Thyrotropin-dependence of the distribution of peroxidase in rat thyroid gland.

Publisher Website
Google Scholar
Abstract
After male rats were injected daily with propylthiouracil [PTU], whale thyrotropin [TSH] or thyroxine [T4] for several days, the thyroid glands were examined for their ultrastructural localization of peroxidase. The PTU treatment caused a marked increase in the number of round, peroxidase-positive vesicles in the apical and middle regions of cytoplasm, and brought about a formation of granular reaction products in the colloid lumen adjacent to the elongated microvilli. Such changes became evident after 2 days of the drug treatment and increased with the time of the effect, until the whole colloid lumen was filled with the reaction products and very elongated microvilli. The effect of exogenous TSH was essentially similar, to a lesser degree, to the drug effect mentioned above. T4 treatment diminished the population of the small vesicles, as usually seen in the case of normal rat thyroids. When the thyroids of TSH-stimulated and unstimulated rats were homogenized and fractionated into particulate fractions and a soluble fraction, almost all the peroxidase activity was contained in the former in both cases. Based on these results, the dynamics and the physiological role of the intracellular peroxidase are discussed.