GPR120 Gene expression and activity in subcutaneous and intramuscular adipose tissues of Angus crossbred steers.

We measured the mRNA abundance and activity of the fatty acid receptor, G protein-coupled receptor 120 (GPR120) in bovine subcutaneous and intramuscular (marbling) adipose tissue. The GPR120 receptor binds to long-chain fatty acids, which reduces cyclic adenosine monophosphate (cAMP) production, thereby decreasing lipolysis. The mRNA amount of GPR120 was similar between subcutaneous and intramuscular adipose tissues. In subcutaneous and intramuscular adipose tissue incubated in vitro, the fatty acids oleic acid and palmitic acid (the most abundant fatty acids in bovine adipose tissue) strongly depressed the production of cAMP and glycerol in subcutaneous adipose tissue and decreased the concentration of free fatty acids in intramuscular adipose tissue (all measured with commercial kits). This indicates that elevations in adipose tissue or plasma fatty acids may promote fat accumulation by decreasing the breakdown of stored lipids via GPR120. The volatile fatty acids acetate and propionate, which bind to G protein-coupled receptor 43 (GPR43) had no effect on cAMP, glycerol, or free fatty acids. This questions the role of GPR43 in the accumulation of adipose tissue lipids in growing steers.