This study investigated the effects of endurance running training on the bones of growing rats. Thirty-two male Wistar rats (7 weeks old) were assigned to a sedentary control group (CON, n = 10), a continuous endurance running group (CEN, n = 10), or an intermittent endurance running group (IEN, n = 12). After an 8-week training period, both exercise groups had significantly less body weight (BW) gain but higher aerobic capacity, shown by increased muscle citrate synthase (CS) activity. Bone area (BA), areal bone mineral density (aBMD), and bone mineral content (BMC) were measured by dual-energy Xray absorptiometry (DXA) in the total femur and sections of femora. Except for showing a significantly higher aBMD in total femora, the CON group was only slightly and nonsignificantly higher in other DXA measurements. In tissue weight measurements, the CON group showed a nonsignificantly higher tissue dry weight (P = 0.146), but a significantly lower tissue water content ratio (WCR, %) as compared to the exercise group. Despite having nonsignificantly lower long bone cross-sectional parameters, both exercise groups showed significantly better biomaterial properties, as measured by a three-point bending test. In extrinsic analysis, femora of the two exercise groups showed no difference in bending load and stiffness, but were significantly higher in post-yield bending energy and total ultimate bending energy (P < 0.05). Similar phenomena were revealed in tissue-level measurements; the CEN and IEN groups were significantly higher in ultimate toughness and post-yield toughness (P < 0.05). Higher post-yield energy shown by two exercise groups implied a change in bone matrix organization. In conclusion, this study demonstrated that two endurance treadmill training modes benefit bone, with subjects showing better tissue biomaterial properties without significantly increasing aBMD, BMC, or bone dimension. Further study would be valuable to investigate the effects of endurance running on other components of bone, such as organization of bone matrix and its relationship with bone biomaterial properties.

Our data suggest that water solution of onion crude powder inhibits osteoclastogenesis from co-cultures of bone marrow stromal cells and macrophage cells via attenuation of RANKL-induced ERK, p38 and NF-kappaB activation.

To investigate the effects of dietary methionine restriction (MetR) and endurance exercise on bone quality under a condition of estrogen deficiency, female Sprague-Dawley rats (36-wk-old) were assigned to a sham surgery group or one of five ovariectomized groups subjected to interventions of no treatment (Ovx), endurance exercise (Exe), methionine restriction (MetR), methionine restriction plus endurance exercise (MetR + Exe), and estrogen treatment (Est). Rats in the exercise groups were subjected to a treadmill running regimen. MetR and control diets contained 0.172 and 0.86% methionine, respectively. After the 12-wk intervention, all animals were killed, and serum and bone tissues were collected for analyses. Compared with estrogen treatment, MetR diet and endurance exercise showed better or equivalent efficiency in reducing body weight gain caused by ovariectomy (P < 0.05). Whereas only the Est group showed evidence for reduced bone turnover compared with the Ovx group, MetR diet and/or endurance exercise demonstrated efficiencies in downregulating serum insulin, leptin, triglyceride, and thiobarbituric acid reactive substances (P < 0.05). Both the Exe and MetR groups showed higher femoral cortical and total volumetric bone mineral density (vBMD), but only the Exe and Est groups preserved cancellous bone volume and/or vBMD of distal femora (P < 0.05) compared with the Ovx group. After being normalized to body mass, femora of the MetR and MetR + Exe groups had relatively higher bending strength and dimension values followed by the Sham, Exe, and Est groups (P < 0.05). In conclusion, both MetR diet and endurance exercise improved cortical bone properties, but only endurance exercise preserved cancellous bone under estrogen deficiency.

BackgroundPhosphate burden in chronic kidney disease (CKD) leads to elevated serum fibroblast factor-23 (FGF-23) levels, secondary hyperparathyroidism and chronic kidney disease-mineral bone disorder (CKD-MBD). However dissociated hyperphosphatemia and low serum FGF-23 concentrations have been observed in experimentally parathyoridectomized rats. The relationships between serum mineral, hormone, and bone metabolism may be altered in the presence of CKD. The aim of our study was to investigate whether a consistent relationship existed between serum FGF-23 levels, specific serum biochemical markers, and histomorphometric parameters of bone metabolism in a parathyroidectomized CKD animal model.ResultsSprague Dawley rats were divided into 3 groups: parathyroidectomy (PTX) and CKD (PTX+CKD, 9 rats), CKD without PTX (CKD, 9 rats), and neither PTX nor CKD (sham-operated control, 8 rats); CKD was induced by partial nephrectomy. At 8 weeks after partial nephrectomy, serum biomarkers were measured. Bone histomorphometries of the distal femoral metaphyseal bone were analyzed. The mean serum FGF-23 levels and mean bone formation rate were the highest in the CKD group and the lowest in the PTX+CKD group. Bone volume parameters increased significantly in the PTX+CKD group. Pearson’s correlation revealed that serum FGF-23 levels associated with those of intact parathyroid hormone, phosphate, collagen type I C-telopeptide, and calcium. Univariate linear regression showed that serum FGF-23 values correlated with bone formation rate, bone volume, and osteoid parameters. Stepwise multivariate regression analysis revealed that circulating FGF-23 values were independently associated with bone volume and thickness (β = -0.737; p < 0.001 and β = -0.526; p = 0.006, respectively). Serum parathyroid hormone levels independently correlated with bone formation rate (β = 0.714; p < 0.001) while collagen type I C-telopeptide levels correlated with osteoid parameter.ConclusionSerum FGF-23 levels independently correlated with bone volume parameters in rats with experimentally induced CKD.

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