[The effect of long-term calcitonin administration on bone cells and bone mineralization in the rat (author's...

The effect of calcitonin on bone tissue was studied in rat cortical and trabecular bone after long-term treatment. The aim of this study was to get exact data on calcitonin action on bone tissue by histomorphometry. Histomorphometric analysis of bone alterations was performed using undecalcified longitudinal as well as grounded cross sections of the tibial metaphysis and diaphysis. In agreement with other authors our experimental results show that calcitonin inhibits clasts but by a reduced cellular resorption activity of osteoclasts. Bone formation is not affected by calcitonin in intact as well as in parathyroidectomized animals. On the contrary bone mineralization is clearly improved under calcitonin administration in parathyroidectomized rats. This favourable effect is probably caused by a direct hormonal influence on calcium transport in the osteoblast.