Femoral Dry Weight Research Articles

Chrysin alleviates alteration of bone-remodeling markers in ovariectomized rats and exhibits estrogen-like activity in silico.

Evidences are beginning to accrue that flavonoids, particularly phytoestrogens, could have beneficial effects against several age-related diseases linked to estrogen deficiency including postmenopausal osteoporosis. In this study, the effect of chrysin on selected bone-remodeling markers in ovariectomized rats and its estrogen-like activity in silico were investigated. The data indicated that administration of chrysin at 50mg/kg and 100mg/kg for 6weeks to OVX rats significantly (p < 0.05) prevented body weight gain and partially reverse uterine weight loss. In addition, treatment of OVX rats significantly (p < 0.01) increased femur dry weight, femur ash weight, bone ash calcium, and phosphorous levels in a dose-dependent manner. However, there was significant (p < 0.001) decline in serum estradiol level in all OVX rats compared to the sham-operated group. Interestingly, administration of chrysin significantly (p < 0.05) reversed the reduction of estradiol induced by ovariectomy compared to untreated OVX rats. Moreover, administration of chrysin to OVX rats significantly (p < 0.05) suppressed excessive elevation of bone-remodeling markers expression compared to untreated OVX rats. Similarly, molecular docking analysis revealed that chrysin interacts with both α and β estrogen receptors with exothermic binding energies of -229.83kcal/Mol and -252.72kcal/Mol, respectively, and also fits perfectly into the active site of both α and β estrogen receptors. This study demonstrated that chrysin exhibits potential antiosteoporotic effects against bone loss in OVX rats through enhanced bone mineral contents and preventing excessive elevation of bone-remodeling markers and bone-resorbing cytokine.

Antioxidative peptide from milk exhibits antiosteopenic effects through inhibition of oxidative damage and bone-resorbing cytokines in ovariectomized rats.

Oxidative stress has been implicated as a crucial pathogenic factor in the development of postmenopausal osteoporosis. Milk-derived antioxidative peptides are gaining much attention toward the development of prodrugs for alleviating several human diseases, including osteoporosis. The aim of the present study was to determine whether antioxidant peptides are good candidates for alleviating postmenopausal osteoporosis. In the present study, an ovariectomized (OVX) osteoporotic rat model was used to investigate the protective effects of buffalo milk casein-derived novel peptide VLPVPQK (PEP) against OVX-induced bone loss and the related mechanisms. Results of the present study indicated that daily administration of antioxidative peptide PEP at 50 and 100μg/kg for 8wk prevents body weight gain, uterine weight loss, and atrophy of endometrial lumen. Moreover, PEP increased femur dry weight, ash weight, bone ash calcium, and serum calcium and phosphorus level. Interestingly, PEP increased bone mineral density and improved trabecular microarchitecture in both femur and tibia of OVX rats. Additionally, PEP increased bone strength, reduced serum bone turnover markers, inhibited bone resorbing cytokines and decreased malondialdehyde level in OVX rat. Furthermore, PEP-elevated serum transforming growth factor-β, increased, reduced glutathione levels, superoxide dismutase, and catalase activity altered by OVX. We demonstrated that PEP exhibits antiosteopenic effects via enhancement of antioxidant activity and reduction of bone-resorbing cytokines expression.

Effect of utilization of maize silage in moult inducing diets on performance, immune response and bone quality in laying hens

