The mechanism of estrogen-induced increase in hyaluronic acid biosynthesis,with special reference to estrogen receptor in the mouse skin

The increase in hyaluronic acid and water contents induced by estradiol treatment in the mouse skin was dependent on dose and the number of treatments of estradiol. The anti-estrogen administered together with estradiol blocked the increase in hyaluronic acid content produced by treatment with estradiol alone. It was suggested that the anti-estrogen may act as an antagonist by competing for the cytoplasmic estrogen receptor on increase in hyaluronic acid synthesis. It was observed that the sensitivity in increase in hyaluronic acid biosynthesis by estradiol was related to the age of the mouse and the content of the cytoplasmic estrogen receptor in the mouse skin.It was suggested that there was a possible relationship between the increase in hyaluronic acid and cytoplasmic estrogen receptor in the mouse skin.     

雌激素和孕激素对不同发情方式小鼠子宫内膜中孕激素受体分布的影响

目的探讨雌（Estrogen,E2）、孕激素（Progesterone,P4）对同期发情与自然发情小鼠子宫内膜中孕激素受体（Progesterone receptor,PR）分布的影响。方法45只同日龄雌鼠,根据处理方式的不同随机分为5组：自然发情组（对照组）、同期发情组、卵巢摘除组、P4处理组和E2处理组,5组小鼠在见栓后第4、6、8天分别取样后,采用免疫组织化学法观察小鼠子宫内膜中PR的分布变化情况。结果免疫组织化学染色结果显示,5个处理组小鼠子宫内膜的三种细胞中都有PR存在;同期发情组小鼠子宫内膜中三种类型细胞PR的表达与自然发情组差异有显著性（P〈0.05）;P4处理组小鼠子宫内膜中三种类型细胞PR的表达在见栓第4、6天显著低于卵巢摘除组（P〈0.05）;E2处理组小鼠子宫内膜腺上皮和间质中PR在第4、6、8天时都显著高于卵巢摘除组（P〈0.05）,而在腔上皮中则显著低于卵巢摘除组（P〈0.05）。结论同期发情处理与自然发情小鼠的子宫内膜上PR的分布,都受E2和P4的特异诱导而变化。     

Involvement of keratinocyte growth factor (KGF)-KGF receptor signaling in developmental estrogenization syndrome of mouse vagina

Exposure of mice to estrogen or keratinocyte growth factor (KGF) in vivo during the neonatal period results in estrogen-independent persistent proliferation and cornification of the vaginal epithelium when the animals become adults. Here, whether and how KGF-signaling is involved in the effects of estrogen on the neonatal mouse vagina were studied with an in vitro method. Newborn mouse vaginae were cultured for 3 days in serum-free medium containing various combinations of estradiol-17 (E₂), KGF, anti-KGF antibody, KGFR inhibitory peptide and heparin, and then transplanted into ovariectomized host mice for 35 days. The vaginae cultured with 5 g/ml E₂ or 5 g/ml KGF had a cornified thick epithelium, while the epithelium of the vehicle-treated controls stayed thin. The E₂ effect was blocked by concurrent treatment with anti-KGF antibody or KGFR inhibitory peptide. KGF treatment alone at doses less than 500 ng/ml did not induce permanent vaginal changes but such changes did occur in vaginae treated with heparin plus as little as 10 ng/ml KGF. On the other hand, heparin inhibited the permanent vaginal changes induced by estrogen. These results suggest that irreversible vaginal changes are induced by the direct action of KGF on the developing vagina and that the developmental estrogenization syndrome of mouse vagina is caused by intensification of endogenous KGF/KGFR signaling by exogenous estrogen.This work was supported by Grants-in-Aid for Scientific Research on Priority Areas (A) and for Encouragement of Young Scientists from the Ministry of Education Science, Sports and Culture, Japan to M.M.     

