Reprod. Nutr. Dev.
Volume 46, Number 6, November-December 2006
|Page(s)||621 - 632|
|Published online||15 December 2006|
Dietary conjugated linoleic acid has limited effects on tissue protein anabolism in sedentary and exercising adult ratsPhilippe Patureau Miranda, Laurent Mosonia, Marie-Agnès Arnal-Bagnarda, Yannick Faulconnierb, Jean-Michel Chardignya and Yves Chilliardb
a INRA, UMR 1019, Clermont-Ferrand - Theix, 63122 Theix, France; CRNH Auvergne, 63001 Clermont-Ferrand, France
b Unité Recherches sur les Herbivores, Centre INRA de Clermont-Ferrand - Theix, 63122 Theix, France
(Received 14 March 2006; accepted 12 June 2006; published online 15 December 2006)
Abstract - The effects of conjugated linoleic acid isomers (CLA) and endurance training on lean body mass are expected to result from their action on tissue protein metabolism. The aim of this study was to analyze their effects on protein metabolism in 2 muscles, the small intestine and liver of adult rats. Four-month-old male Wistar rats were fed diets containing either no CLA, cis-9, trans-11 CLA isomer (1 g.100 g-1), trans-10, cis-12 CLA isomer (1 g.100 g-1) or both isomers (1 g.100 g-1 each) for 6 weeks. Half of the rats were subjected to endurance training by running on a treadmill. At the end of this period, the rats were injected with a flooding dose of 13C-valine to determine protein synthesis rates in the post-absorptive (experiment 1) and in the post-prandial (experiment 2) states. No effect of CLA or endurance training were detected in the small intestine. Training reduced food intake and protein synthesis rates in the liver but no effect was found on the protein synthesis rates in muscles. In the post-absorptive state, protein synthesis rate was increased by feeding the trans-10, cis-12 CLA isomer alone in the liver (+9%) or in combination with the cis-9, trans-11 isomer in the gastrocnemius (+30%), mostly in sedentary rats. In the post-prandial state, the cis-9, trans-11 CLA isomer tended to reduce the protein synthesis rate in the gastrocnemius muscle. However, no effect of CLA was found on muscle protein amounts. In conclusion, CLA isomers would have limited but differential effects on tissue protein metabolism in adult rats.
Key words: conjugated linoleic acid / protein metabolism / exercise / muscle / liver / intestine
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© INRA, EDP Sciences 2006