Magnesium deficiency-induced osteoporosis in the rat: uncoupling of bone formation and bone resorption.

Magnesium (Mg) intake has been linked to bone mass and/or rate of bone loss in humans. Experimental Mg deficiency in animal models has resulted in impaired bone growth, osteopenia, and increased skeletal fragility. In order to assess changes in bone and mineral homeostasis that may be responsible, we induced dietary Mg deficiency in adult Simonsen albino rats for 16 weeks. Rats were fed either a low Mg diet (0.002 percent) or a normal control Mg diet (0.063 percent). Blood was obtained at baseline, 4 weeks, 8 weeks, 12 weeks and 16 weeks in both groups for serum Mg, calcium, PTH, and 1.25(OH)2-vitamin D determinations. Femora were harvested at 4 weeks and 16 weeks for mineral analysis and histomorphometry. Serum Mg fell in the Mg depleted group to 0.6 mg/dl (mean) by 16 weeks (controls = 2.0 mg/dl). The serum calcium (Ca) concentration was higher in the Mg depleted animals at 16 weeks, 10.8 mg/dl (controls = 8.9 mg/dl). Serum PTH concentration fell progressively in the Mg deficient rats to 30 pg/ml by week 16 (control = 96 pg/ml). Serum concentration of 1.25(OH)2-vitamin D also fell progressively in the Mg deficient animals by 16 weeks to 14 pg/ml (control = 30 pg/ml). While the percent ash weights of Ca and phosphorus in the femur were not different at any time point, the percent ash weight of Mg progressively fell to 0.54 percent vs control (0.74 percent) by 16 weeks. The percent ash weight of potassium also fell progressively in the Mg deficient group to approximately 30 percent of control by 16 weeks. Histomorphometric analyses showed a significant drop in trabecular bone volume in Mg deficient animals by 16 weeks (percent BV/TV = 13.2 percent vs 17.3 percent in controls). Evaluation of the endosteal bone surface features showed significantly greater bone resorption in the Mg depleted group as reflected in increased number of tartrate-resistant positive osteoclasts/mm bone surface (7.8 vs 4.0 in controls) and an elevated percent of bone surface occupied by osteoclasts (percent OcS/BS = 12.2 percent vs 6.7 percent in controls. This increased resorption occurred in the presence of an inappropriate lowered bone forming surface relative to controls; a decreased number of osteoblasts per mm bone surface (0.23 vs 0.94 in control) and a decrease in percent trabecular surface lined by osteoid (percent OS/BS = 0.41 vs 2.27 percent in controls) were also noted. Our findings demonstrate a Mg-deficiency induced uncoupling of bone formation and bone resorption resulting in a loss of bone mass. While the fall in PTH and/or 1.25(OH)2-D may explain a decrease in osteoblast activity, the mechanism for increased osteoclast activity is unclear. These data suggest that Mg deficiency may be a risk factor for osteoporosis.     

辛伐他汀和吉非罗齐对高脂血症伴骨量减少患者骨代谢和骨密度的影响

目的观察辛伐他汀和吉非罗齐对高胆固醇血症伴骨量减少患者骨代谢指标及骨密度的影响。方法高脂血症合并骨量减少患者128例,分两组后分别予以辛伐他汀和吉非罗齐治疗,并在治疗前及治疗后分别检测血脂、骨吸收标志物血清I型胶原羧基末端肽（sCTX）、骨形成标志物总骨Ⅰ型前胶原N端肽（P1NP）和桡骨远端骨密度（BMD）。结果辛伐他汀组平均治疗周期（10.24±1.89）个月,治疗后总胆固醇（TC）、甘油三酯（TG）、低密度脂蛋白（LDL-C）明显降低（P〈0.05）,同时sCTX降低（P〈0.01）,P1NP增高（P〈0.05）,BMD增加（P〈0.01）,而吉非罗齐治疗后虽TC、TG、LDL-C明显降低（P〈0.05）但sCTX、P1NP和BMD无明显变化。结论较大剂量辛伐他汀具有抑制骨吸收、增强骨形成和增加BMD的作用,可能与血脂水平降低无关。     

