Postprandial lysophospholipid suppresses hepatic fatty acid oxidation: the molecular link between group 1B phospholipase A2 and diet-induced obesity.

Decrease in fat catabolic rate on consuming a high-fat diet contributes to diet-induced obesity. This study used group 1B phospholipase A₂ (Pla2g1b)-deficient mice, which are resistant to hyperglycemia, to test the hypothesis that Pla2g1b and its lipolytic product lysophospholipid suppress hepatic fat utilization and energy metabolism in promoting dietinduced obesity. The metabolic consequences of hypercaloric diet, including body weight gain, energy expenditure, and fatty acid oxidation, were compared between Pla2g1b^+/+ and Pla2g1b^-/- mice. The Pla2g1b^-/- mice displayed normal energy balance when fed chow, but were resistant to obesity when challenged with a hypercaloric diet. Obesity resistance in Pla2g1b^-/- mice is due to their ability to maintain elevated energy expenditure and core body temperature when subjected to hypercaloric diet, which was not observed in Pla2g1b^+/+ mice. The Pla2g1b^-/- mice also displayed increased postprandial hepatic fat utilization due to increased expression of peroxisome proliferator-activated receptor (PPAR)-α, PPAR-δ, PPAR-γ, cd36/Fat, and Ucp2, which coincided with reduced postprandial plasma lysophospholipid levels. Lysophospholipids produced by Pla2g1b hydrolysis suppress hepatic fat utilization and down-regulate energy expenditure, thereby preventing metabolically beneficial adaptation to a high-fat diet exposure in promoting diet-induced obesity and type 2 diabetes. [ABSTRACT FROM AUTHOR]