Expression of the α1, α2, and β1 T3-receptor mRNAs in the fasted rat measured using competitive PCR

Fasting is associated with a decrease in the maximal binding capacity of the T-3-receptor in different tissues and the responsiveness of some genes to exogenous T-3 is not as pronounced as normal, One possible explanation for these observations is a change in the expression of one or all of the isoform mRNAs, We set out to measure the levels of the alpha 1, alpha 2, and beta 1 isoform mRNAs in liver and heart of fasted rats using a competitive PCR method. We constructed competitors based on the isoforms themselves so the amplification efficiencies of the target and the competitor are similar. Using this method we found that during fasting levels of alpha 2 mRNA in the liver of rats increased threefold (P < 0.002) over a 48-h period, whereas alpha 1 and beta 1 did not show any change. In the heart, no change in any of the TR isoform mRNAs was found, (C) 1998 Academic Press.