Disproportional skeletal growth and markedly decreased bone mineral content in growth hormone receptor -/- mice

Growth hormone (GH) is important for skeletal growth as well as for a normal bone metabolism in adults. The skeletal growth and adult bone metabolism was studied in mice with an inactivated growth hormone receptor (GHR) gene. The lengths of femur, tibia, and crown-rump were, as expected, decreased in GHR-/- mice. Unexpectedly, GHR-/- mice displayed disproportional skeletal growth reflected by decreased femur/crown-rump and femur/tibia ratios. GHR-/- mice demonstrated decreased width of the growth plates in the long bones and disturbed ossification of the proximal tibial epiphysis. Furthermore, the area bone mineral density (BMD) as well as the bone mineral content (BMC)/body weight were markedly decreased in GHR-/- mice. The decrease in BMC in GHR-/- mice was not due to decreased trabecular volumetric BMD but to a decreased cross-sectional cortical bone area In conclusion, GHR-/- mice demonstrate disproportional skeletal growth and markedly decreased bone mineral content.     

The effect of long-term glucocorticoids on bone metabolism in systemic lupus erythematosus patients: the prevalence of its anti-inflammatory action upon bone resorption

The study was made to evaluate bone turnover in systemic lupus erythematosus (SLE) patients undergoing long-term glucocorticoid therapy. Thirty-eight female patients with established SLE were compared with a control group consisting from 160 age-matched healthy women. Serum concentrations of proinflammatory cytokines: interleukin-1alpha, interleukin-6, tumor necrosis factor-alpha, granulocyte-macrophage colony stimulating factor (GM-CSF) and some biochemical markers of osteoporosis (osteocalcin, total and bone alkaline phosphatase, procollagen type I carboxyterminal propeptide, carboxyterminal telopeptides of type I collagen--CTx) were measured. Additionally, morning urine excretions of deoxypyridinoline and calcium/creatinin ratios were determined. The forearm densitometry (DXA) was performed in all patients. Bone mineral content (BMC) and bone mineral density (BMD) in the SLE group was not significantly different from the controls, and no relationship was found between the glucocorticoid exposure and the BMC/BMD. However, biochemical markers of bone resorption--CTx and calcium/creatinin ratio--were significantly increased in the patient group. Our results suggest that BMD/BMC is preserved in glucocorticoid-treated SLE patients despite accelerated bone turnover.     

Prolonged increase in dietary phosphate intake alters bone mineralization in adult male rats

Excessive intake of dietary phosphate without the company of calcium causes serum parathyroid hormone (s-PTH) concentration to rise. We investigated the effect of a modest but prolonged increase in dietary intake of inorganic phosphate on the bone quantitative factors of mature male rats. Twenty Wistar rats were divided into two groups and fed a high-phosphate diet (1.2% phosphate) or a control diet (0.6% phosphate) for 8 weeks. In the beginning and at the end of the study period, femur and lumbar bone mineral density (BMD), bone mineral content and area were measured using DXA, s-PTH was analyzed from the blood sample, and after sacrifice, right femur was cut loose and processed into paraffin cuts. Bone diameter, inner diameter and cortical width was measured from the hematoxylin- and eosin-dyed femur cuts. Tibias were degraded and calcium and phosphate content was analyzed by inductively coupled plasma-mass spectrometer. Femoral BMD increased significantly more in the control group than in the phosphate group (P=.005). Lumbar BMD values decreased in both groups, and the fall was greater in the control group (P=.007). The phosphate group had significantly higher s-PTH values (P=.0135). Femoral histomorphometric values or tibial mineral contents did not differ between groups. In conclusion, increase in dietary phosphate intake caused s-PTH to rise and hindered mineral deposition into cortical bone, leading to lower BMD. The effect on trabecular bone was opposing as mineral loss was less in the lumbar spine of phosphate group animals. These results are in concurrence with the data stating that skeletal response to PTH is complex and site dependent.     

