Skeletal Muscle Angiopoietin-Like Protein 4 and Glucose Metabolism in Older Adults after Exercise and Weight Loss

Angiopoietin-like protein 4 (ANGPTL4) is an adipokine that plays an important role in energy homoeostasis and lipid and lipoprotein metabolism. This study was designed to determine the effect of an exercise plus weight loss intervention on ANGPTL4 expression and its relationship with metabolic health. Thirty-five obese sedentary men (n= 18) and postmenopausal women (n= 17), (X +/- SEM, age: 61 +/- 1 years, BMI: 31.3 +/- 0.7 kg/m(2), VO(2)max: 21.7 +/- 0.9 L/kg/min) completed a 6 month program of 3x/week aerobic exercise and 1x/week dietary instruction to induce weight loss (AEX + WL). Participants underwent vastus lateralis muscle biopsies, a hyperinsulinemic-euglycemic clamp, oral glucose tolerance tests and body composition testing. Basal skeletal muscle ANGPTL4 mRNA was lower in men than women (p< 0.01). Peroxisome proliferator-activated receptor (PPAR) alpha (PPAR alpha) mRNA expression was higher in men than women (p< 0.05). There were no significance changes in serum or skeletal muscle ANGPTL4 (basal or insulin-stimulated) or muscle PPAR alpha mRNA expression after AEX + WL. Muscle mRNA ANGPTL4 is correlated with serum ANGPTL4 (r= 0.41,p< 0.05), body fat (r= 0.64,p< 0.0001), and glucose utilization (r= 0.38,p< 0.05). AEX + WL does not change basal or insulin-stimulated skeletal muscle ANGPTL4 mRNA expression, suggesting other factors contribute to improved insulin sensitivity after the loss of body fat and improved fitness.