Variations in immunocytochemical localization of cathepsin B and thyroxine in follicular cells of the rat thyroid gland and plasma TSH concentrations over 24 hours

Abstract

Immunocytochemical localization of cathepsin B and thyroxine (T4) in follicular cells of the rat thyroid gland and plasma concentrations of thyroid stimulating hormone (TSH) were examined at six evenly spaced times over 24 h. By light- and electron microscopy, immunodeposits for cathepsin B were localized in cytoplasmic granules of various sizes, whereas those for T4 were detected mainly in larger granules of the cells and in the colloid lumen. The size and location of cytoplasmic granules showing immunoreactivity for cathepsin B and T4 in the cells varied over 24 h, corresponding to a change in plasma TSH concentrations. These immunopositive large granules appeared in the apical cytoplasm at 12.00 h, when the level of TSH was highest. At 20.00 h when the level of TSH was lowest, T4-positive granules almost disappeared, and cathepsin B-positive small granules were abundantly seen in the basal region. From 00.00 h to 08.00 h, these positive granules changed in the same manner as those seen from 12.00 h to 20.00 h, associated with an increase in plasma TSH levels. These results suggest that newly formed colloid droplets migrate from the apical to the basal regions. Cathepsin B may play a role not only in the degradation of thyroglobulin but in the maturation of thyroid hormones during the migration of the granules.

Lysosomal cysteine proteinases in rat epididymis.

“…which also reflect the activities of cathepsins B and H, are not detected in the rat epididymis. The method used in the present study, i.e., rapid freezing in Freon 22 cooled by liquid nitrogen, freeze-drying, and vapor-phase fixation, has a great advantage in preserving proteins within the limiting membrane, such as lysosomes and secretory granules Uchiyama et al, 1989aUchiyama et al, ,b,1990Uchiyama et al, ,1991Matsuba et al, 1989;Watanabe et al, 1989;Grube, 1980). With this method, the present study demonstrated the clear-cut distribution of cathepsins B and H in epithelial cells of the rat epididymis.…”

Cell and Tissue Distribution of Lysosomal Cysteine Proteinases, Cathepsins B, H, and L, and their Biological Roles.

“…Using immunohisto/cytochemical techniques, the localization of these enzymes have been precisely examined in the kidney (81,113), liver (27,105,111), pancreatic islets (108), heart (112), lung (31,32), thyroid gland (101,102), pituitary gland (92,93), gastro-intestine (24), parathyroid gland (26), submandibular gland (69), central nervous system (CNS) (7-10, 80), bone (68), and epididymis (82 (32,100,105). In rat liver, immunodeposits for cathepsins B and H are localized in hepatocytes and Kupffer cells (Fig.…”