RNA interference affects tumorigenicity and expression of insulin-like growth factor-1, insulin-like growth factor-1 receptor, and basic fibroblast growth factor-2 in rat C6 glioma cells

BACKGROUND： Human gliomas are more likely to express basic fibroblast growth factor-2 （FGF-2） insulin-like growth factor-1（IGF-1）, and IGF-1 receptor （IGF-1R） than normal brain tissue. These factors activate signal transduction systems of Ras/MAPK and PI3K/Akl, which promote glioma growth. OBJECTIVE： To utilize RNA interference （RNAi） technique to down-regulate FGF-2, IGF-1, and IGF-1R gene expression, and to investigate the effects of these genes on rat C6 glioma cells, as well as the feasibility of RNAi for treating glioma. DESIGN, TIME AND SETTING： This neurooncological, randomized, controlled, in vivo and in vitro experiment, which used RNAi methodology, was performed at the Laboratory of Molecular Biology, Institute of Biochemistry, Chinese Academy of Sciences between August 2005 and February 2008. MATERIALS： Rat C6 cell lines were purchased from Shanghai Institute of Cellular Biology Affiliated to Chinese Academy of Sciences. Small interfering RNA （siRNA） was synthesized by Shanghai GenePharma. Anti-IGF-1, anti-IGF-1R, anti-FGF-2, anti-mouse and anti-rabbit IgG G1-HRP antibodies were provided by Santa Cruz Biotechnology, USA. Four to six week-old BALB/c nude mice were purchased from the Laboratory Animal Center, Chinese Academy of Sciences. METHODS： C6 glioma cells were transfected with siRNA, which was chemically synthesized in vitro to correspond to endogenous FGF-2, IGF-1, and IGF-1R genes. The inhibition ratio of targeting mRNA expression was detected by semiquantitative RT-PCR, and protein expression was determined by Western blot analysis. C6 glioma cell proliferation was observed using a growth curve C6 glioma cell apoptosis rate and cell cycle were detected by flow cytometry. C6 glioma cell growth regression was observed by transwell migration assay. In addition, nude mouse subcutaneous tumor models were used in this study. For studying the anti-tumor effects of IGF-1 and IGF-1R siRNA, two blank control groups, with six mice each, were set up： A （2.5 μg siRNA was injected one week after C6 cells were inoculated, Le., when tumor volume reached 8 mm × 8 mm） and B （siRNA was injected at the same time with C6 cells were inoculated. To study the effects of FGF-2 siRNA, the groups consisted of a blank control group, negative control group, 2.6 μg siRNA group, 4 μg siRNA group, and 5.3 μg siRNA group, with six mice each. MAIN OUTCOME MEASURES： mRNA and protein inhibition ratio of FGF-2, IGF-1, and IGF-1 R; C6 glioma cell proliferation, apoptosis, and cycle growth arrest; C6 glioma cell growth regression and subcutaneous tumorigenicity rates. RESULTS： All siRNA constructs proved to be effective. After 48 hours, transfection of 200 nmol/L siRNA resulted in a FGF-2 or IGF-1R gene inhibition ratio 〉 80% and an IGF-1 gene inhibition ratio of approximately 70%. Protein expression levels for FGF-2, IGF-1, and IGF-1R decreased in a dose-dependent manner following siRNA transfection, with an inhibition rate 〉 85%, 60%, and 50%, respectively. C6 glioma cell proliferation and apoptosis rates increased in proportion to siRNA. The apoptosis rate of C6 glioma cells induced by FGF-2, IGF-1, and IGF-1R siRNA was 39.96%, 15.07% and 22.47%, respectively （P 〈 0.01）. Transfection of 200 nmol/L IGF or IGF-1R siRNA for 48 hours suppressed C6 glioma cell migration. At 30 days after intratumoral injection of 2.6, 4, and 5.3 tJg FGF-2 siRNA, tumor growth regression rate of FGF-2 siRNA was 56%, 67%, and 86%, respectively. The tumor growth regression rate was 71.88% and 45.71%, respectively, when IGF-1 or IGF-1R siRNA was intratumorally injected 1 week after C6 glioma cell transplantation. When IGF-1 or IGF-1 R siRNA was intratumorally injected during C6 glioma cell transplantation, the tumor growth regression rate was 78.13% and 74.29%, respectively. CONCLUSION： siRNA transfection downregulated gene expression of FGF-2, IGF-1, and IGF-1R In addition, siRNA treatment markedly suppressed glioma cell proliferation, growth, and migration, and concomitantly reduced subcutaneous tumorigenicity.     

