乳酸介导高强度间歇训练骨合成代谢的作用机制OA

Objective To investigate the role and mechanism of lactate(Lact)in bone anabolism mediated by high-intensity interval training(HIIT).Methods ①Eighteen mice were divided into Con group(no treatment),HT group(underwent HIIT only),and Lact group(injected with sodium L-lactate only),with 6 mice in each group.Blood samples were then obtained for Lact detection.②Postmeno-pausal osteoporosis mouse model was established by ovariectomy(OVX).The mice were then divided into OVX group(OVX only),OVX+HIIT group(underwent HIIT after modeling),OVX+HIIT+lactate transporter inhibitor α-cyano-4-hydroxycinnamic acid(α-CHCA)group(underwent HIIT combined with intraperitoneal injection of α-CHCA after modeling),and OVX+Lact group(underwent subcutaneous injection of sodium L-lactate after modeling),with 10 mice in each group.Mice in the Sham group(n=10)did not undergo modeling.Bone microstructural parameters were analyzed using Micro-CT scanning.The number of osteoblasts(N.Ob)and number of osteoclasts(N.Oc/BS)were assessed by HE staining and tartrate-resistant acid phosphatase(TRAP)staining,respectively.The following microstructural parameters were measured using a Scanco Micro-CT40 scanner:bone mineral density(BMD),bone volume over total volume(BV/TV),trabecular number(Tb.N),trabecular thickness(Tb.Th),trabecular separation(Tb.Sp),cortical thickness(Ct.Th),and bone area over total area(BA/TA).③Mouse preosteoblast MC3T3-E1 cells were cultured in vitro and divided into the Control group(normal culture),Lact-C group(treated with 20 mmol/L sodium L-lactate),α-CHCA group(treated with 0.4 mmol/L α-CHCA),and Lact+α-CHCA group(treated with both 20 mmol/L sodium L-lactate and 0.4 mmol/L α-CHCA).Osteogenic differentiation and mineralized nodule formation were evaluated by alkaline phosphatase(ALP)staining and alizarin red S staining.LC3 expression was detected by immunofluorescence staining.Western blot was used to detect the expression of Runt-related transcription factor 2(Runx2),Osterix(Osx),osteopontin(OPN),autophagy-related protein Beclin-1,autophagy adaptor protein p62,GATA-binding protein 4(GATA4),Parkin protein,and the LC3-Ⅱ/LC3-Ⅰ ratio.Results ①In mice,plasma Lact levels peaked at 30 minutes after HIIT and at 60 minutes after Lact injection.②Compared with the OVX group,the OVX+HIIT and OVX+Lact groups exhibited increased BMD,BV/TV,Tb.N,Tb.Th,Ct.Th,BA/TA and N.Ob in bone tissue,as well as decreased Tb.Sp and N.Oc/BS,all with statistically significant differences(P<0.05).③In vitro experiments showed that Lact treatment enhanced osteoblast mineralization and differentiation activity,significantly promoted autophagic flux,as evidenced by increased LC3-Ⅱ/LC3-Ⅰ ratio,Beclin-1 level and osteogenic markers Runx2,Osx,and OPN expression,decreased p62 and GATA4 proteins.These effects were attenuated by inhibiting Lact transport.Conclusion In HIIT-mediated bone anabolism,Lact promotes the decrease of GATA4 protein expression by activating autophagy-related proteins,thereby driving osteoblast differentiation and alleviating osteoporosis.