IGF-1联合BMP-2对糖尿病合并骨质疏松股骨骨折大鼠中的骨折愈合影响分析

摘要 目的：探讨胰岛素生长因子-1（insulin-like growth factor, IGF-1）联合骨形态发生蛋白（bone morphogenetic protein,BMP）-2对糖尿病合并骨质疏松股骨骨折大鼠中的骨折愈合影响。方法：8周龄雌性SD大鼠60只,饲养一周后根据随机数字表法进行分组,每组12只,之后进行造模,造模成功50只,成功率为83.33 %。将其分为5组,包括正常组（n=10）,糖尿病+卵巢切除+骨折组（n=9）,糖尿病+卵巢切除+骨折+ IGF-1组（骨折处注射IGF 30 μg/kg,n=11）,糖尿病+卵巢切除+骨折+BMP-2组（骨折处注射100 μL BMP-2基因慢病毒1×10⁸,n=10）、糖尿病+卵巢切除+骨折+IGF-1+BMP-2组（参照上述,n=10）,其余进行等剂量溶剂注射,均连续注射两天。分组处理6周后,观察5组大鼠的一般情况。对比5组大鼠的血清钙、骨钙素、碱性磷酸酶水平,对比5组的最大应力、最大载荷及刚度,检测5组大鼠组织中的IGF-1、BMP-2及TGF-β1 mRNA表达水平。结果：A组大鼠无明显异常反应,大鼠体重逐渐增加,大小便、饮食均正常,毛色光亮;B、C、D、E组大鼠精神萎靡、反应迟缓、毛色光亮性较差、体重无明显减轻或增加、大鼠的饮水量、饮食增加,多尿症状较为明显。5组大鼠的血清钙、骨钙素、碱性磷酸酶水平：B组结论：IGF-1联合BMP-2可促进糖尿病合并骨质疏松股骨骨折大鼠中的骨折愈合。     

HGF调控β-catenin信号通路对家兔股骨颈骨折修复的影响

摘要 目的：探究HGF调控β-catenin信号通路对家兔股骨颈骨折修复的作用和影响机制。方法：15只股骨颈骨折家兔动物模型随机分为半合成细胞外基质样水凝胶组（sECM组）、sECmM+HGF组和脱钙骨基质组（DBM组）,自体右侧作为实验侧,左侧作为对照侧,对比各组家兔一般情况、骨折愈合质量评分骨痂最大载荷、挠度和刚度、BMSC细胞中BMP-2、TGF-β1、PDGF、bFGF mRNA表达水平和COL-I、Wnt5a、β-catenin和Lef-1蛋白表达水平。结果：术后各周sECM+HGF组和DBM组实验侧骨折愈合质量评分高于对照侧（P<0.05）,且高于同期sECM组实验侧（P<0.05）。术后8周,sECM+HGF组和DBM组实验侧骨痂最大荷载、挠度和刚度均优于对照侧（P<0.05）,且优于sECM组实验侧（P<0.05）。术后2周及4周,sECM+HGF组和DBM组实验侧BMP-2、TGF-β1、PDGF和bFGF表达显著高于对照侧（P<0.05）。且高于同期sECM组实验侧（P<0.05）,术后8周sECM+HGF组和DBM组实验侧BMP-2表达高于sECM组实验侧（P<0.05）。术后2周,sECM+HGF组和DBM组实验侧COL-I表达高于对照侧（P<0.05）。术后2周、4周sECM+HGF组和DBM组实验侧COL-I表达均显著高于同期sECM组实验侧（P<0.05）。术后8周,sECM+HGF组和DBM组实验侧wnt5a表达低于对照侧（P<0.05）且低于sECM组实验侧,β-catenin、Left-1表达显著高于对照侧（P<0.05）,且高于sECM组实验侧（P<0.05）。结论：HGF通过激活Wnt/β-catenin信号通路,上调BMP-2、TGF-β1、PDGF、bFGF和COL-1的表达,显著促进股骨颈骨折家兔的骨折修复过程。     