Comparison of mandibular bone mineral density in osteoporotic, osteopenic and normal elderly edentulous subjects measured by the dual-energy X-ray absorptiometry technique

doi: 10.1111/j.1741‐2358.2012.00625.x Comparison of mandibular bone mineral density in osteoporotic, osteopenic and normal elderly edentulous subjects measured by the dual‐energy X‐ray absorptiometry technique Objective: The aim of this study was to compare the mandibular body bone mineral density according to bone mineral density status of spine and femur measured by dual‐energy X‐ray absorptiometry (DXA) technique in elderly edentulous individuals. Background: One of the factors that affect the survival rate of implants is bone mineral density (BMD) of the jaws. Materials and methods: Fifty edentulous elderly patients’ (27 women and 23 men) spine, femur and the mandibular body BMDs were measured using DXA technique. BMD scans of the AP lumbar spine (L2–L3) and femur were classified using World Health Organisation criteria for bone mass. Results: There was a statistically significant difference between the normal femur group’s–osteoporosis group’s mandibular body BMD (p = 0.001) and femoral osteopaenia group’s–osteoporosis group’s mandibular body BMD (p < 0.001). The femoral osteoporosis group’s mandibular body BMDs were lower than those of both the normal femoral and the femoral osteopaenia group subjects’. Conclusion: Classification of edentulous mandibles according to low and high bone mineral densities is a problem in implant dentistry. The results of this study demonstrated that femoral bone mineral density status may be used to provide preliminary information about the bone mineral density of the mandibular body region in elderly edentulous subjects.     

Age, sex, and grip strength determine architectural bone parameters assessed by peripheral quantitative computed tomography (pQCT) at the human radius

The purpose of this study was to estimate the relation of some noninvasively derived mechanical characteristics of radial bone including architectural parameters for bone strength to grip strength and muscle cross-section. Sixty-three males between 21 and 78yr of age and 101 females between 18 and 80yr of age were measured at the nondominant forearm using peripheral quantitative computed tomography (pQCT). We assessed the integral bone mineral density (BMD(I)) and content (BMC(I)) by pQCT at the distal and at the mid-shaft radius. Integral bone area (Area(I)), cortical thickness (C-th), and a newly proposed index for bone strength; the stress-strain index (SSI) were also calculated. The dynamometrically measured maximum grip strength was taken as a mechanical loading parameter and muscle cross-section as a substitute for it. Sex, grip strength, BMC(I) and BMD(I) (distal radius) were identified in a multiple regression analysis to significantly predict bone strength as expressed by SSI, after adjusting for all other independent variables, including age and sex (p<0.0001). Grip strength was closest related to age, sex, BMD(I) and SSI(p) of the distal radius. The cross-sectional area of muscle was not significantly determining the grip strength within the analysis model. In conclusion, our results suggested that architectural parameters at the distal radius were better related to grip strength than to cross-sectional muscle area in both males and females. Maximum muscle strength as estimated by grip strength might be a stronger determinant of mechanical characteristics of bones as compared with cross-sectional muscle area.     

Short term effects on bone quality associated with consumption of soy protein isolate and other dietary protein sources in rapidly growing female rats

Beneficial effects of soy protein consumption on bone quality have been reported. The effects of other dietary protein sources such as whey protein hydrolysate (WPH) and rice protein isolate (RPI) on bone growth have been less well examined. The current study compared effects of feeding soy protein isolate (SPI), WPH and RPI for 14 d on tibial bone mineral density (BMD) and bone mineral content (BMC) in intact and ovariectomized (OVX) rapidly growing female rats relative to animals fed casein (CAS). The effects of estrogenic status on responses to SPI were also explored. Tibial peripheral quantitative computerized tomography (pQCT) showed all three protein sources had positive effects on either BMD or BMC relative to CAS (P < 0.05), but SPI had greater effects in both intact and OVX female rats. SPI and E2 had positive effects on BMD and BMC in OVX rats (P < 0.05). However, trabecular BMD was lower in a SPI + E2 group compared to a CAS + E2 group. In OVX rats, SPI increased serum bone formation markers, and serum from SPI-fed rats stimulated osteoblastogenesis in ex vivo. SPI also suppressed the bone resorption marker RatLaps (P < 0.05). Both SPI and E2 increased alkaline phosphatase gene expression in bone, but only SPI decreased receptor activator of nuclear factor-kappaB ligand (RANKL) and estrogen receptor gene expression (P < 0.05). These data suggest beneficial bone effects of a soy diet in rapidly growing animals and the potential for early soy consumption to increase peak bone mass.     

Relation of bone mineral density and content to mineral content and density of the fat-free mass.

