影响家畜黄体早期发育过程中血管新生因素分析

家畜卵巢黄体早期发育过程中血管新生是保证黄体形成所必须的营养与激素得到供应。血管新生是血管生长的一个过程,主要局限于健康成年动物的生殖系统。在哺乳动物中,黄体是血管新生比较强烈的地方,所以黄体是理想的研究血管生成的细胞和分子调控机制的模式系统。目前对其分子机制研究发现,血管内皮生长因子VEGF在这个过程中期主要作用,通过拮抗剂特异性阻断体内黄体时期的作用,发现黄体血管形成和功能被显著抑制。对黄体时期VEGF依赖性血管生成的分子机制研究,将有助于开发新的策略用于治疗黄体相关的不孕症,以及改善动物繁殖性能。本文在先前的研究基础上,对影响家畜黄体早期发育过程中血管新生的因素进行分析,旨在为畜牧生产上的应用提供理论依据与指导。     

IFN-α对猪黄体细胞增殖及VEGF基因表达的影响

为了探讨α干扰素(IFN-α)对体外培养猪黄体细胞增殖及VEGF基因表达的影响,试验分离猪卵巢中的黄体组织进行消化处理,制成细胞悬液,体外培养猪黄体细胞,采用MTT比色法测定猪黄体细胞的增殖,ELISA法测定培养液中孕酮的浓度;Real time PCR和Western-blot检测血管内皮生长因子(VEGF)基因表达。结果表明:IFN-α对猪黄体细胞增殖的抑制作用随着浓度升高而增强。在IFN-α浓度低于100 IU/m L时,对猪培养黄体细胞分泌孕酮呈现抑制作用;当IFN-α浓度高于100 IU/m L时,对猪培养黄体细胞分泌孕酮呈现促进作用。IFN-α下调猪黄体细胞中VEGF mRNA和VEGF蛋白表达。说明IFN-α抑制黄体细胞增殖并具有浓度依赖性,对猪黄体细胞中孕酮的分泌没有影响,下调猪黄体细胞中VEGF基因的表达。     

血管内皮生长因子(VEGF)及其受体在雌性动物繁殖上的研究进展

血管内皮因子(VEGF)是一种由各种正常细胞和肿瘤细胞合成和分泌的一种糖蛋白。VEGF家族包括VEGF-A,VEGF-B,VEGF-C,VEGF-D,PGF 5个成员,VEGF有3种受体,即:Flt-1,Flt-4,Flk-1/KDR。VEGF与受体结合具有促进血管内皮细胞的增生和提高血管通透性的作用。VEGF及其受体在雌性动物卵巢上的卵泡、黄体正常发育与维持,子宫内膜的周期性变化及胚胎发育与附植等方面均具有重要作用。     

血管新生调控因子在非霍奇金淋巴瘤中的研究进展

1992年Folkman等首次证实,肿瘤在缺乏血管新生的条件下仅能生长2~3 mm,并提出了肿瘤的生长依赖血管形成的假说。自此,血管新生在肿瘤领域内的研究有了重大进展。血管新生是指在已经存在的血管的基础上以出芽的方式形成新的微血管,是肿瘤生长和播散所必需的。血管发生受各种不同的正、负生成血管因子的调控。促进血管生成的因子包括血管内皮生长因子(VEGF)、碱性成纤维细胞生长因子(bFGF)、肝细胞生长因子(HGF)、胰岛素样生长因子-I(IGF-1)等;抗血管生成因子包括血管抑制素、内抑制素、白介素-1(IL-1)等,其中VEGF及bFGF是作用最强、特异性最高的血管新生正调控因子。本文就VEGF、bFGF在非霍奇金淋巴瘤(NHL)中的研究现况作一综述。1 VEGF、bFGF简述1.1 VEGF的生物学特性VEGF是一种结构具有高度保守的同源二聚体糖蛋白,人类VEGF基因全长为28kb。人至少有4种VEGF,其中VEGF 121和VEGF165为可溶性分泌蛋白,能促进血管内皮细胞有丝分裂及增加内皮通透性;VEGF189和VEGF206为不可溶性分泌蛋白,与肝素紧密结合。VEGF165为最常见的形式,也是主要效应...     

