Effect of chronic exercise on DNA fragmentation and on lipid profiles in rat skeletal muscle

Abstract

The concentration and fatty acid composition of phospholipids in animal cells are important determinants of membrane function. Membrane function may influence apoptosis, a biological process that is crucial for the normal development and function of the body. Few and conflicting data exist regarding the effect of chronic exercise on apoptosis in skeletal muscle, and no data exist regarding the effect of chronic exercise on the fatty acid composition of individual muscle phospholipids. We therefore examined the effects of 8 weeks of voluntary wheel running on DNA fragmentation (an index of apoptosis) and on the concentration and fatty acid composition of individual muscle phospholipids and ceramide (a lipid involved in apoptotic signalling) in rat gastrocnemius muscle by comparing 11 trained and 14 untrained male Wistar rats. The trained animals had significantly (P < 0.05) higher cytochrome c oxidase activity (an index of aerobic adaptation) and lower phosphatidyl inositol concentration compared with their untrained counterparts. Groups did not differ in DNA fragmentation or any other lipid parameter. Our findings suggest that chronic wheel running did not affect apoptosis or the concentration and fatty acid composition of most phospholipids and ceramide in rat gastrocnemius muscle. Given the participation of several phospholipids and ceramide in apoptotic signalling, it appears that the lack of changes in the lipid parameters is in agreement with the lack of change in DNA fragmentation with exercise.

Aerobic Training in Rats Increases Skeletal Muscle Sphingomyelinase and Serine Palmitoyltransferase Activity, While Decreasing Ceramidase Activity

“…The ceramide level does not change in the trained group although the activities of the key enzymes of ceramide metabolism changed. The data regarding the content of ceramide are in agreement with the results reported previously, where 8 week training did not affect the ceramide content in rat gastrocnemius muscle [44]. In human skeletal muscle, training did not change the total ceramide content [27].…”

Decreased DNA fragmentation and apoptotic signaling in soleus muscle of hypertensive rats following 6 weeks of treadmill training

“…sistent with these previous data, we observed a significant exercise training-dependent reduction in DNA fragmentation in soleus of hypertensive rats. Previous research in healthy rats found that regular exercise training nonsignificantly (33%; P ϭ 0.06) reduced skeletal muscle DNA fragmentation (60); however, not all reports support such reductions in healthy muscle (67). The level of DNA fragmentation is relatively low in healthy skeletal muscle (47); thus, further reductions may not be possible or may be below detectable limits.…”

Visualization of dynamic change in contraction-induced lipid composition in mouse skeletal muscle by matrix-assisted laser desorption/ionization imaging mass spectrometry

“…During muscle contractions, plasma FAs are uptaken and/or stored in muscle cells as an important energy source, then lipolyzed to generate energy. Small changes in total lipid amounts with muscle contraction have been detected by conventional biochemical methods such as thin-layer chromatography, [4][5][6], suggesting that dynamic change in lipid composition, rather than lipid amount, occurs during muscle contraction. However, it is poorly understood what type of molecular species is changed by muscle contractions because a valid methodology has not been established.…”