Endocrine control of extrathyroidal peroxidases and iodide metabolism

The role of the thyroid and adrenal glands on iodide transport and peroxidase-catalyzed formation of iodotyrosines in extrathyroidal tissues such as stomach and submaxillary glands has been investigated. Thyroidectomy stimulates iodide concentration and iodotyrosine formation in stomach, sensitive to the administration of thyroxine but having no effect on the peroxidase activity. In contrast, although thyroidectomy stimulates the submaxillary peroxidase which is reversed on treatment with thyroxine, it has no effect on iodide concentration and organification in the submaxillary gland. Gastric peroxidase activity is specifically stimulated by adrenalectomy and is inhibited by glucocorticoids which also inhibit iodotyrosine formation in stomach.