Figure 4. Mechanical loading upregulates bone genes in older mice.

Bilateral tibias (left, Control; right, Loaded) were harvested after 1 week of unilateral mechanical loading. mRNA was isolated, quantified by real-time RT-PCR, normalized to the housekeeping gene cyclophilin, and then expressed as fold difference of loaded relative to control. There were no significant differences between loaded and control limbs at 2 months age. However, with increasing age there was an increase in relative expression of osteoblast and bone matrix genes in loaded versus control limbs. (n = 7–8; mean ± SD; p-values for Age, Load and Age-Load interaction are from 2-factor ANOVA; * loaded different from control, p<0.05).