Effect of low doses of stable strontium on bone metabolism in rats

The effects of low doses of oral stable strontium (0.19-0.40% of strontium chloride) on mineral and bone metabolism were examined in normal rats using biochemical and histomorphometrical methods. The strontium levels in serum and bone rose according to the intake of the element. Oral strontium supplementation did not produce deleterious effects on body growth or on mineral homeostasis except a transitory slight decrease in serum calcium. At the dosage level of 0.40% however, strontium induced a slight defective bone mineralization. At lower levels, treated rats showed stimulated bone formation evidenced by increased amount of osteoid and increased extent of tetracycline double-labelled surface while the mineralization lag time remained normal. The osteoclastic surface and the number of acid phosphatase-stained chondroclasts and osteoclasts remained unchanged. Stimulation of bone formation without apparent change in bone resorption resulted in a 10% increase in the trabecular calcified bone volume. The strontium-induced increased osteogenesis was not associated with changes in circulating levels of 1,25(OH)2 vitamin D or in parathyroid hormone effects. The results show that small doses of oral strontium may stimulate bone formation without altering bone resorption in the rat.