Calbindin-D28k对小鼠骨质生长的影响

目的 探讨小鼠肾脏Calbindin-D28k(CaBP-D28k)在钙代谢中的作用.方法 构建维生素D受体(Vitamin D Recep-tor,VDR)/Calbindin-D28k双基因剔除小鼠模型,在普通及高钙饮食下,检测小鼠体重、摄食量、血尿参数值、下肢骨的长度、密度以及胫骨切片组织学染色等.结果 普通饮食下,VDR(-/-)/CaBP-D28k(-/-)小鼠发育更迟缓,体重比VDR(-/-)小鼠轻42%,尿钙的分泌更高,发展为更严重的佝偻病骨表型,表现为骨密度较低和骨小梁区生长板变形更多.高钙饮食下,VDR(-/-)及VDR(-/-)/CaBP-D28k(-/-)小鼠的血钙离子正常,VDR(-/-)/CaBP-D28k(-/-)小鼠的骨骼异常未得到完全纠正.结论 CaBP-D28k对骨质的生长发育起了重要作用,它对钙代谢的作用大都可被CaBP-D9k补偿.     

上皮钙通道基因在维生素D受体和Calbindin-D28k双基因敲除鼠中的变化

目的研究上皮钙通道TRPV5和TRPV6基因与维生素D受体(VDR)和钙结合基因Calbindin-D28k的关系,以及肾钙的重吸收减少是否与TRPV5和TRPV6基因表达减少有关。方法制备VDR和CaBP-D28k双基因敲除小鼠,普通和高钙食物喂养下,检测野生型鼠(WT),CaBP-D28(-/-),VDR(-/-),和VDR(-/-)/CaBP-D28k(-/-)鼠的体重、摄食量及血尿参数值,用实时RT-PCR的方法检测各种鼠肾脏TRPV5和TRPV6的mRNA水平。结果普通饮食下,双基因敲除小鼠尿钙的分泌和血清甲状旁腺激素水平更高。TRPV5和TRPV6两者的表达在CaBP-D28k敲除鼠中均无变化,而在VDR敲除鼠和双基因敲除鼠中下调的幅度相当。高钙饮食下,VDR及双基因敲除小鼠的血离子钙水平正常。所有小鼠这两个基因的表达普遍降低,而在VDR和双基因敲除鼠中的表达更低。结论这些结果证实了上皮钙通道基因受钙和维生素D的调节,CaBP-D28k的缺失对两者无影响。肾钙的重吸收减少与TRPV5和TRPV6基因表达无明显关系。     

膳食钙降低饮食诱导肥胖大鼠体重的机制

目的 研究膳食钙对饮食诱导肥胖大鼠的治疗作用及其机制。方法 以雄性Wistar大鼠为实验对象，用高脂饮食诱导大鼠肥胖模型。将肥胖大鼠按体重随机分为4组：A组为基础饲料组，B组为高脂低钙组(含0．25％钙)，C组为高脂正常钙组(含0．5％钙)，D组为高脂高钙组(含1％钙)。于第10周末处死动物，计算脂／体比，测定血糖、血脂和激素水平。结果 高钙膳食降低饮食诱导肥胖大鼠的体重和体脂含量，改善血脂代谢紊乱状态和胰岛素抵抗；膳食高钙通过促进瘦素分泌，降低神经肽Y分泌，升高血中游离T3和生长激素水平，起到降低饮食诱导肥胖大鼠体重和体脂含量的作用。结论 高钙膳食可以影响血中瘦素、神经肽Y、T3和生长激的水平，从而降低饮食诱导肥胖大鼠的体重。     

育龄妇女钙吸收与维生素D受体基因多态性

目的在我国城市居民代表性膳食条件下，探讨育龄妇女膳食钙吸收与维生素D受体（VDR）基因BsmI酶切多态性间的关系。方法从300名18～23岁女大学生中筛选40名受试对象，并通过特定引物对VDR基因扩增产物，以限制性内切酶BsmI酶切电泳条带分布分型。3d代表性膳食适应后，开始为期12d的代谢实验。研究对象所摄取的食品和饮品为城市代表性膳食，称重（包括饮水）并采集备份样品分析测定；采集研究对象的粪便和尿液。测定并计算出每位研究对象膳食钙的吸收率。结果不同VDR基因BsmI酶切型别的育龄妇女膳食钙吸收率不同，即Bb〈bb，且差异有统计学意义（P〈0．05）。结论VDR基因Bb型别的育龄妇女膳食钙吸收率低，应引起关注。     

