Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità Roma, Italy.
Front Cell Neurosci. 2013 May 23;7:62. doi: 10.3389/fncel.2013.00062. eCollection 2013.
Brain activity is associated with structural changes in the neural connections. However, in vivo imaging of the outer cortical layers has shown that dendritic spines, on which most excitatory synapses insist, are predominantly stable in adulthood. Changes in dendritic spines are governed by small GTPases of the Rho family through modulation of the actin cytoskeleton. Yet, while there are abundant data about this functional effect of Rho GTPases in vitro, there is limited evidence that Rho GTPase signaling in the brain is associated with changes in neuronal morphology. In the present work, both chronic in vivo two-photon imaging and Golgi staining reveal that the activation of Rho GTPases in the adult mouse brain is associated with little change of dendritic spines in the apical dendrites of primary visual cortex pyramidal neurons. On the contrary, considerable increase in spine density is observed (i) in the basal dendrites of the same neurons (ii) in both basal and apical dendrites of the hippocampal CA1 pyramidal cells. While confirming that Rho GTPase-dependent increase in spine density can be substantial, the study indicates region and dendrite selectivity with relative stability of superficial cortical circuits.
大脑活动与神经连接的结构变化有关。然而，对皮质外层层的活体成像显示，树突棘（其上附着大多数兴奋性突触）在成年期主要是稳定的。树突棘的变化受 Rho 家族的小 GTP 酶通过调节肌动蛋白细胞骨架来控制。然而，尽管有大量关于 Rho GTPase 在体外的这种功能效应的数据，但有限的证据表明大脑中的 Rho GTPase 信号与神经元形态的变化有关。在本工作中，慢性活体双光子成像和高尔基染色均显示，成年小鼠大脑中 Rho GTPase 的激活与初级视觉皮层锥体神经元顶树突棘的微小变化有关。相反，在同一神经元的基底树突（ii）和海马 CA1 锥体神经元的基底和顶树突中均观察到棘密度的显著增加（ii）。该研究既证实了 Rho GTPase 依赖性棘密度增加的可观性，又表明了相对稳定的浅层皮质回路的区域和树突选择性。