Restricted growth and insulin-like growth factor-1 deficiency in mice lacking presenilin-1 in the neural crest cell lineage

Presenilin-1 (PS1) is a transmembrane protein that is in many cases responsible for the development of early-onset familial Alzheimer's disease. PS1 is essential for neurogenesis, somitogenesis, angiogenesis, and cardiac morphogenesis. We report here that PS1 is also required for maturation and/or maintenance of the pituitary gland. We generated PS1-conditional knockout (PS1-cKO) mice by crossing floxed PS1 and Wnt1-cre mice, in which PS1 was lacking in the neural crest-derived cell lineage. Although the PS1-cKO mice exhibited no obvious phenotypic abnormalities for several days after birth, reduced body weight in the mutant was evident by the age of 3–5 weeks. Pituitary weight and serum insulin-like growth factor (IGF)-1 level were also reduced in the mutant. Histologic analysis revealed severe atrophy of the cytosol in the anterior and intermediate pituitary lobes of the mutant. Immunohistochemistry did not reveal clear differences in the expression levels of thyroid-stimulating hormone, adrenocorticotropic hormone, or prolactin in the mutant pituitary. In contrast, growth hormone expression levels were reduced in the anterior lobe of the mutant. PS1 was defective in the posterior lobe, but not the anterior or intermediate lobes, in the mutant pituitary. These findings suggest that PS1 indirectly mediates the development and/or maintenance of the anterior and intermediate lobes in the pituitary gland via actions in other regions, such as the posterior lobe.     

癫痫患者神经元特异性烯醇化酶和胰岛素样 生长因子1的变化及临床意义

目的观察癫痫发作3 d内患者血清神经元特异性烯醇化酶(NSE)和胰岛素样生长因子1(IGF-1)浓度的变化及其临床意义。方法选取63例特发性癫痫患者作为病例组,以37例年龄及性别相匹配的体检健康者作对照组。采用ECLIA、ELISA测定血清NSE和IGF-1的浓度。结果病例组血清NSE和IGF-1浓度与对照组比较明显升高,差异有统计学意义(P<0.05)。血清NSE和IGF-1ROC曲线下面积分别为0.767和0.663。癫痫患者血清NSE和IGF-1浓度之间存在相关性(r=0.379,P<0.01)。结论血清NSE、IGF-1浓度在痫性发作后3 d内升高,提示其可作为判断痫性发作后早期脑损伤及机体早期启动神经保护的生化指标,具一定临床应用价值。癫痫患者血清NSE和IGF-1浓度之间存在相关性,提示它们可能共同参与了癫痫的发病过程。     

胰岛素样生长因子1和成纤维细胞生长因子7与毛乳头细胞的生长*

背景：毛乳头细胞凝集性生长与其诱导毛发生长有关。毛乳头细胞分泌的多种生长因子如胰岛素样生长因子1、成纤维细胞生长因子7可能对毛乳头细胞生长具有重要的影响。 目的：观察正常人毛乳头细胞的增长与生长方式与胰岛素样生长因子1、成纤维细胞生长因子7的相关性。 方法：采用二步酶消化法分离培养毛乳头细胞,免疫组化法和流式细胞仪分别检测两种生长因子在凝集性与非凝集性生长的毛乳头细胞中的表达,MTT法检测2.5~100 μg/L质量浓度胰岛素样生长因子1对人毛乳头细胞增殖的影响。 结果与结论：胰岛素样生长因子1与成纤维细胞生长因子7均表达于细胞胞浆,但表达量随时间减弱,其中第3代明显比第9代毛乳头细胞中成纤维细胞生长因子7的表达强烈(P < 0.05)。与对照组相比,不同质量浓度胰岛素样生长因子1均有明显促进毛乳头细胞增殖的作用(P < 0.05),其中以2.5 μg/L最为显著。提示毛乳头细胞的凝集性生长状态的改变可能与胰岛素样生长因子1、成纤维细胞生长因子7表达下降有关,胰岛素样生长因子1可明显刺激毛乳头细胞增殖。     

Expression of MyoD and myogenin in dystrophic mice, mdx and dy, during regeneration

