Quantitative reverse transcriptase polymerase chain reaction assay for mouse androgen receptor mRNA

A quantitative reverse transcriptase polymerase chain reaction (RT-PCR) assay for mouse androgen receptor (AR) mRNA was developed to study relative changes in AR gene expression. Serial dilutions of a standard comprising a fragment of the ampicillin resistance gene flanked by the primer sequences of the AR mRNA were added to a constant amount of total RNA for RT-PCR. Primers were designed to generate a 541-bp fragment of mouse AR mRNA (target [T]) and a 460-bp fragment of the standard (S). PCR products were resolved by gel electrophoresis and quantitated by densitometry. A standard curve was generated for each sample by plotting the logarithm of T/S products vs the logarithm of the amount of S added. The amount of T was determined from the standard curve where intensities of PCR products of T and S were equal. The assay was validated by measuring the relative abundance of AR mRNA in 10 mouse tissues, and results were consistent with studies of AR expression in rat tissues. Assay reproducibility, tested by repeating assays on four different tissues on different days from the RT step, had a coefficient of variation of 6-16%. The current assay is thus both reproducible and valid in quantitation of mouse AR mRNA.