Modification of beta-adrenergic receptor binding in rat brain following thyroxine administration.

The effect of repeated administration of thyroxine on beta-adrenergic receptor binding was studied in several brain regions in the rat using [3H]dihydroalprenolol as a ligand. Thyroxine treatment resulted in an increased density of beta-adrenergic receptors in the cerebral cortex while a decreased binding was found in subcortical tissue representing the thalamus, striatum and parts of the limbic system. There was no change in binding in the cerebellum or in the brainstem. The results indicate that thyroxine may regulate beta-adrenergic receptors in certain brain areas.