Cone and rod inputs to murine retinal ganglion cells: Evidence of cone opsin specific channels
Cone and rod inputs to murine retinal ganglion cells: Evidence of cone opsin specific channels
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DOI：
10.1017/s0952523805226172
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发表时间：
2005-11-01
影响因子：
1.9
通讯作者：
Gouras, P
中科院分区：
文献类型：
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作者：
Ekesten, B;Gouras, P
为了鉴定小鼠视网膜神经节细胞中的紫外线（UV）和中波长（M）敏感的锥和杆信号，在麻醉的光适应的C57/BL 6小鼠中研究了单个神经节细胞的反应，其中钨微电极驱动通过巩膜和玻璃体到达神经视网膜。在34只小鼠的43个视网膜中检查了154个神经节细胞。在存在和不存在强稳定的橙子适应光的情况下，用紫外（360 nm）或绿色（520 nm）光的漫射闪光和/或脉冲刺激视网膜。在暗适应视网膜中研究了12个神经节细胞，以识别杆的信号。发现三种功能不同的神经节细胞：（1）无自发活动、脉冲幅度大的阶段性反应细胞（31%），（2）自发活动不规则、频率低（5-10 Hz）、脉冲幅度小的强直性反应细胞（60%），（3）无自发活动、脉冲幅度大的阶段性反应细胞（31%），（4）无自发活动、脉冲幅度小的强直性反应细胞（60%），（5）无自发活动、脉冲幅度小的强直性反应细胞（60%）。（3）节律器样细胞（9%），自发活动频率较高（20-40 Hz）。少数细胞（1%）有习惯性反应。遇到的每个细胞都受到弥漫性刺激的影响。更常见的两种类型在刺激的ON或OFF或ON和OFF相位时被激发。III型细胞的反应较弱，有时只能通过关灯来抑制。在光适应状态下，大多数细胞接收来自UV-和M-视锥的相同极性的信号，但UV-视锥的输入通常更占优势，特别是在腹侧视网膜。一部分细胞仅接收来自UV-（18%）或M-（3%）视锥细胞的信号。在极少数情况下（2%），这些锥输入在同一细胞上具有相反的极性。在暗适应状态下，所有细胞对绿色光的敏感度至少比紫外光高出4或5个对数单位。结果表明，共同表达的UV-和M-视锥视蛋白不能普遍存在于小鼠视网膜。一些视锥细胞，特别是UV视锥细胞，在不存在任何功能性M-视锥视蛋白的情况下存在。这就解释了为什么有些神经节细胞只接受来自紫外视锥的输入，而有些神经节细胞则接受来自紫外视锥和M视锥的极性相反的输入。这些结果支持了这样的假设，即小鼠视网膜具有将信号传递到大脑的生理能力，该信号允许感知色彩对比度和色觉。
To identify ultraviolet (UV) and middle- (M) wavelength-sensitive cone and rod signals in murine retinal ganglion cells, single ganglion cell responses were studied in anesthetized, light-adapted C57/BL6 mice with tungsten microelectrodes driven through the sclera and vitreous to the neural retina. One hundred fifty-four ganglion cells were examined in 43 retinas of 34 mice. The retina was stimulated with diffuse flashes and/or pulses of ultraviolet (360 nm) or green (520 nm) light in the presence and absence of a strong steady orange adapting light. Twelve ganglion cells were studied in the dark-adapted retina in order to identify the signals of rods. Three functionally different types of ganglion cells were found: (1) phasic responding cells (31%) with no spontaneous activity and large impulse amplitudes; (2) tonic responding cells (60%) with irregular, low frequency (5-10 Hz) spontaneous activity and smaller impulse amplitudes; and (3) metronome-like cells (9%) with regular, relatively high-frequency (20-40 Hz) spontaneous activity. A few cells (1%) had habituating responses. Every cell encountered was affected by diffuse stimulation. The more common two types were excited at either the ON or OFF or at both the ON and OFF phases of stimulation. Type III cells had weaker responses, sometimes only inhibited by turning off a light. In the light-adapted state, most cells received signals of the same polarity from UV- and M-cones but UV-cone inputs were usually more dominant, especially in ventral retina. A fraction of cells received signals from only UV- (18%) or only M- (3%) cones. In rare cases (2%) these cone inputs had an opposite polarity on the same cell. In the dark-adapted state, all cells were at least four or five logarithmic units more sensitive and more to green than ultraviolet light. The results indicate that co-expression of both UV-and M-cone opsins cannot be ubiquitous in murine retina. Some cones, especially UV cones, exist without the presence of any functional M-cone opsin. This must be the case to explain the presence of ganglion cells that receive inputs only from UV-cones and others that receive inputs of opposite polarity from UV- and M-cones. The results support the hypothesis that murine retina has the physiological capacity to relay signals to the brain that allow the sensing of chromatic contrast and color vision.