The aim of the study was to evaluate the utilization of maize silage (MS) in moult induction and its effects on immune response and bone quality in laying hens. Laying hens were subjected to 1 of 6 treatments: full-fed (control; FF); total feed withdrawal (positive control for moult induction; FW); 100 MS (M100); 90 MS + 10 layer ration (LR) (M90); 80 MS + 20 LR (M80); and 70 MS + 30 LR (M70). After 9 days body weight loss occurred in all moulting treatments. The examined treatments caused cessation of egg production on day 4 (M90), 5 (FW, M100) and 7 (M70, M80). On day 6 the heterophil : lymphocyte (H:L) ratio did not differ between all MS treatments and FF; however FW caused its increasing only in comparison to FF, M80 and M70. On day 9 H:L ratio for FF did not differ only from M70 and M90. Antibody production against sheep red blood cell was unaffected by all moulting treatments. The femur dry weight for FF did not differ from M70, M80, M100; however there was observed no difference between FW and M70, M90, M100. The treatments caused decrease of femur ash content in comparison to FF group (except M70) with the lowest value in FW. In conclusion, obtained data indicate that the use of MS mixed with LR results in moult induction. Likewise, it is suggested to use 70 MS addition because of reduced moulting stress in birds and smaller losses of bone mineralization.

An Uncoupling Agent Containing Strontium Prevents Bone Loss by Depressing Bone Resorption and Maintaining Bone Formation in Estrogen‐Deficient Rats

AbstractTrabecular bone loss in estrogen deficiency is associated with enhanced bone resorption with a smaller increase in bone formation. We previously reported that low doses of strontium can increase trabecular bone volume in rodents by affecting bone resorption and formation. In this study we determined the effect of a new divalent strontium salt (S12911) on bone loss induced by E2 deficiency. Sprague‐Dawley female rats (230 g, n = 15–25 per group) were sham operated or ovariectomized (OVX) and treated with 17β‐estradiol (E2, 10 μg/kg/day, sc) or S12911 by gavage at the dose of 77, 154, or 308 mg/kg/day or the vehicle. Treatment for 60 days with S12911 resulted in a dose‐dependent increase in plasma, urine, and bone strontium concentrations without any deleterious effect on total or skeletal growth. OVX rats were osteopenic compared to sham rats as shown by decreased femoral dry bone weight and mineral content measured on bone ash and by DXA. Treatment of OVX rats with S12911 prevented bone loss as bone ash and bone mineral content were restored to the values in sham rats. Trabecular bone volume measured by histomorphometry on the tibial metaphysis was decreased by 46% in OVX rats and was corrected by E2. Treatment of OVX rats with S12911 increased the trabecular bone volume by 30–36%. Histomorphometric indices of bone resorption (osteoclast surface and number) were increased in OVX rats and were reduced by S12911 to the levels in sham rats. In contrast to this inhibitory effect on bone resorption, the osteoid surface, osteoblast surface, mineral apposition rate, and bone formation rate were as high in OVX rats treated with S12911 as in untreated OVX rats. In addition, plasma osteocalcin (OC) and alkaline phosphatase (ALP) levels remained elevated or were further increased in OVX rats treated with S12911. In contrast, treatment with E2 reduced both bone resorption and formation and plasma ALP and OC to the levels in sham rats. The data indicate that the divalent strontium salt S12911 is acting as an uncoupling agent that can prevent the femoral osteopenia and partially prevent the trabecular bone loss in E2‐deficient rats by inhibiting bone resorption without reducing bone formation.

Bipedal Loading During Recovery from Lactation Increases Femoral Skeletal Mass in Rats

0423 During lactation the maternal skeleton can lose as much as 4.8% BMD in the femoral neck and 5.1% in the lumbar spine in humans (Sowers et al., 1993). Bone lost during lactation can partially recover (Bowman & Miller, 1999). Mechanical loads to the skeleton play a major role in the accumulation and maintenance of skeletal mass and strength. PURPOSE: To determine the effects of bipedal loading during recovery from lactation on femoral skeletal mass. A secondary aim was to determine if bipedal loading during lactation could mitigate bone mass loss at the femur. METHODS: Nulliparous rats (N = 32) were mated and were permitted to go through two reproductive cycles. The day after the second parturition rats were randomized into four groups: Lactation (Lac; n = 8), Lactation, Raised Cage (Lac RC, n = 8), Lactation Recovery (Lac-Rec, n = 8), and Lactation Recovery, Raised Cage (Lac-Rec RC, n = 8). Lac and Lac RC groups were sacrificed after 21 days of lactation and the recovery groups continued on for an additional 6 weeks to assess loading during the recovery period. Femurs were excised at necropsy and were dehydrated, defatted, and weighed to obtain dry weight (g). The bones were ashed in a muffle furnace and weighed again to determine ash weight (g). RESULTS: There were no significant differences between Lac and Lac RC on femoral dry weight (0.652 ± 0.018 vs. 0.623 ± 0.017 g, p = 0.26) or ash weight (0.394 ± 0.011 vs. 0.374 ± 0.011 g, p = 0.22). Lac-Rec RC had greater femoral dry weight (0.724 ± 0.012 vs. 0.681 ± 0.013, p = 0.03) and femoral ash weight (0.450 ± 0.008 vs. 0.423 ± 0.009, p = 0.04) than Lac-Rec. CONCLUSIONS: Bipedal loading during recovery from lactation induced increases in skeletal mass. Bipedal loading during lactation had no effect, possibly because energy needs during lactation are too great. Supported by NIH grant AR044806.

