Effect of Thyrocalcitonin on the Experimental Osteoporosis in Rat

Abstract

Thyrocalcitonin (TC) exerts its hypocalcemic effect by an action on bone.
The mode of action of TC has been extensively studied both in vivo and in vitro and there is now a substantial evidence that TC inhibits bone resorption.
Since it has been shown that TC is also effective in man, it would be logical to expect the effect of TC in the treatment of osteoporosis which is characterized by increased bone resorption.
We have produced experimental osteoporosis in rats by feeding low calcium diet and studied the effect of TC in these animals by analysing the ash weight and histological findings of the femur, tibia, humerus and tail bones. When rats were fed low calcium diet for 3 weeks, there was a marked decrease in the ash content of the bones together with the thinning of the cortex. Simultaneous administration of thyrocalcitonin did not prevent these changes except for the tail bones. The ash content and density of the tail bones in the TC-treated rats were apparently larger than those in the non-treated animals.
Subsequently therapeutic effect of TC was studied by the administration of TC to osteoporotic rats. Again, it was found that TC did not improve the decreased ash content of the femur, tibia and humerus except for the tail bones.
In conclusion, TC showed a small effect in the treatment of experimental osteoporosis in rats.