Effect Of Mechanical Vibration On Hippocampal Estrogen In Ovariectomized Osteoporotic Fracture Rats

Objective: In this study,the effects of mechanical vibration on the expression of hippocampal estrogen and mir-214-3p at the broken end of bone fracture in rats with ovariectomized osteoporotic fracture were studied by establishing a rat model of osteoporotic fracture with ovariectomized osteoporosis and using mechanical vibration intervention,so as to explore the mechanism of hippocampal estrogen's participation in the regulation of fracture healing in mechanical vibration.Methods : 30 3-month-old female Wistar rats were randomly divided into 3 groups,the fracture control group(Sham,n=10),the osteoporotic fracture model group(OVX,n=10),and the osteoporotic fracture vibration group(ovx-v,n=10).The osteoporosis model was established after 1 week of adaptive feeding.Bilateral ovaries were removed successively in the OVX group and ovx-v group,and adipose tissue of the same weight around the ovaries was removed in the Sham group.Five months after ovariectomy,the fracture model was established,and the central femur fracture was caused by external force added by scalpel,and the fracture was reduced and fixed.Five days after fracture surgery,rats in the ovx-v group were treated with systemic mechanical vibration.The rats were placed in a box on a vibration platform in a natural position.Vertical vibration with a frequency of 35 Hz,an amplitude of 2mm and an acceleration of 2.94m/s2 was adopted for 20 minutes each time,5 times a week.The Sham group and the OVX group were placed on the vibration platform for free movement for the same time without vibration treatment.Hippocampal and bone tissue samples of each group were collected at week 2 and week 6 of mechanical vibration intervention,respectively.The hippocampal estrogen content of the rats was detected by enzyme-linked immunoadsorption assay(ELISA),and the hippocampal ER? 9mRNA?broken end of bone ER? 9mRNA and mir-214-3p were detected by rt-pcr.Results:(1)Hippocampal estrogen expression: Week 6 compared to week 2,the hippocampal estrogen content in the sham group increased slightly,while that in the OVX group increased slightly;The content of hippocampal estrogen in OVX-V group increased significantly.In the second week,there was a significant difference between the sham group and the OVX group(P = 0.001 < 0.01).There was a significant difference between the OVX-V group and the OVX group(P = 0.000 < 0.01).At week 6,there was a significant difference between the sham group and the OVX group(P = 0.000 < 0.01).There was a significant difference between the OVX-V group and the OVX group(P = 0.000 < 0.01).(2)Expression of hippocampal estrogen receptor ER? 9mRNA: Week 6 compared to week 2,the expression level of hippocampal estrogen receptor ER? 9mRNA in the sham group showed a slightly decreasing trend,while the expression level of hippocampal estrogen receptor ER? 9mRNA in the OVX group showed an increasing trend.The content of ER? 9mRNA in hippocampus of OVX-V group increased significantly.In the second week,there was a significant difference between the sham group and the OVX group(P = 0.019 < 0.05).There was a significant difference between the OVX-V group and the OVX group(P = 0.004 < 0.01).At week 6,there was a significant difference between the sham group and the OVX group(P = 0.005 < 0.01).There was no significant difference between the OVX-V group and the OVX group(P = 0.170 > 0.05).(3)The expression of estrogen receptor ER? 9mRNA at the broken end of fracture: Week 6 compared to week 2,the ER? 9mRNA at the broken end of fracture in the sham group showed a slightly increasing trend,and the ER? 9mRNA at the broken end of fracture in the OVX group showed an increasing trend.The ER? 9mRNA at the broken end of fracture in OVX-V group increased.In the second week,there was a significant difference between the sham group and the OVX group(P = 0.000 < 0.01).There was a significant difference between the OVX-V group and the OVX group(P = 0.011 < 0.05).In the sixth week,there was a significant difference between the sham group and the OVX group(P = 0.008 < 0.01).There was no significant difference between the OVX-V group and the OVX group(P = 0.164 > 0.05).(4)The expression of mir-214-3-p at the broken end of fractures: Week 6 compared to week 2,the content of mir-214-3-p at the broken end of fractures in the sham group showed a decreasing trend,while the content of mir-214-3-p at the broken end of fractures in the OVX group showed an increasing trend.The content of mir-214-3-p at the broken end of fracture in OVX-V group showed a decreasing trend.In the second week,there was a significant difference between the sham group and the OVX group(P = 0.001 < 0.01).There was no significant difference between the OVX-V group and the OVX group(P = 0.4 > 0.05).At week 6,there was a significant difference between the sham group and the OVX group(P = 0.001 < 0.01).There was a significant difference between the OVX-V group and the OVX group(P = 0.000 < 0.01).Conclusion:(1)Bone damage is present in the hippocampus,and simple fracture can gradually heal itself.(2)Oarian removal,osteoporosis and fracture in rats with hippocampal estrogen compensated for peripheral estrogen to promote fracture healing,but hippocampal estrogen alone had limited effect on fracture healing.(3)Mechanical vibration intervention in the fracture of ovariectomized rats after osteoporosis can increase the expression of hippocampal estrogen and promote fracture healing.