Expression of two myogenic regulatory factors, MyoD and myogenin, was studied in regenerating muscles of dystrophic mice and compared to a chemically induced regeneration process. First, the distribution of the two proteins was determined immunohistochemically at various time points after single administrations of a local anaesthetic, bupivacaine hydrochloride, which causes myonecrosis followed by regeneration. Detectable levels of MyoD appeared at 18 h and the expression reached their maximum levels at 48 h after the injection, which coincide with the stage when satellite cells are activated and start to proliferate. Myogenin became detectable in 24 h and its expression reached its highest level at 72 h after injection when newly formed myotubes appeared. The two genes were also expressed in the dystrophic muscles from dy and mdx mice which exhibit dystrophic pathological features but are associated with different phenotypes. In mdx mice the two genes were expressed at reasonably high levels in parallel with the active regenerating process, whereas in dy mice MyoD and myogenin expressions decreased as fibrosis progressed. However, MyoD was relatively more strongly expressed in the larger mature myotubes of dy mice than in those of mdx mice, suggesting prolonged regenerative activity. In dy and mdx mice, MyoD and myogenin were expressed in different quantities, indicating that these animals have distinct regenerating activities. Our findings confirm that expression of both MyoD and myogenin genes is necessary in the regenerative process for the proliferation of satellite cells (myoblasts) and for the development of early regenerating fibers (myotubes) even in dystrophic muscles. Received: 9 March 1999 / Revised: 30 August 1999 / Accepted: 6 September 1999     

脓毒症大鼠模型脑胰岛素生长因子1表达的变化及影响

目的：探讨脓毒症大鼠模型胰岛素生长因子1（IGF-1）表达的变化及影响。方法采用盲肠结扎穿孔法（CLP）制作脓毒症大鼠模型,应用免疫荧光染色观察皮层IGF-1阳性细胞, western blot法检测IGF-1和caspase-3蛋白表达,TUNEL染色观察脑神经元凋亡。在脓毒症模型基础上,给予侧脑室定位注射IGF-1或生理盐水,相同方法检测caspase-3蛋白表达及脑神经元凋亡。结果与假手术组相比,脓毒症组大鼠皮层IGF-1阳性细胞数明显减少,caspase-3表达增高,IGF-1表达减低,神经元凋亡增加（均P＜0．05）。侧脑室注射IGF-1后,caspase-3表达和神经元凋亡较假手术组无明显变化;而侧脑室给予生理盐水大鼠caspase-3表达和神经元凋亡与脓毒症组相似。结论脓毒症大鼠的脑皮层IGF-1表达明显减低,细胞凋亡增多。给予外源性IGF-1后,细胞凋亡减少。提示IGF-1可能通过抑制caspase-3的上调对脓毒症大鼠起到脑保护作用。     

Effects of exercise and steroid on skeletal muscle apoptosis in the mdx mouse

Reports concerning the influence of exercise loading and steroid administration on dystrophinopathy are inconsistent. To investigate the effect of muscle exercise in Duchenne muscular dystrophy (DMD), 15 control and 15 mdx mice, an animal model of DMD, were divided into free-living (n = 6), exercise (n = 6), and immobilization (n = 3) groups. Free-living and exercise groups were further divided into steroid-treated and sham-treated groups to evaluate the effect of steroid administration. We measured apoptotic changes by in situ DNA nick-end labeling (TUNEL), DNA fragmentation assay, and Western blotting for Bcl-2 and BAX. Apoptosis was most prominent in the sham-treated exercise group, and it was significantly reduced in the steroid-treated exercise group. The steroid-treated free-living group showed a higher rate of apoptotic change than the sham-treated free-living group. Apoptosis was minimized in the free-living condition, whereas exercise loading and immobilization caused apoptotic change in this muscular dystrophy animal model. Steroid administration induced apoptosis in muscle of free-living mice, but alleviated the apoptotic damage caused by exercise loading in mdx mice. These findings suggest that steroid administration may be effective in preventing a postexercise deterioration of skeletal muscle in animal models of DMD.     

Dystrophy and myogenesis in mdx diaphragm muscle

In order to determine why the diaphragm is more severely affected by progressive dystrophy than limb muscles in the mdx mouse, we examined how regional variations in diaphragm dystrophy, the measures of disease and repair, proliferation by committed myogenic cells, and the expression of mitogenic basic fibroblast growth factor (bFGF) could contribute to muscle-specific disease phenotypes. There were regional variations in new myotube formation in the diaphragm, with disease more severe in crural than costal leaflets. New repair increased in hyperthyroidism without changes in accumulated repair, probably due to fiber loss. General proliferation was nearly twofold higher in limb than diaphragm mononuclear cells. Since only 2.5–8.4% of committed muscle precursors were proliferating, the higher proliferation by myf5+ myogenic cells in diaphragm did not account for muscle-specific differences. Proliferation by bFGF+ mononuclear cells and an immunogold labeling index for bFGF protein in diaphragm myoblasts were lower in diaphragm than limb muscle. In culture, mixed limb myoblast and fibroblasts contained more S phase cells than diaphragm cells, although myoblasts cycled similarly between muscles. Therefore while muscle architecture and the formation and number of new myotubes certainly affect disease phenotype, the differential outcome of regeneration in mdx diaphragm and limb muscle appears to be contributed by both nonmyogenic and myogenic cells. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21: 1153–1165, 1998.     