Differences in the mineral fraction of the fat-free mass (M(FFM)) and in the density of the FFM (D(FFM)) are often inferred from measures of bone mineral content (BMC) or bone mineral density (BMD). We studied the relation of BMC and BMD to the M(FFM) and D(FFM) in a heterogeneous sample of 216 young men (n = 115) and women (n = 101), which included whites (n = 155) and blacks (n = 61) and collegiate athletes ( n = 132) and nonathletes (n = 84). Whole body BMC and BMD were determined by dual-energy X-ray absorptiometry (DXA; Hologic QDR-1000W, enhanced whole body analysis software, version 5.71). FFM was estimated using a four-component model from measures of body density by hydrostatic weighing, body water by deuterium dilution, and bone mineral by DXA. There was no significant relation of BMD to M(FFM) (r = 0.01) or D(FFM) (r = -0.06) or of BMC to M(FFM) (r = -0.11) and a significant, weak negative relation of BMC to D(FFM) (r = -0.14, P = 0.04) in all subjects. Significant low to moderate relationships of BMD or BMC to M(FFM) or D(FFM) were found within some gender-race-athletic status subgroups or when the effects of gender, race, and athletic status were held constant using multiple regression, but BMD and BMC explained only 10-17% of the variance in M(FFM) and 0-2% of the variance in D(FFM) in addition to that explained by the demographic variables. We conclude that there is not a significant positive relation of BMD and BMC to M(FFM) or D(FFM) in young adults and that BMC and BMD should not be used to infer differences in M(FFM) or D(FFM).     

Hormone replacement therapy improves distal radius bone structure by endocortical mineral deposition

Hormone replacement therapy (HRT) produces a small increase in bone mineral density (BMD) when measured by dual energy X-ray absorptiometry (DXA). The corresponding decrease in fracture risk is more impressive, implying that other factors that contribute to bone strength are favourably modified by HRT. We investigated, using peripheral quantitated computed tomography (pQCT), the changes produced by HRT in both the distribution of mineral between cortical and trabecular bone and the changes produced by HRT in the apparent structure of trabecular bone, expressed as average hole area and apparent connectivity. Twenty-one postmenopausal women starting HRT and 32 control women were followed for 2 years, with distal radius pQCT measurements every 6 months. HRT prevented the loss of total bone mass seen in controls (p < 0.02). HRT also produced an apparent rapid loss of trabecular bone mass within the first 6 months of the study (p < 0.02), with an associated rapid loss in the apparent connectivity (p = 0.034). Average hole area also increased but not to a statistically significant extent. Exogenous estrogen apparently fills small marrow pores close to the endocortical surface, such that the pQCT-defined boundary between trabecular and cortical bone is shifted in favour of cortical bone. Trabecular bone structure indices are adversely affected, as the central, poorly interconnected trabecular bone with greater than average marrow spaces constitutes a greater fraction of the remaining trabecular bone. This study suggests that the improvements in fracture risk resulting from HRT are explained by a reversal of net endocortical resorption of bone.     

Epistasis between QTLs for bone density variation in Copenhagen × dark agouti F2 rats

The variation in several of the risk factors for osteoporotic fracture, including bone mineral density (BMD), has been shown to be strongly influenced by genetic differences. However, the genetic architecture of BMD is complex in both humans and in model organisms. We previously reported quantitative trait locus (QTL) results for BMD from a genome screen of 828 F2 progeny of Copenhagen and dark agouti rats. These progeny also provide an excellent opportunity to search for epistatic effects, or interaction between genetic loci, that contribute to fracture risk. Microsatellite marker data from a 20-cM genome screen was analyzed along with weight-adjusted bone density (DXA and pQCT) phenotypic data using the R/qtl software package. Genotype and phenotype data were permuted to determine genome-wide significance thresholds for the full model and epistasis (interaction) LOD scores corresponding to an alpha level of 0.01. A novel locus on chromosome 15 and a previously reported chromosome 14 QTL demonstrated a strong epistatic effect on BMD at the femur by DXA (LOD = 5.4). Two novel QTLs on chromosomes 2 and 12 were found to interact to affect total BMD at the femur midshaft by pQCT (LOD = 5.0). These results provide new information regarding the mode of action of previously identified QTL in the rat, as well as identifying novel loci that act in combination with known QTL or with other novel loci to contribute to BMD variation.     

Hindlimb unloading has a greater effect on cortical compared with cancellous bone in mature female rats.

