Cajal Institute, Madrid, Spain.
Dev Neurobiol. 2010 Apr;70(5):384-96. doi: 10.1002/dneu.20778.
Insulin-like growth factor I (IGF-I) belongs to an ancient family of hormones already present in early invertebrates. The insulin family is well characterized in mammals, although new members have been described recently. Since its characterization over 50 years ago, IGF-I has been considered a peptide mostly involved in the control of body growth and tissue remodeling. Currently, its most prominent recognized role is as a quasi-universal cytoprotectant. This role connects IGF-I with regulation of lifespan and with cancer, two areas of very active research in relation to this peptide. In the brain, IGF-I was formerly considered a neurotrophic factor involved in brain growth, as many other neurotrophic factors. Other aspects of the neurobiology of IGF-I are gradually emerging and suggest that this growth factor has a prominent role in brain function as a whole. During development IGF-I is abundantly expressed in many areas, whereas once the brain is formed its expression is restricted to a few regions and in very low quantities. However, the adult brain appears to have an external input from serum IGF-I, where this anabolic peptide is abundant. Thus, serum IGF-I has been proven to be an important modulator of brain activity, including higher functions such as cognition. Many of these functions can be ascribed to its tissue-remodeling activity as IGF-I modulates adult neurogenesis and angiogenesis. Other activities are cytoprotective; indeed, IGF-I can be considered a key neuroprotective peptide. Still others pertain to the functional characteristics of brain cells, such as cell excitability. Through modulation of membrane channels and neurotransmission, IGF-I impinges directly on neuronal plasticity, the cellular substrate of cognition. However, to fully understand the role of IGF-I in the brain, we have to sum the actions of locally produced IGF-I to those of serum IGF-I, and this is still pending. Thus, an integrated view of the role played by IGF-I in the brain is not yet possible. An operational approach to overcome this limitation would be to consider IGF-I as a signal coupling environmental influences on body metabolism with brain function. Or in a more colloquial way, we may say that IGF-I links body "fitness" with brain fitness, providing a mechanism to the roman saying "mens sana in corpore sano."
胰岛素样生长因子 I（IGF-I）属于一个古老的激素家族，在早期的无脊椎动物中就已经存在。胰岛素家族在哺乳动物中得到了很好的描述，尽管最近也有新成员被描述。自 50 多年前被描述以来，IGF-I 一直被认为是一种主要参与控制身体生长和组织重塑的肽。目前，它最突出的作用是作为一种准普遍的细胞保护剂。这种作用将 IGF-I 与寿命调节和癌症联系起来，这是与这种肽非常相关的两个活跃研究领域。在大脑中，IGF-I 以前被认为是一种神经营养因子，参与大脑生长，就像许多其他神经营养因子一样。IGF-I 的神经生物学的其他方面正在逐渐显现，表明这种生长因子在大脑功能的整体中起着重要作用。在发育过程中，IGF-I 在许多区域中大量表达，而一旦大脑形成，其表达就局限于少数区域，并且数量非常低。然而，成年大脑似乎从富含合成代谢肽的血清 IGF-I 中获得外部输入。因此，血清 IGF-I 已被证明是大脑活动的重要调节剂，包括认知等更高的功能。其中许多功能可以归因于其组织重塑活性，因为 IGF-I 调节成年神经发生和血管生成。其他活性具有细胞保护作用；事实上，IGF-I 可以被认为是一种关键的神经保护肽。还有一些与脑细胞的功能特征有关，如细胞兴奋性。通过调节膜通道和神经传递，IGF-I 直接影响神经元可塑性，即认知的细胞基础。然而，要全面了解 IGF-I 在大脑中的作用，我们必须将局部产生的 IGF-I 的作用与血清 IGF-I 的作用结合起来，而这仍然是未知的。因此，IGF-I 在大脑中的作用还没有一个整体的认识。克服这一限制的一种可行方法是将 IGF-I 视为一种信号，将环境对身体代谢的影响与大脑功能联系起来。或者更通俗地说，我们可以说 IGF-I 将身体的“健康”与大脑的“健康”联系起来，为罗马谚语“mens sana in corpore sano”提供了一种机制。
