神经生长因子对哮喘大鼠气道炎症中TNF-α表达的调节作用

目的 探讨神经生长因子(NGF)在哮喘发病中对气道炎症TNF-α mRNA表达的调节作用.方法 实验分为对照组、哮喘组、NGF阻断组.免疫组化方法结合显微图像分析检测NGF的表达,以及抗NGF干预后哮喘的发作情况、嗜酸性粒细胞及TNF-α mRNA表达的关系.结果 NGF阻断组与哮喘组比较,哮喘发作次数、嗜酸性粒细胞计数显著减少(均P＜0.01),肺组织炎症表现显著减轻.哮喘组大鼠肺组织内NGF mRNA表达水平较对照组显著增高(P＜0.05),NGF阻断组肺组织内TNF蛋白及TNF-a mRNA的表达较哮喘组明显减少(P＜0.05).结论 NGF阻断可减少肺部嗜酸粒细胞浸润、哮喘的发作次数及TNF-α mRNA蛋白的表达,并可以抑制气道炎症.     

糖皮质激素对哮喘气道重塑大鼠骨桥蛋白水平及骨桥蛋白mRNA表达的影响

目的探讨糖皮质激素对哮喘气道重塑大鼠骨桥蛋白(OPN)水平及OPN mRNA表达的影响。方法2014年12月—2016年1月,选取30只雄性Wistar大鼠并采用随机数字表法分为正常对照组、哮喘模型组、糖皮质激素组,各10只。建立哮喘动物模型,哮喘模型组大鼠于造模第15天予以卵清蛋白(OVA)雾化吸入激发致敏;正常对照组大鼠于造模第15天予以等量0.9%氯化钠溶液腹腔注射及雾化吸入;糖皮质激素组大鼠处理同哮喘模型组,并于OVA雾化吸入激发致敏前1 h雾化吸入布地奈德混悬液(BUD)。比较3组大鼠气道壁厚度,支气管壁平滑肌厚度及胰岛素样生长因子-I(IGF-I)、神经生长因子(NGF)、核因子-κB(NF-κB)水平,OPN水平及OPN mRNA表达情况,并进行相关性分析。结果哮喘模型组大鼠气道壁厚度、支气管壁平滑肌厚度大于糖皮质激素组和正常组对照组(P0.05);糖皮质激素组大鼠气道壁厚度、支气管壁平滑肌厚度大于正常组对照组(P0.05)。哮喘模型组大鼠IGF-I、NGF、NF-κB水平高于糖皮质激素组和正常组对照组(P0.05);糖皮质激素组大鼠IGF-I、NGF、NF-κB水平高于正常组对照组(P0.05)。哮喘模型组大鼠OPN水平和OPN mRNA相对表达量高于糖皮质激素组和正常组对照组(P0.05);糖皮质激素组大鼠OPN水平和OPN mRNA相对表达量高于正常组对照组(P0.05)。哮喘气道重塑大鼠气道壁厚度、支气管壁平滑肌厚度及IGF-I、NGF、NF-κB水平分别与OPN水平(r值分别为0.91、0.84、0.80、0.79、0.83)、OPN mRNA相对表达量(r值分别为0.83、0.87、0.79、0.76、0.81)呈正相关(P0.05)。结论糖皮质激素可抑制哮喘大鼠气道重塑的发生,延缓气道壁及支气管壁平滑肌增厚,降低IGF-I、NGF、NF-κB、OPN水平及OPN mRNA的表达。     

