The study, published in the British Journal of Nutrition, looked at whether there was a synergistic relationship between calcium and a hormone secreted naturally by the parathyroid glands (exogenous parathyroid hormone 1–34 fragments (PTH 1–34)). In particular it examined the impact on osteoblasts – bone cells that reabsorb bone tissue and are key in skeletal maintenance and repair.
The researchers from the Nanjing University School of Medicine in China fed adult male mice a normal diet (1% calcium), a high-calcium diet (2% calcium), a PTH-treated diet or a high-calcium diet combined with 80 mg/kg per day of the injected hormone for a period of four weeks.
They found that bone mineral density, trabecular bone volume, osteoblast number, alkaline phosphatase (ALP)- and type I collagen-positive areas, and the expression levels of osteoblastic bone formation-related genes and proteins were increased significantly in all diets but most “dramatically” in the calcium-hormone group.
They suggested this effect was due to an upping of the expression of the calcium-sensing receptor and parathyroid hormone receptor in the mice as well as the activation of relevant signalling pathways.
“These results indicate that dietary Ca and PTH play synergistic roles in promoting osteoblastic bone formation by stimulating osteoblast proliferation and differentiation,” they wrote.
They identified the impact using radiology, histopathology (the examination of tissue using a microscope) and cellular and molecular biology techniques.
Source: British Journal of Nutrition
Published online ahead of print, doi:10.1017/S0007114514004309
“Synergistic effects of high dietary calcium and exogenous parathyroid hormone in promoting osteoblastic bone formation in mice”
Authors: Y. Feng, M. Zhou, Q. Zhang, H. Liu, Y. Xu, L. Shu, J. Zhang, D. Miao and Y. Ren