(A) Study design and adaptive mechanical loading protocol for 16-week-old Ctrl and NT3-Cre+ mice. One bout of cyclic loading per day was performed a total of 9 times. Calcein green and alizarin red fluorochromes were given on study days 4 and 11, respectively. Strain gauging was used to determine the force required to achieve an equivalent microstrain in each genotype, as shown. (B) (top) Representative cross-section of the loaded tibia for each genotype and (bottom) inset view of the area of peak compressive strain highlighting the enhanced bone formation seen in NT3-Cre+ mice. Quantification of fluorochrome labeling shown as (C) Ps.MS/BS, (D) Ps.MAR, and (E) Ps.BFR/BS (n=10–12 per group). Results are presented as mean ± SD. black = male Ctrl and green = male NT3-Cre+. Right tibiae were loaded (LOAD, triangles) and left tibiae served as non-loaded (NL, circles) controls. Student’s, paired, two-tailed t-test (LOAD vs NL within each genotype) or 2-way ANOVA followed by Tukey’s multiple comparison test (cross-genotype comparisons): n.s. - not significant, *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. Ps.BFR/BS = periosteal bone formation rate per bone surface; Ps.MS/BS = periosteal mineralizing surface per bone surface; Ps.MAR = periosteal mineral apposition rate