L-精氨酸对哮喘大鼠气道平滑肌细胞增殖的影响

目的 观察L-精氨酸(L-Arg)对哮喘气道重构大鼠气道平滑肌细胞(ASMC)的细胞周期分布及细胞周期调节蛋白(CCRP)表达水平的影响,探讨L-Arg体内干预哮喘大鼠ASMC增殖的可能作用机制.方法 实验分成对照组、哮喘组、L-Arg组,建立大鼠哮喘气道重构模型,检测血清NO-2/NO-3含量、肺内支气管内管壁和平滑肌层厚度及ASMC核数、ASMC的细胞周期分布以及ASMC内细胞周期素E(cyclin E)、cyclin A、cyclin B、蛋白27kip1(P27kip1)的表达.结果 哮喘组大鼠支气管内管壁、平滑肌层的厚度和ASMC数目显著大于对照组(P<0.05);L-Arg组大鼠支气管内管壁的厚度、平滑肌层的厚度和ASMC数目显著小于哮喘组(P<0.05).哮喘组血清一氧化氮(nitricoxide,NO)水平显著低于对照组(P<0.05);L-Arg组血清NO水平显著高于哮喘组(P<0.01).哮喘组G0/G1期ASMC比例及P27kip1表达水平显著低于对照组(P<0.01),G2/M+S期ASMC比例及cyclin E、cyclin A和cyclin B表达水平显著高于对照组(P<0.01);L-Arg组G0/G1期ASMC比例及P27kip1表达水平显著高于哮喘组(P<0.05),G2/M+S期ASMC比例及cyclin E和cyclin A表达水平显著低于哮喘组(P<0.05).结论 L-Arg通过调控CCRP的表达水平阻滞细胞从G1期进入S期而抑制哮喘ASMC的增殖.     

神经生长因子对支气管哮喘大鼠肾上腺素释放障碍的机制研究

目的探讨支气管哮喘(简称哮喘)状态下肾上腺髓质嗜铬细胞释放肾上腺素不足的可能原因,明确神经生长因子(NGF)在哮喘发病机制中的作用。方法雄性SD大鼠32只,按随机数字表法分为对照组、哮喘组、NGF干预组、抗NGF组,每组8只。对照组以生理盐水代替抗原行致敏和激发,NGF干预组、抗NGF抗体干预组建立哮喘模型后分别用NGF和抗NGF抗体干预哮喘大鼠。电镜观察肾上腺髓质嗜铬细胞超微结构的改变,免疫组织化学结合显微图像分析各组大鼠髓质嗜铬细胞中苯乙醇胺N-甲基转移酶(PNMT)的表达变化,用酶联免疫吸附试验(ELISA)法检测各组大鼠血清中肾上腺素和去甲肾上腺素的变化。结果电镜观察可见:(1)哮喘组、NGF组和抗NGF抗体干预组大鼠肾上腺髓质细胞线粒体增多,嗜铬颗粒减少;(2)NGF组肾上腺髓质嗜铬细胞膜可见杵状和绒毛状突起。图像分析结果显示NGF组PNMT平均灰度(A)值为218±38,与对照组(182±25)、哮喘组(198±33)和抗NGF组(195±41)比较差异有统计学意义(t值分别为23.42、19.76、17.93,P均<0.05);ELISA结果显示NGF组血清肾上腺素浓度为(2.9±0.5)ng/ml、与对照组[(7.1±0.4)ng/ml]、哮喘组[(5.9±1.7)ng/ml]、抗NGF组[(5.7±0.6)ng/ml]比较差异均有统计学意义(t值分别为7.64、5.41、4.96,P均<0.01),哮喘组与对照组比较差异也有统计学意义(t=5.64,P<0.01),哮喘组和抗NGF组肾上腺素水平比较差异无统计学意义(t=0.87,P>0.05)。结论NGF通过启动肾上腺髓质嗜铬细胞的功能冗余性使其表型和功能发生转化,导致肾上腺素水平下降而参与哮喘的发生与发展。     

