[Effects of dietary calcium-deficiency on bone development in growing rats and the mechanism involved].

The effects of calcium on bone development in growing rats were studied by bone histomorphometry and the hormone changes in a model of calcium-deficient rats. Thirty growing Wistar rats were randomly allocated into three groups fed with low calcium diet, calcium-sufficient diet at libitum or pair fed with low calcium diet for 8 weeks. The calcium-deficient rats showed low bone mass, significantly decreased bone density and mineral content. The disorder of bone molding and ultrastructure at the femoral distal diaphysis of the calcium deficient rats were showed by histomorphometric parameters. The concentration of serum parathyroid hormone was significantly higher, calcitonin was significantly lower, and the content of hydroxyproline in bone was significantly lower. The results indicated that dietary calcium-deficiency might stimulate the secretion of parathyroid hormone, decrease bone mineral content and inhibit the synthesis of bone matrix, which might induce a defect on bone mineralization.