Ivashkina O I, Vorobyeva N S, Gruzdeva A M, Roshchina M A, Toropova K A, Anokhin K V
Department of Neuroscience, National Research Center "Kurchatov Institute", Akademika Kurchatova pl. 1, Moscow, 123182, Russia.
Center for Neural and Cognitive Sciences, Lomonosov Moscow State University, Leninskie Gory 1 , bldg. 27, Moscow, 119991, Russia.
Acta Naturae. 2018 Apr-Jun;10(2):37-47.
In this study, we describe use of Cre-mediated recombination to obtain a permanent genetic labeling of the brain neuronal networks activated during a new experience in animals. This method utilizes bitransgenic Fos-Cre-eGFP mice in which a green fluorescent protein is expressed upon tamoxifen-induced Cre-recombination only in the cells where immediate early gene expression takes place due to the new experience. We used the classical fear conditioning model to show that microscopy of the eGFP protein in Fos-Cre-eGFP mice enables mapping of the neurons of the various brain regions that undergo Cre-recombination during acquisition of a new experience. We exposed the animals to the new environment in brief sessions and demonstrated that double immunohistochemical staining enables a characterization of the types of neocortical and hippocampal neurons that undergo experience-dependent Cre-recombination. Notably, Fos-Cre-eGFP labeled cells appeared to belong to excitatory pyramidal neurons rather than to various types of inhibitory neurons. We also showed that a combination of genetic Cre-eGFP labeling with immunohistochemical staining of the endogenous c-Fos protein allows one to identify and compare the neuronal populations that are activated during two different episodes of new experiences in the same animal. This new approach can be used in a wide spectrum of tasks that require imaging and a comparative analysis of cognitive neuronal networks.
在本研究中，我们描述了利用Cre介导的重组来获得动物在新经历期间被激活的脑神经网络的永久性遗传标记。该方法利用双转基因Fos-Cre-eGFP小鼠，其中仅在因新经历而发生即刻早期基因表达的细胞中，在他莫昔芬诱导的Cre重组后才表达绿色荧光蛋白。我们使用经典的恐惧条件反射模型来表明，对Fos-Cre-eGFP小鼠中的eGFP蛋白进行显微镜观察能够绘制出在新经历习得过程中经历Cre重组的各个脑区的神经元图谱。我们让动物在短时间内暴露于新环境中，并证明双重免疫组织化学染色能够表征经历依赖于经验的Cre重组的新皮质和海马神经元的类型。值得注意的是，Fos-Cre-eGFP标记的细胞似乎属于兴奋性锥体神经元，而不是各种类型的抑制性神经元。我们还表明，遗传Cre-eGFP标记与内源性c-Fos蛋白的免疫组织化学染色相结合，能够在同一只动物的两次不同新经历事件中识别和比较被激活的神经元群体。这种新方法可用于广泛的需要对认知神经网络进行成像和比较分析的任务中。
