虫草多糖对大鼠Ito细胞增殖及胶原基因表达的影响

目的　研究虫草多糖（ＣＰ）对大鼠Ｉｔｏ细胞增殖及Ⅰ、Ⅲ型前胶原基因ｍＲＮＡ表达的影响,探索ＣＰ抗肝纤维化的作用机制。方法分离、培养大鼠Ｉｔｏ细胞,采用~３Ｈ－胸腺嘧啶（~３Ｈ－ＴｄＲ）和~３Ｈ－脯氨酸（~３Ｈ－Ｐｒｏ）掺入法测定Ｉｔｏ细胞增殖及胶原合成;用原位杂交法检测Ｉｔｏ细胞Ⅰ、Ⅲ前胶原基因ｍＲＮＡ含量。结果　在０．１～８０μｇ／ｍ剂量范围内,ＣＰ可明显抑制Ｉｔｏ细胞~３Ｈ－ＴｄＲ和~３Ｈ－Ｐｒｏ的掺入。当ＣＰ浓度为１０μｇ／ｍｌ时,抑制率分别为２７．９％和４５．４％（Ｐ均＜０．０５）。随着浓度的增加和作用时间的延长,其抑制作用逐渐加强,１０μｇ／ｍｌ ＣＰ可显著抑制Ⅰ、Ⅲ型前胶原ｍＲＮＡ的表达,抑制率分别为３２．６０％和３７．３２％（Ｐ均＜０．０１）。结论 ＣＰ在体外可抑制Ｉｔｏ细胞的增殖和胶原合成,下调Ⅰ、Ⅲ型前胶原ｍＲＮＡ表达,并呈剂量和时间依赖性,提示ＣＰ对Ｉｔｏ细胞增殖和胶原合成的抑制可能是其体内抗肝纤维化作用的主要途径。     

川芎嗪,丹参治疗大鼠肺纤维化对Ⅰ,Ⅲ型前胶原基因表达的影响

目的观察川芎嗪、丹参治疗大鼠肺纤维化对胶原基因表达的影响。方法大鼠随机分为正常对照、３个模型、川芎嗪、丹参和氢化可的松琥珀酸钠（氢可）组７个组。博莱霉素复制模型后１５～２８天给药,２９天取肺作ＨＥ染色及检测α１（Ⅰ）、α１（Ⅲ）前胶原ｍＲＮＡ的原位杂交,进行组织病理学检查及图像分析定量。结果模型组两种前胶原ｍＲＮＡ在第７天表达至高峰,２９天Ⅰ型仍保持高水平,Ⅲ型已恢复正常。经治疗川芎嗪组的α１（Ⅰ）前胶原ｍＲＮＡ降至正常（Ｐ＞０．０５）,丹参、氢可组仍较高（Ｐ＜０．０１）。各组的α１（Ⅲ）前胶原ｍＲＮＡ均达正常（Ｐ＞０．０５）。结论川芎嗪通过抑制α１（Ⅰ）前胶原ｍＲＮＡ而起到抗肺纤维化作用,丹参和氢可的作用次之。     

骨质疏松相关基因在骨质疏松中的作用

骨质疏松（osteoporosis OP)是以骨质量的丢失以及骨组织的退变为特征的骨代谢疾病。近年来，骨质疏松相关基因如：维生素D受体（VDR）基因型，雌激素受体（ER）基因型，I型胶原A1（COLIAI）基因型，骨钙素基因，白细胞介素基因等在骨质疏松的形成和转归方面的作用日益成为人们关注的焦点。 雌激素可以增加破骨细胞的产物－转移生长因子β1（TGF-β1）在骨中富含，对病人带有的T等位基因发挥作用。中国妇女的BMD与VDR基因型有关。白细胞介素1（IL－1）是促进皮骨细胞的骨吸收作用因子，它随雌激素的减少而增加；在成骨细胞中近似于对雌激素的受体后效应，还可以促进破骨细胞凋亡，这种多效性维持着骨的稳态（homeostasis）。     

