Dopamine and L-Dopa, Precursors of Norepinephrine: Effects on Thyroxine Release
Norepinephrine (NE), epinephrine, and their precorsors have been shown to enhance iodide organification in calf thyroid tissue through alpha-adrenergic receptors (1). In an in vitro mouse thyroid preparation, NE concomitantly stimulated iodide organification and inhibited thyrotropin (TSH)stimulated thyroxine (T4) release (2,3). Recently such inhibition of TSHstimulated T4 release was confirmed in vivo (4). In the present study, dopamine (DA) and L-DOPA also inhibited TSH-stimulated T4 release through alpha-adrenergic and dopaminergic receptors; cAMP appeared to be an unlikely mediator.
KeywordsThyroid Lobe Dopaminergic Receptor Acid Decarboxyl Thyroidal Iodine Iodide Organification
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