Bone Calcium Content Research Articles

Silicon and boron differ in their localization and loading in bone

Silicon and boron share many similarities, both chemically and biochemically, including having similar effects on bone, although their mechanisms of action are not known. Here we compared the loading of silicon and boron into bone, their localization and how they are influenced by age (growth & development), to obtain further clues as to the biological effects of these elements and, especially, to see if they behave the same or not. Bone samples were obtained from two different studies where female Sprague Dawley rats had been maintained on a normal maintenance diet for up to 43weeks. Total bone elemental levels were determined by ICP-OES following microwave assisted acid digestion. Silicon and boron levels in the decalcified bones (i.e. the collagen fraction) were also investigated. Silicon and boron showed marked differences in loading and in their localization in bone. Highest silicon and lowest boron concentrations were found in the under-mineralized bone of younger rats and lowest silicon and highest boron concentrations were found in the fully mineralized bone of the adult rat. Overall, however total bone silicon content increased with age, as did boron content, the latter mirroring the increase in calcium (mineral) content of bone. However, whereas silicon showed equal distribution in the collagen and mineral fractions of bone, boron was exclusively localized in the mineral fraction. These findings confirm the reported association between silicon and collagen, especially at the early stages of bone mineralization, and show that boron is associated with the bone mineral but not connective tissues. These data suggest that silicon and boron have different biological roles and that one is unlikely, therefore, to substitute for the other, or at least boron would not substitute for Si in the connective tissues. Finally, we noted that silicon levels in the mineral fraction varied greatly between the two studies, suggesting that one or more nutritional factor(s) may influence the loading of Si into the mineral fraction of bone. This and the nature of the interaction between Si and collagen deserve further attention.

Zinc Deficiency Increases Serum Concentrations of Parathyroid Hormone through a Decrease in Serum Calcium and Induces Bone Fragility in Rats.

We hypothesized that a zinc-deficient diet alters the mineral (calcium, magnesium, and phosphorus) components of bones, as well as hormones related to bone remodeling, and negatively affects bone metabolism. Four-week-old male Wistar rats were randomly assigned to one of three groups for 4 wk: a zinc-adequate group (C, 30 ppm); a zinc-deficient group (ZD, 1 ppm); and a pair-fed group (PF, 30 ppm), which was pair-fed to the ZD group. Bone mineral density and bone mechanical properties were reduced in the ZD group compared to the C and PF groups. Compared with the C and PF groups, serum osteocalcin, a bone formation marker, was reduced in the ZD group. Conversely, urine deoxypyridinoline, a bone resorption marker, was increased in the ZD group compared to the C and PF groups. Calcium and phosphorus concentrations in bone were not different among all groups. The bone magnesium concentration was significantly higher in the ZD group than in the PF and C groups. Interestingly, compared with the C and PF groups, the ZD group showed a reduction in serum calcium concentration along with an increase in serum parathyroid hormone (PTH) concentration. Although serum 1,25-dihydroxycholecalciferol concentration was significantly higher in the ZD and PF groups than in the C group, the rate of apparent calcium absorption was significantly lower in the ZD group than in the C and PF groups. Therefore, zinc deficiency is suspected to cause an increase in serum PTH concentration owing to an inability to maintain calcium homeostasis, resulting in bone fragility.

Impairment of bone growth of wistar rat fetuses of diabetic and hypercholesterolemic mothers

Patients with either diabetes or hypercholesterolemia develop atherosclerosis and impair healing of bone. In the present work we illustrated their role in limb ischemia during bone cells differentiation of Wistar rat fetuses. Pregnant Wistar rats (n = 20 each) were arranged in three groups: control, diabetic or hypercholesterolemic. Diabetes was induced at the fifth day of gestation using streptozotocin, and hypercholesterolemia was carried by feeding virgin rats a diet containing 3% cholesterol for 6 wks prior to the onset of conception. At 13, 15, 17, and 19 d prenatal, pregnant rats were sacrificed, dissected, and fetuses were removed. Hind limbs were separated and subjected to histological and transmission electron microscopic examination, ossification, total calcium content of fetuses, isoenzymes alkaline and acid phosphatase and lactic dehydrogenase electrophoresis and DNA damage. Fetuses of diabetic or hypercholesterolemic mothers exhibited delayed histo-cytological differentiation of chondrocytes, and decreased periosteal ossification. Alkaline and acid phosphatase as well as lactic dehydrogenase isoenzymes showed altered diffusion rate and intensities of their bands reflecting their activities in both diseases comparing with the control. Assessments of bone calcium contents revealed marked reduction. Genomic expression of the degree of laddering (total DNA fragmented) or single-cell gel electrophoresis was found to be increased in cartilage and bone cells of fetuses of diabetic or hypercholesterolemic mothers. The authors concluded that both diseases had a selective, dramatic effect during fetus development in this model by retarding the histo- and cytological differentiation during limb bone growth. Both diseases increased the average cell death in skeletal elements and blood vessels as a consequence of altered alkaline and acid phosphatases and lactic dehydrogenase isoenzymes in accordance with DNA damage.