风湿性心脏病瓣膜胶原及转化生长因子β1改变的初步研究

为了解风湿性心脏病（风心病）病变二尖瓣和主动脉瓣组织中Ⅰ型胶原、Ⅲ型胶原及转化生长因子β１（ＴＧＦ－β１）基因表达的改变。用斑点杂交法测定９例风心病人和３例尸检中除外心血管病与胶原系统疾病者的二尖瓣和主动脉瓣中Ⅰ型胶原α１链［α１（Ⅰ）］ｍＲＮＡ、Ⅲ型胶原α１链［α１（Ⅲ）］ｍＲＮＡ、ＴＧＦ－β１ｍＲＮＡ的含量。结果显示：以对照组值为１．００，风心病人二尖瓣α１（Ⅰ）ｍＲＮＡ为２．３１±０．４８（Ｐ＜０．０１），α１（Ⅲ）ｍＲＮＡ为１．５９±０．１７（Ｐ＜０．０１），ＴＧＦ－β１ｍＲＮＡ为１．５７±０．２１（Ｐ＜０．０１）；主动脉瓣的结果分别为２．１０±０．４９（Ｐ＜０．０１），１．６６±０．２７（Ｐ＜０．０１），１．５２±０．１８（Ｐ＜０．０１）。结论：提示风心病病变瓣膜成纤维细胞胶原基因表达增强，使胶原合成增加，导致瓣膜纤维化。ＴＧＦ－β１基因表达增强的意义尚需进一步研究。     

雌二醇对人成骨样细胞基质金属蛋白酶及其抑制因子的作用

目的 探讨雌二醇（Ｅ２对人成骨样ＭＧ－６３细胞基质金属蛋白酶（ＭＭＰ）及基质金属蛋白酶抑制因子（ＴＩＭＰ）的作用和雌激素缺乏致骨质疏松（ＯＰ）的发病机制。方法 ＭＭＰ和ＴＩＭＰ用酶联免疫吸了会法和免疫印迹法检测,ｍＲＮＡ用逆转录聚合酶链反应检测。ＭＭＰ活性用明胶酶谱法检测。结果 人成骨样ＭＧ－６３细胞在２４ｄ的培养中表达ＭＭＰ－１、ＭＭＰ－２、ＴＩＭＰ－１和ＴＩＭＰ－２,但不表达ＭＭＰ－３、ＭＭＰ     

细胞间粘附分子1mRNA在哮喘豚鼠支气管组织中的原位表达

为了解哮喘豚鼠支气管组织中的细胞间粘附分子１（ＩＣＡＭ－１）ｍＲＮＡ表达情况，将实验豚鼠随机分为正常对照组、氟美松组和哮喘组，采用原位杂交方法显示ＩＣＡＭ－１ｍＲＮＡ的表达变化，用ＨＥ染色方法来测定炎细胞在支气管粘膜中的浸润程度。原位杂交结果显示，ＩＣＡＭ－１ｍＲＮＡ主要在支气管粘膜下的小血管、毛细血管内皮细胞以及支气管上皮细胞的胞浆内表达。定量分析结果表明，哮喘组豚鼠支气管组织表达ＩＣＡＭ－１ｍＲＮＡ较正常对照组及氟美松组显著增加（Ｐ＜０．０２，Ｐ＜０．０５），哮喘豚鼠支气管组织ＩＣＡＭ－１ｍＲＮＡ的表达量与炎细胞总数之间显著相关（Ｐ＜０．０５）。提示支气管粘膜组织ＩＣＡＭ－１ｍＲＮＡ表达与哮喘支气管粘膜嗜酸细胞为主的炎细胞浸润有关，糖皮质激素能够抑制细胞粘附分子的表达。     

牛磺酸抑制实验性肝纤维化大鼠细胞外基质沉积

目的研究牛磺酸抗肝纤维化作用。大法用四氯化碳（ＣＣＩ４）制备肝纤维化模型;免疫组化检测肝Ⅰ、Ⅲ、Ⅵ型胶原和透明质酸、层粘连素沉积;Ｎｏｒｔｈｅｒｎｂｌｏｔ杂交检测肝Ⅰ、Ⅲ型前胶原、组织金属蛋白酶抑制因子－１（ＴＩＭＰ—１）ｍＲＮＡ含量。结果ＣＣＩ４肝纤维化大鼠肝脏Ⅰ、Ⅲ、Ⅵ型胶原、透明质酸和层粘连素染色明显增多;Ⅰ、Ⅲ型前胶原、ＴＩＭＰ－１ｍＲＮＡ显著增加。牛磺酸处理的大鼠,上述各指标的阳性染色明显减少,并可明显抑制Ⅰ、Ⅲ型前胶原基因表达,而对ＴＩＭＰ—１ｍＲＮＡ却无明显影响。结论牛磺酸对ＣＣＩ４诱导的大鼠肝纤维化具有保护作用,可明显抑制纤维生成与沉积。提示它对防治肝纤维化有一定的临床意义。     