This study was designed to determine the effects of 28 days of hindlimb unloading (HU) on the mature female rat skeleton. In vivo proximal tibia bone mineral density and geometry of HU and cage control (CC) rats were measured with peripheral quantitative computed tomography (pQCT) on days 0 and 28. Postmortem pQCT, histomorphometry, and mechanical testing were performed on tibiae and femora. After 28 days, HU animals had significantly higher daily food consumption (+39%) and lower serum estradiol levels (-49%, P = 0.079) compared with CC. Proximal tibia bone mineral content and cortical bone area significantly declined over 28 days in HU animals (-4.0 and 4.8%, respectively), whereas total and cancellous bone mineral densities were unchanged. HU animals had lower cortical bone formation rates and mineralizing surface at tibial midshaft, whereas differences in similar properties were not detected in cancellous bone of the distal femur. These results suggest that cortical bone, rather than cancellous bone, is more prominently affected by unloading in skeletally mature retired breeder female rats.     

Linking chronic tryptophan deficiency with impaired bone metabolism and reduced bone accrual in growing rats

There is increasing evidence that serotonin may regulate bone metabolism. However, its role remains to be clarified. Serotonin seems to be either beneficial or detrimental for bone tissues depending on the pharmacological manipulation used. In this study we evaluated the impact of a reduction of serotonergic stores induced by chronic tryptophan (TRP) depletion on various bone parameters in growing rats. For this purpose rats received a TRP‐free diet for 60 days. Bone mass, mineral content and density were measured by DXA and by pQCT in the appendicular skeleton. Bone metabolic markers included urinary deoxypyridinoline and serum osteocalcin measurements. IGF‐I levels were also evaluated. In TRP‐free diet rats, we found a decrease in body weight, a delayed femoral bone growth and bone mineral content as measured by DXA. pQCT analysis showed that these effects were related to a reduction of both cortical and trabecular bone and are associated with a reduction of bone strength. These effects are due to a negative shift in the balance between bone formation and resorption with a significant decrease in bone formation as evidenced by a reduction both in osteocalcin and IGF‐I levels. The present data extend our overall knowledge on the participation of serotonin in the regulation of growing bone and could be of interest in studying the impairment of bone growth in depressed subjects under particular condition of rapid bone accrual such as childhood and adolescence. J. Cell. Biochem. 107: 890–898, 2009. © 2009 Wiley‐Liss, Inc.     

Critical ages and stages of puberty in the accumulation of spinal and femoral bone mass: the validity of bone mass measurements

In growing children, lumbar and femoral areal bone mineral density (aBMD), as measured by dual-energy X-ray absorptiometry (DXA), is influenced by skeletal growth and bone size. Correction of lumbar bone mineral density (BMD) for bone volume (volumetric BMD [vBMD]), by the use of mathematical extrapolations, reduces the confounding effect of bone size, but vBMD remains dependent on age and bone size during growth. Femoral (neck and mid-shaft) vBMD, assessed by DXA, is independent of age prior to puberty, but a slight increase occurs in late puberty and after menarche. Femoral (mid-shaft) cortical bone density and radial cortical and trabecular bone densities, assessed by quantitative computed tomography (QCT), show no peak during childhood or adolescence. Bone strength index, calculated by peripheral QCT, increases with age and correlates with handgrip strength, bone cross-sectional area and cortical area. Puberty is one of the main factors that influences lumbar bone mineral content and aBMD accumulation, but a high incidence of fractures occurs during this period of life, which may be associated with a reduced aBMD.     

The Lichfield bone study: the skeletal response to exercise in healthy young men

The skeletal response to short-term exercise training remains poorly described. We thus studied the lower limb skeletal response of 723 Caucasian male army recruits to a 12-wk training regime. Femoral bone volume was assessed using magnetic resonance imaging, bone ultrastructure by quantitative ultrasound (QUS), and bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA) of the hip. Left hip BMD increased with training (mean ± SD: 0.85 ± 3.24, 2.93 ± 4.85, and 1.89 ± 2.85% for femoral neck, Ward's area, and total hip, respectively; all P < 0.001). Left calcaneal broadband ultrasound attenuation rose 3.57 ± 0.5% (P < 0.001), and left and right femoral cortical volume by 1.09 ± 4.05 and 0.71 ± 4.05%, respectively (P = 0.0001 and 0.003), largely through the rise in periosteal volume (0.78 ± 3.14 and 0.59 ± 2.58% for right and left, respectively, P < 0.001) with endosteal volumes unchanged. Before training, DXA and QUS measures were independent of limb dominance. However, the dominant femur had higher periosteal (25,991.49 vs. 2,5572 mm(3), P < 0.001), endosteal (6,063.33 vs. 5,983.12 mm(3), P = 0.001), and cortical volumes (19,928 vs. 19,589.56 mm(3), P = 0.001). Changes in DXA, QUS, and magnetic resonance imaging measures were independent of limb dominance. We show, for the first time, that short-term exercise training in young men is associated not only with a rise in human femoral BMD, but also in femoral bone volume, the latter largely through a periosteal response.     