Combination therapy of Chinese herbal medicine Fructus Ligustri Lucidi with high calcium diet on calcium imbalance induced by ovariectomy in mice

Context: Our previous biological study demonstrated that Fructus Ligustri Lucidi (FLL), the fruit of Ligustrum lucidum Ait. (Oleaceae), could be used to maintain calcium balance and prevent age-related osteoporosis since it effectively decreased calcium loss and increased calcium retention in rats.Objective: This study investigates the combination effect of the Chinese herbal medicine FLL and a high calcium diet on calcium imbalance induced by ovariectomy in mice.Materials and methods: The ovariectomized (OVX) mice were orally treated with vehicle, FLL extract (700 mg/kg), milk powder (5 g/mice) fortified with calcium (1.0% Ca) and the combination of FLL with milk powder. After 6 weeks of treatment, urine, serum, and tibia were preserved for biochemical analysis and kidneys were taken for gene expression analysis.Results: The combination treatment of FLL and a high calcium diet significantly increased bone calcium content (6.80 ± 0.34 mg) by 22% (p < 0.05) and decreased urine calcium excretion (0.099 ± 0.009 mg/mg) by 62% (p < 0.01) as compared with those of the OVX group (bone Ca, 5.57 ± 0.31 mg; urine Ca/Cr, 0.261 ± 0.017 mg/mg). The mRNA expression of renal calcium-binding protein-9k (CaBP-9k) and calcium-sensing receptor (CaSR) in combination treatment group was significantly up-regulated and down-regulated, respectively, as compared with those of the OVX group.Conclusion: The beneficial effects of this combination therapy on calcium balance of OVX mice were, at least partially, attributed to its regulation on mRNA expression of CaBP-9k and CaSR in kidney.

Osteoprotective effect of geraniin against ovariectomy-induced bone loss in rats

In the present study, we investigated the antiosteoporotic effect of geraniin on osteoporosis induced by OVX in rats. The analysis of biochemical parameters showed that geraniin could significantly increase serum calcium, estradiol and calcitonin levels, and decrease serum ALP, tartrate-resistant acid phosphatase, serum crosslinked C-terminal telopeptide of type I collagen, and urinary deoxypyridinoline/creatinine ratio levels, respectively. Geraniin was also found to prevent OVX-induced bone loss in bone mineral density and bone mineral content, to elevate femur weight and bone calcium content, and to enhance the bone mechanical properties as compared with OVX group. In addition, geraniin was demonstrated to improve the histomorphological parameters of OVX-induced bone loss, including bone trabecular number, thickness, and separation. These results indicated that geraniin have a protective effect against OVX-induced rat osteoporosis.

Effects of commercial in ovo injection of 25-hydroxycholecalciferol on bone development and mineralization in male and female broilers , ,