神经生长因子、白血病抑制因子调控支气管哮喘大鼠神经源性炎症机制的研究

目的研究神经生长因子(NGF)、白血病抑制因子(LIF)调控支气管哮喘(简称哮喘)大鼠气道神经源性炎症的机制,寻求治疗哮喘的新靶点。方法成年清洁级雄性SD大鼠36只,按随机数字表法分为对照组、哮喘组和抗NGF组,每组12只。采用免疫组织化学和原位杂交技术观察哮喘大鼠肺组织、C7～T5背根神经节内NGF、LIF、P物质(SP)的表达状态及抗NGF干预对其表达的影响。结果(1)哮喘组大鼠肺组织NGF、LIF蛋白及其mRNA的平均灰度值分别为157±7、138±8、156±6、141±10,对照组分别为183±7、190±7、187±7、181±8,抗NGF干预组分别为177±6、169±9、178±7、172±9,三组比较差异有统计学意义(t分别=19.40、15.80、0.38、14.79,P均<0.01);(2)哮喘组大鼠C7～T5背根神经节NGF、LIF、SP蛋白及SPmRNA的灰度值分别为136±8、148±6、140±8、128±8,对照组分别为185±7、187±8、174±7、180±8,抗NGF干预组分别为164±6、170±8、163±9、157±7,三组比较差异有统计学意义(t分别=29.50、22.65、23.12、28.71,P均<0.01)。结论促进背根神经节细胞合成和释放SP可能是NGF、LIF参与哮喘气道神经源性炎症形成的机制之一,抗NGF干预能够有效地将其抑制。     

神经生长因子对哮喘大鼠Th1/Th2类细胞因子表达的调控研究

目的探讨在支气管哮喘中神经生长因子(NGF)对T1亚群辅助淋巴细胞(Th1)与T2亚群辅助淋巴细胞(Th2)类细胞因子表达的调控作用机制。方法于2004年3月至2004年12月对中南大学湘雅二医院应用鸡卵清蛋白(OVA)建立鼠哮喘模型,并将SD大鼠随机分为4组:哮喘组、正常对照组、外源性NGF干预组(NGF组)、抗NGF抗体干预组(抗NGF抗体组),每组8只。模型建立后取肺组织分别作以下研究:通过逆转录-聚合酶链反应(RT-PCR)半定量检测哮喘组和对照组NGFmRNA;同时测定4组Th1类细胞因子干扰素-γ(IFN-γ)、Th2类细胞因子白细胞介素4(IL-4)的mRNA表达改变。结果(1)哮喘组与对照组相比较:肺组织NGFmRNA表达明显增强[(90.4±7.6)%对(51.8±12.3)%,P<0.01];IL-4mRNA表达明显增强[(48.0±8.1)%对(19.4±8.4)%,P<0.05],IFN-γmRNA表达明显减低[(32.8±8.1)%对(43.4±8.9)%,P<0.01];哮喘组中肺组织的NGFmRNA相对表达量与IFN-γ/IL-4mRNA表达比值呈显著负相关(r=-0.963,P<0.01)。(2)NGF组与哮喘组相比较,IL-4mRNA表达显著增高[(62.0±12.2)%对(48.0±8.1)%,P<0.01];IFN-γmRNA表达显著降低[(19.9±8.1)%对(32.8±8.1)%,P<0.01]。(3)抗NGF抗体干预组与哮喘组相比较,肺组织中IL-4mRNA表达显著减低[(20.1±7.1)%对(48.0±8.1)%,P<0.01],IFN-γmRNA表达显著增高[(45.4±9.4)%对(32.8±8.1)%,P<0.05]。结论NGF下调Th1类细胞因子表达,上调Th2类细胞因子表达,由此参与促进放大哮喘Th1/Th2类细胞因子免疫失衡效应。     