Effects of a CRF2R agonist and exercise on mdx and wildtype skeletal muscle

Corticotrophin-releasing factor 2 receptor (CRF2R) agonists prevent muscle atrophy due to immobilization, denervation, and corticosteroid-induced muscle atrophy in wildtype mice. We hypothesized that a CRF2R agonist will increase skeletal muscle mass in mdx mice. Mdx (C57BL/10ScSn-Dmd(mdx)) and wildtype (C57BL/6) mice were divided into four groups: sedentary placebo, sedentary CRF2R agonist, exercised placebo, and exercised CRF2R agonist. Mice exercised on a treadmill twice weekly for 30 min (8-12 m/min, 8 weeks). Muscle and heart weights, serum creatine kinase, and gamma-glutamyltransferase activities were measured. The CRF2R agonist increased extensor digitorum longus and soleus muscle weights (P < 0.05) in wildtype and mdx mice. Sedentary mdx CRF2R and exercised mdx placebo mice had lower serum creatine kinase activity than sedentary mdx placebo mice. CRF2R-treated mice had decreased heart weights compared to placebo-treated mice. We conclude that CRF2R agonists should be further evaluated as a potential therapy for dystrophinopathies.     

胰岛素样生长因子与运动性心肌肥大

背景：胰岛素样生长因子1对心脏具有重要的生物学效应,可以促进心肌和血管平滑肌的生长和代谢。 目的：综述胰岛素样生长因子1的生物学效应,以期明确其对运动性心肌肥大的发生机制。更好地利用运动对IGF1的影响来实现心脏适应性肥大。 方法：以“exercise-induced cardiac hypertrophy, insulin-like growth factor, exercise”为检索词,检索Pubmed数据库(1990-01/2009-04);以运动性心肌肥大,胰岛素样生长因子,运动为检索词,检索CNKI数据库(1990-01/2009-04)。文献检索语种限制为英文和中文。纳入与胰岛素样生长因子联系紧密的动物实验研究和临床应用研究;排除内容陈旧的文献和Meta分析。 结果与结论：计算机初检得到41篇文献,根据纳入排除标准,对其中31篇文献进行分析。胰岛素样生长因子与其他生长因子一起协同促进多种细胞的分化成熟。现有资料表明血清及心脏局部胰岛素样生长因子 1对心肌肥大的发生具有重要作用。文章采用文献资料法,分析了循环和心肌胰岛素样生长因子的产生和作用机制,探讨了心脏局部胰岛素样生长因子的功能以及运动对其的影响;得出了运动能改变循环和心肌胰岛素样生长因子的表达以及心脏局部胰岛素样生长因子与运动性心肌肥大的形成有关。     

Paravertebral fascial massage promotes brain development of neonatal rats via the insulin-like growth factor 1 pathway

Massage in traditional Chinese medicine can promote body and brain development of premature and normal newborn infants. In the present study, neonatal rats (1 day old) underwent paravertebral fascial massage (15 consecutive days), followed by subcutaneous injection of insulin-like growth factor 1 receptor antagonist, JB1 (9 consecutive days). Paravertebral fascial massage significantly increased insulin-like growth factor 1 expression and cell proliferation in the subventricular zone of the lateral ventricle and dentate gyrus of the hippocampus. However, JB1 inhibited this increase. Results suggest that paravertebral fascial massage can promote brain development of neonatal rats via the insulin-like growth factor 1 pathway.     

