eCite Digital Repository
Beta2 -adrenergic agonist clenbuterol increases energy expenditure and fat oxidation, and induces mTOR phosphorylation in skeletal muscle of young healthy men
Citation
Jessen, S and Solheim, SA and Jacobson, GA and Eibye, K and Bangsbo, J and Nordsborg, NB and Hostrup, M, Beta2 -adrenergic agonist clenbuterol increases energy expenditure and fat oxidation, and induces mTOR phosphorylation in skeletal muscle of young healthy men, Drug Testing and Analysis, 12, (5) pp. 610-618. ISSN 1942-7603 (2020) [Refereed Article]
Copyright Statement
Copyright 2019 John Wiley & Sons, Ltd.
DOI: doi:10.1002/dta.2755
Abstract
Clenbuterol is a beta2-adrenoceptor agonist marketed as an asthma reliever but is
not approved for human use in most countries due to concerns of adverse cardiac
effects. Given its demonstrated hypertrophic and lipolytic actions in rodents,
clenbuterol is one of the most widely abused doping substances amongt athletes and
recreational body-builders seeking leanness. Herein, we examined the effect of
clenbuterol ingestion on metabolic rate as well as skeletal muscle mammalian target
of rapamycin (mTOR) phosphorylation and protein kinase A (PKA)-signaling in six
young men. Before and 140 min after ingestion of 80 μg clenbuterol, resting metabolic rate and contractile function of the quadriceps muscle were measured, and
blood samples as well as vastus lateralis muscle biopsies were collected. Clenbuterol
increased resting energy expenditure by 21% (P < 0.001), and fat oxidation by 39%
(P = 0.006), whereas carbohydrate oxidation was unchanged. Phosphorylation of
mTORSer2448 and PKA substrates increased by 121% (P = 0.004) and 35%
(P = 0.006), respectively, with clenbuterol. Maximal voluntary contraction torque
decreased by 4% (P = 0.026) and the half-relaxation time shortened by 9%
(P = 0.046), while voluntary activation, time to peak twitch, and peak twitch torque
did not change significantly with clenbuterol. Glycogen content of the vastus lateralis
muscle did not change with clenbuterol. Clenbuterol increased circulating levels of
glucose (+30%; P < 0.001), lactate (+90%; P = 0.004), insulin (+130%; P = 0.009), and
fatty acids (+180%; P = 0.001). Collectively, these findings indicate that clenbuterol is
an efficient thermogenic substance that possibly also exerts muscle hypertrophic
actions in humans. For these reasons, the restrictions imposed against clenbuterol in
competitive sports seem warranted.
Item Details
Item Type: | Refereed Article |
---|---|
Keywords: | beta2-agonist, muscle doping, clenbuterol, anabolic, muscle hypertrophy |
Research Division: | Biomedical and Clinical Sciences |
Research Group: | Pharmacology and pharmaceutical sciences |
Research Field: | Pharmacology and pharmaceutical sciences not elsewhere classified |
Objective Division: | Health |
Objective Group: | Clinical health |
Objective Field: | Clinical health not elsewhere classified |
UTAS Author: | Jacobson, GA (Professor Glenn Jacobson) |
ID Code: | 138843 |
Year Published: | 2020 |
Web of Science® Times Cited: | 10 |
Deposited By: | Pharmacy |
Deposited On: | 2020-05-01 |
Last Modified: | 2020-06-17 |
Downloads: | 0 |
Repository Staff Only: item control page