Improved bone development and mineralization in broilers have been attributed to the use of 25-hydroxylcholecalceiferol [25(OH)D3] as a dietary supplement. In this study, effects of the in ovo injection of 25(OH)D3 delivered in commercial diluent on 18 d of incubation (doi) on subsequent bone development and mineralization in male and female Ross × Ross 708 broilers were investigated. The variables investigated included bone mineral density and breaking strength, bone ash concentration, and calcium and phosphorus bone ash concentrations. In a single-stage incubator, with 6 treatments on each of the 10 tray levels, a total of 2,400 experimental broiler hatching eggs were evenly and randomly set. Eggs were treatment-injected and transferred to corresponding hatching baskets on 18 doi. Experimental treatment groups were those that received 0.2, 0.6, 1.8, or 5.4 µg of 25(OH)D3 that were delivered in 100 µL of commercial diluent. Noninjected and diluent-injected controls were also included. On 21 doi, chicks were pulled and placed in corresponding floor pens, and on each of d 0, 14, and 28 posthatch (poh), 2 birds of each sex from each pen were randomly selected for necropsy and extraction of both of their tibia bones. Bones from the right leg were subjected to mineral density analysis and those from the left leg were used to determine breaking strength and residual bone ash concentration. Furthermore, ash calcium and phosphorus concentrations on d 14 and 28 poh were determined. There was a treatment × sex × age interaction for bone breaking strength. Bone breaking strength in male birds on d 28 poh was higher in the 0.20, 0.60, and 1.80 µg of 25(OH)D3-injected treatment groups than in the diluent-injected control group. In conclusion, although the in ovo injection of 25(OH)D3 had no positive effect on the bone development of Ross × Ross 708 broilers through d 28 poh compared with noninjected controls, it may provide a benefit to those subjected to an injection of commercial vaccine diluent.

Evaluating the Bioavailability of Calcium Phosphate Nanoparticles as Mineral Supplement in Broiler Chicken

An experiment was carried out with the objective of determining the bioavailability of calcium phosphate nanoparticles by supplementing calcium phosphate nanoparticles at graded levels from 50 to 100% of phosphorus content to the standard source (Dicalcium phosphate - coarse particle) at 10 per cent increment. Tibial bone morphometry, bone and serum mineral profile and carcass characters in broiler chicken were studied with mash form of feed in 70 male broiler chicks (Cobb 400) from day 1 to 28 indicated that the there was no significant variation in the parameters studied. The tibial bone ash, calcium and phosphorus content are unison for both the control and 50% calcium phosphate nanoparticles supplemented groups. The results indicated that the bioavailability of phosphorus in calcium phosphate nanoparticles was 200 per cent when compared to dicalcium phosphate. This finding may help the poultry managers to minimize the feed transport cost and also minimize the mineral wastages.

Bone Mineralization of Broiler Chicks Challenged with Salmonella enteritidis Fed Diet Containing Probiotic (Bacillus subtilis).

The present study was carried out to determine the effect of probiotic, Bacillus subtilis, on ash and calcium contents of tibia bone in unchallenged and challenged broiler chicks with Salmonella enteritidis. In a completely randomized design, 160 chicks were divided into four groups. Each group had four replicates with 10 birds each. Treatments were control group, probiotic-treated group, challenged group and challenged probiotic-treated group. Ash and calcium contents of tibia at 21 and 42 days of age were determined. At 21 days of age, the highest contents of ash and calcium were related to probiotic-treated group and the lowest means to challenged chicks (P < 0.05). At this period, inclusion of probiotic to diet of challenged chick increased (P < 0.05) ash and calcium contents of tibia. With increases in age, the negative effects of challenging and beneficial effects of probiotic on bone mineralization diminished; since at 42 days of age, challenging or probiotic treatment had no effect on ash and calcium contents of tibia.

&lt;b&gt;Dry and wet diets with and without phytase for growing and finishing pigs

The present study assessed the effect of adding water and phytase to middling diets on digestibility, metabolism, performance, carcass characteristics, and the bone mineralization of growing and finishing pigs. For the digestibility trial, 16 pigs were distributed in randomized blocks, placed in digestibility cages following a 2 x 2 factorial design (dry and wet diets, with and without phytase). For the performance trial, 48 piglets were distributed into a complete randomized design. During the growing period, wet diets presented higher values for digestibility and energy metabolism. In the finishing stage, the addition of water to the feed caused a greater weight gain and interfered with the carcass length. The balance of the mineral matter and the availability of calcium and phosphorus were influenced by the diets with phytase. The addition of water to the diets in the growing phase improved the digestibility and energy metabolism, and increased the weight gain, carcass length and calcium content in bones during the finishing period. The supplementation of phytase improved energy metabolism and the digestibility of calcium and phosphorus, and the balance of mineral matter.

