Expression of thyroid hormone receptor isoforms in rat oligodendrocyte cultures. Effect of 3,5,3'-triiodo-L-thyronine.

3,5,3'-Triiodo-L-thyronine (T3) acts at the genomic level by interacting with nuclear T3 receptors (T3Rs). We have used double immunostaining to follow the expression of T3Rs and oligodendrocytes (OL) lineage markers in rat secondary cultures consisting of 85-90% OL. Using antibodies against different synthetic peptides of T3Rs (alpha common: alpha 1 + alpha 2 and beta 1) we find that alpha-T3R is expressed in both O-2A progenitors and in mature OL, while beta 1-T3R is expressed only in mature OL. In cultured OL, beta 1-T3R mRNA is upregulated the most by T3. OL exhibit more numerous and longer processes when treated by T3.