Decrease of bone mineral density during estrogen substitution therapy

A decrease in bone mineral density (BMD) in patients treated with hormone replacement therapy (HRT) is sometimes observed in clinical practice. In order to assess the frequency and the characteristics of these cases, we reviewed the data of 102 women treated with HRT for more than 2 years, and who had undergone at least 3 lumbar BMD measurements during that period. For each patient, a linear function was fitted to the BMD data in relation to time. The slope was calculated. There was an overall gain in BMD during treatment, mean (± S.E.M.) values of slope 0.007 g/cm²/year (± 0.002). Fifty-three patients had a slope higher than 0.005, 28 a slope close to 0 (between 0.005 and −0.005) and 21 a slope lower than −0.005. By dividing the patients in tertiles of slopes (tertile l: slope < 0; tertile II: 0 < slope < 0.011; tertile III: slope > 0.011), significant differences were observed between the three groups of slope for the initial BMD (P < 0.001), hydroxyproline/creatinine ratio (P < 0.01), weight, DHEAS and alkaline phosphatase (P < 0.05). Only 1 of the 15 patients with a low bone mass (lower than mean ± I S.D.) had a negative slope, while 9 of the 16 with a high-bone mass (higher than mean ± I S.D.), had a negative slope. Under HRT, about 21% of postmenopausal women have a slight decrease in BMD as assessed by DPA. Because of the DPA coefficient of variation, however, the exact number of bone losers cannot be determined. Nevertheless, the present study suggests that patients with low bone mass are likely to respond better than patients with high bone mass.     

The effect of tibolone on bone mineral density in postmenopausal women with osteopenia or osteoporosis--8 years follow-up

OBJECTIVES: This longitudinal observational study evaluated the effect of 8 years of uninterrupted treatment of tibolone on bone mineral density (BMD) in postmenopausal women with significant osteopenia or osteoporosis. MATERIAL AND METHODS: Subjects were 66 postmenopausal women (29 with moderate or severe osteopenia and 37 with osteoporosis) who took tibolone (2.5 mg nocte) uninterruptedly for over 8 years and who attended for annual BMD assessments. Their mean age was 66.7 (0.86) years (range 50-86 years). BMD measurements at the lumbar spine and proximal femur were performed annually by dual-energy X-ray absorptiometry (DEXA). RESULTS: During the 8 years of treatment with tibolone there was a significant increase in BMD at the spine (P < 0.001) and at the hip (P < 0.001). Women who did not have previous oestrogen therapy had significantly greater response to tibolone than those who had previous treatment with conventional hormone replacement therapy (HRT). CONCLUSION: This long-term observational study provides evidence of the effectiveness of tibolone in postmenopausal women with moderate/severe osteopenia and osteoporosis in terms of a significant increase in BMD.     

雌激素受体基因多态性与老年妇女的骨密度

背景：雌激素受体α基因多态性与骨质疏松的发生相关有一定的关系,但是对于危险基因型的研究还存在商榷余地。 目的：分析雌激素受体基因多态性与老年妇女骨密度的相关性。 方法：选择检查的老年健康妇女120例,提取全血基因组DNA,选择限制性内切酶PvuⅡ和XbaⅠ进行酶切,分析基因型的分布与频率。同时选择双能X射线骨密度仪测股骨颈、大转子及Ward三角处的骨密度值。 结果与结论：XbaⅠ酶切基因型XX 6例,Xx 78例,xx 36例;PvuⅡ酶切PP 32例,Pp 50例,pp 38例。不同基因型老年妇女的年龄、绝经年龄与体质量指数值对比差异无显著性意义(P > 0.05)。PvuⅡ酶切PP基因型妇女的大转子与ward三角处的骨密度值明显大于Pp及pp妇女(P < 0.05);而XbaⅠ酶切基因多态性在老年妇女中股骨颈、大转子与Ward三角的骨密度均无显著差异(P > 0.05)。说明雌激素受体基因多态性与老年妇女骨密度有一定的相关性,P等位基因对老年妇女大转子与Ward三角处的骨密度的维持有一定作用。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