A comparison of histological and chemical analysis in mechanically separated meat

The aim of this study was evaluation of quality of mechanically separated chicken meat (MSCM) samples obtained by three different separators, by means of a histological (qualitative and quantitative) and chemical examination. Histological examinations used Green Trichrome and Alizarine red staining. The examination was focused on the evaluation of muscle, fat, collagenous connective tissue, bone fragment and calcium content and on the degree of damage to the muscle fibres. Chemical analysis was focused on calcium-, fat- and collagenous connective tissue content. The product obtained by the separator 1 (hard separation) gave similar good results to the separator 3 (soft separation), while separator 2 (hard separation) gave worse results as for being bone fragments and calcium content. As demonstrated, the quality of the product obtained by the separator 1 has improved over the years. The results of the histological analysis were in accordance with the results of chemical analysis. For the quantitative determination of collagen, calcium and bone fragments, image analysis was used. In the present study, good correlation between quantitative histological analysis and chemical analysis was observed (0.673, 0.718 and 0.809, α = 0.01).

Gold nanoparticles stimulate differentiation and mineralization of primary osteoblasts through the ERK/MAPK signaling pathway

Gold nanoparticles (AuNPs) have shown great promise for a variety of applications, including chemistry, biology, and medicine. Recently, AuNPs have found promising applications in cartilage and bone repair. However, to realize the above promised applications, more work needs to be carried out to clarify the interactions between biological systems and AuNPs. In the present study, primary osteoblasts were used to evaluate the biocompatibility of 20-nm and 40-nm AuNPs, including morphology, proliferation, differentiation, gene and protein expression, and the underlying mechanisms. The results demonstrated that AuNPs were taken up by osteoblasts and aggregated in perinuclear compartment and vescular structures, but no morphological changes were observed. AuNPs could significantly promote the proliferation of osteoblasts, enhance the ALP activities, and increase the number of bone nodules and calcium content in vitro. In addition, the expression of BMP-2, Runx-2, OCN and Col-1 was remarkably up-regulated in the presence of AuNPs. It is noteworthy that 20-nm AuNPs are more potent than 40-nm AuNPs in regulating osteoblast activities. Besides, AuNPs increased the level of ERK phosphorylation/total ERK, suggesting the activation of ERK/MAPK pathway is involved in above activities. In conclusion, AuNPs exhibited great biocompatibility with osteoblasts, and have tremendous potential to be used as drug and/or gene delivery carrier for bone and tissue engineering in the future.

Effects of desalted duck egg white peptides and their products on calcium absorption in rats

The effects of desalted duck egg white peptides (DPs), phosphorylated DPs (PDPs) and DPs–calcium complexes (DPs-Ca) on calcium absorption in vivo were investigated. Ninety fast-growing male rats were divided into 10 groups and treated with different dosages of CaCO3, calcium gluconate, DPs-Ca as well as CPPs, DPs and PDPs supplemented with CaCO3. Eight-week oral administration results indicated that the high dosage PDPs+CaCO3 group was significantly higher than the high dosage DPs+CaCO3 group in calcium absorption, bone calcium content, BMD and maximum stress, but lower in ALP activity (P < 0.05). Additionally, the high dosage DPs-Ca group showed higher bone indices than the high dosage DPs+CaCO3, calcium gluconate and CaCO3 groups (P < 0.05). These results suggest that in vivo, phosphorylated DPs are more effective than DPs in improving calcium absorption and bone strength, and DPs–calcium complexes are more beneficial to bone tissues than the DPs and CaCO3 mixture.

Effect of glimepiride on the skeletal system of ovariectomized and non-ovariectomized rats