Bipedal Loading During Recovery from Lactation Increases Femoral Skeletal Mass in Rats

0423 During lactation the maternal skeleton can lose as much as 4.8% BMD in the femoral neck and 5.1% in the lumbar spine in humans (Sowers et al., 1993). Bone lost during lactation can partially recover (Bowman & Miller, 1999). Mechanical loads to the skeleton play a major role in the accumulation and maintenance of skeletal mass and strength. PURPOSE: To determine the effects of bipedal loading during recovery from lactation on femoral skeletal mass. A secondary aim was to determine if bipedal loading during lactation could mitigate bone mass loss at the femur. METHODS: Nulliparous rats (N = 32) were mated and were permitted to go through two reproductive cycles. The day after the second parturition rats were randomized into four groups: Lactation (Lac; n = 8), Lactation, Raised Cage (Lac RC, n = 8), Lactation Recovery (Lac-Rec, n = 8), and Lactation Recovery, Raised Cage (Lac-Rec RC, n = 8). Lac and Lac RC groups were sacrificed after 21 days of lactation and the recovery groups continued on for an additional 6 weeks to assess loading during the recovery period. Femurs were excised at necropsy and were dehydrated, defatted, and weighed to obtain dry weight (g). The bones were ashed in a muffle furnace and weighed again to determine ash weight (g). RESULTS: There were no significant differences between Lac and Lac RC on femoral dry weight (0.652 ± 0.018 vs. 0.623 ± 0.017 g, p = 0.26) or ash weight (0.394 ± 0.011 vs. 0.374 ± 0.011 g, p = 0.22). Lac-Rec RC had greater femoral dry weight (0.724 ± 0.012 vs. 0.681 ± 0.013, p = 0.03) and femoral ash weight (0.450 ± 0.008 vs. 0.423 ± 0.009, p = 0.04) than Lac-Rec. CONCLUSIONS: Bipedal loading during recovery from lactation induced increases in skeletal mass. Bipedal loading during lactation had no effect, possibly because energy needs during lactation are too great. Supported by NIH grant AR044806.

Ingestion of water-soluble soybean fiber improves gastrectomy-induced calcium malabsorption and osteopenia in rats

OBJECTIVE: Total gastrectomy produces calcium malabsorption and osteopenia. We examined the effects of feeding water-soluble soybean fiber (WSSF), a highly fermentable dietary fiber with low viscosity, on calcium absorption and bone characteristics in totally gastrectomized rats. METHODS: Male Sprague-Dawley rats were assigned to two groups: sham operation and gastrectomy. After the postoperative recovery period, rats of each group were fed diets with or without WSSF (50 g/kg diet) for 4 wk. RESULTS: Net calcium absorption and femoral dry weight and calcium content and maximum breaking force were lower in the gastrectomy groups than in the sham groups. In the gastrectomy groups, calcium absorption and these femoral parameters were higher in rats fed the WSSF diet than in rats fed the WSSF-free diet. Feeding WSSF increased the concentrations of short-chain fatty acids and soluble calcium and decreased the pH in cecal contents. Net calcium absorption in gastrectomized rats correlated positively with the concentration of total short-chain fatty acids (the sum of acetic, propionic, and butyric acids) in cecal contents ( r = 0.545, P < 0.05) and negatively with cecal pH ( r = −0.628, P < 0.05). CONCLUSIONS: These findings indicate that ingestion of WSSF partly prevents the diminished calcium absorption after total gastrectomy in rats, resulting in the improvement of postgastrectomy osteopenia. The increase of calcium absorption may be associated with cecal fermentation of WSSF.