血小板源生长因子对动脉平滑肌细胞增殖,Ⅰ、Ⅲ型前胶原信使核糖核酸的表达及胶原蛋白合成的调节作用

目的：研究血小板源生长因子（ＰＤＧＦ）对培养的人主动脉平滑肌细胞增殖、胶原蛋白合成、分泌及Ⅰ、Ⅲ型前胶原信使核糖核酸（ｍＲＮＡ）表达和转移生长因子βｍＲＮＡ表达的调节作用。方法：氚胸腺嘧啶脱氧核苷（３ＨＴｄＲ），氚脯氨酸参入及Ｎｏｒｔｈｅｒｎ杂交分析。３ＨＴｄＲ，氚脯氨酸参入的比较采用ｔ检验。结果：ＰＤＧＦ能促进人主动脉平滑肌细胞脱氧核糖核酸（ＤＮＡ）合成和胶原蛋白合成、分泌；ＰＤＧＦ能上调Ⅰ、Ⅲ型前胶原ｍＲＮＡ表达和转移生长因子βｍＲＮＡ表达。结论：血小板源生长因子能通过上调Ⅰ、Ⅲ型前胶原ｍＲＮＡ表达和转移生长因子βｍＲＮＡ表达促进平滑肌细胞胶原蛋白的合成、分泌。     

转化生长因子β_1对纤维母细胞Ⅰ、Ⅲ型前胶原及胶原酶mRNA表达的影响

目的纤维母细胞是重要的胶原合成细胞，观察转化生长因子β１（ＴＧＦ－β１）对纤维母细胞Ⅰ、Ⅲ型前胶原及胶原酶ｍＲＮＡ表达的影响，以了解ＴＧＦ－β１在肝纤维化中的作用机制。方法首先对含有Ⅰ、Ⅲ型前胶原及胶原酶ｃＤＮＡ片段的质粒进行扩增、提纯及酶切，然后用自由引物延伸法进行地戈辛标记，并对探针进行检测；其次对纤维母细胞进行培养，加用ＴＧＦ－β１孵育后收集细胞并提取细胞总ＲＮＡ，最后将ＲＮＡ点样于尼龙膜上，并与上述探针进行斑点杂交。结果杂交结果显示ＴＧＦ－β能明显促进纤维母细胞Ⅰ型前胶原ｍＲＮＡ的表达（Ｐ＜０．０５），也能促进其Ⅲ型前胶原ｍＲＮＡ的表达（Ｐ＝０．０９）；而对其胶原酶ｍＲＮＡ的表达则起抑制作用（Ｐ＜０．０５）。结论ＴＧＦ－β可以从细胞及分子水平发挥其抗纤维化作用。     

右心室肥大时心肌间质胶原改建及其前胶原基因的表达

目的了解法乐四联症肥大右室心肌间质Ⅰ、Ⅲ型胶原的改建及与前胶原基因ｍＲＮＡ表达的关系,为防治心肌间质胶原改建提供新的依据和途径。方法用生化方法定量分析了２２例法乐四联症患者和８例非心血管及胶原系统疾病尸检者的右室心肌间质中的胶原含量和Ⅰ、Ⅲ型胶原比值,以及用斑点杂交法测定法乐四联症患者右室心肌间质Ⅰ、Ⅲ型前胶原基因ｍＲＮＡ的表达。结果法乐四联症组心肌间质胶原含量为（１４８５±２４８）μｇ／ｍｇ总蛋白,较对照组（７５５±１８９）μｇ／ｍｇ总蛋白明显增多（Ｐ＜００５）;其Ⅰ／Ⅲ型胶原比值为５１０±１８４,较对照组２２７±０５８显著增高（Ｐ＜００５）;法乐四联症组右室心肌间质胶原含量与Ⅰ、Ⅲ型前胶原基因表达强度的相关系数分别为０８０（Ｐ＜０００１）、－０２７７（Ｐ＞０１０）。右室心肌间质胶原Ⅰ／Ⅲ型比值与Ⅰ／Ⅲ型前胶原基因表达强度比值呈正相关,ｒ＝０４７（Ｐ＜００５）。结论提示法乐四联症肥大右室心肌间质存在以胶原含量增多和Ⅰ／Ⅲ型比值增高为特点的胶原改建,且主要与Ⅰ型前胶原基因ｍＲＮＡ转录水平上调有关。     