BackgroundDiabetes mellitus type 2 and osteoporosis are major health problem, especially in postmenopausal women. Glimepiride is a third-generation sulfonylurea derivative and is used as a first-line drug in the treatment of type 2 diabetes mellitus. The effect of this drug on bone tissue is unknown. The aim of the present study was to investigate the influence of glimepiride on the skeletal system in ovariectomized and non-ovariectomized rats. MethodsThe experiment was conducted on 3-month-old female Wistar rats, divided into 4 groups (n=10 per group): I (NOVX)–non-ovariectomized control rats, II (NOVX+G)–non-ovariectomized rats receiving glimepiride (0.8mg/kg po), III (OVX)–ovariectomized control rats, IV (OVX+G)–ovariectomized rats receiving glimepiride (0.8mg/kg po). Bilateral ovariectomy was performed 7 days before the start of the experiment, under ketamine-xylazine anesthesia. Glimepiride was administered once daily for 28 days. The effect of glimepiride on the skeletal system was assessed based on macrometric parameters, histomorphometric parameters and mechanical properties of the tibial metaphysis, femoral diaphysis and femoral neck. Bone mass, mineral mass, calcium and phosphorus content, as well as serum estrogen, osteocalcin and RatLaps levels were also studied. ResultsEstrogen deficiency in ovariectomized rats caused increased bone remodeling, with an intensification of bone resorption and formation, and mineralization impairment. Glimepiride in ovariectomized rats inhibited the development of changes in the skeletal system caused by estrogen deficiency, intensifying bone formation. In the presence of estrogens (in non-ovariectomized rats), glimepiride also intensified bone formation, but to a lesser extent. ConclusionsGlimepiride, in the therapy of type 2 diabetes mellitus in postmenopausal women, may have a beneficial effect on bone remodeling and may reduce the risk of development of osteoporosis.

Value of dual energy spectral CT for detecting uric acid deposition in tophaceous gout with base material mapping

Objective To assess the feasibility and diagnostic value in detecting uric acid deposition among patients with tophaceous gout by using Gemstone spectral imaging(GSI)-based qualitative analysis technique.Methods Thirty-one patients with clinical obvious tophaceous gout and 10 healthy volunteers underwent Discovery CT 750 HD scan with GSI mode.Uratoma more than 10 mm in diameter,muscles,cortical bone,and cancellous bone were analyzed and compared between patients and controls by using CT imaging spectroscopy quantitative parameters [uric acid (Ca) concentration,calcium (uric acid) concentration,calcium (water) concentration,and water (Ca) concentration].Univariate analysis of variance was applied within the patient group,and independent samples t test was used to compare the abovedmentioned quantitative parameters between patient group and control group.Results Base substance concentration in patients was as follows:uric acid (Ca) concentration (1 268.8 ± 32.2) mg/cm3,calcium (uric acid) concentration (19.4 ± 9.5) mg/cm3,calcium (water) concentration (10.8 ± 9.5) mg/cm3,and water (calcium) concentration (1 171.0 ± 26.8) mg/ cm3.The cortical bone of the base substance concentration was as follows:uric acid (Ca) concentration (1 333.6 ± 83.8) mg/ cm3,calcium (uric acid) concentration (271.1 ± 85.0) mg/cm3,calcium (water) concentration (262.6 ± 85.4) mg/cm3,and water (calcium) concentration (1 230.8 ± 77.0) mg / cm3.The muscles of the base substance concentration was as follows:uric acid (Ca) concentration (1 143.5 ± 15.7) mg / cm3,calcium (uric acid) concentration (12.3 ± 5.0) mg /cm3,calcium (water) concentration (4.4 ± 1.9) mg / cm3,and water (calcium) concentration (1 054.1 ± 14.6) mg / cm3.The cancellous bone of the base substance concentration was as follows:uric acid (Ca) concentration (1 070.9 ± 26.4)mg / cm3,calcium (uric acid) concentration (85.1 ± 46.9) mg/cm3,calcium (water) concentration (77.4 ± 46.7) mg/cm3,and water (calcium) concentration (988.0 ± 23.4) mg / cm3.There were significant differences(F value were 665.04,646.13,642.10,and 692.41,respectively,P ＜ 0.01).The uric acid (Ca) concentration and water (calcium) concentration in tophi,muscle,cortical and cancellous bone showed differences between the two groups (P ＜ 0.05),while calcium (uric acid) concentration and calcium (water) concentration showed significant differences between tophi and cortical bone or cancellous bone (P ＜ 0.05).Between patient group and control group,cortical and cancellous bone calcium (uric acid) concentration and calcium (water) concentration showed significant difference (P ＜ 0.05),and muscle uric acid (Ca) concentration and water (calcium) concentration also showed significant difference (P ＜ 0.05).Conclusion Dual-energy spectral CT can detect the gout tophi within the peripheral joints in patients quantify the concentrations of the base materials,thus providing a new imaging method for the quantitative monitoring of clinical outcomes. Key words: Hyperuricemia; Tomography,X-ray computed; Comparative study