Distribution of insulin receptors among mouse liver endomembranes

Specific binding of insulin to highly purified preparations of rough endoplasmic reticulum, Golgi apparatus, and plasma membrane of mouse liver was determined. ¹²⁵I-labeled insulin bound maximally to the plasma membrane in radio-receptor assays. Golgi apparatus fractions exhibited binding 10–20% that of plasma membrane and rough endoplasmic reticulum exhibited only 1–2% of plasma membrane binding. Binding was proportional to membrane concentration and dose vs. response curves were very similar for the different fractions. Scatchard analysis of the insulin binding data for the plasma membrane and Golgi apparatus fractions showed curvilinear plots yielding similar apparent binding affinities (0.9 and 3.0 · 10⁸ M^?1, respectively). Purity of the isolated endomembranes was analyzed by morphometry and (Na⁺ + K⁺ + Mg²⁺)-ATPase and these preparations displayed less than 1% contamination by plasma membrane. These findings provide important confirmation of the presence of insulin receptors in Golgi apparatus membranes comparable to those located on the plasma membrane. Finally, the present study did not allow us to verify the existence of insulin receptors in the endoplasmic reticulum.     

Persistent trefoil factor 1 expression imprinted on mouse vaginal epithelium by neonatal estrogenization

Exposure of female mice to estrogenic substances during the neonatal period induces developmental defects in the reproductive tract such as estrogen-independent persistent proliferation of the vaginal epithelium, which often leads to carcinogenesis in adulthood. In this study, several estrogen-regulated genes have been identified in the neonatal mouse vagina by DNA microarray hybridization analysis. Among the genes up-regulated in the developing vagina by a high dose of estrogen, trefoil factor 1 (TFF1), a mucin-associated gastrointestinal growth factor, showed a unique expression pattern in accordance with the irreversible changes induced by neonatal estrogenization in the vagina. Vaginal expression of TFF1 mRNA was markedly increased by estrogen in neonatal mice but not in adults, and pronouncedly intensified expression of the gastrointestinal gene was observed in the vagina of neonatally estrogenized mice even at adulthood. The specific localization of TFF1 protein in the epithelium of neonatally estrogenized vagina was confirmed by immunohistochemistry. Moreover, without any obvious alteration in the expression of gel-forming mucin genes, the lumen of the neonatally estrogenized vagina became filled with periodic-acid-Schiff-stained mucinous gel, which was possibly caused by the overexpression of TFF1. Thus, estrogen acts directly on the developing vagina in the permanent induction of TFF1 gene expression, and the gene induction does not appear to be related to hypermethylation of the cis-promoter of the TFF1 gene. TFF1 may be a useful marker for developmental estrogenization syndrome of the mouse vagina. This work was supported by a Grant-in-Aid for Encouragement of Young Scientists from the Ministry of Education, Science, Sports, and Culture, Japan, and grants from the University of Tsukuba to M. M.     

雌激素受体亚型及其配体调节基因转录机制的研究

本文综述雌激素受体亚型（ERα和ERβ）的结构,功能,组织分布,生理作用及雌激素受体配体调节基因转录的机制,目的是深入系统地了解植物雌激素和选择性雌激素受体调节剂的作用路径及其组织特异性的发生机制,最终为提高雌激素类药物的选择性,优化以临床为基础的药物设计提供一条较为系统的思路。结果表明,ERα和ERβ对不同雌激素类化合物产生不同应答,配体的结构不同,调节基因转录的路径不同和募集的辅调节蛋白的不同是雌激素受体两种亚型组织特异性激活或抑制的主要原因。     

