Comparison of isoproterenol and dibutyryl adenosine cyclic 3',5'-monophosphate stimulation of thyroxine 5'-deiodinase activity in cultured pineal glands from euthyroid and hypothyroid rats.

Thyroxine 5'-deiodinase was increased by isoproterenol and dibutyryl adenosine cyclic 3',5'-monophosphate in a dose- and time-related manner in cultured rat pineal gland. Basal and stimulated activity was higher in glands from hypothyroid than from euthyroid animals. Our data suggest direct beta-adrenergic stimulation of intracellular cyclic AMP may be involved in the regulation of pineal thyroxine 5'-deiodinase activity.