Creatine increases muscle fiber size in embryonic chick muscle cells and age-dependent swimming performance in zebrafish

Creatine supplementation for human health and exercise performance has been widely studied in recent years, yet several aspects related to its use remain unsolved. Several biological models have been studied, since each model has particular advantages. Here, we sought to investigate comparatively the effects of creatine in two well-established vertebrate muscle models: in vitro chick muscle cell culture and in vivo zebrafish. Chick (Gallus gallus) myogenic cell culture is a robust system for studies of skeletal muscle cells without the interference of other tissues and/or organs. On the other hand, zebrafish (Danio rerio) have the advantage of being an in vivo whole organism with high genetic homology with humans and particularly convenient to test physical performance (swimming). We analyzed the effects of creatine in these two models using confocal fluorescence microscopy of chick cultured cells and automatic detection and tracking of individual zebrafish movement in real-time video imaging. Our results show that creatine supplementation enhances myogenesis through the formation of larger striated muscle fibers, compared to untreated chick cultures. Furthermore, creatine supplementation for 8 weeks induces a significant increase in swimming performance in aged zebrafish, compared to younger fish. This data adds to the wealth of information regarding the use of creatine as a supplement for the improvement of exercise training and muscle performance.