神经生长因子在实验性支气管哮喘小鼠发病中上调磷脂酶C-γ表达

目的 研究支气管哮喘(简称哮喘)小鼠下呼吸道及内脏感觉传入部位磷脂酶C-γ(PLC-γ)的表达,及神经生长因子(nerve growth factor,NGF)对PLC-γ在上述部位的调节作用,探讨NGF介导的信号转导通路在哮喘发病机制中的作用.方法 BABL/C 30只,按随机数字表法分为正常对照组、哮喘组及NGF阻断组.利用AniRes2005肺功能仪测BABL/C小鼠气道阻力,应用免疫组织化学方法和免疫印记法(Western blotting),观察PLC-γ在哮喘小鼠下呼吸道及内脏感觉传人部位的表达及NGF被阻断后PLC-γ表达水平的变化,Metamoph图象分析系统对结果进行分析.结果 气道阻力检测结果显示,哮喘组小鼠较正常对照组气道阻力明显增高(P<0.01),NGF阻断组气道阻力均较哮喘组明显降低(P<0.01).免疫组织化学结果显示PLC在NGF阻断组小鼠肺组织(0.273±0.018),C7～T5段脊神经节(0.158±0.012),以及相应节段的脊髓后角内(0.168±0.022)表达明显低于哮喘组(0.423±0.023,0.351±0.018,0.368±0.014)(P<0.01).Western blotting结果显示NGF阻断组肺(0.921±0.014)及C7～T5节段脊髓(0.835±0.023)PLC-γ MOD值与β-actin MOD值的比值明显低于哮喘组(1.476±0.017,1.251±0.019)(P<0.01).结论 PLC-γ在哮喘小鼠肺、C7～T5节段脊神经节及相应的脊髓后角过表达,NGF上调哮喘上述部位PLC-γ的表达,提示NGF可通过调节肺内及内脏传人部位PLC的表达参与哮喘发病过程.     

L-精氨酸对哮喘大鼠气道平滑肌细胞增殖的影响

目的 观察L-精氨酸（L-Arg）对哮喘气道重构大鼠气道平滑肌细胞（ASMC）的细胞周期分布及细胞周期调节蛋白（CCRP）表达水平的影响,探讨L-Arg体内干预哮喘大鼠ASMC增殖的可能作用机制。方法实验分成对照组、哮喘组、L-Arg组,建立大鼠哮喘气道重构模型,检测血清NO2^-／NO3^-含量、肺内支气管内管壁和平滑肌层厚度及ASMC核数、ASMC的细胞周期分布以及ASMC内细胞周期素E（cyclin E）、cyclinA、cyclinB、蛋白27^kip1（P27^kip1）的表达。结果 哮喘组大鼠支气管内管壁、平滑肌层的厚度和ASMC数目显著大于对照组（P〈0．05）;L-Arg组大鼠支气管内管壁的厚度、平滑肌层的厚度和ASMC数目显著小于哮喘组（P〈0．05）。哮喘组血清一氧化氮（nitricoxide,NO）水平显著低于对照组（P〈0．05）;L-Arg组血清NO水平显著高于哮喘组（P〈0．01）。哮喘组G0／G1期ASMC比例及P27^kip1表达水平显著低于对照组（P〈0．01）,G2／M＋S期ASMC比例及cyclinE、cyclinA和cyclinB表达水平显著高于对照组（P〈0．01）;L-Arg组G0／G1期ASMC比例及P27^kip1表达水平显著高于哮喘组（P〈0．05）,G2／M＋S期ASMC比例及cyclinE和cyclinA表达水平显著低于哮喘组（P〈0．05）。结论 L-Arg通过调控CCRP的表达水平阻滞细胞从G1期进入S期而抑制哮喘ASMC的增殖。     