The significant effects of bone structure on inherent patient-specific DXA in vivo bone mineral density measurement inaccuracies

An extended analytic exposition is developed of the effects bone structure has on the form and extent of systematic inaccuracies in planar dual-energy x-ray absorptiometry (DXA) in vivo bone mineral density (BMD) measurements. Explicit expressions for absolute and percentage BMD inaccuracies are derived and criteria governing these BMD inaccuracies delineated. It is shown that the effect of bone structure is to introduce a scale factor which modulates the sizable and unavoidable DXA in vivo/in situ BMD inaccuracies that arise directly from patient-specific anthropometric and x-ray absorptiometric disparities among the several soft tissues present within the scan region of interest of any given bone site (i.e., lean muscle tissue, interposed and admixed fat, and red/yellow marrow combinations). Different magnitudes and patterns of BMD inaccuracies are shown to pertain for bone structures that are (i) essentially wholly trabecular, (ii) wholly cortical, and (iii) those containing both cortical and trabecular bone. Over the range of soft tissue anthropometrics typical of adult patients, the overall percentage inaccuracies in DXA-measured BMD are shown to be quite sizable and to vary considerably for different bone structures. For a typical lumbar vertebral bone site, BMD inaccuracies are found to be as large as approximately 25% for normal patients, to exceed approximately 35% for osteopenics, and to approach 50% for osteoporotic individuals. For bone sites with non-negligible cortical surrounds of trabecular structures (e.g., distal radius, some segments of proximal femur, etc.), it is shown that BMD percentage inaccuracies range up to approximately 20% for normal, approximately 25% osteopenic, and approximately 35% for osteoporotic patients. The BMD % inaccuracies associated with wholly cortical bone (trabecular-free) sites (e.g., mid-shaft femur, mid-shaft radius, etc.) are comparatively small, being less than approximately 2%. Depending on bone structure, bone size and shape, and patient-specific intra- and extra-osseous soft tissue particulars of any given adult patient, DXA in vivo BMD measurements can be grossly inaccurate, and can severely under- or over-estimate the true value of BMD and mask or exaggerate true changes in BMD in ways not previously elucidated. It is concluded that in vivo DXA-measured and actual BMD cannot be considered to be synonymous, and clinical reliance upon the two being the same may readily conduce to seriously flawed and misleading diagnostic, prognostic, and prospective results.     

绝经后女性骨密度与雌激素水平、免疫细胞因子和骨代谢指标的相关性研究

目的:分析绝经后女性骨密度变化及其与雌激素水平、免疫细胞因子和血清骨代谢指标的相关性。方法:将135 名绝经后女性根据其腰椎骨密度(BMD)分为骨质疏松(OP)组(54 例)、骨量减少组(43 例)及正常组(38 例)。测定三组研究对象血清雌二醇(E2)、骨源性碱性磷酸酶(BALP)、骨钙素(BGP)、抗酒石酸酸性磷酸酶-5b(TRAP-5b)、白细胞介素-6(IL-6)、白细胞介素-10(IL-10)、肿瘤坏死因子-α(TNF-α)、转化生长因子-β(TGF-β1)水平,并分析其与BMD 的相关性。结果:与正常组比,OP 组和骨量减少组血清E2、TGF-β1、IL-10 水平均显著降低(P<0.05),血清BALP、BGP、TRAP-5b、IL-6 及TNF-β水平均显著升高(P<0.05);与骨量减少组比,OP 组的血清E2 水平更低,血清BALP、BGP、TRAP-5b、IL-6 及TNF-β水平均更高,差异有统计学意义(P<0.05)。E2、TGF-β1、IL-10 与BMD 呈正相关(P<0.05);BALP、BGP、TRAP-5b、IL-6 及TNF-α均与BMD 呈负相关(P<0.05)。低血清E2 水平和高血清BALP、BGP、TRAP-5b、IL-6、TNF-α水平是绝经后女性BMD 降低的独立影响因素(P<0.05)。结论:绝经后女性E2 水平降低,引起骨重建失衡及骨免疫炎症反应,该变化与BMD 降低有关。     

