Long-term action of potassium bromide on the rat thyroid gland.
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 micron 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 thyroid 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.
Velický
J
J
Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague.
Titlbach
M
M
Lojda
Z
Z
Dusková
J
J
Vobecký
M
M
Strbák
V
V
Raska
I
I
D000284:Administration, Oral; D000818:Animals; D001965:Bromides / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D008297:Male; D017680:Potassium Compounds / Q000008:administration & dosage*; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D013954:Thyroglobulin / Q000737:chemistry; D013961:Thyroid Gland / Q000737:chemistry / Q000187:drug effects* / Q000473:pathology* / Q000648:ultrastructure; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
D001965:Bromides; D017680:Potassium Compounds; D014284:Triiodothyronine; D013972:Thyrotropin; D013954:Thyroglobulin; C039004:potassium bromide; D013974:Thyroxine