哮喘大鼠肾上腺髓质嗜铬细胞表型转化与神经生长因子表达水平初探

目的观察支气管哮喘状态下大鼠肾上腺髓质嗜铬细胞(AMCC)形态和功能的改变以及神经生长因子(NGF)在肾上腺髓质嗜铬细胞中的表达,探讨肾上腺髓质嗜铬细胞与支气管哮喘的关系。方法2005年10月至2006年3月,在中南大学湘雅医院呼吸内科将雄性SD大鼠16只,随机分为对照组和哮喘组,每组8只。哮喘组以鸡卵清蛋白(OVA)致敏和激发哮喘,对照组以生理盐水代替OVA进行致敏和激发。光镜和电镜下观察2组大鼠肾上腺髓质嗜铬细胞的组织结构和超微结构改变,免疫组织化学结合显微图像分析观察肾上腺髓质嗜铬细胞中NGF的表达变化,酶联免疫吸附法(ELISA)检测血清中肾上腺素和去甲肾上腺素的变化。结果HE染色光镜下可见哮喘组大鼠肾上腺髓质嗜铬细胞不同程度的空泡变性样改变,脂质增多,少数可见纤维样物质伸向皮质。电镜下哮喘组大鼠髓质嗜铬细胞线粒体丰富,脂质增多,嗜铬颗粒浓度降低,并且部分出现核膜皱缩现象。与对照组相比,哮喘大鼠NGF免疫阳性反应在肾上腺髓质嗜铬细胞明显上调(P<0.05),ELISA示哮喘组大鼠肾上腺素水平明显低于对照组(P<0.05),去甲肾上腺素水平没有明显变化(P>0.05)。结论支气管哮喘时肾上腺髓质嗜铬细胞NGF的表达增高,增高的NGF可能使肾上腺髓质嗜铬细胞发生表型的转化导致肾上腺素合成与释放不足而参与哮喘的发生、发展。     

H2松弛素对慢性阻塞性肺疾病大鼠支气管平滑肌增殖的抑制作用

目的探讨H2松弛素对慢性阻塞性肺疾病(COPD)大鼠支气管平滑肌增殖的抑制作用。方法观察正常对照组、COPD模型组及松弛素治疗组大鼠肺组织的病理变化,比较各组大鼠支气管壁及平滑肌厚度,检测基质金属蛋白酶(MMP)-1、MMP-9、基质金属蛋白酶组织抑制剂(TIMP)-1表达水平及MMP-1/TIMP-1、MMP-9/TIMP-1比值。结果与正常对照组大鼠相比,COPD模型组大鼠肺支气管壁及平滑肌厚度显著增厚,且松弛素治疗组大鼠肺支气管壁厚度及平滑肌厚度与COPD模型组大鼠相比显著降低(P0.05)。COPD模型组大鼠组织中MMP-1、MMP-9、TIMP-1的表达水平均高于正常对照组(P0.05),且MMP-1/TIMP-1、MMP-9/TIMP-1比值与正常对照组相比,呈现明显升高趋势(P0.05);而对比COPD模型组大鼠,松弛素治疗组大鼠组织中MMP-1、MMP-9、TIMP-1的表达有所降低(P0.05),且MMP-1/TIMP-1、MMP-9/TIMP-1比值与COPD模型组相比均降低(P0.05)。结论松弛素能抑制大鼠肺组织结构病理变化,抑制COPD气道平滑肌的增殖。     

Platelet-derived growth factor

Platelet-derived growth factor (PDGF) is a basic (pI congruent to 10) 30 000 molecular weight protein circulating in normal blood sequestered within the platelet alpha-granules. It binds with high affinity (Kd = 10(-11) M) to a specific cell-surface receptor found on many connective tissue cell types in culture. It is active in stimulating the metabolism and multiplication of connective tissue cells at very low concentrations (ED50 = 10(-11) M). It is likely that PDGF is released from platelets at sites of vascular damage and that it contributes toward the cell proliferation and connective tissue formation seen in healing wounds and in arteriosclerotic lesions. PDGF which does not bind to responsive cells at the wound site is largely inactivated by a plasma binding protein and is rapidly cleared from the circulation.     

Nerve growth factor binding domain of the nerve growth factor receptor.

