HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 292/5/E1474    most recent 00292.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Faraut, B. Articles by Bendahan, D. Search for Related Content PubMed PubMed Citation Articles by Faraut, B. Articles by Bendahan, D.

Downregulation of uncoupling protein-3 in vivo is linked to changes in muscle mitochondrial energy metabolism as a result of capsiate administration

¹Centre de Résonance Magnétique Biologique et Médicale, Faculté de Médecine de Marseille, France; and ²Institut de Biologie du Développement de Marseille Luminy, Université de la Méditerranée, Marseille, France

Submitted 20 June 2006 ; accepted in final form 24 January 2007

Although it has been suggested that the skeletal muscle mitochondrial uncoupling protein-3 (UCP3) is involved in regulating energy expenditure, its role is still poorly understood. In the present study, we aimed at investigating noninvasively, using magnetic resonance techniques, metabolic changes occurring in exercising muscle as a result of capsiate treatment, which has been previously linked to UCP3 upregulation. We showed that capsiate ingestion strongly reduced UCP3 gene expression in rat gastrocnemius muscle. This large underexpression was accompanied by a significant increase in the rate of mitochondrial ATP production and phosphocreatine level both at rest and during muscle stimulation. Similarly, the stimulation-induced ATP fall and ADP accumulation were significantly less after capsiate administration than in untreated rats. The larger oxidative ATP production rate could not be explained by a proportional decrease in the anaerobic component, i.e., glycolysis and phosphocreatine breakdown. In addition, the mechanical performance was not affected by capsiate administration. Finally, the plasma free fatty acid (FFA) level increased in capsiate-treated rats, whereas no significant change was observed after muscle stimulation in the control group. Considering the corresponding enhanced UCP3 mRNA expression occurring in the control group after muscle stimulation, one can suggest that changes in FFA level and UCP3 mRNA expression are not mechanistically correlated. Overall, we have shown that capsiate administration induced a UCP3 downregulation coupled with an increased mitochondrial ATP synthesis, whereas the muscle force-generating capacity was unchanged. This suggests that a decrease in muscle efficiency and/or additional noncontractile ATP-consuming mechanisms result from UCP3 downregulation.

energy expenditure; skeletal muscle contraction; uncoupling proteins

This article has been cited by other articles:

				T. Marqueste, B. Giannesini, Y. L. Fur, P. J. Cozzone, and D. Bendahan Comparative MRI analysis of T2 changes associated with single and repeated bouts of downhill running leading to eccentric-induced muscle damage J Appl Physiol, July 1, 2008; 105(1): 299 - 307. [Abstract] [Full Text] [PDF]