Omega‐3 multiple effects increasing glucocorticoid‐induced muscle atrophy: autophagic, AMPK and UPS mechanisms

Muscle atrophy occurs in many conditions, including use of glucocorticoids. N‐3 (omega‐3) is widely consumed due its healthy properties; however, concomitant use with glucocorticoids can increase its side effects. We evaluated the influences of N‐3 on glucocorticoid atrophy considering IGF‐1, Myostatin, MEK/ERK, AMPK pathways besides the ubiquitin‐proteasome system (UPS) and autophagic/lysosomal systems. Sixty animals constituted six groups: CT, N‐3 (EPA 100 mg/kg/day for 40 days), DEXA 1.25 (DEXA 1.25 mg/kg/day for 10 days), DEXA 1.25 + N3 (EPA for 40 days + DEXA 1.25 mg/kg/day for the last 10 days), DEXA 2.5 (DEXA 2.5 mg/kg/day for 10 days), and DEXA 2.5 + N3 (EPA for 40 days + DEXA 2.5 mg/kg/day for 10 days). Results: N‐3 associated with DEXA increases atrophy (fibers 1 and 2A), FOXO3a, P‐SMAD2/3, Atrogin‐1/MAFbx (mRNA) expression, and autophagic protein markers (LC3II, LC3II/LC3I, LAMP‐1 and acid phosphatase). Additionally, N‐3 supplementation alone decreased P‐FOXO3a, PGC1‐alpha, and type 1 muscle fiber area. Conclusion: N‐3 supplementation increases muscle atrophy caused by DEXA in an autophagic, AMPK and UPS process.