A structural analysis of the rat low-affinity nerve growth factor (NGF) receptor was undertaken to define the NGF binding domain. Mutant NGF receptor DNA constructs were expressed in mouse fibroblasts or COS cells, and the ability of the mutant receptor to bind NGF was assayed. In the first mutant, all but 16 amino acid residues of the intracellular domain of the receptor were removed. This receptor bound NGF with a Kd comparable to that of the wild-type receptor. A second mutant contained only the four cysteine-rich sequences from the extracellular portion of the protein. This mutant was expressed in COS cells and the resultant protein was a secreted soluble form of the receptor that was able to bind NGF. Two N-terminal deletions, in which either the first cysteine-rich sequence of the first and part of the second cysteine-rich sequences were removed, bound NGF. However, a mutant lacking all four cysteine-rich sequences was unable to bind NGF. These results show that the four cysteine-rich sequences of the NGF receptor contain the NGF binding domain.     

B-cell growth factor: distinction from T-cell growth factor and B-cell maturation factor.

A T-cell hybridoma was derived by somatic cell hybridization between concanavalin A-activated BALB/c spleen cells and the AKR thymoma BW 5147. Media conditioned by hybridoma cells, even at high dilutions (1:1,000) support the growth of lipopolysaccharide-stimulated B-cell blasts but not that of T-cell growth factor (TCGF)-reactive T-cells. This activity, herein designated B-cell growth factor (BCGF), has a Mr of approximately equal to 20,000 and it can readily be separated from TCGF (Mr approximately equal to 30,000) by gel filtration. BCGF is constitutively produced by the hybridoma cells, it is removed from conditioned media by incubation with target cells at +4 degrees C, and it is equally effective on B-cell blasts carrying different major histocompatibility complex and Ig haplotypes. BCGF shows no T-cell replacing factor (TRF) activity, and it is poor in supporting the development of Ig-secreting plaque-forming cells in B-cell blast cultures. Terminal maturation, however, can be induced in BCGF-dependent blasts by addition of conditioned media from normal helper T cell cultures, suggesting that two distinct factors are involved in the helper cell-dependent growth and maturation of B lymphocytes.     

Epidermal growth factor and insulin-like growth factor I upregulate the expression of the epidermal growth factor system in rat liver

BACKGROUND/AIM: Both epidermal growth factor and insulin-like growth factor I play a role in connection with the liver. In the present study, the possible interaction of these two growth factor systems was studied by investigating the effect of epidermal growth factor or insulin-like growth factor I treatment on the expression of the epidermal growth factor receptor, and its activating ligands, transforming growth factor-alpha and epidermal growth factor. METHODS: Fifty-five male rats received no treatment, human recombinant epidermal growth factor or human recombinant insulin-like growth factor I for either 3 or 7 days. The amount of epidermal growth factor receptor, transforming growth factor-alpha, and epidermal growth factor mRNA was quantitated by a calibrated user-friendly RT-PCR assay (CURT-PCR), and the expression of transforming growth factor-alpha and epidermal growth factor peptides was quantitated by ELISA. RESULTS: Control liver (n=16) contained a mean (+/-SD) value of 12.7+/-7.4x10(-18) mol epidermal growth factor receptor mRNA, 3.8+/-2.0x10(-18) mol transforming growth factor-alpha mRNA and 0.8+/-0.4x10(-18) mol epidermal growth factor mRNA per microg total RNA and 9.8+/-1.6 fmol/mg protein epidermal growth factor and 144+/-22 fmol/mg protein transforming growth factor-alpha. Both epidermal growth factor and insulin-like growth factor I treatment increased the expression of mRNA for transforming growth factor-alpha and epidermal growth factor receptor, as well as the expression of transforming growth factor-alpha peptide. The level of epidermal growth factor receptor and transforming growth factor-alpha mRNA expression was found to correlate both in control and growth factor-treated animals, whereas the expression of epidermal growth factor receptor and epidermal growth factor showed no correlation. Marked differences were seen upon activation of the two growth factor systems, as epidermal growth factor, but not insulin-like growth factor I treatment, increased the plasma concentration of urea and decreased the concentration of insulin-like growth factor I and the liver enzymes, alanine aminotransferase and alkaline phosphatase. CONCLUSION: Our results show that epidermal growth factor and insulin-like growth factor I, which belong to two different growth factor systems, both induce a correlated upregulation of transforming growth factor-alpha and epidermal growth factor receptor mRNA in rat liver. Although marked differences were observed after treatment with either epidermal growth factor or insulin-like growth factor I on the liver as reflected in the plasma concentrations of e.g. liver enzymes, a common motif in their action involves an upregulation of the expression of the epidermal growth factor system.     

