REVERSIBILITY OF THE INHIBITORY EFFECT OF SALMON-CALCITONIN ON BONE-RESORPTION IN RATS

Inhibition of osteoclastic bone resorption has been induced in growing rats with high doses of salmon calcitonin. This effect was evaluated by measuring the perichondrial ring height of the proximal tibial meta physis. The aim was to assess whether osteoclastic activity resumed af ter a period of inhibition with high doses of calcitonin. 20 male Spra gue-Dawley rats were treated for 21 days with 100 units/kg/day of salm on calcitonin subcutaneously and killed after 0-60 days, together with non-treated controls at 0 and 60 days. Arrest of metaphyseal modeling and increased height of the perichondrial ring at the end of the peri od of therapy (P 0.002 versus controls) were observed. Recovery of bon e resorption was evident 20 and 40 days after withdrawal of calcitonin .