Influence of physical exercise on polyamine synthesis in the rat skeletal muscle

Background Physical exercise and testosterone administration result in a se ries of adaptive anabolic phenomena in the skeletal muscle. The role of pol yamines in these processes has been poorly explored. Design We measured the activities of polyamine-synthesising enzymes, ornith ine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) and polyamine content in skeletal muscle of male rats exposed to endurance or r esistance exercise, or a single testosterone treatment. Soleus muscle (cons isting mainly of slow-twitching oxidative fibres-STO) and extensor digitoru m longus (mainly fast-twitching glycolytic muscle fibres-FTG) were analysed for polyamine content by HPLC, and ODC and SAMDC activity. Results Both endurance and resistance exercise induced a threefold increase in endogenous testosterone production. Two hours after exercise, ODC was i ncreased in STO fibres, returning to baseline after 24 h; in FTG fibres the increase was less prominent. An increase in SAMDC activity occurred in a m ore sustained manner, with its peak 8 h after exercise. Polyamines were sub sequently accumulated in both skeletal muscle fibres, with a rise in putres cine concentration after 2 h, and a fall corresponding to conversion of put rescine to spermidine and spermine by SAMDC. Single dose of 17 alpha-methyl testosterone resulted in a similar increase in polyamine-synthesising enzym e activities and polyamine concentrations in the skeletal muscle. Conclusion Polyamine accumulation in the skeletal muscle after physical exe rcise is likely to occur secondary to testosterone production. Polyamines a re apparently involved in the oxidative, but not in glycolytic processes re lated to muscle adaptation to exercise.