Effect of salmon calcitonin on experimental osteoporosis induced by ovariectomy and low-calcium diet in the rat.

To investigate the action and effect of calcitonin on osteoporosis, this study was performed in osteoporotic rats that had been ovariectomized and maintained on a low-calcium diet. Significant bone loss was noted in ovariectomized rats compared with those that underwent sham surgeries, and histological findings proved bone turnover to be increased. In comparison with this osteoporotic rat group, those given calcitonin showed less bone loss; the reduction in bone loss was obvious in the vertebral body, and rats given a high dose of calcitonin over a long duration showed even less bone loss, but this was hardly seen in the proximal tibial metaphysis. Histological findings proved that calcitonin inhibited the bone resorption that was stimulated by the ovariectomy. Values for osteoblast surfaces were relatively higher while those of reversal surfaces were lower. The results confirm that salmon calcitonin has an inhibitory action on bone resorption as well as being effective in maintaining and stimulating bone formation in vivo. These effects of calcitonin prevented progress of the osteoporosis that had been induced by ovariectomy, and the effects appeared differently in each region.