Expression of thyroid hormone receptors mRNAs in rat cerebral hemisphere neuronal cultures.
We have studied the expression of the alpha and beta thyroid receptors mRNAs (TR-mRNAs) in cerebral hemisphere neuronal cultures, initiated from 15-day-old rat embryos, by northern analysis. In the cultures grown in the absence of L-triiodothyronine (L-T3), the alpha 2 TR-mRNAs were the predominant form of TR-mRNAs and were approximately 8 to 20-fold higher than the levels of the alpha 1 TR-mRNAs, depending on the age of the cultures. The levels of alpha 2 TR-mRNAs significantly increased by 1.8 fold between day 8 and 15 and remained on a plateau value thereafter until day 22. Over the same time period, there were no significant changes on the levels of alpha 1 TR-mRNAs. The ratio alpha 1/alpha 1 + alpha 2 TR-mRNAs decreased between day 8 and 15. The beta 1 TR-mRNAs increased by 8 fold between day 8 and day 22. On day 8, the beta 1 TR-mRNAs were 1.8 fold lower than the levels of the alpha 1 TR-mRNAs while they were 6 fold higher on day 22. L-T3 treatment of the cultures had no effect on the levels of the alpha 1, alpha 2 and beta 1 TR-mRNAs. The differential temporal expression of the alpha 1 and beta 1 TR-mRNAs suggests distinct functions for both types of T3 receptors in neuronal maturation.
Puymirat
J
J
Department of Ontogenesis and Molecular Biology, CHUL Research Center, Sainte-Foy, Canada.
l'Hereault
S
S
Dussault
J H
JH
D000818:Animals; D015152:Blotting, Northern; D001921:Brain / Q000196:embryology / Q000502:physiology*; D002478:Cells, Cultured; D005333:Fetus; D015870:Gene Expression; D005865:Gestational Age; D009474:Neurons / Q000502:physiology*; D011061:Poly A / Q000235:genetics / Q000302:isolation & purification; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011988:Receptors, Thyroid Hormone / Q000096:biosynthesis* / Q000235:genetics
D012333:RNA, Messenger; D011988:Receptors, Thyroid Hormone; D011061:Poly A; D012313:RNA