Enhancing Effect of Zinc and Vitamin K2 (Menaquinone-7) on Bone Components in the Femoral Tissue of Female Elderly Rats.

The effect of zinc and vitamin K2 (menaquinone-7) on bone components in the femoral tissue of female elderly rats was investigated. Rats were orally administrated either vehicle (distilled water), zinc sulfate (1.0 mg Zn/100 g body weight), menaquinone-7 (MK-7, 0.5 mg/100 g) or zinc (1.0 mg/100 g) plus MK-7 (0.5 mg/100 g) once a day for 7 days. Femoral dry weight was significantly increased by the administration of both zinc and MK-7, although a significant change was not seen by zinc or MK-7 alone. Calcium content in the femoral-diaphyseal and metaphyseal tissues was significantly increased by zinc administration. Such an increase was not found by MK-7. Bone calcium content was synergistically enhanced by the administration of both zinc and MK-7. Alkaline phosphatase activity and deoxyribonucleic acid (DNA) content in the diaphyseal and metaphyseal tissues were significantly increased by zinc or MK-7 administration; these increases were additively enhanced by both zinc and MK-7. Moreover, the intake of supplement containing both zinc (1.675 mg/100 g) and MK-7 (168.8 μg/100 g) once a day for 15 days caused a significant increase in femoral dry weight, alkaline phosphatase activity, DNA, calcium and zinc contents in the diaphyseal and metaphyseal tissues. This study demonstrates that the administration of both zinc and MK-7 can enhance additively or synergistically bone components in female elderly rats, suggesting a role in the prevention of osteoporosis with increasing age.

Effects of dietary calcium depletion and repletion on dynamic determinants of tibial bone volume in two inbred strains of mice

As an adjunct to our efforts to identify the genes that determine peak bone density, we examined phenotypic differences between two inbred strains of mice, C3H/HeJ (C3H) and C57BL/6J (B6), which are of similar size but differ with respect to peak bone density (e.g., C3H mice have 53% higher femoral bone density than B6 mice). The current studies were intended to compare the skeletal responses of C3H and B6 mice to 2 weeks of dietary calcium (Ca) depletion, followed by 2 weeks of Ca repletion. Initial studies showed that: (a) femur dry weight decreased during Ca depletion in both C3H and B6 mice (by 25% and 19%, respectively, p < 0.001) and most of this loss was recovered during Ca repletion; and (b) serum alkaline phosphatase (ALP) activity increased during Ca depletion, in both strains of mice ( p < 0.001), and returned to normal after Ca repletion. Histological analyses of ground cross sections prepared at the tibiofibular junction showed that Ca-depletion increased medullary area in both C3H and B6 mice (indicating endosteal bone loss, p < 0.01), with reversal during Ca repletion. There were no effects of Ca depletion or repletion on periosteal bone growth. Endosteal bone forming surface and endosteal mineral apposition decreased during Ca depletion and increased during repletion in both C3H and B6 mice ( p < 0.05). Net bone formation decreased during Ca depletion in C3H mice, but not B6 mice ( p < 0.01), and was normal during Ca repletion in both strains. Endosteal bone resorbing surface and net bone resorption increased during Ca depletion and decreased during repletion in both strains ( p < 0.01). A supplemental study (of Ca depletion without repletion) confirmed the effects of Ca depletion on femoral dry weight and serum ALP activity ( p < 0.001 for each). This supplemental study also showed that Ca deficiency increased serum parathyroid hormone (PTH) ( p < 0.05) and decreased (tibial) cortical bone area and cortical mineral content ( p < 0.05 to p < 0.001) in both strains of mice. Together, these data demonstrate that the skeletal responses to Ca depletion and repletion are, qualitatively, similar in C3H and B6 mice.