The effects of physical exercise on body fat distribution and bone mineral density in postmenopausal women

OBJECTIVE: The present cross-sectional study investigated the effects of physical exercise on body fat distribution and bone mineral density (BMD). METHODS: Subjects were 57 postmenopausal women (mean age, 60.5+/-6.4 years) who had exercised regularly for at least 2 years. Controls were 130 age-matched sedentary women. Age, years since menopause (YSM), height, weight, and body mass index (BMI, wt./ht.(2)) were recorded. Total fat mass, percentage of body fat, trunk fat mass, leg fat mass, the ratio of trunk fat mass to leg fat mass (trunk-leg fat ratio), total body lean mass, percentage of body lean, and lumbar spine BMD (L2-L4) were measured by dual-energy X-ray absorptiometry. RESULTS: Baseline characteristics and leg fat mass did not differ between the two groups. Total fat mass, percentage of body fat, trunk fat mass, and trunk-leg fat ratio were lower (P<0.05, P<0.01, P<0.01 and P<0.001, respectively), while total body lean mass, percentage of body lean mass, and lumbar spine BMD were higher in exercising women (P<0.05, P<0.05 and P<0.01, respectively). Performing physical exercise was inversely correlated with trunk-leg fat ratio (standardized regression coefficient=-0.178, P<0.01), but positively correlated with BMD (0. 203, P<0.01) irrespective of age, height, YSM, and total fat mass. CONCLUSION: Physical exercise has beneficial effects on body fat distribution and BMD in postmenopausal women. Reduction of upper body fat distribution with physical exercise may be more attributable to the decrease in trunk fat mass.     

A micro-imaging study linking bone cancer pain with tumor growth and bone resorption in a rat model

Bone metastases represent a frequent complication of advanced breast cancer. As tumor growth-induced bone remodeling progresses, episodes of severe pain and fractures of weight-bearing limbs increase. All of these skeletal-related events influence the patient’s quality of life and survival. In the present study, we sought to determine whether some of these pain-related behaviors could be directly correlated to tumor progression and bone remodeling. For this purpose, we used a rat model of bone cancer pain based on the implantation of mammary carcinoma cells in the medullary cavity of the femur. The bone content and tumor growth were monitored over time by magnetic resonance imaging (MRI) and micro X-ray computed tomography (μCT). The same animals were evaluated for changes in their reflexive withdrawal responses to mechanical stimuli (allodynia) and weight-bearing deficits. As assessed by MRI, we found a negative correlation between tumor volume and allodynia or postural deficits throughout the experiment. Using μCT, we found that the bone volume/total volume (BV/TV) ratios for trabecular and cortical bone correlated with both mechanical hypersensitivity and weight-bearing impairment. However, whereas trabecular BV/TV stabilized between days 7 and 10 post-tumor detection, the cortical bone loss reached its maximum at that time. Our imaging approach also allowed us to consistently detect the tumor before the onset of pain, paving the way for the preemptive identification of at-risk patients. Altogether, these results improve our understanding of the events leading to tumor-induced bone pain and could eventually help in the design of novel strategies for the management of bone diseases.     

Effect of mineral content of human bone on in vitro resorption

Summary Osteoclasts, mechanically isolated from chick long bones, were grown in vitro on slices of human rib and femur. Evidence of their activity was assessed by secondary electron and backscattered electron (BSE) imaging in the SEM. BSE imaging was also used to study the relative degree of mineralisation of the bone matrix in which resorption had taken place. All bone phases were resorbed, from osteoid through to densely mineralised interstitial bone and reversal (cement) lines. Resorbing osteoclasts crossed reversal lines between osteons of different mineral density and moved both from higher to lower and lower to higher density phases. Where single loci spanned reversal lines, and thus breached bone of two different mineral densities, depth of demineralisation was inversely related to mineral density. The presence of an annular zone around some resorption loci, which may be caused by demineralisation beneath the osteoclast clear zone, was confirmed. Also, BSE imaging of polished substrata showed that significantly more osteoclastic activity had occurred at their surfaces than was apparent from the amount of cavitation present.     