Flaxseed oil and inflammation-associated bone abnormalities in interleukin-10 knockout mice

Interleukin-10-/- (IL-10) knockout (KO) mice develop an intestinal inflammation that closely mimics human inflammatory bowel disease (IBD) which is accompanied by inflammation-associated bone abnormalities and elevated serum proinflammatory cytokines. The objective of this study was to use the IL-10 KO mouse model to determine whether flaxseed oil (FO) diet, rich in alpha-linolenic acid (ALA), attenuates intestinal inflammation and inflammation-associated bone abnormalities, compared to a corn oil (CO) control diet. Male wild-type (WT) or IL-10 KO mice were fed a 10% CO or 10% FO diet from weaning (postnatal day 28) for 9 weeks. At necropsy, serum, intestine, femurs and lumbar vertebrae were collected and analyzed. IL-10 KO mice fed CO had lower femur bone mineral content (BMC; P<.001), bone mineral density (BMD; P<.001), peak load (P=.033) and lumbar vertebrae BMD (P=.02) compared to WT mice fed either diet. Flaxseed oil had a modest, favorable effect on IL-10 KO mice as femur BMC, BMD and peak load were similar to WT mice fed CO or FO. In addition, lumbar vertebra BMD was similar among IL-10 KO mice fed FO and WT mice fed CO or FO. The fact that FO attenuated serum tumor necrosis factor-alpha (TNF-alpha) among IL-10 KO mice suggests that the positive effects of FO on femur BMC, BMD, peak load and vertebral BMD in IL-10 KO mice may have been partly mediated by changes in serum TNF-alpha. In conclusion, these findings suggest that a dietary level of ALA attainable from a 10% flaxseed oil diet results in modest improvements in some bone outcomes but does not attenuate intestinal inflammation that is characteristic of IL-10 KO mice.     

pQCT provides better prediction of canine femur breaking load than does DXA

Our study was designed to examine the validity of dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) measurements as predictors of whole bone breaking strength in beagle femora. DXA was used to determine the bone mineral content, bone area, and 'areal' bone mineral density. PQCT was used to determine the cross-sectional moments of inertia, volumetric densities of the bone, and to calculate bone strength indices based on bone geometry and density. A three-point bending mechanical test was used to determine maximal load. Three variables from the pQCT data set explained 88% of the variance in maximal load, with the volumetric bone mineral density explaining 32% of the variance. The addition of the volumetric cortical density increased the adjusted r(2) to 0.601 (p=0.001) and the addition of an index created by multiplying volumetric cortical bone density by the maximum cross-sectional moment of inertia made further significant (p<0.001) improvements to an adjusted r(2) of 0.877. In comparison, when only the DXA variables were considered in a multiple regression model, areal bone mineral density was the only variable entered and explained only 51% (p<0.001) of the variance in maximal load. These results suggest that pQCT can better predict maximal load in whole beagle femora since pQCT provides information on the bone's architecture in addition to its volumetric density.     

Estimation of bone mineral density and architectural parameters of the distal radius in hemodialysis patients using peripheral quantitative computed tomography

We analyzed bone changes in a series of hemodialysis patients followed up for a maximum of 299 months by assessing bone mineral density (BMD) and architectural parameters of the distal radius using peripheral quantitative computed tomography (pQCT), and determined the predictors of skeletal changes in these patients. No significant differences in trabecular BMD (BMD(T)) were found compared with BMD(T) of the normal control. In contrast, cortical BMD (BMD(C)) was significantly decreased compared with BMD(C) of the normal controls. Hemodialysis patients had significantly lower values for cortical bone area, cortical thickness, moment of inertia, and polar moment of inertia than the age-matched controls. From single and multiple regression analysis, the most significant predictor of metabolic bone disease in these cases was found to be duration of hemodialysis. In addition, increases in serum alkaline phosphatase and intact parathyroid hormone in secondary hyperparathyroidism were found to correlate with a decrease in pQCT values in cortical bone; as such, these increases were also found to be a predictive. The present study confirms that the reduction in both BMD(C) and architectural parameters in hemodialysis patients occurs partly because of prolonged hemodialysis and secondary hyperparathyroidism. In addition, immobilization, dietary factors, daily intake of calcium or vitamin D, and so on must be taken into account when clarifying the causes of skeletal complications resulting from hemodialysis.     