Estrogen inhibition of periosteal bone formation in rat long bones: down-regulation of gene expression for bone matrix proteins

Estrogen is important for both the sexual dimorphism of the skeleton during growth and the maintenance of bone balance in adults. This report describes the in vivo effects of estrogen on bone formation and gene expression in the tibial diaphysis of ovariectomized rats. Rats were ovariectomized at 8 weeks of age and were given diethylstilbestrol (DES) or placebo 1 week later as sc sustained release pellets. Histomorphometry revealed that that the periosteal bone formation and apposition rates were reduced at the tibial diaphysis 1 week after beginning estrogen treatment and further reduced after 2 weeks. Interestingly, DES treatment had no effect on endosteal bone formation, but suppressed endosteal bone resorption. Northern analysis of freshly isolated periosteal cells from tibiae and femora revealed that DES treatment resulted in dramatic decreases in steady state mRNA levels for the bone matrix proteins osteocalcin, prepro alpha 2(I) chain of type 1 collagen, osteonectin, and osteopontin as well as the osteoblast marker enzyme alkaline phosphatase. The results suggest that the inhibitory effects of estrogen on radial bone growth in rats are mediated, or at least accompanied, by the inhibition of the expression of bone matrix protein genes in periosteal cells.     

慢性心房颤动心房肌间质纤维化的分子机制研究

目的 研究心脏瓣膜病慢性心房颤动(房颤)患者心房肌间质纤维化的分子生物学机制.方法心脏瓣膜病接受瓣膜置换手术患者45例,慢性房颤27例,窦性心律18例,手术中取右心耳组织,采用半定量逆转录-聚合酶链反应测定Ⅰ型胶原、Ⅲ型胶原、基质金属蛋白酶(MMPs)中胶原酶(MMP1、MMP8、MMP13)以及基质金属蛋白酶抑制剂(TIMPs)中TMP1、TMP2、TMP3、TMP4的mRNA表达水平.结果 (1)与窦性心律组比较,慢性房颤组Ⅰ型胶原、MMP13、MMP1的mRNA表达上调(P<0.05),TMP1、TMP2、TMP3的mRNA表达下调(P<0.05).(2)MMP1的mRNA表达与Ⅰ型胶原的mRNA表达、左心房内径呈正相关,与TMP1的mRNA表达呈负相关.MMP13的mRNA表达与Ⅰ型胶原的mRNA表达、左心房内径呈正相关,与TMP3的mRNA表达呈负相关.结论 慢性房颤患者心房肌组织中MMP1/TMP1以及MMP13/TMP3的基因转录表达水平失衡引起Ⅰ型胶原转录水平的改变,可能是慢性房颤患者心房肌间质纤维化的分子基础.     

阿托伐他汀钙对原代成骨细胞OPG、RANKL、M—CSF基因表达的影响

目的观察不同浓度阿托伐他汀钙对体外培养原代成骨细胞增生和对OPG、RANKL、M—CSF基因表达的影响,探讨阿托伐他汀钙抗骨质疏松的分子机制,为临床用药提供实验依据。方法采用胰酶和I型胶原酶混合酶消化法分离获得原代成骨细胞;采用差速贴壁法进行纯化。光镜下观察细胞的形态结构和生长状况,通过碱性磷酸酶染色和I型胶原免疫组化SABC法对细胞进行鉴定。用不同浓度的阿托伐他汀钙（10^-9、10^-8、10^-7、10^-6和10^-5mol／L）干预成骨细胞,在24、48和72h后,用实时荧光定量方法检测OPGmRNA、RANKLmRNA、M—CSFmRNA的表达水平。结果镜下观察显示细胞具有成骨细胞的典型特征,细胞多为单核,呈三角、多边、长梭等形态,并伸有粗大伪足;碱性磷酸酶染色及I型胶原免疫组化染色呈阳性。实时荧光定量PCR结果显示：不同浓度的阿托伐他汀钙（10^-9、10^-8、10^-7、10^-6、10^-5mol／L）均可以促进OPGmRNA的表达,抑制RANKLmRNA的表达,对M—CSFmRNA基因的表达也具有促进作用,且与药物浓度及作用时间有关。结论采用胰酶和I型胶原酶混合酶消化法体外分离成骨细胞,采用多次“差速贴壁法”可以获得数量多、纯度高且活性好的成骨细胞。阿托伐他汀钙可以促进成骨细胞OPG基因mRNA的表达,抑制RANKL基因mRNA的表达,对M—CSF基因的表达也有一定的促进作用。     