雌激素和多巴胺对大鼠垂体组织中雌激素受体基因表达的影响

目的研究雌激素和多巴胺激动剂对雌激素受体在大鼠垂体组织表达的作用。方法20只成年雌性Wistar大鼠,切除卵巢后,随机分2组：（1）对照组（n=5）,皮下植入空白硅胶管;（2）雌激素组（n=15）皮下植入含有乙烯雌酚的硅胶管,8周后,两组各处死5只大鼠,雌激素组剩余大鼠（n=10）取出硅胶管,随机再分2组,安慰剂组（n=5）给予自来水灌胃,多巴胺组（n=5）给予溴隐亭（多巴胺激动剂）灌胃,用药4周后处死动物。放免法测定血清PRL水平,用反转录一聚合酶链反应（RT-PCR）方法检测ERs在各组垂体组织中的表达,以β-actin作为内参照,借助于计算机凝胶成像系统分析表达量。结果ERa,ERβ以及TERP在各组大鼠垂体组织均有表达,其中ERα和TERPmRNA水平在雌激素组明显高于对照组（P〈0．001）,在安慰剂组和多巴胺组的表达无明显差别。结论大鼠垂体组织中存在ER的表达,雌激素对ERα和TERP的表达具有升调节作用,多巴胺不影响雌激素受体的表达。     

Estrogen receptor subtypes localization shifts in cultured mouse ovarian follicles

Estrogens play an important role in the growth, differentiation, and function of female reproductive tissues. Estrogen signals through estrogen receptors (ERs), members of the nuclear receptor superfamily. The two major forms, ERalpha and ERbeta, are expressed in the mouse ovary, where ERbeta is predominantly expressed in granulosa cells, and ERalpha in theca cells. In this study, we determined the expression pattern of ER subtypes within mouse follicles cultured from the early preantral stage up to the preovulatory stage and after an ovulatory stimulus in different culture conditions. Immunohistochemical studies performed at different time points of culture revealed that ERbeta was found exclusively in granulosa cell nuclei regardless of follicular growth stage or culture conditions. In contrast, ERalpha was found in oocyte, granulose, and theca cells, and its subcellular localization differed between follicular growth stages and culture conditions. A shift from a predominant cytoplasmic to a predominant nuclear immunolocalization was observed in granulosa cells as follicles reached the antral growth phase, and was postponed in culture conditions with minimal growth factor supplementation. In response to hCG, ERbeta protein levels in luteinized granulosa cells spectacularly declined to undetectable levels, while ERalpha immunostaining again shifted to cytoplasmic regions, but not in theca cells.     

Estrogen Receptors Alpha (ESR1) and Beta (ESR2) Are Expressed in Circulating Human Lymphocytes

Bone marrow thymocytes in part mediate the bone-preserving effects of estrogen by decreasing their production of osteoclast growth factors such as interleukin-1 and -6 and tumor necrosis factor alpha in the presence of physiological amounts of estradiol. Although several in vitro studies implicate the T-lymphocyte as a candidate mediator of estrogen signaling in the skeleton, whether these cells or any lymphocytes ordinarily express one or both nuclear estrogen receptors was previously unresolved. The purpose of our investigation was therefore to ascertain, by using real-time PCR, immmunoblotting, and cytometric techniques, if any of the nuclear estrogen receptors could be detected in normal peripheral blood mononuclear cells (PBMNC) collected from healthy volunteers. The results of immunoblotting experiments revealed that both estrogen receptor alpha (ESR1) and beta (ESR2) proteins are expressed in nuclei, but not in the cytoplasm of PBMNC harvested from all of the 15 healthy male and female volunteers (aged 23–50 years) we tested. PBMNCs contained mRNA coding for the two major full-length isoforms of ESR2 and the expression of ESR2 protein was localized within a lymphocyte subpopulation by cytometric analysis. Our data provide further evidence that lymphocytes and monocytes are responsive to estrogen and underscore its importance in modulating the immune response, as well as the vascular and skeletal health of men and women.     

