Effect of swimming on myostatin expression in white and red gastrocnemius muscle

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Exp Physiol. 2006 Jul 27

Effect of swimming on myostatin expression in white and red

gastrocnemius muscle and in cardiac muscle of the rats.

Matsakas A, Bozzo C, Cacciani N, Caliaro F, Reggiani C, Mascarello F,

Patruno M.

University of Padua.

The aim of this study was to test the hypothesis that swim training

might differentially impact myostatin expression in skeletal muscles

depending on fibre type composition and in cardiac muscle of the rat.

Myostatin expression was analysed by Real time PCR, Western blot and

immuno-histochemistry in red deep portion (mainly composed of slow

and 2A fibres) and in the superficial white (composed of fast 2X and

2B fibres) portion of the gastrocnemius muscle in adult male Wistar

rats i) subjected to two consecutive swimming bouts for 3 hours, ii)

subjected to an intensive swimming training for four weeks and iii)

in control sedentary rats.

Myostatin mRNA content was in all cases higher in white than in red

muscles. Two bouts of swimming did not alter myostatin expression,

whereas swimming training for 4 weeks resulted in a significant

reduction of myostatin mRNA contents, significant both in white and

red muscles but more pronounced in white muscles. Western blot did

not detect any change in the amount of myostatin protein.

Immunohistochemistry showed that, in control rats, myostatin was

localised in presumptive satellite cells of a few muscle fibres.

After training the number of myostatin positive spots decreased

significantly. Myostatin mRNA content in cardiac muscle was lower

than in skeletal muscle and was significantly increased by swimming

training.

In conclusion, the results obtained showed that intense training

caused a decreased expression of myostatin mRNA in white and red

skeletal muscles but determined an increase in cardiac muscle.