COX-2和血管内皮生长因子过表达与犬乳腺肿瘤血管生成的相关性

本研究旨在探讨环氧合酶-2(COX-2)和血管内皮生长因子(VEGF)在犬乳腺肿瘤血管生成中可能的作用。对70例肿瘤病例(28例良性和42例恶性)进行免疫组织化学分析,检测其COX-2和VEGF的表达情况;以CD31免疫标记测定微血管密度(MVD)来评估肿瘤血管生成。结果显示,在恶性病例中COX-2和VEGF的表达,MVD均显著高于良性病例(P<0.001)。在恶性组中,COX-2阳性肿瘤病例的MVD显著高于COX-2阴性肿瘤病例(P=0.026)。同样,VEGF阳性肿瘤病例的MVD也显著高于VEGF阴性肿瘤病例(P<0.001)。本研究结果提示,COX-2和VEGF的过度表达可能有助于恶性肿瘤的血管生成和侵袭。     

血管内皮生长因子在哺乳动物皮肤毛囊周围血管新生过程中的调控作用

血管内皮生长因子（Vascular endothelial growth factor, VEGF）是一种特异的作用于血管内皮细胞的生长因子,具有促进血管生成活性的功能性蛋白,也是新近发现的一种作用于毛囊的生长因子。毛囊具有周期性生长的特性,而在毛囊周期性变化过程中伴随着血管的新生。作者对毛囊周围血管新生及VEGF在该过程中的调控机制的研究进展予以综述。     

黄体机能与生长因子关系的研究进展

论述了黄体的形成和机能 ,同时介绍了EGF、TGF、IGF和VEGF等生长因子对黄体的调控作用     

家畜黄体新生血管形成的分子机制及其意义

黄体的发育依赖于早期新生血管的形成,黄体血管网的建立始于排卵前的卵泡,在促黄体生成素的刺激下排卵,形成早期黄体,开始迅速的生长,并伴有强烈的血管形成。该文综述了黄体新生血管形成的分子机制,为进一步理解黄体功能及操纵黄体提供重要的理论依据。     

Advances in studies on vascular endothelial growth factor receptor and its small-molecule inhibitors

目前抗血管生成治疗是抗肿瘤研究的热点.血管内皮生长因子(VEGF)是刺激血管生成的重要因子之一,血管内皮生长因子受体(VEGFR)在肿瘤新生血管中高表达,因此成为肿瘤靶向治疗的理想靶点.以VEGF、VEGFR为靶点的抗肿瘤药物除了常见的单克隆抗体药物阿伐斯汀外,小分子抑制剂舒尼替尼、索拉非尼等也已经广泛使用;另外,一些具有上市潜力的药物,如范得他尼、西地尼布、瓦他拉尼、阿西替尼等也值得关注.已上市和正在进行临床研究的VEGFR小分子抑制剂按结构大致分为6类:喹啉及喹唑啉类、哒嗪类、吲唑类、咪唑和吡咯嘧啶类、吲哚类和其他结构等.对VEGF、VEGFR的生物学功能,其代表性的小分子抑制剂研究进行综述.     

三氧化二砷对鸡马立克病病毒诱导鸡肝脏肿瘤中血管生长相关因子表达的影响

为了探讨三氧化二砷(As2O3)对马立克病病毒(MDV)诱导鸡肝脏肿瘤中血管生长相关因子表达的影响,构建了鸡马立克病病例模型,通过腹腔注射As2O3(3.0 mg/kg体重),于35 d,40 d与45 d观察临床症状及血管组织病理学改变,采用半定量RT-PCR法检测肝脏肿瘤中血管生长相关因子VEGF、KDR及bFGF mRNA表达水平。结果表明,MD病鸡肝脏肿瘤内VEGF、KDR及bFGF mRNA均高水平表达,As2O3能够下调肿瘤组织内VEGF、KDR与bFGF mRNA的表达水平,并呈现时间效应。揭示As2O3能够通过下调肝脏肿瘤组织中VEGF、KDR与bFGF mRNA的表达水平,减少血管的生成,进而抑制肿瘤生长,这是As2O3抗肿瘤作用机制之一。     

Angiogenesis in Developing Follicle and Corpus Luteum

Angiogenesis is a process of vascular growth that is mainly limited to the reproductive system in healthy adult animals. The development of new blood vessels in the ovary is essential to guarantee the necessary supply of nutrients and hormones to promote follicular growth and corpus luteum formation. In developing follicles, the pre-existing endothelial cells that form the vascular network in the theca layer markedly develop in response to the stimulus of several growth factors, mainly produced by granulosa cells, such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF). The angiogenic factors also promote vessel permeability, thus favouring the antrum formation and the events inducing follicle rupture. After ovulation, newly formed blood vessels cross the basement membrane between theca and granulosa layers and continue a rapid growth to sustain corpus luteum development and function. The length of luteal vascular growth varies in cycling and pregnant animals and among species; both angiogenesis and subsequent angioregression are finely regulated by systemic and local factors. The control of angiogenic development in the ovary could be a useful tool to improve animal reproductive performances.     

