The conflicting results of previous evaluations of the influence of
hypercalcemia on thyroid C-cells and the absence of reports on its influence on
calcitonin (CT)-producing cells of the airways prompted this study. It aims to evaluate the activity and changing dynamics in CT-producing cells in rat thyroid glands and lungs after prolonged
hypercalcemia. The
hypercalcemia was induced by an
intraperitoneal injection of 100,000IU of
vitamin D(3) (Vigantol), Merck). Control and experimental rats were examined after 1, 7 and 14 days.
Calcium and CT concentrations were measured in blood plasma.
Paraffin wax embedded sections of thyroid and lungs were stained with
hematoxylin and
eosin. CT was detected immunohistochemically in thyroid C-cells and lung endocrine cells. Results showed increased
calcium and CT concentrations in rat blood after
vitamin D(3) administration, a statistically significant reduction in number of CT-positive cells in the thyroid with indications of their increased activity, and a statistically non-significant reduction of the number of cells immunopositive for CT in lungs after 1 day, and an increase after 7 days, compared to the control group. Lack of an obvious correlation in lung neuroendocrine cells among the rats with
hypercalcemia may indicate the presence of other, perhaps local, functions for
calcitonin.