Loss of brown adipose tissue uncoupling protein mRNA on deacclimation of cold-exposed rats.

The effect of environmental temperature on the level of uncoupling protein mRNA from rat brown adipose tissue was examined using a cDNA probe. A 4.4 fold increase in the mRNA level was observed after 1 day exposure of rats to 6 degrees C, which was followed by a slow loss with longer times of exposure. When rats were returned to a thermoneutral environment, there was a dramatic loss of uncoupling protein mRNA within 1 day. Comparison wih poly(A)+ RNA levels suggest that the response to temperature is specific for uncoupling protein mRNA.