Hoffman G E, Smith M S, Verbalis J G
Department of Physiology, University of Pittsburgh, Pennsylvania.
Front Neuroendocrinol. 1993 Jul;14(3):173-213. doi: 10.1006/frne.1993.1006.
Expression of c-Fos, or other immediate early gene products, by individual neurons can be used as a marker of cell activation, making staining of these proteins an extremely useful technique for functional anatomical mapping of neuroendocrine systems. Because these proteins are located in the nucleus, identification of the phenotype of the activated neuron using substances located within the cytoplasm can be accomplished with standard double-labeling immunocytochemical techniques. Although it is clear that neurons have the capacity to express a number of immediate early gene products, what remains to be established is whether there is a different pattern of expression following various stimuli. In our studies, we focus primarily on expression of one immediate early gene product, the c-Fos protein. We also include some experiments using expression of other members of the Fos family and Jun proteins as markers for neuronal activation. Our studies describe uses of c-Fos expression in both parvocellular and magnocellular hypothalamic systems to address the following issues: (a) identification of neuroendocrine cells activated by specific treatments and conditions, (b) ascertainment of functional differences in subpopulations activated by specific stimuli, (c) evaluation of neuronal activity in complex areas containing multiple neuroendocrine systems, (d) identification of other brain areas activated in conjunction with neuroendocrine systems following specific stimuli, (e) analysis of connectivity of activated neuroendocrine systems with other parts of the brain, and (f) identification of stimuli that decrease neuronal activity. The neuroendocrine systems studied include those that secrete arginine vasopressin (AVP), oxytocin (OT), corticotropin-releasing hormone (CRH), luteinizing hormone-releasing hormone (LHRH), and dopamine (DA). The use of c-Fos expression has permitted functional neuroanatomical mapping of these systems in response to specific stimuli such as cholecystokinin (CCK), hyperosmolality, and volume depletion, or during various physiological states such as the proestrous ovulatory luteinizing hormone (LH) surge and lactation. Although the use of c-Fos as a marker of neuronal activation will continue to be an extremely powerful technique, future studies will also be directed at relating immediate early gene expression to changes in neuroendocrine gene expression. To this end, we have shown that both c-Fos and c-Jun are expressed in neuroendocrine neurons in response to a number of stimuli, setting the stage for potential regulatory drive to genes containing AP-1 binding sites.
单个神经元中c-Fos或其他即刻早期基因产物的表达可作为细胞激活的标志物，使得这些蛋白质的染色成为神经内分泌系统功能解剖图谱绘制的一项极其有用的技术。由于这些蛋白质位于细胞核中，利用位于细胞质内的物质来鉴定被激活神经元的表型可通过标准的双标记免疫细胞化学技术来完成。虽然很明显神经元有能力表达多种即刻早期基因产物，但仍有待确定的是在各种刺激后是否存在不同的表达模式。在我们的研究中，我们主要关注一种即刻早期基因产物即c-Fos蛋白的表达。我们还进行了一些实验，利用Fos家族的其他成员和Jun蛋白的表达作为神经元激活的标志物。我们的研究描述了c-Fos表达在小细胞和大细胞下丘脑系统中的应用，以解决以下问题：(a) 鉴定被特定处理和条件激活的神经内分泌细胞；(b) 确定被特定刺激激活的亚群中的功能差异；(c) 评估包含多个神经内分泌系统的复杂区域中的神经元活性；(d) 鉴定在特定刺激后与神经内分泌系统一起被激活的其他脑区；(e) 分析被激活的神经内分泌系统与脑的其他部分之间的连接性；以及(f) 鉴定降低神经元活性的刺激。所研究的神经内分泌系统包括那些分泌精氨酸加压素(AVP)、催产素(OT)、促肾上腺皮质激素释放激素(CRH)、促黄体生成素释放激素(LHRH)和多巴胺(DA)的系统。c-Fos表达的应用使得能够针对特定刺激如胆囊收缩素(CCK)、高渗和容量耗竭，或在各种生理状态如动情前期排卵促黄体生成素(LH)高峰和泌乳期间，对这些系统进行功能性神经解剖图谱绘制。虽然将c-Fos用作神经元激活的标志物将仍然是一项极其强大的技术，但未来的研究也将致力于将即刻早期基因表达与神经内分泌基因表达的变化联系起来。为此，我们已经表明，c-Fos和c-Jun在神经内分泌神经元中会响应多种刺激而表达，为对含有AP-1结合位点的基因进行潜在的调控驱动奠定了基础。
