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Inorganic Nitrate Mimics Exercise-Stimulated Muscular Fiber-Type Switching and Myokine and γ-Aminobutyric Acid Release

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Roberts, LD 
Ashmore, T 
McNally, BD 
Murfitt, SA 
Fernandez, BO 

Abstract

Exercise is an effective intervention for the prevention and treatment of type 2 diabetes. Skeletal muscle combines multiple signals that contribute to the beneficial effects of exercise on cardiometabolic health. Inorganic nitrate increases exercise efficiency, tolerance, and performance. The transcriptional regulator peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) coordinates the exercise-stimulated skeletal muscle fiber-type switch from glycolytic fast-twitch (type IIb) to oxidative slow-twitch (type I) and intermediate (type IIa) fibers, an effect reversed in insulin resistance and diabetes. We found that nitrate induces PGC1α expression and a switch toward type I and IIa fibers in rat muscle and myotubes in vitro. Nitrate induces the release of exercise/PGC1α-dependent myokine FNDC5/irisin and β-aminoisobutyric acid from myotubes and muscle in rats and humans. Both exercise and nitrate stimulated PGC1α-mediated γ-aminobutyric acid (GABA) secretion from muscle. Circulating GABA concentrations were increased in exercising mice and nitrate-treated rats and humans; thus, GABA may function as an exercise/PGC1α-mediated myokine-like small molecule. Moreover, nitrate increased circulating growth hormone levels in humans and rodents. Nitrate induces physiological responses that mimic exercise training and may underlie the beneficial effects of this metabolite on exercise and cardiometabolic health.

Description

Keywords

Adipocytes, Aged, Aminoisobutyric Acids, Animals, Beta vulgaris, Chromatography, Liquid, Double-Blind Method, Female, Fibronectins, Fruit and Vegetable Juices, Gas Chromatography-Mass Spectrometry, Growth Hormone, Humans, Immunohistochemistry, In Vitro Techniques, Insulin Resistance, Male, Mass Spectrometry, Mice, Mice, Transgenic, Middle Aged, Muscle Fibers, Fast-Twitch, Muscle Fibers, Skeletal, Muscle Fibers, Slow-Twitch, Muscle, Skeletal, Nitrates, Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha, Physical Conditioning, Animal, Rats, Rats, Wistar, Transcriptome, gamma-Aminobutyric Acid

Journal Title

Diabetes

Conference Name

Journal ISSN

0012-1797
1939-327X

Volume Title

66

Publisher

American Diabetes Association
Sponsorship
Medical Research Council (MR/P011705/1)
Biotechnology and Biological Sciences Research Council (BB/H013539/2)
LDR is supported by the Diabetes UK RD Lawrence Fellowship (16/0005382) and the MRC-HNR Elsie Widdowson Fellowship. This work was supported by the BBSRC (Bb/H013539/2; bb/I000933/I), the British Heart Foundation and the MRC (UD99999906).