Long-term action of potassium bromide on the rat thyroid gland

• Published in: Acta histochemica 1998-02, Vol.100 (1), p.11-23
• Main Authors: Velický, Jan, Titlbach, Milan, Lojda, Zdeněk, Dušková, Jaroslava, Vobecký, Miloslav, Štrbák, Vladimír, Raška, Ivan
• Format: Article
• Language: English
• Subjects: Administration, Oral; Animals; Bromides - administration & dosage; Bromine; Drug Administration Schedule; histology; immunohistochemistry; Male; Potassium Compounds - administration & dosage; radio(immuno)analysis; Radioimmunoassay; rat; Rats; Rats, Wistar; Thyroglobulin - chemistry; thyroid gland; Thyroid Gland - chemistry; Thyroid Gland - drug effects; Thyroid Gland - pathology; Thyroid Gland - ultrastructure; Thyrotropin - blood; Thyroxine - blood; Triiodothyronine - blood
• ISSN: 0065-1281; 1618-0372
• DOI: 10.1016/S0065-1281(98)80003-2

Male rats fed by a standard diet with determined of bromine and iodine content were exposed to a 133-day oral administration of KBr (100, 200, 400 mg Br -/l drinking water). Their thyroid glands showed increased growth of the epithelial cells reflected by a microfollicular rearrangement of the parenchyma due to proliferation of very small follicles with a low or zero content of colloid. Morphometric analysis of thyroids of Br --exposed animals revealed a significant decrease in the volume of intrafollicular colloid and marked increase in the number of the smallest follicles (areas up to 100 and 100-300 µm 2). In addition, the nuclei of thyrocytes showed an increased number of mitoses. The vascularization was increased as well. In the blood plasma of the Br --exposed animals the T4 concentration was significantly decreased in dependence on the bromine concentrations. Thyroglobulin immunoreactivity in the colloid of Br --exposed animals decreased after administration of 400 mg Br -/l drinking water. Increasing concentrations of Br - in the drinking water caused an increased bromine concentration in the thyroid, a decreased iodine content and a decreased I/Br molar ratio. The changes in the rat thyraid caused by long-term administration of 100 mg Br -/l were similar to hyperplastic parenchymal goitre and were comparable to those induced in previous experiments by the same bromine concentration administered over a 16- and 66-day period respectively.