Changes in the composition of fatty acids of total lipids in various tissues and serum due to physical training and food restriction in the rat

Abstract

Rats, 5 weeks of age, were subjected to 8 weeks of intensive treadmill running to study the effect of physical training on the fatty acid composition of total lipids in various tissues and serum. In liver and adipose tissue the percentage of longer chain and polyunsaturated fatty acids increased. In skeletal and cardiac muscle a significant lower content of palmitoleic and higher content of stearic acid could be found, respectively. Sedentary rats (pair-fed for weight to trained rats) with a food restriction of 24% fatty acids with shorter hydrocarbon chains showed increases in liver and adipose tissue as compared to rats fed ad libitum. Mono-unsaturated fatty acid had a higher and polyunsaturated fatty acids a lower percentage (only in liver) in these tissues. No significant differences could be found in skeletal and cardiac muscle. It is suggested that adaptations in the fatty acid pattern in liver and adipose tissue are due to stimulated chain elongation, polydesaturation, and/or depressed monodesaturation as a result of physical training. Dietary restriction of 24% induces inverse effects. Changes in the composition of fatty acids in adipose tissue do not reflect those in serum. Probably they are the consequence of similar mechanism(s) as in the liver. The minor changes in muscle tissues may be explained by a low activity of chain elongation and desaturation and a high oxidation rate of fatty acids in these tissues which may counteract each other in some way.

Key Words:

• chain elongation
• desaturation
• exercise
• fatty acids
• oxidation