Angiogenesis and Interstitial Pressure in a Rat Tumour Model

Introduction and Aim:  The corpus luteum is one of the most intensely vascularized tissues. Luteal angiogenesis is strictly controlled and blood vessels regress completely within a short period of time. The aim of this study was to investigate vascular dynamics in relation to cellular and molecular mechanisms of luteal angiogenesis and anti-angiogenesis.
Material and Methods:  Endothelial cells of blood vessels in paraffin sections of bovine corpora lutea from different stages were examined by labelling with the lectin Bandeiraea simplicifolia agglutinin I. Angiogenesis was studied by morphometry of the capillaries, and immunolocalization of the angiogenic factor VEGF and VEGF-receptor 2. Presence of apoptotic luteal and endothelial cells was investigated using the TUNEL test and transmission electron microscopy.
Results:  During development of the corpus luteum (day 3–8 of the oestrous cycle) a dense capillary network (8–12% area ratio) is established and maintained until day 17. Early regression (day 18–24) is characterized by a remarkable decrease of capillaries (1% area ratio). In the regressing corpus luteum the number of apoptotic luteal cells is closely correlated ( r  = 0.9) to the number of apoptotic endothelial cells. VEGF is immunolocalized in luteal cells (day 3–17), smooth muscle cells and endothelial cells of arterioles of the regressing corpus luteum. During late luteal regression, a moderate increase of capillaries (2.5% area ratio) is obvious.
Conclusions:  The dynamic changes of the capillarity during development and regression of the cyclic corpus luteum correlate with VEGF and VEGF-R2 activities. In contrary to expectations the late stage of luteal regression is accompanied by angiogenesis. One reason for this phenomenon may be an increase in metabolic activity resulting in re-organization of blood vessels already regressed.     

Angiogenesis and Vascular Regression in the Corpus Luteum Periodicum

Introduction and Aim: The corpus luteum is one of the most intensely vascularized tissues. Luteal angiogenesis is strictly controlled and blood vessels regress completely within a short period of time. The aim of this study was to investigate vascular dynamics in relation to cellular and molecular mechanisms of luteal angiogenesis and anti‐angiogenesis. Material and Methods: Endothelial cells of blood vessels in paraffin sections of bovine corpora lutea from different stages were examined by labelling with the lectin Bandeiraea simplicifolia agglutinin I. Angiogenesis was studied by morphometry of the capillaries, and immunolocalization of the angiogenic factor VEGF and VEGF‐receptor 2. Presence of apoptotic luteal and endothelial cells was investigated using the TUNEL test and transmission electron microscopy. Results: During development of the corpus luteum (day 3–8 of the oestrous cycle) a dense capillary network (8–12% area ratio) is established and maintained until day 17. Early regression (day 18–24) is characterized by a remarkable decrease of capillaries (1% area ratio). In the regressing corpus luteum the number of apoptotic luteal cells is closely correlated (r = 0.9) to the number of apoptotic endothelial cells. VEGF is immunolocalized in luteal cells (day 3–17), smooth muscle cells and endothelial cells of arterioles of the regressing corpus luteum. During late luteal regression, a moderate increase of capillaries (2.5% area ratio) is obvious. Conclusions: The dynamic changes of the capillarity during development and regression of the cyclic corpus luteum correlate with VEGF and VEGF‐R2 activities. In contrary to expectations the late stage of luteal regression is accompanied by angiogenesis. One reason for this phenomenon may be an increase in metabolic activity resulting in re‐organization of blood vessels already regressed.     