人脐带间充质干细胞对脊柱骨折大鼠愈合及神经功能的影响

摘要 目的：探讨人脐带间充质干细胞(Human umbilical cord mesenchymal stem cells,hUC-MSCs)对脊柱骨折大鼠愈合及神经功能的影响。方法：脊柱骨折Sprague-Dawley雄性大鼠模型30只随机分为hUC-MSCs组与对照组,各15只。hUC-MSCs组大鼠在骨折部位移植0.5 mL的hUC-MSCs(细胞浓度为2×10⁶/mL),对照组大鼠移植同体积的生理盐水,记录大鼠愈合及神经功能变化情况。结果：两组造模后15 min、30 min、90 min的平均动脉压都波动明显,不过组间对比差异无统计学意义(P>0.05)。与造模后2 w对比,两组造模后4 w的神经功能BBB评分均升高,且hUC-MSCs组造模后2 w、4 w的神经功能BBB评分都高于对照组(P<0.05)。hUC-MSCs组造模后8 w的骨体积分数高于对照组(P<0.05)。hUC-MSCs组骨折部位附近有少量骨痂生长,骨折线逐渐消失;骨痂已明显包裹骨折部位。hUC-MSCs组造模后8 w的脊髓细胞凋亡指数低于对照组(P<0.05)。结论：hUC-MSCs在脊柱骨折大鼠的应用能促进骨折愈合与改善神经功能,也可以抑制脊髓细胞凋亡,从而发挥很好的治疗作用。     

姜黄素通过激活Wnt/β-catenin信号通路促进骨折愈合

摘要 目的：探讨姜黄素治疗骨折的潜在应用价值及其对Wnt/β-catenin信号通路的可能影响。方法：本研究建立了胫骨骨折SD大鼠模型（模型组）,然后应用不同剂量的姜黄素（50、100和200 mg/kg/d）治疗胫骨骨折大鼠4周。治疗4周后,通过苏木精和伊红（HE）染色评价骨折区域的形态,通过ELISA法测定大鼠血清中TGF-β、BMP-2、OC和CTX-I水平。应用不同浓度的姜黄素（0、5、10、20、和50 μM）或Wnt/β-catenin信号通路抑制剂ICG-001（10 μM）处理成骨细胞3 d,然后检测细胞的ALP活性、PCNA和COL-1的含量及Wnt /β-catenin信号通路相关分子的表达水平。结果：不同剂量的姜黄素处理组大鼠的小梁状骨和胶原明显增多。与模型组相比,不同剂量的姜黄素处理组大鼠血清中的TGF-β、BMP-2和OC水平均升高,而CTX-I水平降低（P<0.05）;与模型组相比,不同剂量的姜黄素处理组大鼠骨折区域中的COL-1阳性率升高（P<0.05）,而COL-2水平未发生显著变化（P>0.05）。在药物干预3 d后,10和20 μM的姜黄素促进了细胞增殖,而100和200 μM的姜黄素抑制了细胞增殖（P<0.05）。与0 μM组比较,10 μM和20 μM的姜黄素组成骨细胞上清液中PCNA和COL-1水平及ALP活性水平均显著升高（P<0.05）。与模型组相比,不同剂量的姜黄素处理组大鼠骨折区域中的Wnt-3a和β-catenin mRNA和蛋白表达水平升高,而GSK-3β降低（P<0.05）。与姜黄素组相比,ICG-001处理后成骨细胞活力、ALP活性和β-catenin的表达水平均显著下降（P<0.05）。结论：姜黄素通过激活Wnt/β-catenin信号通路促进骨折愈合并刺激成骨细胞的增殖和分化。     