钙代谢相关基因与单纯性肥胖症关系的研究

[目的]探讨高脂饮食诱导下肥胖易感（obesity-prone,OP）与肥胖抗性（obesity-resistant,OR）大鼠在体重、脂肪湿重及白色脂肪组织（white adipose tissue,WAT）中钙代谢相关基因脂肪酸合成酶（fatty acid synthase,FAS）、维生素D受体（vitamin D receptor,VDR）、解偶联蛋白2（uncoupling protein 2,UCP2）的表达差异.[方法]72只SD大鼠,随机选取12只为标准对照组,基础饲料饲养7周,余60只基础饲料饲养1周后,按体重增值分为OP组、OR组和高脂组,分组后改用高脂饲料继续饲养6周,观察各组大鼠体重变化、脂肪湿重等;用RT-PCR技术分析WAT中FAS、VDR、UCP2基因mRNA表达水平.[结果]①OP组体重增值、脂肪湿重均高于OR组（P＜0.05）;②OP组FAS基因mRNA表达水平高于OR组（P＜0.05）;OR组UCP2基因mRNA表达水平则显著高于OP组、高脂组和标准组（P＜0.001）,后三组间差异无显著性;OP、OR、高脂组三组间的VDRmRNA无差异,但均低于标准组（P＜0.05）.[结论]OP与OR组间存在的生理学差异,与OP组FAS表达增强、UCP2表达减弱导致产热减少密切相关,与VDR的参与可能有关.     

绝经妇女基因多态性与骨代谢相关性分析

目的探讨雌激素受体（ER）和维生素D受体（VDR）基因多态性对骨代谢及钙相关激素的影响.方法应用多聚酶链反应-限制性片断长度多态性（PCR-RPLP）检测汉族45～65岁绝经妇女的ER和VDR基因多态性,根据ER的Px单倍体型随机抽取90人测定血、尿中与骨相关的生化指标,采用双能X线吸收仪（DXEA）测量腰椎及髋部骨密度（BMD）.结果 Px单倍体组甲状旁腺激素水平（PTH）、抗酒石酸酸性磷酸酶（STR-ACP）和血清钙磷水平均高于non-Px单倍体组,但差异无统计学意义（P＞0.05）.同时考察ER和VDR基因多态性时,Px＋BB/Bb的STR-ACP的活性最高,而血清磷水平以non-Px＋bb的最低（P＜0.05）;Px单倍体组雌二醇（E2）水平与大转子（Troch,r=0.29,P=0.04）和Ward三角的BMD显著相关（r=0.31,P=0.03）,PTH水平与Troch的BMD相关（r=0.3,P=0.04）,而在non-Px单倍体组则无相关性.结论绝经妇女的ER基因多态性会影响骨代谢及钙相关激素与BMD的关系.     

甲状旁腺素、维生素D_3对Caco-2细胞钙结合蛋白D9k mRNA表达的影响

目的探讨甲状旁腺素(PTH)对小肠细胞钙结合蛋白(CaBP)D9k mRNA表达的影响以及探讨PTH是否影响1,25-(OH)2-D3对Caco-2细胞钙结合蛋白D9k mRNA表达的促进作用。方法以人结肠癌上皮细胞株Caco-2细胞作为小肠细胞体外模型,PTH分三个剂量10-8、10-9和10-12mol/L分别干预Caco-2细胞5、10、20、40和80min;10-8mol/L1,25-(OH)2-D3干预Caco-2细胞2、4、8、16和24h,溶剂对照为0.1%乙醇;10-8mol/L1,25-(OH)2-D3联合以上三剂量PTH干预Caco-2细胞2、4、8、16和24h,溶剂对照亦为0.1%乙醇。运用RT-PCR方法进行CaBP-D9k mRNA测定,以GAPDH作为内对照。结果10-8mol/LPTH作用20min,10-12mol/L作用10min,CaBP-D9k mRNA表达量高于空白组,其余时间点低于空白组;10-8mol/L1,25-(OH)2-D3干预Caco-2细胞2、4、8、16和24h,CaBP-D9k mRNA的表达均高于溶剂对照(0.1%乙醇);与10-8mol/L1,25-(OH)2-D3单独作用比较,10-8mol/L1,25-(OH)2-D3联合以上三剂量PTH作用,CaBP-D9k mRNA相对表达量均低于单独作用的表达量。结论10-8mol/L、10-12mol/LPTH可能促进Caco-2细胞CaBP-D9k mRNA瞬时(1~20min)合成增加;10-8mol/L1,25-(OH)2-D3可明显诱导Caco-2细胞CaBP-D9k mRNA的表达;PTH可能抵消或者抑制1,25-(OH)2-D3促进Caco-2细胞CaBP-D9k mRNA表达的作用。     

