Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, University of Alabama at Birmingham, 1825 University Blvd, Birmingham, AL, 35294, USA.
Mol Brain. 2021 Nov 18;14(1):169. doi: 10.1186/s13041-021-00878-4.
Rho-associated kinase isoform 2 (ROCK2) is an attractive drug target for several neurologic disorders. A critical barrier to ROCK2-based research and therapeutics is the lack of a mouse model that enables investigation of ROCK2 with spatial and temporal control of gene expression. To overcome this, we generated ROCK2 mice. Mice expressing Cre recombinase in forebrain excitatory neurons (CaMKII-Cre) were crossed with ROCK2 mice (Cre/ROCK2), and the contribution of ROCK2 in behavior as well as dendritic spine morphology in the hippocampus, medial prefrontal cortex (mPFC), and basolateral amygdala (BLA) was examined. Cre/ROCK2 mice spent reduced time in the open arms of the elevated plus maze and increased time in the dark of the light-dark box test compared to littermate controls. These results indicated that Cre/ROCK2 mice exhibited anxiety-like behaviors. To examine dendritic spine morphology, individual pyramidal neurons in CA1 hippocampus, mPFC, and the BLA were targeted for iontophoretic microinjection of fluorescent dye, followed by high-resolution confocal microscopy and neuronal 3D reconstructions for morphometry analysis. In dorsal CA1, Cre/ROCK2 mice displayed significantly increased thin spine density on basal dendrites and reduced mean spine head volume across all spine types on apical dendrites. In ventral CA1, Cre/ROCK2 mice exhibited significantly increased spine length on apical dendrites. Spine density and morphology were comparable in the mPFC and BLA between both genotypes. These findings suggest that neuronal ROCK2 mediates spine density and morphology in a compartmentalized manner among CA1 pyramidal cells, and that in the absence of ROCK2 these mechanisms may contribute to anxiety-like behaviors.
Rho 相关激酶同种型 2（ROCK2）是几种神经疾病的有吸引力的药物靶点。基于 ROCK2 的研究和治疗的一个关键障碍是缺乏能够在空间和时间上控制基因表达来研究 ROCK2 的小鼠模型。为了克服这一障碍，我们生成了 ROCK2 小鼠。在大脑皮层兴奋性神经元中表达 Cre 重组酶的小鼠（CaMKII-Cre）与 ROCK2 小鼠（Cre/ROCK2）杂交，研究了 ROCK2 在行为以及海马、内侧前额叶皮层（mPFC）和基底外侧杏仁核（BLA）中的树突棘形态中的作用。与同窝对照相比，Cre/ROCK2 小鼠在高架十字迷宫的开放臂中花费的时间减少，在明暗箱测试中的黑暗时间增加。这些结果表明 Cre/ROCK2 小鼠表现出焦虑样行为。为了检查树突棘形态，针对 CA1 海马、mPFC 和 BLA 中的单个锥体神经元进行离子电泳荧光染料的微注射，然后进行高分辨率共聚焦显微镜和神经元 3D 重建以进行形态计量分析。在背 CA1 中，Cre/ROCK2 小鼠在基底树突上的薄棘密度显著增加，在所有棘突类型的顶树突上的平均棘突头体积减少。在腹 CA1 中，Cre/ROCK2 小鼠的顶树突上的棘突长度显著增加。两种基因型之间的 mPFC 和 BLA 中的棘突密度和形态相似。这些发现表明神经元 ROCK2 以分区方式调节 CA1 锥体神经元中的棘突密度和形态，并且在没有 ROCK2 的情况下，这些机制可能有助于焦虑样行为。
