Mechanism Of Moderate-Intensity Treadmill Exercise On The Loss Of Lumbar Vertebrae Bone Mass In Ovariectomized Rats

Objective:The purpose of this study was to explore the mechanism of moderate-intensity treadmill exercise on the loss of bone mass of lumbar vertebrae in ovariectomized rats.Methods:Forty-five female Sprague-Dawley rats were randomly divided into following four groups:sham-operation(Sham), ovariectomized (OVX), ovariectomized exercised (EX,18 m/minute,45 min/day,5 uphill,5 times/week) and ovariectomized treated with estrogen (E2,25μg/kg,3 times/week). After treatment for 15 weeks, weighed the body weight, the wet weight of abdominal fat and the wet weight of uterus; detected the serum level of TC, TG, LDL, HDL, ALP and E2. Moreover, the L5 bone mineral density (BMD) and bone mineral content (BMC) were detected by dual-energy X-ray absiorptiometry, and the dry weight of L5 were weighed; the morphological changes of L3 were observed by HE staining; the protein expression of L4 PPARy and GSK-3βwere detected by Western blotting.Result:(1) The body weight, wet weight of abdominal fat in OVX were significantly higher than the other three groups; uterus weight was significantly lower than that in Sham and E2 group, however no difference with EXE group. (2) The level of serum E2 in OVX was significantly lower than the other three groups; TC, TG and LDL level were significantly higher than that in Sham and EX group, however, there was no difference with E2 group; the level of HDL/TC was significantly lower than that in Sham group, however, there was no difference with other groups; ALP level was significantly higher than that in Sham and E2 group, no difference with EX group. (3) The BMD and BMC of L5, dry weight of lumbar vertebrae/body weight in OVX group were significantly lower than the other three groups. However, the number of bone marrow adipocytes in OVX group was significantly higher than other three groups. (4) PPARγprotein expression of L4 in OVX group was significantly higher than other three groups; P-GSK-3β/GSK-3βprotein expression was significantly lower than other three groups.Conclusion:Moderate-intensity treadmill exercise can benefit the disorder of serum lipids; increase the level of serum E2; prevent the bone mass losing of lumbar vertebrae, inhibit the increase of bone marrow adipocytes and improve the bone morphology in OVX rats; inhibiting the protein expression of PPARy and increase the protein expression of P-GSK-3β/GSK-3βof lumbar vertebrae in OVX rats.