Changes in expression levels of genes involved in fatty acid metabolism: upregulation of all three members of the PPAR family (alpha, gamma, delta) and the newly described adiponectin receptor 2, but not adiponectin receptor 1 during neonatal cardiac development of the rat.
During neonatal cardiac development, the heart changes its substrate preference from glucose to fatty acids. The aim of this study was to investigate the changes in mRNA expression levels of genes involved in the control of cardiac fatty acid metabolism in the transition from neonatal to adult life.


METHODS
mRNA expression levels for peroxisome proliferator activated receptor (PPAR) alpha, gamma and delta, PPARgamma co-factor 1 alpha and beta (PGC-1 alpha and beta), 9-cis retinoc-acid-activated receptor alpha, beta and gamma (RXR alpha, beta, gamma), 5'-AMP activated protein kinase (AMPK) alpha1 and alpha2, adiponectin receptor 1 and 2 (AR 1 and AR 2) were measured in heart tissue of neonatal 0-day, 7-day and 21- day old rats.


RESULTS
mRNA expression of all three members of the PPAR family were upregulated significantly from day 0 to day 21 (alpha +117%, gamma +133%, delta +203%). In addition, m-RNA expression of all RXR isoforms increased from day 0 to day 7 (alpha +125%, beta +69%; gamma +41%). AR 2 exhibited a small but significant increase in mRNA expression (+ 46%).


CONCLUSIONS
We were able to demonstrate for the first time that in addition to PPARalpha, also PPARgamma and delta, as well as all RXR isoforms and AR 2 are upregulated in the heart during neonatal development.
Steinmetz
Michael
M
Department of Pediatric Cardiology and Intensive Care Medicine, Georg-August-University Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany. m.steinmetz@medizin.uni-goettingen.de
Quentin
Thomas
T
Poppe
Andrea
A
Paul
Thomas
T
Jux
Christian
C
D000818:Animals; D000831:Animals, Newborn; D005227:Fatty Acids / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D006321:Heart / Q000254:growth & development* / Q000502:physiology; D009206:Myocardium / Q000378:metabolism; D047493:PPAR alpha / Q000235:genetics; D047494:PPAR delta / Q000235:genetics; D047495:PPAR gamma / Q000235:genetics; D047492:Peroxisome Proliferator-Activated Receptors / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D054419:Receptors, Adiponectin; D011956:Receptors, Cell Surface / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation
D005227:Fatty Acids; D047493:PPAR alpha; D047494:PPAR delta; D047495:PPAR gamma; D047492:Peroxisome Proliferator-Activated Receptors; D012333:RNA, Messenger; D054419:Receptors, Adiponectin; D011956:Receptors, Cell Surface; C475419:adiponectin receptor 1, mouse; C504339:adiponectin receptor 1, rat; C506573:adiponectin receptor 2, rat