of the metalloprotease ADAM17. Moreover, acute and chronictreatment improved glucose tolerance in diabetic mice (db/db). Acute treatment loweredglycemia by activating ErbB3, Akt and FOXO1 in the livre. Thus, NRG1 might play a key role inthe regulation of glucose homeostasis in people who suffers from metabolic disorders.Training might a good tool to activate this pathway in skeletal muscle.

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