Concentrations of hepatocyte growth factor, basic fibroblast growth factor, and vascular endothelial growth factor in pericardial fluid and plasma

Some angiogenic factors, including hepatocyte growth factor (HGF), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF), have been reported to promote angiogenesis and improve myocardial perfusion in experimental models of ischemic heart disease. These factors are produced in various tissues, including myocardium. We measured the concentrations of HGF, bFGF, and VEGF by enzyme-linked immunosorbent assay in plasma and in pericardial fluid sampled during open heart surgery (12 patients with ischemic heart disease and 17 with nonischemic heart disease). HGF levels were significantly higher in plasma than in pericardial fluid (12.0 +/- 1.8 versus 0.26 +/- 0.04 ng/mL, P < 0.0001). On the other hand, bFGF levels were significantly higher in pericardial fluid than in plasma (243.5 +/- 50.9 versus 49.6 +/- 7.8 pg/mL, P = 0.009). VEGF levels were not significantly different between pericardial fluid and plasma (47.2 +/- 17.6 versus 24.5 +/- 3.6 pg/mL, P = 0.23). Concentrations of angiogenic factors in pericardial fluid and in plasma were not significantly different between patients with ischemic and nonischemic heart disease. These results suggest that the production, secretion, and kinetics of HGF, bFGF, and VEGF are different. These angiogenic factors may have different pathophysiologic roles.     

Interaction of receptors for insulin-like growth factor I, platelet-derived growth factor, and fibroblast growth factor in rat aortic cells

Serum contains various growth factors which regulate the proliferation of cells. We investigated the growth of cultured arterial smooth muscle cells under the influence of insulin-like growth factor I (IGF I), fibroblast growth factor (FGF), and platelet-derived growth factor (PDGF), and examined the effect of these growth factors on the binding of [125I] IGF I and on the binding of [125I]PDGF to these cells. IGF I, FGF, and PDGF stimulated [6-3H]thymidine incorporation into DNA of confluent cultures of cells which were incubated in modified Dulbecco's modified Eagle medium. However, the effect of these growth factors on DNA synthesis was much more potent in Dulbecco's modified Eagle medium with 1% fetal calf serum. FGF and PDGF potentiated the growth-promoting effect of IGF I. The binding of [125I]IGF I to the cells was increased after a preincubation with FGF and PDGF. The binding was potently increased by FGF (100 ng/ml) after a preincubation time of 30 min. There was an increase in binding during the first 3 h of preincubation followed by a decrease after 4-5 h. PDGF (10-1000 ng/ml) stimulated [125I]IGF I binding only after 2 h of preincubation. The stimulation was dose dependent. Maximal stimulation of the binding was observed after 3 h of preincubation followed by a decrease after 4-5 h of preincubation. Specific binding sites for PDGF on smooth muscle cells could be demonstrated too. A preincubation of confluent cells with IGF I caused a dose-dependent increase in [125I]PDGF binding. These results support the hypothesis that the regulation of the binding of a specific growth factor by a second growth factor is important for the control of cell growth.     

Nerve growth factor as an angiogenic factor

Nerve growth factor (NGF), a neurotrophin that plays a crucial role in promoting neurotrophic and neurotropic effects in sympathetic neurons, has recently been identified as a novel angiogenic molecule, which exerts a variety of effects in the cardiovascular system and on endothelial cells. In fact, NGF may contribute to maintenance, survival, and function of endothelial cells by autocrine and/or paracrine mechanisms. This review summarizes the involvement of NGF in the regulation of angiogenesis in both normal and pathological conditions.