糖尿病对大鼠骨折愈合影响的实验研究

目的:观察糖尿病大鼠的骨折愈合过程,探讨糖尿病影响大鼠骨折愈合的可能的机制,为临床实践提供理论依据。方法:雄性Wister大鼠140只,随机分成二组,每组70只,A组为糖尿病骨折组;B组为非糖尿病骨折组。建立糖尿病动物模型后,无菌条件下在各组大鼠胫骨中点用手术方法制成骨折模型。术后1周、2周、4周、6周、8周各时间点进行X线检查,观察骨折愈合情况。术后1周、2周、3周、4周、6周、8周分别用ELISA法检测血清中IGF-1含量。分别在1、2、4、6、8周各时间点观察5只大鼠骨痂生长情况并取骨折断端组织行HE染色光镜观察。术后4周、6周、8周每组处死10只大鼠留取双侧胫骨标本,冷冻保存后集中进行生物力学检测。结果:1、大体标本观察结果:各时间点A组骨痂生长减缓延迟。2、X线结果:A组骨折愈合质量在各时间点均明显低于B组。3、生物力学测定结果:4周、6周、8周个时间点A组骨折处骨痂的机械强度均明显低于B组。4、组织学染色显示:术后各时间点1、2、4、6、8周A组与B组相比骨折处局部骨痂成熟延迟并且软骨细胞肥大。5、血清IGF-1含量测定:A组大鼠血清中IGF-1含量低于B组,且高峰延迟1周。结论:1.患有糖尿病后大鼠骨折愈合质量差,比较容易出现愈合延迟甚至不愈合;2.患有糖尿病的大鼠骨折后血清中的IGF-1表达明显低于对照组,且高峰推迟1周。     

丹参酮结合有氧运动对高血压大鼠血管功能的影响及作用机制分析

摘要 目的：分析丹参酮ⅡA（TIIA）结合有氧运动（AE）对高血压大鼠血管功能的影响及作用机制。方法：选择30只自发性高血压大鼠（SHR）,随机分为模型组、TⅡA组、TⅡA+AE组,每组10只,另选取10只健康大鼠作为对照组。TⅡA组大鼠给予20 mg/kg的TⅡA,TⅡA+AE组在此基础上进行中等强度的有氧运动,模型组和健康对照组大鼠均灌胃给予等体积的生理盐水溶液。观察各组大鼠收缩压（SBP）和舒张压（DBP）的变化,HE染色观察胸主动脉组织形态学变化,测定血管舒缩功能,检测血清血管紧张素Ⅱ（AngⅡ）、内皮素-1（ET-1）和一氧化氮（NO）的表达水平,测定胸主动脉中腺苷酸活化蛋白激酶（AMPK）、核因子E2相关因子（Nrf2）、血红素加氧酶1（HO-1）、醌氧化还原酶1（NQO-1）蛋白的相对表达。结果：TⅡA组和TⅡA+AE组大鼠的SBP和DBP均低于同期的模型组大鼠;TⅡA+AE组大鼠的SBP和DBP在第8周时均低于同期TⅡA组大鼠（P<0.05）;与模型组相比,在1×10^-7、1×10^-6和1×10^-5mol/L的PE浓度下TⅡA组和TⅡA+AE组大鼠胸主动脉血管环的收缩率均降低,且TⅡA+AE组大鼠低于同浓度下的TⅡA组（P<0.05）;在1×10^-8、1×10^-7和1×10^-6的Ach浓度下TⅡA组和TⅡA+AE组大鼠胸主动脉血管环的舒张率高于模型组,且ⅡA+AE组大鼠高于同浓度下的TⅡA组（P<0.05）;TⅡA组和TⅡA+AE组大鼠血清AngⅡ和ET-1的表达水平低于模型组、NO的表达水平高于模型组（P<0.05）;与TⅡA组相比,TⅡA+AE组大鼠血清AngⅡ和ET-1的表达水平较低、NO的表达水平较高（P<0.05）;TⅡA组和TⅡA+AE组大鼠胸主动脉中AMPK、Nrf2、HO-1、和NQO-1蛋白的相对表达显于模型组,且TⅡA+AE组高于TⅡA组（P<0.05）。结论：TⅡA联合有氧运动可降低SHR的血压,改善血管舒缩功能和内皮功能,其机制可能与AMPK/Nrf2信号通路有关。     

