Modulation of tubulin synthesis by tri-iodothyronine in the embryonic chick brain

In organ cultures of embryonic chick brain, tri-iodothyronine is shown to elicit an age-dependent stimulation of the synthesis of tubulin. In cultures of brains from 8-day embryos where the response is maximal, a 70-100% increase in the rate of synthesis of tubulin is elicited by T<SUB>3</SUB> within 2 h. The stimulatory response is dose-dependent, requires transcription, and is temporally coincident with the early phase of the normal ontogenic rise in level of tubulin and of intense neuronal differentiation in the embryonic chick brain. The overall results indicate the involvement of T<SUB>3</SUB> in regulating the biogenesis of tubulin in the developing brain