Influence of maternal nicotine exposure on neonatal rat bone: protective effect of pentoxifylline

Limited research in young adults and immature animals suggests a detrimental effect of tobacco on bone during growth. The aim of this study was to determine the adverse effects of maternal nicotine exposure during pregnancy and lactation on neonatal rat bone development, and to determine a protective effect of pentoxifylline (PTX). Gravid rats were assigned into four groups, one control (group I) and three experimental (groups II, III, and IV). In group II, pregnant rats received 3 mg/kg/day nicotine alone, subcutaneously, until 21 days postnatal. In group III, pregnant rats received nicotine (3 mg/kg/day) and PTX (60 mg/kg/day). In group IV, pregnant rats received PTX alone (60 mg/kg/day). Whole body mineral density (BMD), content (BMC), area (BA), and histopathologic and morphologic findings of the femur were determined at 21 days of age. The study revealed that nicotine exposure (group II) decreased birth weight, pregnancy weight gain, and length of femur compared with other groups (P < 0.01). Birth weight was higher in groups III (PTX + nicotine) and IV (PTX) than in group II (nicotine). Body weight at 21 days of age was higher (P = 0.009) in the PTX alone group (group IV) compared with the other groups. BMD was higher (P < 0.001) in the PTX-treated groups (group III and IV) compared with other groups. In addition, there were more apoptotic chondrocytes in the hypertrophic zone of rats exposed to nicotine alone (group II) compared with the other groups (P < 0.001). In conclusion, maternal nicotine exposure resulted in decreased birth weight, pregnancy weight gain, and bone lengthening, and increased apoptosis. Pentoxifylline supplementation was found to prevent the adverse effects of maternal nicotine exposure on BMD and birth weight.     

Green tea polyphenols mitigate bone loss of female rats in a chronic inflammation-induced bone loss model

The purpose of this study was to explore the bioavailability, efficacy and molecular mechanisms of green tea polyphenols (GTP) related to preventing bone loss in rats with chronic inflammation. A 2 [placebo vs. lipopolysaccharide (LPS)]×2 (no GTP vs. 0.5% GTP in drinking water) factorial design enabled the evaluation of effects of LPS administration, GTP levels, and LPS×GTP interaction. Urinary GTP components and 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels were determined by high-pressure liquid chromatography for bioavailability and molecular mechanism, respectively. Efficacy was evaluated by examining changes in femoral mineral content (BMC) and density (BMD) using dual-energy X-ray absorptiometry, and bone turnover biomarkers [osteocalcin (OC) and tartrate-resistant acid phosphatase (TRAP)] using respective ELISA kits. The mRNA expression of tumor necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2) in spleen was determined by real-time RT-PCR. Neither LPS administration nor GTP levels affected body weight and femoral bone area throughout the study period. Only GTP supplementation resulted in increased urinary epigallocatechin and epicatechin concentrations. LPS administration led to a decrease in femur BMC and BMD, and serum OC levels, but an increase in serum TRAP, urinary 8-OHdG and spleen mRNA expression of TNF-α and COX-2 levels. GTP supplementation resulted in higher values for femur BMC, BMD and serum OC, but lower values for serum TRAP, urinary 8-OHdG and spleen mRNA expression of TNF-α and COX-2 levels. We conclude that GTP mitigates bone loss in a chronic inflammation-induced bone loss model by reducing oxidative stress-induced damage and inflammation.     

Bone mass, bone strength, and their relationship in developing CD-1 mice

Optimizing nutrition during development may provide effective prevention strategies to protect against osteoporosis during later life. Because the mouse model is commonly used to test nutritional interventions on bone health, the overall objective of this study was to determine how bone develops during the first 4 months of life by assessing bone mass (bone mineral content (BMC) and bone mineral density (BMD)) and biomechanical strength properties such as peak load in male and female CD-1 mice. Bone outcomes were assessed at 1 month intervals from 1 to 4 months of age. Femur and spine BMC and BMD at 3 months were similar to 4 months, indicating that the accumulation of bone mass occurs primarily during the first 3 months of life. In contrast, the timing of changes in peak load, a measure of bone strength, varied by skeletal site. Regression analyses demonstrated that femur BMC is a significant predictor of femur peak load at the femur midpoint and neck. The study findings suggest that nutritional interventions aimed at optimizing peak bone mass to prevent osteoporosis may be most effective during pubertal growth.