胫骨横向骨搬移术联合封闭引流技术治疗糖尿病足溃疡的临床比较研究

摘要 目的：观察胫骨横向骨搬移术联合封闭引流技术（VSD）治疗糖尿病足溃疡（DFU）的治疗效果。方法：选取2018年4月~2020年7月我院收治的65例DFU患者。根据治疗方式的不同将患者分为A组（32例,VSD治疗）和B组（33例,胫骨横向骨搬移术联合VSD治疗）。对比两组围术期指标、患足皮温、视觉模拟评分法（VAS）评分、踝肱指数（ABI）和血清相关指标变化,记录两组并发症发生率。结果：两组术后1个月,患足皮温、ABI升高,VAS评分下降,且B组的变化幅度明显大于A组（P<0.05）。两组完全负重时间、下地行走时间组间对比无差异（P>0.05）。B组的溃疡愈合时间、去除外固定架时间明显短于A组（P<0.05）。两组术后1个月血管内皮生长因子（VEGF）水平升高,白细胞计数（WBC）、C反应蛋白（CRP）水平下降,且B组的变化幅度明显大于A组（P<0.05）。两组并发症发生率组间对比无统计学差异（P>0.05）。结论：胫骨横向骨搬移术联合VSD治疗DFU,可促进创面愈合,效果显著。     

注射用七叶皂苷钠在胫腓骨骨折术后患者中的应用效果及对患者血清BMP、IGF、VEGF水平的影响

目的:观察注射用七叶皂苷钠在胫腓骨骨折术后患者中的应用效果及对患者血清骨形态发生蛋白(BMP)、胰岛素样生长因子(IGF)、血管内皮生长因子(VEGF)水平的影响。方法:选择2014年7月~2016年7月我院收治的108例胫腓骨骨折患者,按不同治疗方式分作对照组与研究组,每组54例,两组患者均采用切开复位内固定治疗,对照组术后进行常规处理,研究组在对照组基础上联合注射用七叶皂苷钠治疗。观察并比较两组肿胀、疼痛、瘀斑消失时间,治疗前后血清BMP、IGF、VEGF水平、骨痂生长评分的变化,功能恢复情况及并发症的发生情况。结果:治疗后,研究组肿胀、疼痛、瘀斑消失时间均显著短于对照组(P0.05)。两组治疗后血清BMP、IGF、VEGF水平、骨痂生长评分均较治疗前显著上升,研究组治疗后以上指标均显著高于对照组(P0.05)。研究组功能恢复优良率显著高于对照组,且并发症发生率明显低于对照组(P0.05)。结论:注射用七叶皂苷钠可有效提高胫腓骨骨折术后患者的临床疗效,有利于骨折的愈合,可能与其增加患者血清BMP、IGF、VEGF水平有关。     