Prolonged intake of fermented soybean ( natto ) diets containing vitamin K 2 (menaquinone-7) prevents bone loss in ovariectomized rats

The effect of the prolonged intake of dietary vitamin K2 (menaquinone-7, MK-7) on bone loss in ovariectomized (OVX) rats was investigated. OVX rats were freely given experimental diets containing the fermented soybean (natto; including 9.4 micrograms MK-7/100 g diet) without or with supplemental MK-7 (containing 14.1 or 18.8 micrograms of MK-7 as total per 100 g diet) for 150 days. Feeding produced a significant elevation of MK-7 concentration in the serum of OVX rats. In this case, the femoral MK-4 content was significantly increased, but MK-7 was not detected in the femoral tissues, indicating degradation of MK-7. Serum gamma-carboxylated osteocalcin concentration was significantly decreased by OVX. This decrease was significantly prevented by the feeding of the natto diets with supplemental MK-7 (18.8 micrograms/100 g diets). OVX caused a significant decrease in femoral dry weight, femoral calcium content, and mineral density. These decreases were significantly prevented by feeding with diets containing natto with MK-7 (total, 18.8 micrograms/100 g diets). This study demonstrates that the prolonged intake of natto dietary including MK-7 has a preventive effect on bone loss induced by OVX. Dietary MK-7 may be useful in the prevention of osteoporosis.

Synergistic Effect of Genistein and Casein Phosphopeptides on Bone Components in Young and Elderly Female Rats.

The effect of genistein and casein phosphopeptides (CPP) on bone components in the femoral tissue of young and elderly rats was investigated. Genistein has been shown to directly stimulate bone formation, and CPP has been reported to increase intestinal calcium absorption. Genistein (10 or 50μg/100g body weight) or CPP (40mg/100g) was orally administered to young (5 weeks old) or elderly (50 weeks old) rats for 14d. The administration of genistein (50μg/100g) resulted in a significant increase in the femoral dry weight, calcium content, alkaline phosphatase activity, and deoxyribonucleic acid (DNA) content in the femoral-diaphyseal and metaphyseal tissue of young and elderly rats. The administration of CPP (40mg/100g) caused a significant increase in the femoral dry weight of young and elderly rats. CPP administration increased significantly the diaphyseal calcium content in young rats, but it did not have an effect on the diaphyseal and metaphyseal alkaline phosphatase activity and DNA content. The genistein (50μg/100g)-increased femoral dry weight, calcium content, alkaline phosphatase activity, and DNA content in the diaphyseal and metaphyseal tissue of young rats was significantly enhanced by the simultaneous administration of CPP (40mg/100g). In elderly rats, this enhancement was resulted in the metaphyseal tissue. This study demonstrates that the combination of genistein and CPP administration has a synergistic-anabolic effect on bone components in rats with increasing age, suggesting that it may have a role in the prevention of osteoporosis.

Supplemental Intake of Isoflavones and Zinc-Containing Mineral Mixture Enhances Bone Components in the Femoral Tissue of Rats with Increasing Age.