Effects of parenteral gibberellic acid and dietary supplementaion of vitamin D3 on egg quality and physiological characteristics in aged laying hens

The aim of this study was to determine the effect of parenteral gibberellic acid (GA3) and/or vitamin D3 supplementation in diet on egg quality and blood physiological characteristics in aged laying hens. A total of 270 Lohmann Brown Classic laying hens aging 73-week were randomly assigned to equal three treatment groups (T1, T2 and T3) with equal 3 replicas in each group. The birds of group T1 (control group) were injected subcutaneously (SC) with sesame oil at 0.2 mL/kg body weight. The birds of group T2 were given with GA3 at 400 μg/kg b.wt., SC, whereas group T3 had diet containing vitamin D3 at 500 IU/kg feed. Relative weight of albumen and egg shell, Haugh unit, shell thickness, serum glucose, serum calcium, serum phosphorous, serum estradiol, and bone calcium absorption were significantly increased in the birds of group T2 and T3. On the other hand, relative weight of yolk, yolk cholesterol, and serum cholesterol were significantly decreased in group T2 and T3 as compared to group T1. However, serum protein and albumen were unaffected in the treatments. In conclusion, the parenteral GA3 and vitamin D3 supplementation in diet could improve egg quality traits and serum blood biochemical perperties in agend laying hens. http://dx.doi.org/10.5455/javar.2014.a39

Quantification of calcium content in bone by using ToF-SIMS–a first approach

The determination of the spatially resolved calcium distribution and concentration in bone is essential for the assessment of bone quality. It enables the diagnosis and elucidation of bone diseases, the course of bone remodelling and the assessment of bone quality at interfaces to implants. With time-of-flight secondary ion mass spectrometry (ToF-SIMS) the calcium distribution in bone cross sections is mapped semi-quantitatively with a lateral resolution of up to 1 μm. As standards for the calibration of the ToF-SIMS data calcium hydroxyapatite collagen scaffolds with different compositions were synthesized. The standards were characterised by loss of ignition, x-ray diffractometry (XRD) and x-ray photoelectron spectroscopy (XPS). The secondary ion count rate for calcium and the calcium content of the standards show a linear dependence. The obtained calibration curve is used for the quantification of the calcium content in the bone of rats. The calcium concentration within an animal model for osteoporosis induction is monitored. Exemplarily the calcium content of the bones was quantified by XPS for validation of the results. Furthermore a calcium mass image is compared with an XPS image to demonstrate the better lateral resolution of ToF-SIMS which advances the locally resolved quantification of the calcium content.

English

The efficacy of Coelatura aegyptiaca shell powder (CES, 500 mg/kg BW) was evaluated as a calcium supplement in ovariectomized (OVX) rats for ten weeks of treatment. The biochemical components and the antioxidant properties of the shell powder were determined. The bone mineral density (BMD), bone mineral content (BMC), calcium (Ca) and phosphorus (P) contents in serum and bone, serum total alkaline phosphatase (TALP) and bone alkaline phosphatase (BALP), serum calcitonin and parathyroid (PTH) hormones were determined. Furthermore, some of the oxidative stress markers [malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx) and total antioxidant capacity (TAC)] were estimated in bone. The current study revealed that CES contained 19.38% Ca, 0.315% P as well as some of antioxidant amino acids which have a potent antioxidant activity against 1,1diphenylpicrylhydrazyl (DPPH) free radical. Administration of CES to OVX rats increased BMD, BMC, tibial Ca and P contents and BALP activity, as compared to OVX rats. An ameliorative effect was recorded in the levels of calcitonin, PTH, MDA, SOD, GPx and TAC subsequent to CES administration to OVX rats.This ameliorative effect of CES powder against osteoporosis may be attributed to its antioxidant efficacy and/or to its Ca content. In conclusion, CES may have the potential to develop a clinically useful anti-osteoporotic agent, since its effect was comparable with alendronate (6.5 mg/kg BW/week).

Do effects of propranolol on the skeletal system depend on the estrogen status?

