Arachidonic acid supplementation enhances in vitro skeletal muscle cell growth via a COX-2-dependent pathway

Abstract

[e.g., prostaglandins (PGs), leukotrienes, and hydroxyeicosatetraenoic acids] has been implicated in skeletal muscle cell growth and development. The collective role of AA-derived metabolites in physiological states of skeletal muscle growth/atrophy remains unclear. The present study aimed to determine the direct effect of free AA supplementation and subsequent eicosanoid biosynthesis on skeletal myocyte growth in vitro. C2C12 (mouse) skeletal myocytes induced to differentiate with supplemental AA exhibited dose-dependent increases in the size, myonuclear content, and protein accretion of developing myotubes, independent of changes in cell density or the rate/extent of myogenic differentiation. Nonselective (indomethacin) or cyclooxygenase 2 (COX-2)-selective (NS-398) nonsteroidal anti-inflammatory drugs blunted basal myogenesis, an effect that was amplified in the presence of supplemental free AA substrate. The stimulatory effects of AA persisted in preexisting myotubes via a COX-2-dependent (NS-389-sensitive) pathway, specifically implying dependency on downstream PG biosynthesis. AAstimulated growth was associated with markedly increased secretion of PGF 2␣ and PGE2; however, incubation of myocytes with PG-rich conditioned medium failed to mimic the effects of direct AA supplementation. In vitro AA supplementation stimulates PG release and skeletal muscle cell hypertrophy via a COX-2-dependent pathway. arachidonic acid; C2C12; growth; nonsteroidal anti-inflammatory drug; skeletal muscle ARACHIDONIC ACID (AA) is a polyunsaturated -6 fatty acid [20:4(6)], present in the diet, that is incorporated into cell membrane phospholipids (PLs) (19). Dietary change elicits rapid alterations in PL fatty acid composition, with supplemental AA increasing plasma PL abundance within days (42). In response to cellular perturbation (e.g., mechanical trauma, cytokines, or growth factors), AA is cleaved from PL molecules via the action of the enzyme PLA 2 . Free intracellular AA serves as a key transient cell-signaling intermediate, undergoing rapid enzymatic conversion to a diverse array of inflammatory autocrine/paracrine eicosanoid lipid mediators. Parallel cyclooxygenase (COX-1/COX-2) and lipoxygenase (5-LOX/ 12-LOX/15-LOX) pathways catalyze the oxidation of AA to ultimately produce the PGs (PGD 2 , PGE 2 , PGF 2␣ , PGI 2 , and thromboxane A 2 ) and the leukotriene (LT)/lipoxin (LX) families of eicosanoids, respectively. Nonsteroidal anti-inflammatory drugs (NSAIDs) are thought to exert their anti-inflammatory, analgesic, and antipyretic action, specifically by inhibition of the COX branch of the AA pathway, indicative of a central role of PG species in mediating the inflammatory response.Skeletal muscle cells express the COX genes COX-1 and COX-2 (49) and locally synthesize/release AA-derived PGs, including PGD 2 (56), PGE 2 /PGF 2␣ (33,40,41,54), and PGI 2 (2). NSAID treatment is associated with deleterious effects on adaptive skeletal muscle growth/regeneration (3, 4, 31, 39 -41, 46), consistent with the inflammatory res...

Cord Blood Metabolome Is Highly Associated with Birth Weight, but Less Predictive for Later Weight Development

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Human inflammatory and resolving lipid mediator responses to resistance exercise and ibuprofen treatment

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Regulation of muscle plasticity and trophism by fatty acids: A short review

“…[7][8][9][10][11] In 1978, Horwitz et al 55 observed that the fatty acids added to the culture medium have a stimulatory effect on the fusion of embryonic myoblasts. The authors observed that the lipid composition of the membrane influences the proliferation and fusion of myoblasts and, consequently, the formation of multinucleated myotubes.…”

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