Conclusions
Our data show that elevated GIP levels prevent age-related loss of bone mass and bone strength and suggest that age-related decreases in GIP receptor expression in BMSCs may play a pathophysiological role in this bone loss. We conclude that elevations in GIP may be an effective countermeasure to age-induced bone loss.
Methods
Changes in BMD, biomechanics, biomarkers of bone turnover, and bone histology were assessed in C57BL/6 GIP Tg(+) versus Tg(-) (littermate) mice between the ages of 1 and 24 mo of age. In addition, age-related changes in GIP receptor (GIPR) expression and GIP effects on differentiation of BMSCs were also assessed as potential causal factors in aging-induced bone loss.
Results
We report that bone mass and bone strength in GIP Tg(+) mice did not drop in a similar age-dependent fashion as in controls. In addition, biomarker measurements showed that GIP Tg(+) mice had increased osteoblastic activity compared with wildtype control mice. Finally, we report for the first time that BMSCs express GIPR, that the expression decreases in an age-dependent manner, and that stimulation of BMSCs with GIP led to increased osteoblastic differentiation. Conclusions: Our data show that elevated GIP levels prevent age-related loss of bone mass and bone strength and suggest that age-related decreases in GIP receptor expression in BMSCs may play a pathophysiological role in this bone loss. We conclude that elevations in GIP may be an effective countermeasure to age-induced bone loss.