Effects of drynaria total flavonoids on mandible structure, serum E2 and OPG/RANKL balance in ovariectomized rats / 西安交通大学学报(医学版)

ABSTRACT

Objective: To explore the effects of drynaria total flavonoids on serum estrogen (E2) level, OPG/RANKL balance and bone microarchitecture of mandible in a rat model of bone loss induced by ovariectomy. Methods: We randomly divided 40 three-month-old female Sprague-Dawley rats into 5 groups (n=8 per group) sham-operation group (Sham), ovariectomized group (OVX), low-dose drynaria total flavonoids group (GB-L), high-dose drynaria total flavonoids group (GB-H) and estradiol valerate group (EV). The mandibular osteoporosis model was established by removing the rats' ovaries. After 12 weeks the rats were killed, and the serum estrogen levels were measured. OPG and RANKL were detected using ELISA method. Therapeutic effect of drynaria total flavonoids was observed by pathomorphology and histomorphometry of the mandibular molar sections. Results: Compared with those in the sham group, the mandible of rats in OVX group was loosely changed, the level of E2 decreased significantly (P<0.001), and OPG/RANKL decreased significantly (P<0.001). Compared with OVX group, the mandible microstructure of rats in EV group got a good repair, while the serum E2 level and OPG/RANKL increased significantly (both P<0.001). Compared with OVX group, the percentage of trabecular bone (%Tb.Ar) and OPG/RANKL increased in all the GB groups (P<0.001, P=0.029), (P<0.001, P=0.007), while GB-H group also had increased thickness of trabecular bone (Tb.Th) and serum OPG levels (P=0.019, P<0.001), reduced trabecular spacing (Tb.Sp)(P=0.001), but no effect on serum E2 level (P=0.432, P=0.459). Conclusion: Drynaria total flavonoids can inhibit the destruction of the mandibular trabecular structure, thus slowing down the mandibular resorption process. However, they cannot improve E2 concentration. The mechanism is realized by adjusting the balance of OPG/RANKL.