title: Extensive sex- and/or hormone-dependent expression of rat housekeeping genes.
abstract: OBJECTIVE
  Identify sex- and hormone-independent housekeeping genes in rat liver by using a commercially available quantitative reverse transcription-polymerase chain reaction array designed to measure the expression of 32 rat housekeeping genes.
  
  
  RESULTS
  We found that the levels of five of the genes were sexually dimorphic, 22 genes were overexpressed, and one was underexpressed in multi-hormone-deficient hypophysectomized rats of both sexes. Only three genes fulfilled the stability criteria determined by geNorm and NormFinder as suitable housekeeping genes. Normalizing quantitative reverse transcription-polymerase chain reaction data with either of these three genes alone, the geometric means of any two of the genes, or even the geometric mean of all the three genes, produced similar results. In contrast, application of unproven housekeeping genes could lead to erroneous conclusions, having found that insulin-like growth factor 1 messenger RNA levels could be calculated dramatically either as male or as female predominant depending on the choice of housekeeping gene.
  
  
  CONCLUSIONS
  It is essential to validate the constancy of housekeeping genes under every experimental condition. (This research protocol was approved by the university's Institutional Animal Care and Use Committee.).
authors.affiliation: Laboratories of Biochemistry, University of Pennsylvania, School of Veterinary Medicine, Philadelphia, PA 19104, USA.
authors.forename: Rajat K
authors.initials: RK
authors.lastname: Das
authors.forename: Sarmistha
authors.initials: S
authors.lastname: Banerjee
authors.forename: Bernard H
authors.initials: BH
authors.lastname: Shapiro
mesh_terms: D000818:Animals; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics*; D020043:Genes, Essential / Q000235:genetics*; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis / Q000235:genetics; D008099:Liver / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000295:instrumentation / Q000379:methods; D012727:Sex Characteristics
chemical_list: D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I