Regulation of cytosol and nuclear progesterone receptors in rabbit uterus by estrogen,antiestrogen and progesterone administration

A synthetic progestin, 16α-ethyl-21-hydroxy-19-nor-4-pregnene-3,20-dione (ORG 2058), was utilized to measure progesterone receptors from the rabbit uterus. This steroid has a high affinity for both cytosol and nuclear receptors, with K_D values of 1.2 nM (at 0–4°C) and 2.3 nM (at 15°C), respectively. Administration of estradiol-17β or a non-steroidal antiestrogen, tamoxifen, for 5 days to estrous rabbits led to a progressive rise in the cytosol receptor levels: from 34 000 to 120 000 (estradiol-17β) and 80 000 (tamoxifen) receptors/ cell, without any major influence on the nuclear receptor content. A single intravenous injection of progesterone (5 mg/kg) elicited a 3-fold increase in the mean nuclear receptor content at 30 min after injection (from 18 000 to 48 000 receptors/nucleus). Nuclear receptor accumulation was short-lived and returned to control levels within 4 h after treatment. A second dose of progesterone given 24 h later doubled the nuclear receptor level (from 18 000 to 35 000 receptor/nucleus). The concomitant decline in the cytosol receptor content was twice that accounted for by the nuclear receptor accumulation (70 000 vs. 30 000, and 40 000 vs. 17 000 receptors/cell, after the first and second progesterone injection, respectively). Following progesterone administration, the cytosol receptor level reached a nadir by 30 min, exhibited minimal replenishment within the ensuing 24 h, and remained at approx. 50% of the pretreatment values. After a single dose or two consecutive doses of progesterone, total uterine progesterone receptor content declined to about 60% of the level prior to each dose, a nadir being reached at 2 h after treatment.     

Estrogens and cell death in murine uterine luminal epithelium

Summary The luminal epithelium of adult ovariectomized mice responds to estradiol-17 with a synchronised wave of DNA synthesis and mitosis. Estriol, however, although producing a similar DNA-synthetic and mitotic response fails to cause an increase in cell number owing to a wave of cell death occurring at mitosis. In the present study it was shown that cells died by two different routes. The majority died by apoptosis but, unusually, a minority also died by necrosis. In the apoptotic cells the cytoplasm became dense, the endoplasmic reticulum and nuclear cisternae dilated; chromatin became marginated the nucleus shrank and became deeply infolded and contorted. Apoptosis, however, was uncharacteristic in that the nucleus failed to fragment, form caps or show disruption before the cells died by membrane rupture. Furthermore, the cells were frequently lost in sheets from the epithelium into the lumen. Part of the biochemical explanation for this onset of cell death comes from the accelerated loss from the tissue of estriol when compared to estradiol-17. This resulted in a decline in protein and rRNA biosynthesis and a failure to complete ribosomal maturation. Evidence in favour of this explanation came from experiments that showed a return to the estradiol-17 level of response and an inhibition of cell death when the occupancy of the estriol receptor was maintained.     

The effects of pregnancy on the mouse thymic epithelium

Changes in the murine thymus during pregnancy were studied using immunocytochemistry with monoclonal antibodies against thymic epithelial, neuroendocrine, and thymulin-producing cells, fibroblasts, blood vessels and connective tissue components. Extensive alterations occur in mid-pregnancy. The medulla was greatly enlarged in the involuted thymus, and there were greater numbers of epithelial cells. These epithelial cells had an altered distribution forming large structures surrounding spherical masses of mononulear cells, lacked epithelial cells and often contained a central blood vessel with fibroblasts and connective tissue. We have called these structures medullary epithelial rings (MERs). To our knowledge these structures have not been described before. Late in pregnancy the loss of the central mononuclear cells leaves collapsed structures in a smaller medulla that nevertheless retains many epithelial cells. In virgins and early-pregnancy, there are cortical channels free of epithelial cells that are very infrequent later in pregnancy. This may reflect the loss of steroid-sensitive thymocytes from the cortex. The influence of sex-steroids neurological impulses and immune activity in causing the changes are discussed, as are the possible consequences in pregnancy of a reduced, thymocyte-depleted cortex and an enlarged medulla that shows great complexity and activity.     

