Rapid synergistic interaction between thyroid hormone and XXXX on mRNAS14 induction.

@entity1375 @entity1735 @entity969 @entity413 @entity35 @entity3363 @entity1954
Recent studies have shown that hepatic mRNAS14 responds rapidly to thyroid hormone administration. Moreover, this mRNA is known to increase in mass with the administration of a high @entity1735 fat-free diet. Therefore, it appears to share many of the same properties of the known hepatic lipogenic enzymes. Because the lipogenic enzymes display a synergistic interaction between thyroid hormones and @entity3363 , we investigated the kinetics of response of mRNAS14 to @entity1735 feeding, as well as its interaction with @entity1954 (T3). We found that mRNAS14 responds rapidly to the dietary administration of @entity969 in euthyroid @entity35 , with a 2-fold increase within 30 min, and a 25-fold increase by 4 h. On the other hand, when given to @entity1375 @entity35 , @entity969 ultimately lead to only a 2-3-fold increase in the level of mRNAS14, attaining a level less than that found in starved euthyroid @entity35 . The diminished response of mRNAS14 to @entity969 in @entity1375 could not be enhanced by insulin administration. However, administration of replacement doses of T3 (400 ng/100 g of body weight) immediately restored the rapid response to @entity969 feeding. The response of @entity969 and T3 was synergistic. Dose-response studies with T3 indicated that the rapid interaction between T3 and @entity969 was limited by the occupancy of the T3 nuclear receptor. A similar synergistic response to T3 and @entity413 was noted in primary hepatocyte cultures, thus indicating that the synergism between these two stimuli is not due to changes in extrahepatic hormones or metabolites. Our data are most consistent with the hypothesis that the T3-nuclear receptor complex multiplies a signal generated by @entity1735 metabolism to induce hepatic mRNAS14. The interaction does not appear to require the preliminary induction of @entity1735 -metabolizing enzymes and their mRNAs.