The effect of the supplemental intake of isoflavone and a zinc-containing mineral mixture on bone components in the femoral tissue of rats was investigated. Rats (5 weeks old) were orally administered either vehicle, isoflavone glycoside (5mg/100g body weight), aglycone isofavone (5mg/100g, including 3.772mg daidzein, 0.395mg genistein, and 0.833mg glycitein), zinc-containing mineral mixture (0.833mg zinc, 50mg calcium, 25mg magnesium, and 0.208μg vitamin D3 per 100g body weight, respectively), or both aglycone isoflavone (5mg/100g) and zinc-containing mineral mixture for 7d. Administrations resulted in a significant increase in femoral dry weight, calcium content, alkaline phosphatase activity, and DNA content in the femoral-diaphyseal and metaphyseal tissues. Femoral zinc content was significantly increased by the administration of zinc-containing mineral mixtures with or without aglycone isoflavone. The effect of aglycone isoflavone in elevating bone components was significantly enhanced in combination with the zinc-containing mineral mixture. Moreover, the oral administration of both aglycone isoflavones and zinc-containing mineral mixture to aged rats (50 weeks old) for 21d resulted in a significant increase in femoral dry weight, zinc content, and bone components. This study demonstrates that supplemental intake of both aglycone isoflavone and a zinc-containing mineral mixture has an anabolic effect on bone components in aged rats, suggesting the role of nutrients in the prevention of osteoporosis with increasing age.

The effect of moderately and severely restricted dietary magnesium intakes on bone composition and bone metabolism in the rat.

Forty 3-week-old male rats, Wistar strain, average weight 59 g, were randomized by weight into five groups of eight rats each. Three groups were fed ad libitum on a semi-purified diet containing (per kg) 400 (adequate), 200 (moderately Mg-restricted) or 20 (severely Mg-restricted) mg Mg for 3 weeks while two groups were pair-fed with the Mg-adequate diet in the same quantities as those consumed by the two Mg-restricted groups respectively. While weight gains and food conversion efficiency values for the Mg-restricted groups were similar to those of the corresponding pair-fed control groups, serum and kidney Mg, and femoral dry weight were reduced by 70, 7 and 9% respectively in the severely Mg-restricted group and were unaffected in the moderately Mg-restricted group. Significant reductions were observed in urinary pyridinoline (Pyr) (by 44 and 34%) and deoxypyridinoline (Dpyr) levels (by 40 and 33%) (markers of bone resorption), serum osteocalcin levels (by 46 and 28%) (marker of bone formation), femoral Mg levels (by 52 and 14%) and osteocalcin mRNA levels (by 46 and 22%) compared with the corresponding pair-fed controls, in the severely and moderately Mg-restricted groups respectively, and these reductions, except for those in urinary Pyr and Dpyr, were more marked in the severely Mg-restricted group. Femoral Ca and P concentrations were unaffected by dietary Mg restriction. These results show that not only severe but also moderate dietary restriction of Mg over 21 d results in qualitative changes in bone (i.e. reduced Mg concentration) as well as in aberrant bone turnover in young growing rats (i.e. severely depressed rates of bone formation and bone resorption), which may impair bone development and bone strength.

Effect of vitamin K2 (menaquinone-7) in fermented soybean (natto) on bone loss in ovariectomized rats.

The effect of dietary vitamin K2 (menaquinone-7) on bone loss in ovariectomized (OVX) rats was investigated. OVX rats were freely given experimental diets containing menaquinone-4 (MK-4; 12mg/100g diet) or menaquinone-7 (MK-7; 18.1mg/100g diet) for 24 days; MK-4 and MK-7 were equal in molar concentrations. This feeding caused a remarkable increase of MK-4 and MK-7 concentrations in the serum and femur of OVX rats. OVX-induced decrease in the femoral dry weight and femoral calcium content was prevented by the feeding of dietary MK-4 or NK-7. In separate experiments, OVX rats were freely given experimental diets containing the fermented soybean (natto; including 9.4 microg MK-7/100g diet) without or with added MK-7 (37.6 microg/100g diet) for 77 days. Feeding produced a significant elevation of MK-4 and MK-7 concentrations in the serum of OVX rats. In this case, a significant increase in the femoral MK-4 content was observed but MK-7 was not detected in the femoral tissues. OVX-induced decreases in the femoral dry weight and femoral calcium content were significantly prevented by the feeding of diets containing natto with MK-7 added (37.6 microg/100g diets). This study demonstrates that the intake of dietary MK-7 has a preventive effect on bone loss caused by OVX. This effect may be partly caused by MK-4, which is formed by degradation of MK-7.