睾酮干预雄兔膝骨关节炎软骨中胰岛素样生长因子1的表达*

背景：睾酮对骨关节炎的作用尚无一致的观点,其调节软骨代谢的作用鲜有文献报道。目的：观察睾酮对膝骨关节炎雄兔关节软骨中胰岛素样生长因子1表达的影响。 方法：24只雄兔随机分成4组,采用改良Hulth法建立右膝骨关节炎模型;假去势组不切除睾丸,其余3组切除双侧睾丸。第8周末处死假去势组和去势8周组兔取材。第9周开始,激素组肌注生理剂量十一酸睾酮(6 mg/kg, 2周1次),去势16周组正常喂养,并于16周末处死并取材。结果与结论：大体和组织学观察显示各组兔膝关节软骨的病变程度为假去势组优于去势8周组,激素组优于去势16周组。免疫组化染色显示胰岛素样生长因子1在所有兔膝关节软骨中均有表达,阳性细胞个数假去势组高于去势8周组(P < 0.05),激素组高于去势16周组(P < 0.05),去势8周组与去势16周组差异无显著性意义(P > 0.05)。说明睾酮可通过上调去势雄兔关节软骨中胰岛素样生长因子1的表达,延缓软骨退变。     

运动神经元病患者血浆胰岛素样生长因子-1的变化

目的 探讨运动神经元病（ＭＮＤ）患者血浆胰岛素生长因子－１（ＩＧＦ－１）变化的临床意义。方法 应用放射免疫法测定２１例ＭＮＤ患者血浆ＩＧＦ－１水平,同时测定其血清胰岛素和空腹血糖水平,并设立正常对照组。结果 与正常对照组比较,ＭＮＤ患者血浆ＩＧＦ＿１水平显著下降,虽然两组血糖水平无明显差异,但口才组血浆胰钫 水平明显下降。结论 ＩＧＦ－１系统参与了ＭＮＤ的发病机理,神经营养支持的缺乏是导致髓运动元     

Effect of Ganoderma lucidum spore on expression of insulin-like growth factor-1, nuclear factor-kappa B, and neuronal apoptosis in the epileptic rat brain

BACKGROUND: It has been reported that Ganoderma lucidum spore powder, a very well known Chinese traditional medicine, can affect immunoregulation, free radical scavenging, and anti-hypoxia responses. OBJECTIVE: To investigate the effect of Ganoderma lucidum spore powder on expression of insulin-like growth factor-1 (IGF-1), nuclear factor-κB (NF-κB) and neuronal apoptosis in rats with pentylenetetrazol (PTZ)-induced epilepsy.DESIGN, TIME AND SETTING: A cellular and molecular biology experiment with randomized controlled study design was performed at the Central Laboratory of Basic Medical College of Jiamusi University from June to August 2005.MATERIALS: Thirty healthy, adult, male, Wistar rats were selected and randomly divided into 3 groups (10rats per group): control, epilepsy model, and Ganoderma lucidum spore powder. A sub-eclampsia PTZ dose (35 mg/kg) was intraperitoneally injected to induce epilepsy in the latter two groups. Wild Ganoderma lucidum spore powder (30 g/L) was provided by the wild Ganoderma lucidum plant nursery at Jiamusi,China. lmmunohistochemical detection and terminal deoxynucleotidyl transferase-mediate dUTP nick end-labeling (TUNEL) kits were purchased from Wuhan Boster Biological Technology Co., Ltd., China.METHODS: Ganoderma lucidum spore powder was intragastrically administered at a dose of 10.0 mL/kg,once a day for 28 days. In the epilepsy and control groups, an equivalent volume of normal saline was intragastrically administered.MAIN OUTCOME MEASURES: lmmunoreactivity for IGF-1 and NF-κB/P65 were detected by immunohistochemical staining. Neuronal apoptosis was detected using TUNEL methods.RESULTS: The hippocampus and cerebral cortex of rats with PTZ-induced epilepsy exhibited a higher number of apoptotic cells at high magnification (x400), compared with the control group. Expression of IGF-1and NF-κB were higher in the epilepsy group, compared with the control group (P < 0.01). In Ganoderma lucidum spore-treated rats, fewer apoptotic cells were observed in the hippocampus and cerebral cortex,expression of NF-κB/P65 was lower, and immunoreactivity to IGF-1 increased more distinctly, compared with the epilepsy group. In addition, seizure latency was longer on 17, 21, and 25 days post-PTZ treatment in the Ganoderma lucidum spore powder group, compared with the epilepsy group (P < 0.05 0.01).CONCLUSION: Ganoderma lucidum spore powder down-regulated expression of NF-κB in brain tissues of rats with PTZ-induced epilepsy, increased immunoreactivity to IGF-1, and inhibited neuronal apoptosis.These results indicated that Ganoderma lucidum spore powder has a neuroprotective effect.     

