Contrasting response of polyamine metabolic enzymes underlying fiber-type specific volume regulation in the skeletal muscle with endurance exercise.

To explore the role of polyamine metabolism in muscle-type-specific hypertrophy, we analyzed changes in the expression profiles of polyamine metabolic enzymes and key enzymes for muscle metabolism induced by voluntary wheel running exercise in different muscle types. Effect of the polyamine precursor, putrescine, which was reported to have potential to regulate muscle volume, was also tested. Polyamine synthetic enzymes were upregulated in hypertrophic soleus muscle whereas polyamine catabolic enzymes were upregulated in non-hypertrophic plantar muscle by exercise in correlation with increased mitochondria-related protein expression. The increased catabolic enzymes of polyamines in the plantar muscle were hypothesized to be possibly involved in restriction of hypertrophy in fast-type skeletal muscles correlating with increased aerobic metabolism. Putrescine administration minimally affected polyamine metabolism and muscle volume indicating that it did not effectively regulate muscle hypertrophy. Polyamine oxidase localized in the perinuclear and inter-myofibrillar region suggesting a correlation between aerobic metabolism and polyamine catabolism.