创伤性骨折血清ALP、OPG表达与Th1/Th2平衡的相关性分析

摘要 目的：探讨创伤性骨折血清碱性磷酸酶（ALP）、骨保护素（OPG）表达与辅助性T细胞1（Th1）/辅助性T细胞2（Th2）平衡的相关性。方法：选取我院2019年2月到2022年12月收治的80例创伤性骨折患者作为研究对象,将其分为观察组,另选取同期来我院体检的80名健康志愿者作为对照组。抽取观察组患者入院后第二天清晨空腹静脉血和对照组清晨空腹静脉血,检测ALP、OPG、Th1、Th2表达水平,并分析血清ALP、OPG表达与Th1/Th2平衡的相关性。术后12个月后对观察组80例患者进行随访,依照患者骨折愈合程度将其分为骨折愈合组（n=54）和延迟愈合组（n=26）,对比两组患者临床一般情况与ALP、OPG、Th1/Th2表达水平,并分析创伤性骨折患者骨折愈合情况影响的多因素。结果：观察组与对照组ALP、OPG表达与辅助性T细胞水平对比差异显著,观察组ALP、OPG、Th2水平明显高于对照组,Th1、Th1/Th2水平明显低于对照组（P＜0.05）;Spearman相关分析结果表明：血清ALP、OPG与Th1/Th2平衡呈负相关（P<0.05）;骨折愈合组和延迟愈合组患者性别、年龄、致伤原因、Th2对比无明显差异（P＞0.05）,两组患者BMI、合并感染ALP、OPG、Th1、Th1/Th2水平对比差异显著（P＜0.05）;对上述单因素分析具有统计学差异指标进行赋值,多因素分析结果表明：ALP、OPG、Th2、Th1/Th2为影响创伤性骨折患者骨折愈合情况的独立影响因素（P＜0.05）。结论：创伤性骨折的发生会导致ALP、OPG水平升高,Th1/Th2平衡改变,患者血清ALP、OPG水平与Th1/Th2平衡关系具有明显相关性。另外,ALP、OPG、Th1、Th1/Th2水平变化可影响创伤性骨折患者术后骨折愈合水平。因此,临床上对于ALP、OPG水平升高,且Th1/Th2失衡患者需警惕骨折愈合不良的发生。     

间充质干细胞联合铂类对肝癌大鼠抗癌效果及对免疫功能、细胞凋亡的影响

摘要 目的：探讨骨髓间充质干细胞（bone marrow mesenchymal stem cells,BMSCs）联合顺铂（cis-diamminodichloroplatinum Ⅱ dichloride,DDP）对肝癌大鼠抗癌效果及其免疫功能和细胞凋亡水平的影响。方法：将40只雄性Wistar大鼠随机分为空白对照组、模型组、DDP组和联合组,各10只。除空白对照组外,其余均采用二乙基亚硝胺饲喂法建立肝癌模型。造模成功后,空白对照组和模型组大鼠静腹腔注射生理盐水并经尾静脉注射DMEM培养液,DDP组大鼠经腹腔注射DDP溶液并经尾静脉注射DMEM培养液,联合组大鼠经腹腔注射DDP溶液并经尾静脉注射BMSCs悬液。移植BMSCs两周后处死大鼠,称量肝脏质量和体质量,采用酶联免疫吸附法检测各组大鼠外周血中白细胞介素-2（interleukin-2,IL-2）、IL-8、肿瘤坏死因子α（tumor necrosis factor α,TNF-α）、血管内皮生长因子（vascular endothelial growth factor,VEGF）和低氧诱导因子-1α（hypoxia-inducible factor-1α,HIF-1α）水平,采用TUNEL技术检测肝细胞凋亡指数。结果：（1）模型组肝脏质量、肝脏质量/体质量均显著大于其他各组,体质量显著小于其他各组（P<0.05）。联合组肝脏质量、肝脏质量/体质量均显著显著小于模型组和DDP组,体质量显著大于模型组和DDP组（P<0.05）。（2）DDP组和联合组大鼠治疗后血清IL-2水平显著升高,IL-8和TNF-α水平显著降低（P<0.05）。联合组大鼠治疗后血清IL-2水平显著高于DDP组,IL-8和TNF-α水平显著低于DDP组（P<0.05）。（3）DDP组和联合组大鼠治疗后血清VEGF和HIF-1α水平显著降低,且显著低于模型组（P<0.05）。联合组大鼠治疗后血清VEGF和HIF-1α水平显著低于DDP组（P<0.05）。（4）联合组和DDP组肝癌细胞凋亡指数显著高于模型组,且联合组也显著高于DDP组（P<0.05）。结论：BMSCs联合DDP能够显著改善肝癌大鼠免疫功能,抑制肿瘤血管生成,促进肝癌细胞凋亡,效果优于DDP单药。     

