Effects of basic fibroblast growth factor on neuron death and learning disability

碱性成纤维细胞生长因子对神经元死亡和学习障碍的影响

基本信息

批准号：
08680821
负责人：
SAKANAKA Masahiro
金额：
$ 1.79万
依托单位：
Ehime University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

Platelet factor 4(PF4), which has a potent affinity for hparin, has shown to inhibit the binding of basic fibroblast growth factor (bFGF) to the cell surface receptor and to counteract the biological activities of bFGF in certain peripheral tissues. In the present in vitro [^<125>I] bFGF binding experiments, the affinity of [^<125>I] bFGF with the receptor was shown to be higher in the ischemic hippocampus than in the normal hippocampus and PF4 consistently inhibited the binding of indicated bFGF to cell membranes of the gerbil hippocampus. To investigate the in vivo function of endogenous bFGF and/or bFGF receptor possibly activated in the ischemic gerbil brain, we infused PF4 continuously into the left lateral ventricle through an osmotic minipump. When PF4 infusion was started within three days after a 3-min ischemic insult, it significantly enhanced ischemia-induced learning disability and ischemic neuronal loss in the CA1 region of the hippocampus, as demonstrated by the results o … More f a step-down passive avoidance task and by subsequent histological examinations. Infusion of PF4 into the cerebral ventricle of intact gerbils did not affect leaning ability or CA1 neuron number. bFGF-neutralizing antibody, when infused continuously in the cerebral ventricle, also exhibited a neurotoxic effect in ischemic but not intact gerbils. bFGF co-infused with heparin, but not bFGF alone, rescued a significant number of ischemic neurons which were destined to degenerate without the infusion of heparinized bFGF, and it prevented ischemia-induced learning disability. bFGF infusion prior to PF4 treatment abolished almost completely the neurotoxic effect of PF4 on the ischemic hippocampal CA1 region. These findings suggest that (1) PF4 as a putative bFGF receptor antagonist exerts a neurotoxic effect on the ischemic hippocampus and so does bFGF-neutralizing antibody ; (2) heparin is indispensible for bFGF to retain neurotrophic activity ; (3) bFGF infused before PF4 treatment occupies the binding sites of bFGF on the cell surfaces of ischemic neurons ; and (4) the later infusion of PF4, even though it blockes, partially, the subsequent binding of bFGF to the receptor, can no longer suppress the bFGF-mediated intracellular signal transduction in favor of neuronal survival. Thus, the present study indicates a pivotal role of endogenous bFGF in the survival and functional recovery of ischemic neurons. In the present study, the neuroprotective effect of heparinized bFGF was also compared with those of other growth factors, cytokines and drugs such as interleukin 6, platelet-derived growth factor, beta-estradiol, TEI-7165, ginsenoside Rb1, epidermal growth factor, erythropoietin and interleukin 3. Less

血小板因子4（PF4）对HPARIN具有潜在的亲和力，已证明可以抑制基本成纤维细胞生长因子（BFGF）与细胞表面受体的结合，并抵消某些周围组织中BFGF的生物学活性。在目前的体外[^<125> I] BFGF结合实验中，[^<125> I] BFGF与受体的亲和力在缺血性海马中比正常海马和PF4高于指示性BFGF对Cell Membranes of thembranes of thembranes gerippambusbusbusbuspuspuspuspuspuspumbuspumbuspumbuspumbuspumbuspuspumbuspumbuspumbuspumbuspuspumbuspumbuspumbuspuspumbuspabuspuspumbuspabuss bfgf持续抑制。为了研究内源性BFGF和/或BFGF受体的体内功能，可能在缺血性的沙鼠脑中激活，我们通过渗透微型蛋白会连续感染PF4。当3分钟缺血性损伤后三天内开始PF4输注时，在海马的CA1区域中，缺血诱导的学习障碍和缺血性神经元丧失显着增强，如结果所证明的那样，这是逐步的被动避免任务和随后的组织学检查。将PF4输注到完整的香鼠的大脑心室中不会影响倾斜能力或CA1神经元数。当在脑室中连续感染BFGF中和抗体时，还暴露了缺血性的神经毒性作用，但没有完整的晶状体。 BFGF与肝素共同介绍，但不单独使用BFGF，反应了大量的缺血性神经元，这些神经元注定会在不输注肝素BFGF的情况下退化，并阻止了缺血诱导的学习障碍。 PF4治疗之前的BFGF输注几乎完全消除了PF4对缺血性海马CA1区域的神经毒性作用。这些发现表明（1）PF4作为推定的BFGF受体拮抗剂对缺血性海马产生神经毒性作用，而BFGF中和化抗体也是如此。（2）BFGF保持神经营养活性是必不可少的；（3）BFGF在PF4治疗案例之前注入了BFGF在缺血性神经元细胞表面上的结合位点；（4）后来的PF4输注，即使它部分阻止了BFGF与受体的随后结合，但也无法再抑制BFGF介导的细胞内信号转导，有利于神经元的生存。这是本研究表明内源性BFGF在缺血性神经元的生存和功能恢复中的关键作用。在本研究中，还将肝素化BFGF的神经保护作用与其他生长因子，细胞因子和药物（例如白介素6，血小板衍生的生长因子，β-雌二醇，TEI-7165，Ginsenoside RB1，Ginsenoside RB1，表皮生长因子，Erythropoietin and Eryythropoietin and Interleeuekin and Interleeuekin and Interleeuiietin和Interleeuietkin 3 3 3）进行了比较。