温和灸对去卵巢大鼠股骨I型胶原表达的影响及意义

目的观察去卵巢大鼠骨I型胶原表达变化及温和灸、苯甲酸雌二醇注射液（BE2）的干预效果,探讨“补虚化瘀”灸法治疗绝经后骨质疏松症（PMO）的机制。方法将50只8月龄雌性Wistar大鼠随机分为假手术组10只和去势组40只,后者行双侧卵巢切除术,并于90d后随机分为模型组、雌激素组、艾灸组和艾灸＋雌激素组各10只,其后假手术组和模型组正常饲养,雌激素组予BE2后肢肌肉注射、艾灸组按“补虚化瘀法”取穴行温和灸治疗,艾灸＋雌激素组同时给予BE2注射和艾灸治疗。疗程结合后处死大鼠,分别以免疫组化法和原位杂交法检测右股骨I型胶原mRNA表达。结果模型组大鼠右股骨I型胶原蛋白及mRNA表达均明显低于假手术组及各治疗组,各治疗组中仅艾灸＋雌激素组mRNA表达阳性反应面积明显大于艾灸组（P〈0．05或0．01）,余各指标比较无显著差异。结论温和灸可明显增强去卵巢大鼠股骨I型胶原表达（效果与BE2相似）,此可能为“补虚化瘀”灸法治疗PMO的机制之一。     

Inhibitory effect of alcohol on osteogenic differentiation in human bone marrow-derived mesenchymal stem cells

BACKGROUND: Alcohol-induced osteoporosis is characterized by a considerable suppression of osteogenesis. The objective of this investigation was to determine the effect of alcohol on gene expression, protein synthesis, and mineralization in human bone marrow-derived mesenchymal stem cells induced toward osteogenic differentiation in vitro. METHODS: Human bone marrow-derived mesenchymal stem cells induced toward osteogenesis were cultured in the presence or absence of 50 mM alcohol. Stem cells were characterized by using SH2 antibody to the cell-surface antigen CD105/endoglin, and their proliferation in the presence of alcohol was quantified. The expression of genes for early, middle, and late markers of the osteogenic lineage was quantified by Northern analysis, and bone matrix protein synthesis was assayed. The effect of alcohol on cell-mediated matrix mineralization in terminally differentiated cultures was determined by von Kossa staining. RESULTS: Fluorescence-activated cell sorting analysis of human mesenchymal stem cells separated with a Percoll gradient proved 99% homogeneity by using SH2 antibody to the surface antigen CD105. Dose-dependent inhibition of proliferation of these stem cells occurred at concentrations greater than 50 mM alcohol. Gene expression of osteoblast-specific factor 2/core binding factor a1 (Osf2/Cbfa1), type I collagen, alkaline phosphatase, and osteocalcin (early, middle, and late markers for osteogenesis, respectively) was analyzed with and without osteogenic induction and treatment with 50 mM alcohol. After induction, Osf2/Cbfa1 levels were unresponsive to alcohol. To determine the effect of alcohol on human mesenchymal stem cell progression along the osteogenic pathway, messenger RNA (mRNA) levels for type I collagen, alkaline phosphatase, and osteocalcin were examined after osteogenic induction. After osteogenic induction, alcohol down-regulated the gene expression of type I collagen and significantly reduced its synthesis. Alcohol did not alter mRNA expression of alkaline phosphatase, a midstage marker for osteogenesis, but significantly decreased its activity compared with osteogenic induction alone. After induction, osteocalcin remained unchanged by alcohol at both the mRNA and protein levels. Histochemistry revealed decreased alkaline phosphatase staining and fewer alkaline phosphatase-positive cells in alcohol-treated human mesenchymal stem cell cultures. von Kossa staining revealed a reduction in the number of mineralizing nodules in stem cell cultures after alcohol treatment. CONCLUSIONS: Collectively, the data suggest that alcohol alters osteogenic differentiation in human bone marrow-derived mesenchymal stem cell cultures during lineage progression and provide further insight into alcohol-induced reduced bone formation.     

Human giant cell tumors of the bone (osteoclastomas) are estrogen target cells.