Association of estrogen receptor alpha gene polymorphisms with bone mineral density in postmenopausal Indian women

Bone mineral density (BMD) is the major determinant of osteoporotic fracture risk with a particular genetic background. However, consensus on the association of BMD with specific gene locus has not been reached. In the present study, we investigated the potential association of estrogen receptor alpha (ER alpha) gene intron I polymorphisms with BMD in 246 postmenopausal Indian women (average age 54.2+/-3.4 years). All the subjects were genotyped for XbaI and PvuII polymorphisms and underwent BMD measurements at spine and hip by dual energy X-ray absorptiometery. The average BMD of subjects with the genotypes XX and PP (absence of restriction sites for XbaI and PvuII, respectively) was 12.7 and 5.4% higher at the spine and 13.1 and 4.6% higher at the hip, respectively, than those with genotypes xx and pp. In age vs. BMD scatterplot, the intercept and slope of regression lines for genotypes xx and pp at spine and hip demonstrated comparatively rapid decrease in BMD across the age. The genotype XX was significantly prevalent (p<0.001) in women with normal bone mass (32%) and genotype xx in women with osteoporotic bone mass (35.3%), within the group. A significantly higher relative risk was associated with xx genotype. The study concludes that genetic variations at ER alpha gene locus, perhaps, are associated with BMD in Indian women and may influence some determinant of bone metabolism resulting in accelerated bone loss with age.     

A study of mineral density surrounding resorption sites in teeth

An investigation of mineral density surrounding lacunar resorption sites in cases of both internal and external root resorption, was carried out on 37 human primary and permanent teeth. In addition, equivalent areas of the roots of 14 normal appearing teeth were studied for comparison. Thirty-two of the teeth were analyzed using microradiographic and microhardness techniques and the remainder were studied microscopically after histologic preparation. The teeth used for microradiographic analysis were embedded in plastic, bisected and half of each tooth was sectioned at 70–100 μ. Microadiographs were taken at 9.5 kv and exposed to 30 milliamperes for 25 to 40 minutes. The other halves of the teeth were used for microhardness tests using a Tukon Microhardness Tester. One series of microhardness measurements was made 10 to 40 μ from sites of active resorption in root dentin and a second series was made 250 to 500 μ from these sites. The hardness measurements of the first series were found to be significantly lower than those of the second in cases of both external and internal resorption. Hardness values of the surface of normal appearing roots were also less than areas 250 to 500 μ deeper in the dentin. Microradiographs did not reveal any definite zone of subsurface demineralization although some resorption sites were bordered by irregular areas of decreased radiodensity which may be due to superimposition of several resorption sites within the thickness of the tooth section. Histologic observations did not reveal a definite subsurface demineralization gradient. The lacunar resorption front was found to be a multilocular and completely interconnected system.     

The effect of simvastatin on bone formation and ceramic resorption in a peri-implant defect model

Experimental use of statins as stimulators of bone formation suggests they may have widespread applicability in the field of orthopaedics. With their combined effects on osteoblasts and osteoclasts, statins have the potential to enhance resorption of synthetic materials and improve bone ingrowth. In this study, the effect of oral and local administration of simvastatin to a beta tricalcium phosphate (betaTCP)-filled defect around an implant was compared with recombinant human bone morphogenetic protein 2 (rhBMP2). On hundred and sixty-two Sprague-Dawley rats were assigned to treatment groups: local application of 0.1, 0.9 or 1.7 mg of simvastatin, oral simvastatin at 5, 10 or 50 mg kg(-1) day(-1) for 20 days, local delivery of 1 or 10 microg of rhBMP2, or control. At 6 weeks rhBMP2 increased serum tartrate-resistant acid phosphatase 5b levels and reduced betaTCP area fraction, particle size and number compared with control, suggesting increased osteoclast activity. There was reduced stiffness and increased mechanical strength with this treatment. Local simvastatin resulted in a decreased mineral apposition rate at 6 weeks and increased fibrous area fraction, betaTCP area fraction, particle size and number at 26 weeks. Oral simvastatin had no effect compared with control. Local application of rhBMP2 increased resorption and improved mechanical strength whereas simvastatin was detrimental to healing. Oral simvastatin was ineffective at promoting either ceramic resorption or bone formation. The effect of statins on the repair of bone defects with graft substitute materials is influenced by its bioavailability. Thus, further studies on the optimal delivery system are needed.     