Acute Regulation of the Epidermal Growth Factor Receptor in Response to Nerve Growth Factor

PC12 cells possess specific receptors for both nerve growth factor and epidermal growth factor, and by an unknown mechanism, nerve growth factor is able to attenuate the propagation of a mitogenic response to epidermal growth factor. The differentiation response of PC12 cells to nerve growth factor, therefore, predominates over the proliferative response to epidermal growth factor. We have observed that the addition of nerve growth factor to PC12 cells rapidly produces a decrease in surface 125I-epidermal growth factor binding capacity. Unlike previously described nerve growth factor effects on 125I-epidermal growth factor binding capacity, which required several days of nerve growth factor exposure, the decreases we report occur within minutes of nerve growth factor addition: A 50% decrease in 125I-epidermal growth factor binding capacity is evident at 10 min. This rapid nerve growth factor response is concentration dependent; inhibition of 125I-epidermal growth factor binding is detectable at nerve growth factor levels as low as 0.2 ng/ml and is maximal at approximately 50 ng/ml, consistent with known ranges of biological activity. No demonstrable differences in the rate of epidermal growth factor receptor synthesis or degradation were observed in cells acutely exposed to nerve growth factor. Scatchard analysis revealed that acute nerve growth factor treatment decreased the number of both high- and low-affinity 125I-epidermal growth factor binding sites, while the receptor affinity remained unchanged. We have also investigated the involvement of various potential intracellular mediators of nerve growth factor action and of known intracellular modulatory systems of the epidermal growth factor receptor for their capacity to participate in this nerve growth factor activity.     

Schwannoma-Derived Growth Factor Interacts with the Epidermal Growth Factor Receptor

Abstract: Schwannoma-derived growth factor (SDGF) is a potent mitogen and neuronal differentiation factor. Because of its relationship to epidermal growth factor (EGF) and the heregulins, it was asked if SDGF interacts with the EGF receptor or HER2/neu. SDGF binds to and causes the phosphorylation on tyrosine of the EGF receptor but not HER2/neu.     

Tyrosine Phosphorylation of β-Catenin and Plakoglobin Enhanced by Hepatocyte Growth Factor and Epidermal Growth Factor in Human Carcinoma Cells

The effect of hepatocyte growth factor /scatter factor (HGF/SF) and epidermal growth factor (EGF) on cadherin-mediated adhesion of human carcinoma cells was studied. HGF/SF induced scattering of colonic adenocarcinoma HT29 and gastric adenocarcinomas MKN7 and MKN74 cells. Likewise, EGF induced scattering of HT29 and MKN7 cells. These cells expressed E-cadherin, which was concentrated at cell-cell contact sites. When the scattering of these cells was induced by HGF/SF or EGF, the E-cadherin concentration at cell-cell boundaries tended to decrease. Irnmunoblotting analyses, however, demonstrated that these growth factor treatments did not alter the expression of E-cadherin and E-cadherin-associated proteins, α- and β-catenin and plakoglobin. β-Catenin, plakoglobin and an unidentified 115-kDa molecule associated with E-cadherin were found to be phosphorylated at tyrosine residues, and these phosphorylations were enhanced by the growth factor treatments. These results suggest that HGF/SF and EGF may modulate the function of the cadherin-catenin system via tyrosine phosphorylation of cadherin-associated proteins.     

成纤维细胞生长因子与其受体相互作用及其抑制剂的研究进展

成纤维细胞生长因子（FGF）有许多重要的生理功能，并与肿瘤的形成有关.为了弄清FGF与成纤维细胞生长因子受体(FGFR)相互作用的机制，人们对FGF和FGFR的各个结合结构域进行了深入、细致的研究，定位了aFGF、bFGF的肝素结合区、bFGF的受体结合区、FGF受体的肝素结合区、配体结合区和FGF受体相互结合区，提出了两个FGF与FGFR相互作用的模型，在此基础上设计了FGF的核酸类、糖类和多肽类抑制剂，为寻找新一代抗癌药物打下了理论基础.     

