Effects Of Ladder Climbing Exercise On LncRNA HOXA11-AS And Bone Formation In Mice At Different Periods Before And After Ovariectomy

Purpose:This study examines the effects of physical exercise intervention on bone microstructure,bone strength,and the expression of lncRNA HOXA11-AS and related osteogenic factors in ovariectomized mice before and after surgery,as well as during the peri-operative period.The study aims to simulate the impact of physical exercise intervention during three distinct periods,namely adolescence,postmenopause,and throughout life,on bone health in postmenopausal women from an animal experimental perspective.The findings may offer theoretical support for exercise-based prevention and treatment of osteoporosis.Methods:After being adaptively fed for one week,40 SPF level C57BL/6 female mice at 5weeks of age were randomly divided into 5 groups:(1)SHAM group with a sham surgery and no exercise,(2)OVX group with ovariectomy and no exercise,(3)PreOVX+E group with exercise training from the 1st to 6th week,(4)OVX+E group with exercise training from the 1st to 6th week and 11 th to 16 th week,and(5)Post-OVX+E group with exercise training from the 11 th to 16 th week.Ovariectomy was performed on the OVX group and the exercise groups in the 7th week,while the SHAM group had only the fat around the ovary removed.All mice rested without exercise intervention for 4 weeks(7th-10 th week)after surgery.After exercise intervention,tibias and femurs were collected for measurements.Micro CT was used to assess the bone microstructure parameters of tibias,and the mechanical properties of the left femurs were measured using a universal material testing machine.q PCR was used to detect the gene expression of lncRNA HOXA11-AS and related osteogenic factors(FGF2,OCN,and OPN)in the right femurs,while protein expression of related osteogenic factors(ATF4,β-catenin)was detected using Western blot analysis in the left femurs.Graph Pad Prism8 was used for data plotting and graphical analysis,and SPSS 20 was used for statistical analysis.P<0.05 indicates significant differences.Results:1)Compared to the SHAM group,the OVX group showed a significant decrease in bone morphology and microstructure,including bone length and weight ratios(P<0.05),uterine weight and weight ratios(P<0.01),and cortical bone TV,BV,Ct.Ar,Tt.Ar,and Ct.Th(P<0.01),and an increase in BS/BV and DA(P<0.01).The trabecular bone BV(P<0.01),BV/TV(P<0.01),BS(P<0.01),Tb.N(P<0.05),and Conn.D(P<0.01)significantly decreased,while Tb.Sp and SMI(P<0.05)significantly increased.In terms of bone strength(mechanical parameters),the OVX group showed a significant decrease in maximum load,bending strength,and maximum deflection(P<0.05).In addition,the expression of lncRNA HOXA11-AS and related osteogenic factors(FGF2,OCN,and OPN)significantly decreased(P<0.01),while β-catenin expression significantly decreased(P<0.05)and miR214 expression significantly increased(P<0.01)in the femurs of the OVX group.2)Compared to the OVX group,the Post-OVX+E group showed significant differences in bone length and uterine weight ratios(P<0.01),and all exercise groups showed an increasing trend in cortical bone BMD but without statistical significance(P>0.05),while the Post-OVX+E group showed a significant increase in trabecular bone BMD(P<0.05).The Post-OVX+E group had significant increases in cortical bone BV,TV,BS,Ct.Ar,and Tt.Ar(P<0.01)and trabecular bone TV(P<0.05).3)Compared to the OVX group,the Post-OVX+E group showed a significant increase in maximum load and maximum deflection(P<0.05).4)Compared to the OVX group,the lncRNA HOXA11-AS and related osteogenic factors(FGF2,OCN,and OPN)expression significantly increased(P<0.01)in the femurs of the OVX+E and Post-OVX+E groups.Meanwhile,miR-214 expression significantly decreased(P<0.01)in the Pre-OVX+E,OVX+E,and Post-OVX+E groups.The protein level of ATF4 significantly increased(P<0.05)in the femurs of the OVX+E group,while the protein level of β-Catenin significantly increased(P<0.05)in the femurs of the Post-OVX+E group.Conclusions:Exercise interventions at different times before and after ovariectomy promote bone formation,with the best results seen in post-ovariectomy stair-climbing exercises,which significantly improve bone microstructure,increase bone strength,and upregulate the expression of lncRNA HOXA11-AS and associated osteogenic factors.The effect of continuous exercise before and after ovary removal was second.The effect of exercise intervention before ovariectomy may be related to the "cessation of training".