Effects of Dietary γ-Linolenic Acid on Insulin- Responsive Glucose Transporter (GLUT 4) Protein Expression in Pigs

Recent study has revealed that dietary γ-linolenic acid (GLA, 18:3(n-6)) reduces body fat contents and enhances activities of liver carnitine palmitoyltransferase and peroxisomal β-oxidation. However, we considered that GLA might affect not only enzymes involved in lipid metabolism but also in glucose metabolism. Insulin-responsive glucose transporter (GLUT 4) represents the rate-limiting step in glucose metabolism and considered to have an important role for energy accumulation. Present study was conducted to determine whether GLA affects GLUT 4 protein expression in pig tissues. Nine pigs (70kg, castrated males) were allotted to two groups and fed either 90g/day GLA-enriched oil (n=5) or soybean oil (n=4, control) with a formula diet for 6 weeks. The GLA-enriched oil contained 25.3% GLA of fatty acids. The GLUT 4 protein levels were determined by immunoblotting using GLUT 4 antiserum and an enhanced chemiluminescent (ECL) system. GLA treatment significantly reduced GLUT 4 protein contents in M. vastus lateralis compared with control (P