Trabecular Bone as Keystone for the Interplay Among Calcium Diet Content, PTH(1-34) Treatment and Balance of Bone Homeostases in Rat Model

The present study aims to determine whether normal-diet restoration, with/without concomitant PTH(1-34) administration, can influence amounts and deposition sites of the total bone mass. Histomorphometric evaluations and immunohistochemical analysis for Sclerostin expression were conducted on the vertebral bodies and femurs in the rat model. Final goals 1) to define timing and manners of bone mass changes when calcium is restored to the diet; 2) to analyze the different involvement of the two bony architectures having different metabolism (i.e. trabecular versus cortical bone); 3) to verify the eventual role of PTH(1-34) administration. Results evidenced the greater involvement of the trabecular bone with respect to the cortical bone, in response to differing levels of calcium content in the diet, and the effect of PTH, mostly in the recovery of trabecular bony architecture. The main findings emerged are: i) the importance of the interplay between mineral homeostasis and skeletal homeostasis in modulating and guiding bone’s response to dietary/metabolic alterations and ii) the evidence that the more involved bony architecture is trabecular bones, the most susceptible to the dynamical balance of mineral and skeletal homeostasis.