Effect of exercise on the bone strength, bone mineral density, and metal content in rat femurs

We have investigated the effect of exercise on the bone strength, bone mineral density (BMD), and metal content in rat femurs. Five Wister rats acting as an exercised group (E group) were exercised at intervals on a treadmill every day for four weeks. Another five rats were fed in a cage, acting as a control group (C group), without any exercise. After four weeks, the bend strength, Young's modulus, BMD value, and metal content of the femurs were measured using a three-point bend test, Dual-Energy X-ray Absorptiometry (DEXA), and chemical analysis. The bend strength of the E group was 101+/-5 MPa, and that of the C group was 86+/-7 MPa. The Young's modulus was 1.16+/-0.03 GPa for the E group, and 0.98+/-0.06 GPa for the C group. The BMD values were 0.179+/-0.002 g/cm(2) for the E group, and 0.166+/-0.002 g/cm(2) for the C group. The Ca concentration was 230600 +/- 1500 microg/g for the E group, and 223000 +/- 2700 microg/g for the C group. The Zn concentration was 160 +/- 7 microg/g for the E group, and 188 +/- 8 microg/g for the C group.     

Trait anxiety and tamoxifen effects on bone mineral density and sex hormone- binding globulin

OBJECTIVE: Tamoxifen therapy preserves BMD of the lumbar spine and increases levels of SHBG. We assessed whether trait anxiety, a factor linked with a reactive endocrine system, is associated with differential changes in BMD and SHBG levels in response to tamoxifen therapy. METHODS: Postmenopausal women (N= 140) with axillary-node-negative breast cancer participated in a 2-year randomized, double-blind, placebo-controlled trial of tamoxifen (10 mg twice a day). Levels of BMD and SHBG were assessed at baseline and at 3, 6, 12, 18, and 24 months. RESULTS: Trait anxiety predicted tamoxifen-induced changes in lumbar spine BMD; high levels of trait anxiety were associated with significantly greater lumbar spine BMD at 3, 12, and 24 months (p values <.05) for women on tamoxifen therapy. High anxiety also was associated with lower levels of SHBG for women using tamoxifen at 3, 12, 18, and 24 months (p values <.05). CONCLUSIONS: Trait anxiety is associated with greater preservation of lumbar spine BMD in response to tamoxifen and with a suppression of tamoxifen-induced increases in SHBG. Trait anxiety and other affective traits may serve as indicators of underlying physiological processes that moderate the effects of estrogen receptor modulators (such as tamoxifen) in clinical trials. Such data may help to elucidate the physiological mechanisms responsible for some of the variation in individual responses to treatment.     

特纳综合征患者早期雌激素替代治疗改善骨密度

目的探讨早期雌激素替代治疗对特纳综合征(TS)患者骨密度(BMD)改善的效果。方法选取2005年8月到2015年8月就诊于北京协和医院内分泌科矮小门诊的27例TS患者,全部测量身高、体质量,雌激素治疗前后的骨密度由LUNAR-PRODGIY型骨密度仪进行测量。比较TS患者雌激素替代治疗前后骨密度的差异,治疗起始年龄对骨密度的影响。结果应用雌激素治疗后1年内、1~3年、3年L2-4的骨密度分别为(0.96±0.13)g/cm~2、(0.92±0.13)g/cm~2、(0.93±0.14)g/cm~2,显著高于基线水平分别为(0.73±0.08)g/cm~2、(0.70±0.13)g/cm~2、(0.75±0.07)g/cm~2;治疗起始年龄18岁组L2-4骨密度(0.96±0.14)g/cm2显著高于治疗起始年龄≥18岁组(0.90±0.10)g/cm~2。结论早期雌激素替代治疗可更有效地改善TS患者骨密度,但影响骨密度的其他因素仍需进一步深入探究。     

