大鼠视网膜神经节细胞的电生理学与形态学特性

Electrophysiological and morphological features of retinal ganglion cells in rats

目的 观察 Wistar大鼠视网膜神经节细胞 (RGCs)的电生理学和形态学特性 ,并分析其在视觉信号传导中的作用。 方法 获得 30只出生后 7～ 30 d Wistar大鼠 112个 RGCs的膜片钳全细胞记录 ,记录其静息膜电流 (RMP) ,电压钳下给予 2 m V的超极化电流 ,记录输入阻抗 (IR) ,然后注入不同强度的去极化电流 ,诱发其产生动作电位 (AP) ;同时向细胞内注入生物素进行组织学染色 ,测量细胞直径。 结果 去极化电流诱发 RGCs产生 3种 AP类型 :单峰型 (2 5个 RGCs)、瞬变型 (4 0个 RGCs)、持续型 (4 7个RGCs)。 3种类型 RGCs的电生理学特性差异有显著性的意义 (P<0 .0 5 )。 5 7.14 %瞬变型 RGCs细胞体直径为 14～ 16 μm,6 2 .5 0 %持续型 RGCs细胞体直径为 10～ 12 μm。持续型与瞬变型 AP最大频率差异有显著性的意义 (P<0 .0 5 )。 结论 RGCs的单峰型电生理学特性是发育过程中的一种前期不成熟状态 ;RGCs形成的持续型和瞬变型电生理学特性对视网膜传导精细分辨力的稳态通路和传导快速运动的瞬态通路的信息编码具有重要作用 ;RGCs的电生理学和形态学特性有一定相关性。

Objective To observe the electrophysiological and morphological features of retinal ganglion cells (RGCs) in rats, and investigate its effect on the visual signal conduction. Methods Whole cell recordings were obtained from 112 RGCs of 30 rats at the age of 7-30 days. Resting membrane potential (RMP) was recorded, and input impedance was noted after given 2 mV hyperpolarizing current by voltage clamp. The action potential (AP) was induced by deplorizing current at different densities. The histological staining was actualized by injecting with biotin into the RGCs, and the diameter of the cells was measured. Results Three different discharge patterns of RGCs in response to maintained depolarizing currents were recorded: single spike (25 RGCs), transient firing (40 RGCs), and sustained firing (47 RGCs). The diameter was 14-16 μm in 57.14% transient firing RGCs, and 10-12 μm in 62.50% sustained firing RGCs. The maximum frequency of AP of sustained firing RGCs was significantly higher than that of transient firing RGCs (P<0.05). Conclusion The single firing of RGCs was an immature electrophysiological feature. The electrophysiological features of transient firing and sustained firing RGCs may be important to make the visual information code in spatial and temporal pathway. The electrophysiological and morphological features of RGCs in rats may be correlated with each other.