EXPRESSION OF THE ALPHA-1, ALPHA-2, AND BETA-1 T-3-RECEPTOR MESSENGER-RNAS 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 som e genes to exogenous T-3 is not as pronounced as normal, One possible explanation for these observations is a change in the expression of on e 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 fast ed rats using a competitive PCR method. We constructed competitors bas ed on the isoforms themselves so the amplification efficiencies of the target and the competitor are similar. Using this method we found tha t 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 isof orm mRNAs was found, (C) 1998 Academic Press.