Femoral bone mineral density and bone mineral content in bromocriptine-treated pregnant and lactating rats

Since hyperprolactinemia was found to induce osteopenia in the metaphysis of long bone in non-mated female rats, pregnant and lactating rats with sustainedly high plasma prolactin (PRL) levels might also exhibit some changes in their long bones. We performed a longitudinal study in pregnant, lactating and post-weaning rats, using dual-energy X-ray absorptiometry to demonstrate site-specific changes (i.e., metaphysis vs. diaphysis) in femoral bone mineral density (BMD) and content (BMC). The results showed that femoral metaphyseal BMD and BMC were higher when compared to their age-matched controls during pregnancy, before decreasing in late lactation and post-weaning. On the other hand, femoral diaphyseal BMC increased during pregnancy, early lactating and mid-lactating periods without change during late lactation and post-weaning. After 7 days of bromocriptine administration which inhibited endogenous PRL secretion, the lactation-induced increases in BMC during early and mid-lactating periods were abolished. Moreover, a decrease in metaphyseal BMD during late lactation was restored to the control levels by bromocriptine. However, bromocriptine did not antagonize the pregnancy-induced increases in BMD and BMC. It could be concluded that the effect of PRL on bone was variable during the reproductive periods. While having no effect on femoral BMD and BMC during pregnancy, PRL was responsible for bone gain in early and mid-lactating periods, but induced bone loss during late lactating period.     

Effect of estrogen on bone resorption and inflammation in the temporomandibular joint cellular elements

Several epidemiological studies have reported that temporomandibular disorder is more prevalent in women, which suggests the involvement of sex hormones, such as estrogen, in the pathogenesis of this disease. PCR amplification and Western blotting were employed to target the expression of estrogen receptors (ERs) in human fibroblast-like synovial and ATDC5 cells. The effect of estrogen was investigated through the expression of RANKL, osteoprotegerin (OPG), M-CSF/CSF-1 and c-fms. We showed expression of M-CSF/ CSF-1 and c-fms, with time-dependent increase in both after the addition of estrogen. Based on previous studies reporting that M-CSF/CSF-1 regulates the proliferation and differentiation of hemopoietic progenitor cells into mature macrophages, we put forward a new hypothesis based on the increased inflammation and tendency of females to suffer more from temporomandibular disorder (TMD) in the presence of external exacerbating factors. Detection of RANKL and OPG in ATDC5 and expression of both in HFLS was confirmed with complete disappearance of the RANKL band, and marked increase in the expression of OPG after 1 h from the addition of estrogen.     

原发性高血压模型大鼠颌骨骨量的吸收

背景：近年研究发现,高血压病患者中骨质疏松发病率较正常人群增高。 目的：观察原发性高血压与颌骨及牙槽骨吸收的关系。 方法：选用原发性高血压大鼠,随机分为模型组和给药组,正常大鼠作为对照组。模型组和对照组均进食未添加降压药物的普通标准饲料颗粒,给药组进食添加有降压药物的标准饲料颗粒。 结果与结论：模型组大鼠从10~22周龄收缩压逐渐上升,22周龄后血压趋于稳定。给药组和对照组血压较低且平稳。同一周龄大鼠血压值模型组>给药组>对照组(P < 0.01)。模型组和给药组大鼠下颌骨骨量均低于对照组(P < 0.01)。模型组骨皮质较薄,骨小梁稀疏、纤细、弯曲不整或断离,骨髓腔扩大,给药组骨质病理变化程度较模型组减轻。结果证实,血压升高可引起原发性高血压大鼠下颌骨骨量减少,使骨小梁变细、排列紊乱,从而增加牙槽骨吸收的风险。