Effects of parathyroid hormone-related protein on the alveolar bone of ovariectomized rats

Objective:To investigate the effect of parathyroid hormone-related protein(PTHrP)on the alveolar bone of ovariectomized rats.Methods:80 female 5-month-old rats were selected.Among them 60 rats were ovariectomized(OVX) and the other 20 rats were sham-ovariectomized(sham-OVX).Six weeks later the OVX rats were further divided into three groups randomly,each grouop consisting of 20 rats:the PTHrP treated group(PTHrP group) which was injected with PTHrP,the estrogen treated group(E2 group) which was injected with Estradiol benzoate,and the placebo group(OVX group)which was with injected saline,while the 20 sham-OVX rats(sham-OVX group) were also injected with saline as the blank control group.60 days later,all the rats were sacrificed and their right mandibles were obtained for measuring bone mineral density(BMD) of molars region.Besides,the alveolar bones of the first molars were cut into tissue spices for histomorphological observation and immunohistochemical staining of Runt-related transcription factor 2(RUNX2).Results:The BMD measure indicated that the PTHrP group had a higher BMD value significantly than the OVX group(P0.05),with no less than the E2 group or even the sham-OVX group(P0.05).The histomorphological observation showed the morphology of alveolar bone of the PTHrP group approximated the E2 group and the sham-OVX group,without bone loss as apparent as the OVX group.Moreover,the analysis of immunohistochemical staining suggested that the RUNX2 expression in PTHrP group was more than either of the other groups,which showed significant statistical differences(P0.05).Conclusions:PTHrP may have an anabolic effect on the alveolar bone of the ovariectomized rats.