Angiogenesis and vascular regression in the ovary

Angiogenesis is prominent during development and downregulated in the adult. Strictly controlled angiogenesis in the healthy adult occurs cyclically in the ovary and corpus luteum, which therefore make an excellent model with which to study vascular growth. Dysfunctional or uncontrolled angiogenesis is involved in a number of diseases and is responsible for growth and dissemination of tumours. This review focuses on the following aspects of the ovary: the gross and microscopical anatomy of the blood vessels, described mainly--but not exclusively--in the bovine; vascularization of the follicle before and after ovulation; angiogenesis in the developing and the mature corpus luteum as well as in the corpus luteum of pregnancy. The potential mechanisms of vascular regression during luteolysis and the potential role of vascular growth in dominance and atresia of follicles will be described. Furthermore, recent research on ovarian angiogenic and potential anti-angiogenic factors including fibroblast growth factor (FGF), vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF), angiopoietin and metalloproteinase inhibitor will be presented. Finally, the role of hormones including FSH, LH, sexual steroids, prostaglandins, prolactin, oxytocin and activin/inhibin in ovarian angiogenesis will be summarized. Future research is likely to yield valuable information that can contribute to the development of novel therapeutic strategies for the treatment of diseases characterized by disregulated angiogenesis and vascular regression.     

Effects of Hypo‐ and Hyperthyroidism on Proliferation,Angiogenesis, Apoptosis and Expression of COX‐2 in the Corpus Luteum of Female Rats

Although thyroid dysfunction occurs frequently in humans and some animal species, the mechanisms by which hypo‐ and hyperthyroidism affect the corpus luteum have not been thoroughly elucidated. This study evaluated the levels of proliferative activity, angiogenesis, apoptosis and expression of cyclooxygenase‐2 in the corpus luteum of female rats with thyroid dysfunction. These processes may be important in understanding the reproductive changes caused by thyroid dysfunction. A total of 18 adult female rats were divided into three groups (control, hypothyroid and hyperthyroid) with six animals per group. Three months after treatment to induce thyroid dysfunction, the rats were euthanized in the dioestrus phase. The ovaries were collected and immunohistochemically analysed for expression of the cell proliferation marker CDC‐47, vascular endothelial growth factor (VEGF), VEGF receptor Flk‐1 and cyclooxygenase‐2 (COX‐2). Apoptosis was evaluated using the TUNEL assay. Hypothyroidism reduced the intensity and area of COX‐2 expression in the corpus luteum (p < 0.05), while hyperthyroidism did not alter COX‐2 expression in the dioestrus phase. Hypothyroidism significantly reduced the expression of CDC‐47 in endothelial cells and pericytes in the corpus luteum, whereas hyperthyroidism did not induce a detectable change in CDC‐47 expression (p > 0.05). Hypothyroidism reduced the level of apoptosis in luteal cells (p < 0.05) and increased VEGF expression in the corpus luteum. In contrast, hyperthyroidism increased the level of apoptosis in the corpus luteum (p < 0.05). In conclusion, thyroid dysfunction differentially affects the levels of proliferative activity, angiogenesis and apoptosis and COX‐2 expression in the corpus luteum of female rats.     

哺乳动物发情周期黄体的组织学研究进展

黄体是排卵后形成的暂时性的内分泌组织 ,在一个较短的存在期限中经历了一系列的结构变化和分泌阶段 ,对于哺乳动物维持正常的生殖功能具有重要作用。人们对黄体细胞的来源、组成、形态及大小持有不同的观点。近年来 ,人们就黄体细胞的功能和退化、溶解进行了较为深入的研究 ,发现不同动物黄体细胞的功能各有不同 ,黄体退化、溶解与细胞凋亡有密切关系。了解哺乳动物发情周期黄体的组织结构对于控制动物的繁殖具有重要意义。文章对哺乳动物发情周期黄体中不同类型黄体细胞的来源、组成、形态、功能及退化、溶解 ,黄体细胞的分泌方式和超声波在黄体研究中的运用作了概述     

Vascular Mimicry of Granulosa Cells: a New Concept of Corpeus Luteum Development?

So far, it was generally accepted that newly formed blood vessels are exclusively comprised of endothelial cells, and complemented by pericyte and myocyte recruitment during vessel maturation. Accordingly, participation of non-endothelial cells in the formation of blood vessels has rarely been suggested. Recently, evidence supporting the existence of tumour vessels lined by non-endothelial cells has emerged. Consequently, the concept of the inherent capacity of non-endothelial cells to behave like endothelial cells has been discussed for tumours, and this pathomechanism has been termed vascular mimicry. The corpus luteum is one of the most intensely vascularized tissues, and angiogenesis in the corpus luteum is more effective than in highly malignant tumours. Our results indicate active involvement of granulosa cells in luteal angiogenesis, and the aim of this study was to shed more light on this exciting prospect. The study was based on cultured granulosa cells isolated from the bovine ovary in different stages of follicle maturation. Morphology of angiogenic granulosa cells was studied by phase contrast, transmission electron and scanning electron microscopy. Expression of angiogenesis-regulating factors and their receptors was demonstrated by polymerase chain reaction (RT-PCR). Cultured granulosa cells underwent changes reminiscent of endothelial angiogenesis, i.e., migration, proliferation, differentiation and three-dimensional organization, and expressed angiogenesis-regulating factors and their receptors. Our results suggest a tight regulatory and structural association of endothelial and granulosa cells in luteal angiogenesis, suggesting physiological vascular mimicry in the ovary.     

