TSH-induced appearance and stimulation of amine-containing mast cells in the mouse thyroid.

Abstract

Intra- and extrathyroidal mast cells in mice were located by their metachromasia and histochemically demonstrable 5-hydroxytryptamine (5-HT) and histamine content, and plasma TSH levels were determined by bioassay. Untreated mice had no detectable plasma TSH ( <0.1 mU/ml), and no or very few intrathyroidal mast cells, whereas numerous mast cells were found in adjacent tissues. During propylthiouracil (PTU) treatment, plasma TSH rose progressively (to 4.0 mU/ml at 4 weeks) and several amine-containing mast cells appeared in the thyroid. Concomitant administration of thyroid hormone prevented these effects, and withdrawal of PTU was followed by decreased plasma TSH levels and a disappearance of the thyroid mast cells. However, the content of amines and metachromatic material in thyroid mast cells seemed inversely related to the plasma TSH level. The extrathyroidal mast cells were never affected by changes in TSH. The findings indicate that, in mice, TSH induces the appearance of 5-HT-and histamine-containin...