A synthetic standard for competitive RT-PCR quantitation of 13 GABA receptor type A subunit mRNAs in rats and mice

We describe a synthetic 769-bp DNA internal standard, GABARQuant 1, for measuring mRNAs of 13 GABA A receptor subunits by reverse transcriptase-polymerase chain reaction (RT-PCR). When it is transcribed into cRNA, added in known amounts to target mRNAs in extracts from rat or mouse tissue, competitively reverse transcribed into cDNA, and amplified by the polymerase chain reaction (PCR), the relative intensities of the amplified, stained target and standard DNA bands enable measurement of small amounts of mRNAs for GABA A receptor subunits α 1–6, β 1–3, γ 1–3 and δ and the three cellular markers β -actin, light neurofilament protein, and glutamine synthetase. For the subunits, most standard products (263–504 bp) differ in size from target products (398–564 bp) by 10–20%. Primer pairs span at least one intron, to prevent interference by genomic DNA, and at least one rat versus mouse restriction fragment length polymorphism (RFLP), to enable rat products to be distinguished from mouse products.