Effect of Pre-Slaughter Autophagic Status on Postmortem Proteolysis in Skeletal Muscle of Mice

Post mortem proteolysis is a key event during the aging process, where muscle converts to meat. However, its precise mechanism remains unclear. In this study, the effects of pre-slaughter autophagic status on post mortem proteolysis were investigated using mouse skeletal muscle. Mice were fasted for 14 h and administered with or without the autophagy inhibitor wortmannin, whereas control mice were given free access to diet. Skeletal muscle samples were collected and stored at 4°C. Muscle proteins were extracted at several time points, followed by evaluation of microtubule-associated protein Light Chain 3 (LC3)-II expression as an autophagic marker and of post mortem changes in water-soluble proteins by High Performance Liquid Chromatography (HPLC) analysis. Mice fasted before sacrifice showed significantly higher expression of LC3-II than control mice and this effect was inhibited by the administration of wortmannin. Results on HPLC analysis indicated typical post mortem changes in water-soluble muscle proteins and these changes were accelerated when autophagy was induced by starvation. In addition, the administration of wortmannin canceled acceleration of post mortem changes by starvation. These findings could suggest that autophagy is a mediator of post mortem proteolysis in skeletal muscle and contributes to meat quality.