Object To explore the effect of Oxtr knockout on estrogen regulating bone metabolism. Methods Three-month old Oxtr+/+ and Oxtr-/- female BABL/c mice (20 mice per genotype) were randomly divided into 8 groups, 5 mice per group: ① wild type group (WT), ② wild type + estradiol group (WT+E2), ③ wild type OVX group (WT OVX), ④ wild type OVX + estradiol group (WT OVX+E2), ⑤ Oxtr knockout group (KO), ⑥ Oxtr knockout + estradiol group (KO+E2), ⑦ Oxtr knockout OVX group (KO OVX), ⑧ Oxtr knockout OVX + estradiol group (KO OVX+E2). After injecting 17β-estradiol (50 µg/mice/day, s.c.) for 4 weeks, spine and femur bone mineral density (BMD) of all group mice were measured. Results BMD of WT OVX group mice were markedly lower than that of WT group mice. Injecting 17β-estradiol observably increased BMD of WT E2 group mice compared with WT group mice. Moreover, the decline in BMD of WT OVX mice was remarkably reversed by 17β-estradiol. But there was no significant difference on BMD between KO group and KO OVX group mice, and both of KO E2 group and KO OVX E2 group mice failed to respond to 17β-estradiol. Conclusion Oxytocin is required for the anabolic action of estrogen on the skeleton. |