THYROTROPIN RECEPTOR EXPRESSION IN CULTURED GRAVES ORBITAL PREADIPOCYTE FIBROBLASTS IS STIMULATED BY THYROTROPIN

Our laboratory has shown recently that the thyrotropin receptor (TSHr) is expressed in orbital adipose/connective tissues from patients with Graves' ophthalmopathy (GO), and that this receptor is not demonstrab le in orbital tissues from normal individuals. In order to study the r egulation of TSHr expression in the orbit in GO, we treated cultures o f Graves' orbital preadipocyte fibroblasts with the TSHr Ligand thyrot ropin (TSH; 100 mU/L). We found increased expression of both intact (2 .4 kb) and variant (1.3 kb) TSHr mRNA and of TSHr protein in orbital f ibroblasts following 72 hr treatment with TSH. These studies suggest t hat the expression of this receptor in the orbit in vivo may be stimul ated by TSH or other TSHr ligands, and that this stimulation may be im portant in the development of GO.