Dietary fish oil alleviates soleus atrophy during immobilization in association with Akt signaling to p70s6k and E3 ubiquitin ligases in rats.
Level 5 - mechanism / opinion, no new human data
Animal study (rodent hindlimb immobilization model)
PubMed 20555375 · doi:10.1139/H10-022
What was done
Rats were fed either a control corn-oil-based diet or a fish-oil-based diet rich in long-chain n-3 polyunsaturated fatty acids for 2 weeks. Rats were then subjected to 10 days of hindlimb immobilization while continuing their respective diets. Researchers evaluated soleus muscle mass, myosin heavy chain levels, Akt and p70 S6 kinase activation, gene expression of E3 ubiquitin ligases (MAFbx and MuRF1), IRS-1 association with the p85 subunit of PI3K, and inflammatory markers (COX-2 and iNOS).
What was found
The abstract does not provide exact numerical values or effect sizes. It reports that 10 days of immobilization caused a marked decrease in soleus muscle mass and myosin heavy chain levels in control rats, whereas these losses were significantly suppressed in fish-oil-fed rats. Fish oil nearly completely attenuated disuse-induced disturbances in Akt and p70 S6 kinase activation, suppressed MAFbx and MuRF1 upregulation, and inhibited changes in COX-2 and iNOS expression without altering IRS-1/p85 association.
Why it matters
This study provides mechanistic preclinical evidence that dietary omega-3 fatty acids may protect against disuse-induced skeletal muscle atrophy by maintaining Akt/p70s6k signaling and suppressing muscle-specific ubiquitin ligase expression.
Limits
The study was conducted in a rodent hindlimb immobilization model, so findings cannot be directly translated to human clinical immobilization or disuse conditions. Exact sample sizes, baseline animal characteristics, and quantitative measurements (magnitudes of mass loss and protein expression changes) were omitted from the abstract.
Cited by
- supports Rodents fed a high-fish-oil diet are protected against disuse muscle atrophy.