钙和维生素D抑制高脂饮食诱发的前列腺上皮细胞增生

本研究目的是观察饮食中添加钙和维生素D对小鼠前列腺上皮细胞增生的影响。将四周龄小鼠随机分成三组，分别给予对照AIN—76A饲料、高脂低钙低维生素D饲料（试验饲料Ⅰ）和高脂加钙和维生素D饲料（试验饲料Ⅱ）。饲养9周后终止试验，小鼠植入渗透泵，灌注溴脱氧尿苷（BrdU）72小时。结果显示，试验饲料Ⅰ组小鼠前列腺背叶上皮细胞BrdU标记指数与对照组比较明显升高（P＜0．05），而试验饲料Ⅱ组的BrdU标记指数与对照组相似（P＞0．05）。本实验研究发现证明，高脂低钙低维生素D饮食能诱发小鼠前列腺背叶上皮细胞增生，同时提示饮食中添加钙和维生素D有助于预防高脂低钙低维生素D饮食的这种不良作用。     

育龄妇女VDR基因酶切多态性与其膳食钙吸收间的关系探讨

目的在我国城市居民代表性膳食条件下,探讨育龄妇女膳食钙吸收与维生素D受体(VDR)基因FokI或BsmI酶切多态性间的关系。方法通过特定引物对VDR基因扩增产物以限制性内切酶FokI或BsmI酶切电泳条带分布确定研究对象的基因型别。3d代表性膳食适应后,开始为期12d的代谢实验。研究对象所摄取的食品和饮品为我们设计的城市代表性膳食,称重(包括饮水)并采集备份样品分析测定;完整采集研究对象的粪便和尿液。测定并计算出每位研究对象膳食钙的吸收率。结果不同VDR基因FokI或BsmI酶切型别的育龄妇女膳食钙吸收率不同,呈现如下趋势ff相似文献   

甲状旁腺激素与妊娠

甲状旁腺素通过对细胞、骨、肾及肠的代谢影响，使血管维持在正常水平，对调节钙、磷代谢并维持细胞外液的内环境恒定，有着极为重要的作用。研究认为，妊娠期妇女对钙磷的需要量较非妊娠妇女增加一倍，尤其是孕中期以后，胎儿发育需钙量大，随孕周延续，母体乏钙，易出现腓肠肌痉挛、腰退痛等低钙表现。孕期钙代谢有赖于甲状旁腺激素，１，２５二羟基维生素Ｄ及降钙素的互相制约、调节，并有雌激素参与。钙代谢异常是妊娠高血压综合征的重要原因之一，补充钙剂是预防和治疗妊高征的有利途径。     

Vitamin D receptor null mutant mice fed high levels of calcium are fertile

Vitamin D receptor (VDR) null mutant mice provide a model to investigate the possible effect of vitamin D on female reproduction. Infertility in these mice has been reported but it is uncertain whether the infertility results from a lack of VDR or from the hypocalcemia that results from a lack of VDR. VDR null mutant mice and wild-type controls were fed a nonpurified, high calcium or medium calcium diet, plus a diet containing lactose and their reproductive efficiency was examined. VDR null mutant mice fed a nonpurified diet were hypocalcemic and were found to be largely infertile with 14% fertility, while the fertility percentage of normocalcemic VDR null mutant mice and wild-type mice was between 86% and 100%. A high calcium or medium calcium diet maintained 100% fertility in the VDR knockout mice; removal of the lactose from this diet did not diminish reproductive capability. Reproductive capacity of VDR null mutant mice was analyzed when they were fed purified diets containing 0.02-2% calcium. Mutant mice fed a low calcium diet (0.47%) had a lower reproductive efficiency than VDR null mutant mice fed a diet that resulted in normal serum calcium concentrations. Thus, high dietary calcium levels are required for normal reproduction in VDR null mutant female mice. It seems that the defect in reproduction reported previously for VDR null mutant mice is not the lack of a direct effect of 1,25-dihydroxycholecalciferol on reproductive function but is the result of hypocalcemia.     