缺氧诱导因子1α、血管内皮生长因子和成纤维细胞生长因子在胰腺癌中的表达及意义

目的：研究胰腺癌组织中缺氧诱导因子1alpha（Hypoxia-inducible factor-1alpha,HIF-1α）、血管内皮生长因子（vascular endothelial growth factor,VEGF）和成纤维细胞生长因子（fibroblast growth factor,FGF）的表达并探讨其意义。方法：Western blot法检测22例胰腺癌及癌旁组织中HIF-1α、VEGF和FGF蛋白的表达,分析HIF-1α与VEGF、FGF之间的相关性以及与性别、年龄、肿瘤大小、淋巴结转移和TNM分期之间的关系。结果：HIF-1α、VEGF和FGF在胰腺癌组织中的蛋白表达水平明显高于胰腺癌周组织（P〈0.01）,HIF-1α与VEGF、FGF之间的表达具有显著相关性（P〈0.01）。HIF-1α的表达与胰腺癌的TNM分期、肿瘤大小和淋巴结转移有关（P〈0.01）,VEGF和FGF的表达与胰腺癌的肿瘤大小和淋巴结转移有关（P〈0.05）。结论：HIF-1α可以上调VEGF和FGF的表达,在胰腺癌的发生、发展中起着重要作用。     

Epidermal Growth Factor and Basic Fibroblast Growth Factor Have Independent Actions on Mesencephalic Dopamine Neurons in Culture

Abstract: Epidermal growth factor (EGF) and basic fibro-blast growth factor (bFGF) are both trophic for dopamine neurons s in cultures of dissociated embryonic rat mesen-cephaion, but the significance of this apparent overlap in neurotrophic activity is not yet known. In this study, we investigated the mechanisms of action of these two growth factors and the potential relationship between them, Using a nuclease protection assay, we determined that bFGF mRNA was expressed in the cultures. Double-label immunocytochemistry revealed that bFGF immunore-active material could be detected in tyrosine hydroxylase immunoreactive neurons and glial fibrillary acidic protein immunoreactive astrocytes. EGF treatment increased bFGF mRNA content per culture dish. As we have previously demonstrated that EGF exerts its dopaminergic neurotrophic activity via an intermediate cell type, studies were designed to address whether the pathway by which EGF acts on dopaminergic neurons is mediated by the release of bFGF. However, the trophic action of EGF on dopamine neurons, represented by high-affinity neuronal dopamine uptake, could not be blocked by immunoneutralization of bFGF, suggesting that the actions of EGF were not mediated by bFGF release. The time course of the effects of EGF and bFGF on dopamine uptake were similar, with significant increases detectable only after 5 days in culture. Both growth factors were active in the picomolar-to-nannomolar range with maximal trophic activity between 0.4 and 2.5 n M. EGF, however, was the more potent mitogen under these conditions. When cultures were simultaneously incubated with maximal concentrations of EGF and bFGF, the effect on dopamine uptake was significantly greater than with either growth factor alone and, in fact, approximated the sum of the individual effects. On the basis of these results we conclude that these growth factors have independent effects on dopamine neurons of the mesencephalon.     

Insulin-Like Growth Factor I Receptor Expression and Function in Nerve Growth Factor-Differentiated PC12 Cells

Abstract: Receptors for insulin-like growth factor I (IGF-I) were studied on PC12EY cells, a subclone of PC12. Differentiation of PC12EY cells with nerve growth factor (NGF) did not alter either the number of IGF-I receptors nor their affinity for IGF-I. IGF-I receptors remained fully functional during differentiation, promoting increases in thymidine incorporation, glucose uptake, amino acid uptake, and the phosphorylation of the S6 protein of the ribosomes. IGF-I also increased the proportion of differentiated cells found in S-phase. But although the addition of IGF-I to naive cells caused an increase in cell number, there was no comparable increase when IGF-I was added to differentiated cells. Thus, although the receptor for IGF-I continues to be present and functional, IGF-I fails to induce cell proliferation in differentiated PC12 cells.     