Short-term healing kinetics of cortical and cancellous bone osteopenia induced by unloading during the reloading period in young rats.

We investigated the short-term recuperation of bone mass during skeletal reloading after a period of unloading in young rats. One hind limb of 4-week-old rats was either unloaded irreversibly by sciatic neurectomy, or unloaded reversibly by external fixation. Other animals were sham-operated. After 9 days, the fixation-unloaded limbs were reloaded for 1-3 weeks and were compared with the hind limbs of age-matched unloaded (neurectomized) and sham-operated controls. Cortical and cancellous bone mass was measured using ashing and histomorphometry. Cortical bone mass (expressed as femoral dry and ash weight and tibial cortical bone area) was reduced in both unloaded groups and was accompanied by production of hypomineralized bone, as shown by a reduction in the percent ash of the dry weight. Cancellous bone mass (expressed as bone area and surface at the tibial metaphysis) was also reduced in both unloaded groups. Cortical bone mass deficit was greater in the fixation group than in the neurectomy group. Thereafter it increased in the neurectomy group despite a normal longitudinal growth rate, but returned to age-matched values in the reloaded group by 3 weeks. The changes in tibial cancellous bone mass were more pronounced but followed a similar pattern and normalized by 2 weeks. These data demonstrate that total unloading produced by external fixation causes a greater degree of bone mass deficit than partial unloading (produced by neurectomy); the rate of bone loss during unloading in the rat hind limb is more rapid than its recovery during reloading; and cancellous bone recuperates during the reloading phase faster than does cortical bone.

Histomorphological confirmation of bone loss in the femoral-metaphyseal tissues of rats with skeletal unloading.

The alteration of mineral content in the femoral metaphysis of rats with skeletal unloading was investigated using a model of hindlimb suspension. Animals were fed for 4 days during the unloading. The femoral length, femoral dry weight and femoral mineral density were significantly decreased by the unloading. The calcium, phosphorus and zinc contents in the femoral metaphysis were appreciably reduced by the unloading, although, except for zinc, similar decreases were not seen in the femoral diaphysis. Moreover, the trabecular bone at the femoral metaphysis was clearly reduced by the unloading. Skeletal unloading caused a decrease in osteoid tissue in the primary and secondary spongiosa, indicating that osteoblastic bone formation may be inhibited. The present results clearly demonstrate that skeletal unloading can induce bone loss in the femoral metaphysis.

Fermentation of soya-bean meal with Aspergillus usami improves phosphorus availability in chicks

The present study examined the effect of the fermentation of soya-bean meal with Aspergillus usami on phosphorus availability in chicks. Thirty 1-week-old male Leghorn-type chicks were divided into three groups and fed following each diet for 4 weeks: 1) a diet containing soya-bean meal (SBM diet; total phosphorus, 5.5 g kg −1 dry matter; nonphytate-phosphorus, 2.0 g kg −1 dry matter), 2) a diet containing soya-bean meal supplying inorganic phosphorus (SBM + P diet; total phosphorus, 7.7 g kg −1 dry matter; nonphytate-phosphorus 4.2 g kg −1 dry matter), or 3) a diet containing the fermented soya-bean meal (FSBM diet; total phosphorus, 5.6 g kg −1 dry matter; nonphytate-phosphorus, 3.6 g kg −1 dry matter). Body weight gain was significantly higher in the chicks fed the FSBM diet and the SBM + P diet than in those fed the SBM diet during the 4-week feeding trial. The 5-week-old chicks were killed and the left femur was collected at the end of the feeding period. Body weight gain, femoral dry weight, ash, calcium and phosphorus contents, as well as ash density, were significantly greater in the chicks fed the FSBM and SBM + P diets than in those fed the SBM diet. Body weight gain and femoral parameters did not differ between the chicks fed the FSBM diet and those fed the SBM + P diet. It was concluded that fermentation improved phosphorus availability of soya-bean meal in chicks and that dietary supplementation of inorganic phosphorus was not necessary for chicks fed FSBM.

