The uptake of labelled exogenous thyroxine by the brain was determined in 10- and
30-day-old rats. It was three times higher and thyroxine was more deiodinated on day
10 than on day 30. On the other hand, the endogenous hormonal iodine content was estimated
in both the brain and the isolated cortical neurones in young rats of the same ages
equilibrated with 125I. On day 10, brain and neurons contained five times more thyroid hormones than on
day 30. These results are discussed in the context of the relations previously discovered
between development of thyroid function and brain maturation.
Thyroxine Uptake and Metabolism - Developing Brain - Isolated Neurones - Rat
