Control of thyroglobulin secretion from the rat thyroid gland

Serum thyroglobulin (Tg), measured by radioimmunoassay, was high in 6-propylthiouracil (PTU)-treated rats but low in thyroxine (T4)-treated animals compared with euthyroid controls. Thyroid-stimulating hormone (TSH) stimulated Tg release in vitro from enzymatically dispersed normal rat thyroid cells in a dose-dependent manner. Thyroid cells prepared from T4-treated animals behaved similarly to cells from control rats, whereas in vitro basal release of Tg from thyroid cells prepared from PTU-treated animals was high and the response to TSH was lost. Our data confirm the TSH dependency of Tg release in vivo and in vitro and our system provides a means of studying the control of Tg secretion in vitro.