Basal cells in the mouse olfactory epithelium after axotomy: immunohistochemical and electron-microscopic studies

Summary The olfactory epithelium of mice after axotomy was investigated to clarify the stem cells of olfactory cells by double immunostaining using antikeratin (MA903) and anti-bromodeoxyuridine (BrdU) antibodies and by conventional electron microscopy. When a single dose of BrdU was given to mice 9 days after axotomy, immunostaining for BrdU was found in the globose basal cells which were negative for MA903, but not in the basal cells proper which were positive for MA903. The BrdU-immunoreactive cells increased 3-to 6-fold over the number of these cells in the controls, indicating active cell proliferation. At other postoperative days (4 and 14 days), fewer BrdU-immunoreactive cells were found. Furthermore, three pulses of BrdU resulted in numerous BrdU-immunolabelings in the globose basal cells and a few in the basal cells proper. There was no detectable difference in the number of labeled basal cells proper in operated and unoperated mice. In the electron micrographs 9 days after axotomy, the basal cells proper, flat-shaped in unoperated mice, appeared cylindrical or pyramidal in shape and the globose basal cells often lay between the basal cells proper. In unoperated controls, the globose basal cells were located above the flat-shaped basal cells proper. The results suggest that the stem cells of the olfactory cells are globose basal cells and not basal cells proper, and that the shape of basal cells proper changes in relation to the active proliferation of stem cells.     

Basal cells express functional TRPV4 channels in the mouse nasal epithelium

Basal cells in the nasal epithelium (olfactory and airway epithelia) are stem/progenitor cells that are capable of dividing, renewing and differentiating into specialized cells. These stem cells can sense their biophysical microenvironment, but the underlying mechanism of this process remains unknown. Here, we demonstrate the prominent expression of the transient receptor potential vanilloid type 4 (TRPV4) channel, a Ca²⁺-permeable channel that is known to act as a sensor for hypo-osmotic and mechanical stresses, in the basal cells of the mouse nasal epithelium. TRPV4 mRNA was expressed in the basal portions of the prenatal mouse nasal epithelium, and this expression continued into adult mice. The TRPV4 protein was also detected in the basal layers of the nasal epithelium in wild-type but not in TRPV4-knockout (TRPV4-KO) mice. The TRPV4-positive immunoreactions largely overlapped with those of keratin 14 (K14), a marker of basal cells, in the airway epithelium, and they partially overlapped with those of K14 in the olfactory epithelium. Ca²⁺ imaging analysis revealed that hypo-osmotic stimulation and 4α-phorbol 12,13 didecanoate (4α-PDD), both of which are TRPV4 agonists, caused an increase in the cytosolic Ca²⁺ concentration in a subset of primary epithelial cells cultured from the upper parts of the nasal epithelium of the wild-type mice. This response was barely noticeable in cells from similar parts of the epithelium in TRPV4-KO mice. Finally, there was no significant difference in BrdU-labeled proliferation between the olfactory epithelia of wild-type and TRPV4-KO mice under normal conditions. Thus, TRPV4 channels are functionally expressed in basal cells throughout the nasal epithelium and may act as sensors for the development and injury-induced regeneration of basal stem cells.     

饮酒小鼠动物模型建立及其对雌性激素的影响

目的建立模拟人类饮酒的小鼠动物模型,并以此动物模型进一步研究酒精对小鼠雌激素水平及乳腺癌的影响。方法 SPF级C57BL/6雌性小鼠,随机分对照组和酒精组两组,酒精组20:00到次日8:00给予含有一定浓度酒精的饮用水,其他时间给予常规饮用水,对照组全天给予常规饮用水。观察两组小鼠的饮水量及体重变化;用ANALOX AM1酒精分析仪检测小鼠凌晨2∶00和8∶00血液的酒精浓度(BEC);酶联免疫法(ELASA)检测两组小鼠血清中雌激素水平的差异。结果饮酒组小鼠血液BEC明显增高,类似人类饮酒水平,饮酒组小鼠的饮水量及体重无明显变化;饮酒组小鼠体内雌激素的水平明显高于对照组。结论成功的建立模拟人类饮酒的动物模型,并通过此动物模型初步证实酒精刺激可以增加小鼠体内血清雌激素的水平。