[C-cells of the thyroid gland in experimental osteoporosis]

The population of thyroid C-cells of female rabbits with ovariectomy-induced osteoporosis was studied using immunohistochemical method with antibodies against calcitonin (CT) and morphometrically. The development of osteoporosis was confirmed using radiology and densitometry. 8 weeks after the operation, after the detection of hypercalcemia and hypercalciuria, some of the animals were given a correcting treatment with calcium-containing drug and vitamin D3 or with a combination of calcium drug with hormonal estrogen-containing drug. 4 weeks after the treatment was started, thyroid C-cells in animals that received the drugs, were significantly larger than in the cells of control and ovariectomized rabbits that received no treatment. Following 12 and 22 weeks, in the animals treated with hormonal drug, both calcium concentrations in blood and urine and C-cell dimensions were normalized. Large C-cells with an intensive reaction to CT were observed at weeks 12 and 22 (weeks 20 and 30 after the operation) in the thyroid gland of the animals that received no treatment and of the animals that received calcium with food. In the last case, the morphological changes of C-cells were more pronounced, despite the insignificant differences in blood calcium concentrations in both groups. These results permit to suggest that the intensity of CT synthesis by C-cells may be influenced by calcium concentrations not only in the blood, but also in the intestinal lumen.