Vitamin D receptor (VDR) knockout mice reveal VDR-independent regulation of intestinal calcium absorption and ECaC2 and calbindin D9k mRNA

To study the role of calbindin D(9k) (CaBP) and epithelial calcium channel ECaC2 in intestinal calcium (Ca) absorption, vitamin D receptor knockout (KO) and wild-type (WT) mice were fed either 0.5% Ca or a 2.0% Ca rescue diet starting at 21 d of age. Ca absorption and parameters involved in this process were measured at 60 or 90 d of age. Compared with WT, KO mice fed the 0.5% Ca diet had higher plasma parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], and lower plasma Ca and insulin-like growth factor-I (IGF-I). Duodenal Ca absorption (% Ca absorbed) in KO mice was reduced 71% relative to WT mice and was associated with 55% lower CaBP mRNA, 47% lower CaBP protein and 95% lower ECaC2 mRNA levels. Compared with WT mice, the percentage of Ca absorbed in KO mice fed the 0.5% Ca diet was inappropriately low for the level of duodenal CaBP. The 2% Ca rescue diet normalized plasma Ca, prevented osteomalacia, increased growth and plasma IGF-I levels, but did not normalize plasma PTH or 1,25(OH)(2)D(3) in KO mice. In addition, the relationship between CaBP protein and the percentage of Ca absorbed was normalized, whereas ECaC2 mRNA fell to near zero. Our data demonstrate that higher CaBP levels do not ensure high rates of duodenal Ca absorption and that transcellular Ca absorption can occur even when ECaC2 gene expression is very low. In addition, our data suggest that the 2% Ca diet promotes a vitamin D receptor-independent anabolic effect on bone formation and calcium absorption, leading to improved calcium balance even in the presence of high PTH levels.     

强化钙与维生素D牛奶对10～12岁女童体格发育的影响

目的 探讨补充强化钙与维生素D牛奶对我国10－12岁女童体格发育的影响。方法 1999年3月至2001年3月,我们进行了为期2年、设有对照的双盲干预实验。将北京市9所小学757名平均年龄10.1岁的女童分为对照组（259人,保持日常饮食）、A组（238人,除日常饮食外,饮用钙强化牛奶144ml/d)和B组（260人,除日常饮食外,饮用钙和维生素D强化牛奶144ml/d)。调查其食物摄入和体力活动情况。干预前、中、后测定研究对象的体重、身高、坐高及膝高。结果 干预2年后,A组和B组的身高增长率（9.52%和9.26%)显著高于对照组的8.59%;A组和B组的体重增长率（34.53%和35.38%)显著高于对照组的30.91%;A组的坐高增长率为9.21%,显著高于B组的8.58%,又高于对照组的7.87%;A组膝高的增长率为9.00%,显著高于B组（8.37%)和对照组（8.44%)。结论 长期补充强化钙与维生素D的牛奶可能会促进我国10－12岁女童的体格发育。     

高脂饮食对载脂蛋白E缺乏鼠维生素D受体表达及一氧化氮合酶活性影响研究

目的了解高脂饮食对载脂蛋白（apoE）缺乏鼠（apoE^-/-）维生素D受体（VDR）表达及内皮型一氧化氮合酶（eNOS）活性影响,探讨VDR在动脉粥样硬化（AS）形成的意义及可能机制。方法apoE^-／-小鼠与作为对照的C57BLP6J小鼠分别按数字表法分为正常食物组与高脂食物组,采用竞争蛋白结合放射免疫法检测小鼠血25-（OH）D水平,采用免疫荧光化学法及RT-PCR法检测小鼠主动脉VDR表达,应用硝酸还原酶法检测小鼠血一氧化氮（NO）含量和eNOS酶活力。结果高脂饮食进一步加重apoE-/-小鼠As病变、降低血25-（OH）D水平[血25-（OH）D：正常饲料C57BLP6J小鼠、高脂饲料C57BLP6J小鼠、正常饲料apoE。一小鼠、高脂饲料apoE-/-小鼠分别为[（26．44±1．28）ng／mL、（22．68±2．07）ng／mL、（1-7.46±4.2．22）ng／mL、（15．88±0．97）ng／mL,P〈0．01]。高脂饮食进一步上调apoE-/-小鼠主动脉VDR蛋白与mRNA表达水平[VDR蛋白分别为0．244±0．088、0．346±0．132、0．547±0．128、0．768±0．162,VDtlmRNA分另U为、0．228±O．08．3、0．375±0．103、0．451±0．117、0．597±0．131,P均〈0．01]。高脂饮食致apoE一小鼠血NO水平、eNOS酶活力明显增高[NO：（39．74±4．81）μmol／L、（48．1±5．24）ixmol／L、（67．34±6．14）tzmol／L、（86．74±8．05）txmol／L;eNOS：（8．6-t-O．77）u／L、（12．28±1．42）U／L、（15．96-t-O．92）U／L、（18．68±1．15）U／L,P均〈0．01]。血25-（OH）D水平与血浆中NO含量、eNOS酶活力及VDR表达呈负相关（P〈0．01）。结论apoE-/-小鼠血25-（OH）D水平降低,VDR表达量明显上调,血NO含量、eNOS酶活力增高,高脂饮食可进一步降低血25-（OH）13、NO水平,上调主动脉VDR表达,增加eNOS酶活力。高脂饮食、维生素D、apoE相互作用,影响As病变可能与NO、eNOS有关。     

