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This Article Full Text Full Text (PDF) All Versions of this Article: 295/2/E287    most recent 00035.2008v1 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 (7) Citing Articles via Google Scholar Google Scholar Articles by Petrovic, N. Articles by Nedergaard, J. Search for Related Content PubMed PubMed Citation Articles by Petrovic, N. Articles by Nedergaard, J.

Thermogenically competent nonadrenergic recruitment in brown preadipocytes by a PPAR agonist

¹Wenner-Gren Institute, The Arrhenius Laboratories, Stockholm University, Stockholm, Sweden; and ²Translational Biomedicine, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, Scotland, United Kingdom

Submitted 18 January 2008 ; accepted in final form 14 May 2008

Most physiologically induced examples of recruitment of brown adipose tissue (BAT) occur as a consequence of chronic sympathetic stimulation (norepinephrine release within the tissue). However, in some physiological contexts (e.g., prenatal and prehibernation recruitment), this pathway is functionally contraindicated. Thus a nonsympathetically mediated mechanism of BAT recruitment must exist. Here we have tested whether a PPAR activation pathway could competently recruit BAT, independently of sympathetic stimulation. We continuously treated primary cultures of mouse brown (pre)adipocytes with the potent peroxisome proliferator-activated receptor- (PPAR) agonist rosiglitazone. In rosiglitazone-treated cultures, morphological signs of adipose differentiation and expression levels of the general adipogenic marker aP2 were manifested much earlier than in control cultures. Importantly, in the presence of the PPAR agonist the brown adipocyte phenotype was significantly enhanced: UCP1 was expressed even in the absence of norepinephrine, and PPAR expression and norepinephrine-induced PGC-1 mRNA levels were significantly increased. However, the augmented levels of PPAR could not explain the brown-fat promoting effect of rosiglitazone, as this effect was still evident in PPAR-null cells. In continuously rosiglitazone-treated brown adipocytes, mitochondriogenesis, an essential part of BAT recruitment, was significantly enhanced. Most importantly, these mitochondria were capable of thermogenesis, as rosiglitazone-treated brown adipocytes responded to the addition of norepinephrine with a large increase in oxygen consumption. This thermogenic response was not observable in rosiglitazone-treated brown adipocytes originating from UCP1-ablated mice; hence, it was UCP1 dependent. Thus the PPAR pathway represents an alternative, potent, and fully competent mechanism for BAT recruitment, which may be the cellular explanation for the enigmatic recruitment in prehibernation and prenatal states.

brown fat; rosiglitazone; norepinephrine; mitochondria; thermogenesis; peroxisome proliferator-activated receptor-

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