BackgroundPropranolol, a nonselective β-adrenergic receptor antagonist, was reported to favorably affect the skeletal system in different animal models. The aim of the study was to investigate whether the effects of propranolol on the skeletal system depend on the estrogen status. MethodsThe in vivo experiments were carried out on the following groups of mature female Wistar rats: sham-operated control rats, sham-operated rats receiving propranolol, ovariectomized (OVX) control rats, OVX rats receiving propranolol, OVX rats receiving estradiol, OVX rats receiving estradiol and propranolol. Propranolol hydrochloride (10mg/kg po) and/or estradiol (0.1mg/kg po) were administered daily for 4 weeks. Bone mass, mineral and calcium content, macrometric and histomorphometric parameters, and mechanical properties were examined. In vitro, effects of estradiol and propranolol on the formation of mouse osteoclasts and on the mRNAexpression of genes related to osteoclastogenesis, bone formation and mineralization, as well as adrenergic and estrogen signalling in mouse osteoblasts were investigated. Results and conclusionPropranolol exerted some favorable effects on the rat skeletal system in vivo, independently of the estrogen status. However, in vitro studies indicated a possibility of some antagonistic relations between the estradiol and propranolol effects.

Prolonged overdose of all-trans retinoic acid enhances bone sensitivity in castrated mice

ObjectivesIntake of multivitamin preparations is very common in developed countries. However, excessive intake of vitamin A was associated with increased bone fragility. The aim of this study was to determine if chronic administration of the active metabolite of vitamin A all-trans-retinoic acid (ATRA) in slight excess is associated with changes of bone turnover and density in intact and castrated mice. MethodThree mo old male mice (C57B1/6) intact and castrated were injected intraperitonealy with 10 mg/kg/d of the ATRA or vehicle (control) once daily for 3 wk. The bone density, ash weights, calcium, and phosphorus content of the femur were measured. Plasma tartrate-resistant acid phosphatase (Tr-ACP) and serum bone alkaline phosphatase (B-ALP) were determined. ResultsATRA decreased bone density in both groups; however, this effect was more pronounced in castrated animals (1.487 ± 0.04 to 1,360 ± 0.05 g/cm3 ) than in intact mice (1.570 ± 0.03 to 1.510 ± 0.03 g/cm3 ). Bone density correlated with decreased B-ALP and increased Tr-ACP in ATRA-treated mice. ATRA treatment led to significantly lower thickness of cortical bone both in the intact and castrated animals. ConclusionOur results indicate that repeated administration of ATRA in slight excess leads to significant bone loss both in intact and castrated mice. This effect was more pronounced in testosterone-deficient animals. Testosterone deficiency as occurs following castration may sensitize the bone to resorption mediated by ATRA. Therefore, chronic vitamin A administration may be a risk factor for osteoporosis, especially in older and testosterone-depleted subjects.

32k Da protein improve ovariectomy-induced bone loss in rats

The objective of the present study was to systematically explore the effects of 32K Da protein (32KP) on postmenopausal osteoporosis. Eighty 3-mo-old female Sprague-Dawley rats were employed and randomly divided into one sham-operated group (SHAM) and five ovariectomy (OVX) subgroups as OVX (control), OVX with 17-ethinylestradiol (E2, 25 g/kg/day), OVX with 32KP of graded doses (50, 50, or 150 mg/kg/day). 32KP or E2 diet was fed on week 4 after operation, for 16 weeks. Bone mass, bone turnover and strength were evaluated by dual-energy X-ray absorptiometry (DEXA), biochemical markers and three-point bending test, respectively. Femur marrow cavity was observed by light microscopy via hematoxylin-eosin staining. It is observed that different dosage treatment of 32KP increased the body weight and prevented the loss of bone mass induced by OVX. The prevention effect against bone loss was presumably due to the altering of the rate of bone remodeling. The bone mineral density and bone calcium content in OVX rats were lower than that in the control group, suggesting that 32KP was able to prevent significant bone loss. In addition, the data from three point bending test and femur sections showed that 32KP treatment enhanced bone strength and reduced the marrow cavity of the femur in OVX rats. In the serum and urine assay, 32KP decreased urinary deoxypyridinoline and calcium concentrations; however, serum alkaline phosphatase activities were not inhibited. It suggested that amelioration of bone loss was changed via inhibition of bone reabsorption. Our findings indicated that 32KP might be a potential alternative drug for the prevention and treatment of postmenopausal osteoporosis.