INHIBITION BY SOMATOSTATIN OF MOUSE THYROID ACTIVITY FOLLOWING STIMULATION BY THYROTROPHIN, ISOPRENALINE AND DIBUTYRYL CYCLIC-AMP

Abstract

The recent discovery of somatostatin-containing cells within the thyroid gland infers that somatostatin may influence thyroid activity. This possibility was investigated by measurements of radio-iodine release in mice pre-treated with 125I and T4 [thyroxine]. The animals were treated with TSH [thyrotropin], isoprenaline or dibutyryl-cyclic AMP with and without concomitant injection of somatostatin. Somatostatin reduced the blood 125I increase in response to each of the 3 thyroid-stimulating agents. The elimination rates of 125I-labeled T4 and T3 [triiodothyronine] were unaffected by somatostatin. Somatostatin may participate in the regulation of thyroid hormone secretion, by an inhibitory effect exerted within the thyroid gland.