Adams Michelle M, Elizabeth Forbes M, Constance Linville M, Riddle David R, Sonntag William E, Brunso-Bechtold Judy K
Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1010, USA.
Growth Factors. 2009 Jun;27(3):181-8. doi: 10.1080/08977190902863639.
Insulin-like growth factor-I (IGF-I), a functionally important neurotrophic factor, impacts tissues throughout the body including the central nervous system. In addition to the significant proportion of IGF-I that is synthesized in the liver and released into the plasma, IGF-I is expressed locally in tissues. The present study investigated the relationship between plasma and local brain levels of IGF-I in two well-characterized models of decreased IGF-I. The first is an adult-onset growth hormone deficiency (AOGHD) model, and the second is a caloric restriction (CR) model. In the first cohort of animals from both models, the hippocampus was removed from the brain immediately following decapitation, and in the second cohort, the animals were perfused transcardially with phosphate buffered saline to remove cerebral blood prior to harvesting the hippocampus. Our results demonstrated that although the plasma IGF-I levels were decreased in the CR and AOGHD rats compared to controls, the hippocampal IGF-I levels did not differ among the groups. These data suggest that local brain IGF-I levels are regulated in a different manner than plasma IGF-I levels.
胰岛素样生长因子-I（IGF-I）是一种功能重要的神经营养因子，对包括中枢神经系统在内的全身组织都有影响。除了很大一部分在肝脏合成并释放到血浆中的IGF-I外，IGF-I也在组织中局部表达。本研究在两种特征明确的IGF-I降低模型中，研究了血浆和局部脑内IGF-I水平之间的关系。第一种是成年期生长激素缺乏（AOGHD）模型，第二种是热量限制（CR）模型。在来自这两种模型的第一组动物中，断头后立即从大脑中取出海马体，在第二组中，在收获海马体之前，用磷酸盐缓冲盐水经心脏灌注动物以清除脑血。我们的结果表明，尽管与对照组相比，CR和AOGHD大鼠的血浆IGF-I水平降低，但各组之间海马体IGF-I水平并无差异。这些数据表明，局部脑内IGF-I水平的调节方式与血浆IGF-I水平不同。
