EXPRESSION OF THYROID-HORMONE RECEPTOR ISOFORMS IN RAT OLIGODENDROCYTE CULTURES - EFFECT OF 3,5,3'-TRIIODO-L-THYRONINE

3,5,3'-Triiodo-L-thyronine (T-3) acts at the genomic level by interact ing with nuclear T-3 receptors (T(3)Rs). We have used double immunosta ining to follow the expression of T(3)Rs and oligodendrocytes (OL) lin eage markers in rat secondary cultures consisting of 85-90% OL. Using antibodies against different synthetic peptides of T(3)Rs (alpha commo n: alpha 1 + alpha 2 and pi) we find that alpha-T(3)R is expressed in both O-2A progenitors and in mature OL, while beta 1-T(3)R is expresse d only in mature OL. In cultured OL, beta 1-T(3)R mRNA is upregulated the most by T-3. OL exhibit more numerous and longer processes when tr eated by T-3.