Inhibitory effect of insulin-like growth factor-binding protein-7 (IGFBP7) on in vitro angiogenesis of vascular endothelial cells in the rat corpus luteum

Angiogenesis in the developing corpus luteum (CL) is a prerequisite for establishment and maintenance of an early pregnancy. To explore the physiological significance of insulin-like growth factor-binding protein-7 (IGFBP7) in the developing CL, the effects of IGFBP7 on vascular endothelial growth factor (VEGFA)- and luteinizing hormone (LH)-induced in vitro tube formation were tested using isolated luteal microvascular endothelial cells (LECs). Capillary-like tube formation of LECs and their proliferation were stimulated by both VEGFA and LH. IGFBP7 treatment suppressed VEGFA- or LH-induced tube formation. The proliferation and migration of LECs, and phosphorylation of mitogen-activated protein kinase kinase and extracellular signal-regulated kinase 1/2 were inhibited by IGFBP7. Furthermore, IGFBP7 attenuated VEGFA-enhanced cyclooxygenase (COX)-2 mRNA expression and prostaglandin E₂ secretion. These findings suggest the possibility that luteal IGFBP7 secretion may suppress the stimulatory effect of VEGFA on angiogenesis in the early CL.     

Vascular and immune regulation of corpus luteum development, maintenance, and regression in the cow

The bovine corpus luteum (CL) is a unique, transient organ with well-coordinated mechanisms by which its development, maintenance, and regression are effectively controlled. Angiogenic factors, such as vascular endothelial growth factor A and basic fibroblast growth factor, play an essential role in promoting progesterone secretion, cell proliferation, and angiogenesis. These processes are critically regulated, through both angiogenic and immune systems, by the specific immune cells, including macrophages, eosinophils, and neutrophils, that are recruited into the developing CL. The bovine luteolytic cascade appears to be similar to that of general acute inflammation in terms of time-dependent infiltration by immune cells (neutrophils, macrophages, and T lymphocytes) and drastic changes in vascular tonus and blood flow, which are regulated by luteal nitric oxide and the vasoconstrictive factors endothelin-1 and angiotensin II. Over the period of maternal recognition of pregnancy, the maternal immune system should be well controlled to accept the semiallograft fetus. The information on the presence of the developing embryo in the genital tract is suggested to be transmitted to the ovary by both the endocrine system and the circulating immune cells. In the bovine CL, the lymphatic system, but not the blood vascular system, is reconstituted during early pregnancy, and interferon tau from the embryo could trigger this novel phenomenon. Collectively, the angiogenic and vasoactive factors produced by luteal cells and the time-dependently recruited immune cells within the CL and their interactions appear to play critical roles in regulating luteal functions throughout the life span of the CL.     

Histomorphological and immunohistochemical study of angiogenesis and angiogenic factors in the ovary of the mare

Cyclical ovaries of 18 mares were examined histologically and immunohistochemically for vascular endothelial growth factor A and B (VEGF A; VEGF B), angiopoietin1 and 2 (Ang1; Ang2), vascular endothelial growth factor receptor 1 and 2 (VEGF-R1; VEGF-R2), angiopoietin receptor (Tie2) and von Willebrand factor. The most intensive coexpression of the examined factors and receptors was detected in the periovulatory period, when a distinctive ovarian angiogenesis takes place, being essential for tertiary follicle maturation and for the endocrine function of the Corpus luteum. Based on the immunohistochemical results, VEGF A, Ang2, VEGF-R2 and Tie2 in particular seem to play a significant role on angiogenesis during follicular and luteal development in the mare, while Ang1 supports vessel stabilisation. The findings of luteal regression and follicular atresia showed that, in the absence of VEGF A, Ang2 and its receptor Tie2 contribute substantially to vessel regression and therefore to luteolysis and follicular atresia.