The Study
The Beta-adrenergic agonist, Ractopamine, increases skeletal muscle expression of Asparagine Synthetase as part of an integrated stress response gene program
This study watched what happened to pig muscles after giving them a special feed additive. It saw that certain genes and proteins changed, but it didn’t prove the additive caused those changes — it just showed they happened together.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
Scientists gave pigs a drug that makes them grow more muscle, and found it didn't just build muscle — it also tricked their muscles into thinking they were stressed, turning on genes that help make amino acids and build proteins.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 519 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1This suggests the drug doesn't just boost muscle growth — it also triggers a hidden stress response that may limit or regulate how fast muscle can grow.
- 2At day 3, ASNS gene expression increased 5th most among all genes; ASNS protein rose by day 7 (p<0.05).
- 3Over 20 stress-response genes (like Sesn2, Cdkn1a) and 6 tRNA synthetases were turned on.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Scientific Reports
Year
2018
Authors
David M. Brown, K. Ryan, Z. Daniel, M. Mareko, R. Talbot, J. Moreton, Tom C. B. Giles, Richard D Emes, C. Hodgman, T. Parr, J. Brameld
Related Content
Claims (6)
Administering beta-agonists to cattle results in increased lean muscle mass and higher body weight by stimulating adrenergic pathways.
Ractopamine exposure in pigs increases the activity of over 20 genes controlled by ATF4, including asparagine synthetase, sestrin-2, and aminoacyl-tRNA synthetases, in skeletal muscle, which reflects activation of the integrated stress response pathway.
Ractopamine raises the levels of sestrin-2 and Cdkn1a messenger RNA in pig skeletal muscle.
In pigs, ractopamine changes the activity of muscle genes differently than recombinant growth hormone, resulting in stronger changes in genes related to amino acid metabolism and stress response.
Feeding growing female pigs ractopamine at 20 parts per million for up to 27 days increases the levels of asparagine synthetase mRNA and protein in the Longissimus Dorsi muscle, with mRNA levels highest on day 3 and protein levels elevated by day 7.
Ractopamine administration in pigs increases the levels of six specific messenger RNA molecules involved in protein synthesis in skeletal muscle within three days, reflecting a measurable increase in the cellular machinery for building proteins.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.