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This Article Full Text Full Text (PDF) All Versions of this Article: 293/3/R1086    most recent 00128.2007v1 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 ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ocloo, A. Articles by Brand, M. D. Search for Related Content PubMed PubMed Citation Articles by Ocloo, A. Articles by Brand, M. D.

APPETITE, OBESITY, DIGESTION, AND METABOLISM

Cold-induced alterations of phospholipid fatty acyl composition in brown adipose tissue mitochondria are independent of uncoupling protein-1

¹Medical Research Council Dunn Human Nutrition Unit, Cambridge, United Kingdom; and ²The Wenner-Gren Institute, The Arrhenius Laboratories, Stockholm University, Stockholm, Sweden

Submitted 22 February 2007 ; accepted in final form 3 July 2007

The recruitment process induced by acclimation of mammals to cold includes a marked alteration in the acyl composition of the phospholipids of mitochondria from brown adipose tissue: increases in 18:0, 18:2(n–6), and 20:4(n–6) and decreases in 16:0, 16:1, 18:1, and 22:6(n–3). A basic question is whether these alterations are caused by changes in the concentration of uncoupling protein-1 (UCP1) or the thermogenesis it mediates—implying that they are secondary effects—or whether they are an integrated, independent part of the recruitment process. This question was addressed here using wild-type and UCP1-ablated C57BL/6 mice acclimated to 24°C or 4°C. In wild-type mice, the phospholipid fatty acyl composition of mitochondria from brown adipose tissue showed the changes in response to cold that were expected from observations in other species and strains. The changes were specific, as different changes occurred in skeletal muscle mitochondria. In UCP1-ablated mice, cold acclimation induced acyl alterations in brown adipose tissue that were qualitatively identical and quantitatively similar to those in wild-type mice. Therefore, neither the increased content of UCP1 nor mitochondrial uncoupling altered the effect of cold on acyl composition. Cold acclimation in wild-type mice had little effect on phospholipid acyl composition in muscle mitochondria, but cold-acclimation in UCP1-ablated mice caused significant alterations, probably due to sustained shivering. Thus, the alterations in brown adipose tissue phospholipid acyl composition are revealed to be an independent part of the recruitment process, and their functional significance for thermogenesis should be elucidated.

knockout mice; adaptive thermogenesis; skeletal muscle