胰岛素样生长因子-1对大鼠脑缺血再灌注损伤的作用机制研究

目的　观察尾静脉注射胰岛素样生长因子 -1(IGF -1)对大鼠脑缺血再灌注损伤的影响 ,探讨IGF -1的作用机制。方法　TTC染色测脑梗死体积 ,光镜检查细胞损伤变化 ,免疫组化法测Caspase -3阳性表达。结果　与缺血再灌注组相比 ,IGF -1用药组脑梗死体积显著缩小 (P <0 0 1) ,光镜下细胞坏死调亡减少 ,Caspase -3阳性细胞数明显下降 (P <0 0 1)。结论　IGF -1对局灶性脑缺血再灌注损伤有保护作用 ,在脑缺血损伤时IGF -1能通过血脑屏障 ,IGF -1可通过抑制神经细胞调亡发挥作用。     

胰岛素样生长因子-1对背根神经节神经元感觉神经肽mRNA表达的调节作用(英文)

目的利用背根神经节(dorsalrootganglion,DRG)神经元,观察胰岛素样生长因子-1(insulin-like growth factor-1,IGF-1)对谷氨酸(Glu)神经毒性引起的编码P物质(substanceP,SP)的前速激肽原(preprotachykinin,PPT)mRNA和降钙素基因相关肽(calcitonin gene-related peptide,CGRP)mRNA表达下降的调节作用。方法取15d胎龄大鼠的DRG神经元,分散培养48h后,在培养液中加入Glu(0.2mmol/L),或同时加入不同浓度的IGF-1(5nmol/L,10nmol/L,或20nmol/L)孵育12h,利用倒置相差显微镜对神经元活细胞进行观察,并用RT-PCR法检测神经元中PPT和CGRP的mRNA表达水平。对照组DRG神经元培养液中不含Glu和IGF-1。结果Glu能引起神经元突起的缩短,而IGF-1则显著减弱这一作用。此外,Glu的神经毒性使得DRG神经元内PPT和CGRP的mRNA水平显著降低,而IGF-1则能明显抑制这种降低,且呈一定的浓度依赖性。结论IGF-1可能通过调节PPT和CGR...     

胰岛素样生长因子-1在难治性癫(癎)患者颞叶中的表达

目的研究胰岛素样生长因子-1(insulin-like growth factor-Ⅰ,IGF-Ⅰ)在难治性癫(癎)患者颞叶中的表达,探讨其对难治性癫(癎)的作用.方法收集难治性癫(癎)患者术后脑组织,按手术时间的先后建立难治性癫(癎)脑组织库,随后在脑库中按随机化原则从中抽取30例(实验组)颞叶,正常对照组为颅脑外伤手术切除的正常颞叶组织12例,采用免疫组化、western blot测定两组的IGF-Ⅰ表达并进行比较.结果免疫组化结果提示IGF-1分布于神经元和胶质细胞膜,在难治性癫(癎)患者颞叶中的表达比对照组明显增加.western blot的结果和免疫组化结果一致.结论IGF-1在难治性癫(癎)患者脑组织的表达升高可能与脑的保护机制有关,这种神经营养因子的存在有利于挽救因癫(癎)发作而损伤的神经元.     

Angiogenic and inflammatory responses following skeletal muscle injury are altered by immune neutralization of endogenous basic fibroblast growth factor, insulin-like growth factor-1 and transforming growth factor-β1

Injured skeletal muscle degeneration comprises early microvascular changes and inflammatory cell infiltration, possibly under the control of several growth factors. We have studied the role of basic fibroblast growth factor (bFGF), insulin-like growth factor-1 (IGF1), and transforming growth factor beta-1 (TGFβ1), by injecting specific anti-growth factor neutralizing antibodies into mouse extensor digitorum longus muscle at the time of injury (denervation and devascularization). Four days later, at the height of damaged myofiber phagocytosis, we assessed quantitatively revascularization, phagocytic activity, and inflammation. The immune neutralization of bFGF reduced the number of capillaries, macrophages and mast cells, and delayed necrotic myofiber phagocytosis. The immune neutralization of IGF1 or TGFβ1 promoted muscle revascularization, macrophage infiltration and necrotic myofiber phagocytosis. While IGF1 neutralization reduced the number of mast cells and did not modify that of T-cells or neutrophils, TGFβ1 neutralization increased the number of all of these cells. This study strongly suggests differing roles for bFGF, IGF1 and TGFβ1 in angiogenic and inflammatory responses during muscle degeneration, apart from their known effects on the behaviour of myogenic cells.