Objective      To observe the effect of myricetin on bone volume of ovariectomized (OVX) rats and primarily explore the mechanism.       Methods      Twelve female SD rats were randomly divided into sham group

OVX group and OVX+myricetin group. In 1 week after modeling

the OVX+myricetin group

sham group and OVX group were intraperi

toneally injected with myricetin 85 mg/kg or methanol solvent

twice per week

for 8 weeks. Subcutaneous injection of alizarin red was conducted on the 10th day and 3rd day before the rats were sacrificed. Distal femurs were analyzed by MicroCT scanning. Trabecular bone (Tb) was tested by HE staining. Serum amino-terminal propeptide of typeⅠprocollagen (PINP) was detected by ELISA. Alizarin red fluorescent strips were observed with fluorescence microscopy. Osteogenesis of BMMSCs was analyzed by ALP staining. ROS level was detected by fluorescence tagging. Gene expression was tested by real-time PCR.       Results      The bone volume/tissue volume (BV/TV)

Tb number and Tb thickness of the OVX group were lower than those of the sham group

whereas the Tb space was higher. Tb of the OVX group was less than that of the sham group. Serum PINP and the distance between two alizarin red fluorescent strips in the OVX group were lower than those in the sham group. BV/TV

Tb number and Tb thickness of the OVX+myricetin group were higher than those of the OVX group

whereas Tb space was lower. Tb of the OVX+myricetin group was more than that of the OVX group. Serum PINP and the distance between two alizarin red fluorescent strips in the OVX+myricetin group were higher than those in the OVX group. The ROS level of endogenous BMMSCs in the OVX group was higher than that in the sham group

the expression of SOD was lower

and ALP activity and osteogenic genes were higher. ROS level of endogenous BMMSCs in the OVX+myricetin group was lower than that of the OVX group

the expression of SOD was higher

and ALP activity and osteogenic genes were lower. Furthermore

ROS level of H

2

O

2

-treated BMMSCs was higher than that of non-treated BMMSCs

the expression of SOD was lower

and ALP activity and osteogenic genes were higher. ROS level of H

2

O

2

-treated BMMSCs declined after treatment with myricetin

the expression of SOD was higher

and ALP activity and osteogenic genes were lower.       Co

nclusion      Myricetin reduces bone loss of OVX rats through lowering endogenous ROS level and restoring osteogenesis of endogenous BMMSCs.