Questions: 

A mitochondrial dysfunction has been described in patients suffering from type 2 diabetes. The present study investigated the influence of regular physical exercise on the adaptation of signalling molecules involved in mitochondrial biogenesis (PGC1a, NRF1, TFAm) in skeletal muscle in type 2 diabetic patients.

Methods: 

Data were obtained from 16 non-insulin-dependent diabetic men (NIDDM) (61±7 yrs) and 7 non-diabetic men (NDM) (53±6 yrs). Half of the NIDDM took part in endurance and the other half in strength training. Muscle fiber diameter, muscle fibre type determination (myosin ATPase staining) and protein content analysis (immunhistochemichal stainings) of peroxisome proliferator-activated receptor gamma coactivator 1a (PGC1a), Nuclear respiratory factor-1(NRF1) and mitochondrial transcription factor A (TFAm) were performed in biopsies from M. vastus lateralis.

Results: 

Under basal conditions, differences were observed neither in muscle fibre type distribution nor in NRF1density between NIDDM and NDM. 8-isoprostane, PGC1a and TFAm were decreased in NIDDM compared to NDM. Regular endurance training significantly increased type 1 fibres, whereas strength training slightly ncreased typ 2b fibres. Fibre diameter 8-isoprostane, PGC1a or TFAm were not altered by the training. The protein contents of NRF1 were decreased in NIDDM after both physical intervention programmes. Changes in mean values did not differ between the training groups.

Conclusions: 

Non-insulin-dependent diabetes mellitus type 2 is associated with a down-regulation of the PGC1a and TFAm expression, NRF1 is not altered at this early stage. Endurance and strength training at moderate intensity two times a week over a period of three months does not restore the diabetic downregulation of PGC1a and TFAm but further induces a downregulation of NRF1.