Bone Repair in Calcium-Deficient Rats: Comparison of Xylitol + Calcium Carbonate with Calcium Carbonate, Calcium Lactate and Calcium Citrate on the Repletion of Calcium

The potential value of xylitol in calcium therapy was evaluated by comparing the effect of dietary xylitol (50 g/kg diet) + calcium carbonate with the effects of calcium carbonate, calcium lactate and calcium citrate on bone repair of young male rats after the rats consumed for 3 wk a calcium-deficient diet (0.2 g Ca/kg diet). After this calcium-depletion period, the rats were fed for 2 wk one of four diets, each containing 5 g Ca/kg diet as one of the four dietary calcium sources. The diet of the control animals was supplemented with CaCO3 (5 g Ca/kg diet) throughout the study. The Ca-deficient rats showed low bone mass, low serum calcium and high serum 1,25-dihydroxycholecalciferol, parathyroid hormone (1-34 fraction) and osteocalcin concentrations. They also excreted magnesium, phosphate and hydroxyproline in the urine in high concentrations, and had high bone alkaline phosphatase and tartrate-resistant acid phosphatase activities. Most of these changes were reversed by the administered of the calcium salts. The highest recoveries of femoral dry weight, calcium, magnesium and phosphate were observed in the groups receiving xylitol+CaCO3 and calcium lactate. Calcium lactate and calcium citrate caused low serum phosphate concentration compared with rats receiving CaCO3 and with the age-matched Ca-replete controls. Xylitol-treated rats excreted more calcium and magnesium in urine than did the other rats, probably due to increased absorption of these minerals from the gut. These results suggest that dietary xylitol improves the bioavailability of calcium salts.

Effects of 17 β-estradiol replacement and treadmill exercise on vertebral and femoral bones of the ovariectomized rat

To evaluate the effect of 17 β-estradiol replacement (10 μg, twice a week) (E 2) and treadmill exercise (18 m/min, 45 min/day) (EX) on long bone and vertebral bone mass and density, 10-month-old rats were ovariectomized (OV) and divided into four groups: OV, OV + E 2, OV + EX, OV + EX + E 2 2 months after surgery. After 7 weeks intervention, the calcium content and the density of lumbar-5 were higher in both OV + E 2 and OV + EX + E 2 groups than in the OV group, but, only the OV + EX + E 2 group had a significantly higher femoral bone weight and density than the OV group. After 16 weeks intervention, the bone-conserving effects of E 2 and EX were significant on lumbar-5 and femoral dry weight and density. The effect of E 2 on both two sides of bones was due to the suppression of the bone turnover rate, while EX suppressed bone turnover rate primarily on the femur. We conclude that the effect of the two interventions on lumbar-5 and femoral bone mass were additive and independent.

Vitamin D independent anabolic action of PTHin vivo

We examined the involvement of endogenous calcium-regulating hormones in the anabolic action of PTH, especially in relation to vitamin D. When normal rats (4 weeks old) were given a subcutaneous injection of hPTH(1-34) everyday or one, two or three times a week for 4 weeks adjusting the total weekly dose to 350µg/kg, femoral dry weight increased in an injection frequency-dependent manner. Daily injection of hPTH(1-34) into normal rats for 12 days caused a dose-dependent increase in serum concentration of 1,25(OH)2D but not calcitonin, associated with a dose-dependent increase in femoral dry weight. Therefore, the effect of hPTH(1-34) was examined under the condition of vitamin D (VD)-deficiency. In VD-deficient rats (13 weeks old), the change in serum immunoreactive PTH after the injection of hPTH(1-34) was the same as that observed in normal rats, although the basal level of serum PTH was significantly higher. Furthermore, VD-deficient rats treated with hPTH(1-34) for 4 weeks showed a dose-dependent increase in femoral dry weight without affecting circulating 1,25(OH)2D. These results suggest the involvement of systemic or local factor(s) independent of the action of VD in the anabolic action of daily PTH treatment.