Epidermal Growth Factor and Basic Fibroblast Growth Factor Protect Dopaminergic Neurons from Glutamate Toxicity in Culture

Abstract: In this report we characterize the toxicity of the excitatory amino acid l -glutamate with respect to dopaminergic neurons cultured from embryonic rat mesencephalon. We also demonstrate that two growth factors, epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF), can protect these neurons from damage. Micromolar concentrations of l -glutamate, as well as agonists that specifically activate N -methyl- d -aspartate (NMDA) and non-NMDA receptors, are all toxic to dopamine neurons in a concentration-dependent manner, as reflected by decreases in high-affinity dopamine uptake and confirmed by decreases in numbers of tyrosine hydroxylase-immunoreactive neurons. Although the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione could attenuate the effects of quisqualate, treatment with this antagonist could not eliminate the effects of glutamate itself. Similarly, (±)-2-amino-5-phosphonopentanoic acid was effective against NMDA toxicity but could not protect cells from quisqualate toxicity. Thus, each type of receptor could mediate neurotoxicity independently of the other. The presence of EGF or bFGF in the culture medium conferred a relative resistance of dopaminergic neurons to glutamate and quisqualate neurotoxicity by increased glutamate transport. However, treatment of the cultures with l - trans -pyrrolidine-2,4-dicarboxylic acid, an inhibitor of glutamate transport, attenuated but did not eliminate the protective effects of both growth factors against glutamate toxicity. When cultures were incubated with conditioned medium from growth factor-treated cultures, neuroprotection was also achieved. These results suggest that both EGF and bFGF can protect neurons from neurotoxicity in culture by increasing the capacity of the culture for glutamate uptake as well as by the secretion of soluble factors into the medium.     

机械生长因子E肽的功能及研究展望

机械生长因子(MGF)E肽是胰岛素样生长因子Ⅰ(IGF-Ⅰ)基因剪接后的一段长40个氨基酸残基的延伸肽,其编码基因由IGF-Ⅰ基因的外显子5、6及部分外显子4组成。近年来的实验证明,MGFE肽能独立发挥促进肌肉肥大、修复肌肉损伤、保护神经元、提高心脏功能等多种重要的生理作用,有望对肌肉萎缩、肌营养不良、神经退行性疾病及大脑局部缺血等相关病症的新型药物开发产生重大推动,引起了国内外学者的广泛关注。     

Expression of Nerve Growth Factor and Nerve Growth Factor Receptor Genes in Human Tissues and in Prostatic Adenocarcinoma Cell Lines

Nerve growth factor (NGF) mRNAs were detected and quantified in a variety of normal and neoplastic human tissues by northern blot hybridization. Human heart contained the highest NGF mRNA levels, whereas lower but comparable levels were found in the placenta, prostate, and kidney. All tissues examined coexpressed the low-affinity NGF receptor (LNGFR), whereas none of these tissues expressed the high-affinity NGF receptor encoded by the trk protooncogene. The widespread distribution of the LNGFR suggests that it plays a role in the regulation of normal cell growth. No overexpression of NGF or LNGFR mRNA was detected in neoplastic tissues, whereas LNGFR-like immunoreactivity was localized outside of tumor cells. Transforming growth factor-alpha and protooncogene c-fos expression in these tissues did not show a systematic correlation with NGF/LNGFR expression. Furthermore, regulation of the human NGF gene was studied in DU145 cells, a prostatic adenocarcinoma cell line that synthesizes significant NGF mRNA levels. Serum induced, whereas dexamethasone inhibited, NGF mRNA synthesis in these cells. Serum induction was preceded by a rapid and transient activation of the c-fos protooncogene.