Group 1B Phospholipase A₂–Mediated Lysophospholipid Absorption Directly Contributes to Postprandial Hyperglycemia

Abstract

Postprandial hyperglycemia is an early indicator of abnormality in glucose metabolism leading to type 2 diabetes. However, mechanisms that contribute to postprandial hyperglycemia have not been identified. This study showed that mice with targeted inactivation of the group 1B phospholipase A₂ (Pla2g1b) gene displayed lower postprandial glycemia than that observed in wild-type mice after being fed a glucose-rich meal. The difference was caused by enhanced postprandial glucose uptake by the liver, heart, and muscle tissues as well as altered postprandial hepatic glucose metabolism in the Pla2g1b^−/− mice. These differences were attributed to a fivefold decrease in the amount of dietary phospholipids absorbed as lysophospholipids in Pla2g1b^−/− mice compared with that observed in Pla2g1b^+/+ mice. Elevating plasma lysophospholipid levels in Pla2g1b^−/− mice via intraperitoneal injection resulted in glucose intolerance similar to that exhibited by Pla2g1b^+/+ mice. Studies with cultured hepatoma cells revealed that lysophospholipids dose-dependently suppressed insulin-stimulated glycogen synthesis. These results demonstrated that reduction of lysophospholipid absorption enhances insulin-mediated glucose metabolism and is protective against postprandial hyperglycemia.