| dc.description.abstract | Two experiments were conducted to demonstrate functional G-coupled protein receptor 43 (GPR43) and GPR120 activity in bovine intramuscular (i.m.) and subcutaneous (s.c.) adipose tissues. We hypothesized that media volatile fatty acids and long- chain fatty acids (LCFA) would affect cAMP concentration, glycerol concentration, and free fatty acid (FFA) concentration differently in i.m. and s.c. adipose tissues taken from steers at 20, 22, 24 mo of age. Fresh s.c. and i.m. adipose tissue from the 5th to 8th longissimus thoracic rib muscle section of Angus crossbred steers was transferred immediately to 6-well culture plates containing 3 mL of KHB/Hepes/5 mM glucose. Samples were preincubated with 0.5 mM theophylline plus 10 μM forskolin for 30 min, after which increasing concentrations of acetate or propionate (0, 1, 5, and 10 mM) in the absence or the presence of 100 μM oleic acid (18:1 n-9) or 100 μM palmitic acid (16:0) were added to the incubation media. In s.c. adipose tissue, cAMP production decreased in the presence of LCFA (P < 0.0001), suggesting that LCFA may induce lipid filling in s.c. adipose tissue, which is consistent with GPR120 receptor activity. At 22 mo of age, the addition of VFAs in the presence of LCFA effectively decreased cAMP production (P = 0.03), indicating increased lipid accumulation at 22 mo of age (P = 0.03). Free fatty acid concentration in the absence of LCFA was greater in i.m. adipose tissue at 22 mo of age (P < 0.0001). The relative expression of GPR120 was greater in s.c adipose tissue than i.m. adipose tissue (P = 0.05). These results provide evidence for functional GPR43 receptors in i.m. adipose tissue and GPR120 receptors in s.c. adipose tissue, both of which suppress lipolysis. | |
