Institute for Research on Neurological Disorders (IDINE), Faculty of Medicine, University of Castilla-La Mancha, 02006, Albacete, Spain.
J Comp Neurol. 2013 Oct 15;521(15):3478-99. doi: 10.1002/cne.23362.
One of the main mechanisms used by neurons and glial cells to promote repair following brain injury is to upregulate activity-dependent molecules such as insulin-like growth factor 1 (IGF-1) and interleukin-1β (IL-1β). In the auditory system, IGF-1 is crucial for restoring synaptic transmission following hearing loss; however, whether IL-1β is also involved in this process is unknown. In this study, we evaluated the expression of IGF-1 and IL-1β within neurons and glial cells of the ventral cochlear nucleus in adult rats at 1, 7, 15, and 30 days following bilateral cochlear ablation. After the lesion, significant increases in both the overall mean gray levels of IGF-1 immunostaining and the mean gray levels within cells of the cochlear nucleus were observed at 1, 7, and 15 days compared with control animals. The expression and distribution of IL-1β in the ventral cochlear nucleus of ablated animals was temporally and spatially correlated with IGF-1. We also observed a lack of colocalization between IGF-1 and IL-1β with either astrocytes or microglia at any of the time points following ablation. These results suggest that the upregulation of IGF-1 and IL-1β levels within neurons-but not within glial cells-may reflect a plastic mechanism involved in repairing synaptic homeostasis of the overall cellular environment of the cochlear nucleus following bilateral cochlear ablation.
神经元和神经胶质细胞在脑损伤后促进修复的主要机制之一是上调活性依赖性分子,如胰岛素样生长因子 1 (IGF-1) 和白细胞介素-1β (IL-1β)。在听觉系统中,IGF-1 对于恢复听力损失后的突触传递至关重要;然而,IL-1β 是否也参与这个过程尚不清楚。在这项研究中,我们评估了双侧耳蜗消融后成年大鼠耳蜗核腹侧神经元和神经胶质细胞中 IGF-1 和 IL-1β 的表达。在损伤后,与对照动物相比,在 1、7 和 15 天,IGF-1 免疫染色的总平均灰度水平和耳蜗核内细胞的平均灰度水平均显著增加。消融动物耳蜗核中 IL-1β 的表达和分布与 IGF-1 呈时间和空间相关性。我们还观察到,在消融后的任何时间点,IGF-1 和 IL-1β 均与星形胶质细胞或小胶质细胞缺乏共定位。这些结果表明,神经元内 IGF-1 和 IL-1β 水平的上调-而不是神经胶质细胞内的上调-可能反映了一种可塑性机制,该机制参与了双侧耳蜗消融后耳蜗核整体细胞环境中突触稳态的修复。