Related Experiment Video
Updated: May 18, 2026

Establishment of Rat Models Mimicking Gender-affirming Hormone Therapies
Published on: January 10, 2025
Extensive sex- and/or hormone-dependent expression of rat housekeeping genes
Rajat K Das1, Sarmistha Banerjee, Bernard H Shapiro
1Laboratories of Biochemistry, University of Pennsylvania, School of Veterinary Medicine, Philadelphia, PA 19104, USA.
Aim:
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.
Conclusion:
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.).
Related Concept Videos
Constitutive and Regulated Gene Expression
Exon Recombination
Exon shuffling follows “splice frame rules.” Each exon has three reading...
Background and Environment Affect Phenotype
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...