The effect of a high-protein, high-sodium diet on calcium and bone metabolism in postmenopausal women and its interaction with vitamin D receptor genotype

The influence of a high-Na, high-protein (calciuric) diet on Ca and bone metabolism was investigated in postmenopausal women (aged 50-67 years) who were stratified by vitamin D receptor (VDR) genotype. In a crossover trial, twenty-four women were randomly assigned to a diet high in protein (90 g/d) and Na (180 mmol/d) or a diet adequate in protein (70 g/d) and low in Na (65 mmol/d) for 4 weeks, followed by crossover to the alternative dietary regimen for a further 4 weeks. Dietary Ca intake was maintained at usual intakes (about 20 mmol (800 mg)/d). Urinary Na, K, Ca, N and type I collagen cross-linked N-telopeptide (NTx; a marker of bone resorption), plasma parathyroid hormone (PTH), serum 25-hydroxycholecalciferol (25(OH)D3), 1,25-dihydroxycholecalciferol (1,25(OH)2D3), osteocalcin and bone-specific alkaline phosphatase (B-Alkphase) were measured in 24 h urine samples and fasting blood samples collected at the end of each dietary period. The calciuric diet significantly (P<0.05) increased mean urinary Na, N, K, Ca and NTx (by 19 %) compared with the basal diet, but had no effect on circulating 25(OH)D3, 1,25(OH)2D3, PTH, osteocalcin or B-Alkphase in the total group (n 24). There were no differences in serum markers or urinary minerals between the basal and calciuric diet in either VDR genotype groups. While the calciuric diet significantly increased urinary NTx (by 25.6 %, P<0.01) in the f+ VDR group (n 10; carrying one or more (f) Fok I alleles), it had no effect in the f- VDR group (n 14; not carrying any Fok I alleles). It is concluded that the Na- and protein-induced urinary Ca loss is compensated for by increased bone resorption and that this response may be influenced by VDR genotype.     

High dietary vitamin D prevents hypocalcemia and osteomalacia in CYP27B1 knockout mice

Mice lacking 25-hydroxycholecalciferol [25(OH)D]-1alpha-hydroxylase (CYP27B1) are growth retarded, hypocalcemic, and have poor bone mineralization. We tested whether high dietary cholecalciferol (VD3) could exert effects in the absence of CYP27B1 in vivo. Weanling male wild-type (WT) and CYP27B1 knockout (KO) mice were fed either a 2% calcium (Ca), 20% lactose rescue diet or an AIN93G diet (0.5% Ca, 0.4% phosphorus) containing 1000 (1K, the rodent requirement, 25 microg), 10,000 (10K, 250 microg), or 20,000 (20K, 500 microg) IU VD3/kg diet until 12 wk when blood and tissues were taken. Serum 25(OH)D was >90 nmol/L in the 1K diet group and increased >4-fold in mice fed 10K and 20K diets. The 1K diet impaired growth and caused hypocalcemia in KO mice; the 10K and 20K diets were as effective as the high Ca rescue diet in preventing these outcomes. High VD3 restored expression of vitamin D-regulated genes in intestine (calbindin D(9K)) and kidney (CYP27B1, 24-hydroxylase, calbindin D(9K)) of KO mice. Micro-computed tomography of femora revealed complete recovery of cortical bone in KO mice fed either the rescue or 10K diets but only partial recovery of trabecular bone measures (e.g. 40% lower bone volume, 20% lower trabecular thickness, and 23% increase in trabecular separation). These data show that very high serum 25(OH)D can influence Ca and bone metabolism independent of its conversion to 1,25 dihydroxycholecalciferol. However, neither high dietary Ca nor high dietary VD3 is sufficient to fully recover the phenotype of CYP27B1 KO mice.