Preferential utilisation of perilipin 2 associated intramuscular triglycerides during one hour of moderate intensity endurance-type exercise

The lipid droplet (LD)-associated protein perilipin 2 (PLIN2) appears to colocalise with LDs in human skeletal muscle fibres, although the function of PLIN2 in the regulation of intramuscular triglyceride (IMTG) metabolism is currently unknown. Here we investigated the hypothesis that the presence of PLIN2 in skeletal muscle LDs helps to increase lipolysis during exercise. We, therefore, measured exercise-induced changes in IMTG and PLIN2 distribution and changes in their colocalisation. Muscle biopsies from the vastus lateralis were obtained from 7 lean, untrained males (22±2 years, BMI 24.2±0.9 kg.m(-2), VO(2peak) 3.35±0.13 L.min(-1)) before and after 1 h of moderate intensity cycling at ~65% VO(2peak). Cryosections were stained for perilipin 2, IMTG, and myosin heavy chain type I and viewed using widefield and confocal fluorescence microscopy. Exercise induced a 50±7% decrease in IMTG content in type I fibres only (P