The decrease in estrogen levels that follows the onset of menopause results in rapid bone loss and osteoporosis. The major effect of estrogen deficiency on bone metabolism is an increase in the rate of bone resorption, but the precise mechanism by which this occurs remains unresolved. A recently developed technique for the isolation of avian osteoclasts has been modified to obtain highly purified multinucleated cells from human giant cell tumors. These osteoclast-like cells have been examined for evidence of estrogen receptors (ERs) and responses to 17 beta-estradiol (17 beta-E2). Analysis of giant-cell RNA demonstrated expression of ER mRNA. Furthermore, immunoblot analysis revealed that the giant cells contained a 66-kDa protein that was recognized by a monoclonal antibody specific for the human ER. When isolated multinucleated cells were cultured on slices of bone, there was a dose-dependent decrease in resorption in response to treatment detectable at 10 pM 17 beta-E2. Treatment with 10 nM 17 alpha-estradiol or vehicle (control) did not inhibit resorption. Moreover, the multinucleated cells isolated from these tumors had decreased mRNA levels for cathepsin B, cathepsin D, and tartrate-resistant acid phosphatase (TRAP) as well as secreted cathepsin B and TRAP enzyme activity in response to treatment with 10 nM 17 beta-E2. In contrast to these data, no change in gene expression was detected in mononuclear cells from these tumors in response to 17 beta-E2 treatment. These data support the proposition that human osteoclasts are target cells for estrogen and that estrogen can inhibit bone resorption by human osteoclasts.     

类风湿关节炎中尿激酶型纤溶酶原激活物及其受体蛋白和基因的表达

目的　检测尿激酶型纤溶酶原激活物 (uPA)及其受体 (uPAR)蛋白和mRNA在类风湿关节炎 (RA)的表达 ,探讨uPA、uPAR基因在RA细胞外基质降解中的作用。方法　采用免疫组化和cDNA mRNA原位分子杂交技术分别检测了 2 4例RA、18例骨关节炎 (OA)和 6例正常滑膜组织中uPA、uPAR蛋白和mRNA的分布及表达情况。结果　 2 4例RA滑膜组织均呈uPA、uPAR蛋白和mRNA的阳性表达 ,uPA、uPAR蛋白的强阳性率高于mRNA。uPA、uPAR蛋白和mRNA阳性信号主要分布在RA滑膜衬里细胞、滑膜下层单核细胞、巨噬细胞样细胞及血管内皮细胞 ;18例OA滑膜组织中 ,uPA、uPAR蛋白和mRNA的表达部位类似于RA ,但阳性率、阳性程度及分布范围均明显低于RA滑膜组织 ,两组之间蛋白和mRNA表达的差异均有显著性 (P <0 0 1或P <0 0 0 1)。 6例正常滑膜组织呈阴性反应。结论　RA滑膜组织存在高水平uPA、uPAR蛋白和mRNA的表达 ,提示在RA的发生发展过程中 ,uPA和uPAR基因起着重要作用 ;RA和OA中uPA、uPAR基因表达水平的差异 ,可能与这两种疾病软骨和骨基质降解的程度及进程等临床表现密切相关     

Mechanism of action of estrogen on intramembranous bone formation: regulation of osteoblast differentiation and activity.

Dynamic bone histomorphometry, [3H]thymidine radioautography, and Northern analysis for bone matrix proteins and insulin-like growth factor-I (IGF-I) were performed in calvariae of ovariectomized (OVX) and estrogen-treated OVX rats. Treatment of OVX rats with diethylstilbestrol (DES) for 2 weeks reduced the periosteal mineral apposition rate, osteoblast number, and osteoblast size in calvarial periosteum. DES treatment also reduced the number of preosteoblasts in the S phase of the cell cycle, suggesting that the decrease in osteoblast number was due in part to inhibition of proliferation of osteoprogenitor cells. One week after ovariectomy, there were small increases in mRNA levels for pre pro-alpha 2 (I) subunit of type I collagen (collagen), osteocalcin, and osteonectin and a large increase in the mRNA level for IGF-I. DES treatment resulted in rapid decreases (3 h) in the mRNA levels for osteonectin, osteocalcin, and IGF-I. In contrast, mRNA levels for collagen were virtually unchanged after short term DES treatment. Uterus and liver served as positive and negative control tissues, respectively, for the effects of DES on IGF-I mRNA levels in OVX rats; mRNA levels were increased in uterus and decreased in liver after hormone treatment. We conclude from these studies that estrogen reduces periosteal bone formation by inhibiting both the differentiation and activity of osteoblasts. Furthermore, down-regulation of mRNA levels for IGF-I and bone matrix proteins precedes the changes in dynamic bone histomorphometry.