Fig. 4. Differential pharmacological actions of PTH^7d, PTH^WT, and LAPTH in mice.

(A) 3-D reconstructed micro-computed tomography (μCT) images of secondary spongia at the distal femurs of mice treated with vehicle, PTH^7d, PTH^WT (PTH^1–34), or LAPTH. Scale bar, 500μm.

(B) Quantifications of skeletal parameters in trabecular (Tb) bone of distal femur, including total bone volume (TV), ratio of Tb bone volume (Tb.BV) to TV (Tb.BV/TV), Tb number (Tb.N), and Tb thickeness (Tb.Th). Parameters were assessed in mice subjected to daily injections of PTH^7d, PTH^WT, LA-PTH, or vehicle (Veh) for 4 weeks. Data are means ± SD from N = 7 mice/group for PTH^7d and PTH^WT injections and N = 14 mice/group for LA-PTH and Veh injections. *P < 0.03, ***P < 0.002, ***P < 0.0002 and ****P < 0.0001 vs Veh control mice by one-way ANOVA with Tukey-Kramer post-hoc test.

(C) Quantification of serum Ca²⁺ (sCa²⁺) and phosphate (sPi) measured 2 hrs after the last of the 4-week daily injections of PTH^7d, PTH^WT, LA-PTH (40 μg/kg body weight/injection), or vehicle (Veh). Data are means ± SD from N = 7 mice/group. *P < 0.03, **P < 0.002, ***P < 0.0002 and ****P < 0.0001 vs Veh control mice by one-way ANOVA with Tukey-Kramer post-hoc test.

(D) Quantification of serum 1.25D measured in mice before or 1, 2, 4, 8, 12, or 24 hrs after a single injection of PTH, PTH^7d, or LA-PTH. Data are means ± SD from N = 7 mice/time point/drug and 15 mice for time “0” controls. Statistical analysis is shown in the Supplementary Materials (fig. S9).