明适应过程中SD大鼠视锥细胞反应的变化规律

1、明适应过程中SD大鼠视锥细胞反应的变化规律         07-08-27 15:41:00     编辑：studa20            作者：顾永昊 张作明 侯豹可 郭群 李莉 龙潭 【关键词】  视锥细胞Properties of rat cone response during light adaptation【Abstract】 

2、 AIM:  To investigate the properties of rat cone response during light adaptation. METHODS:  Thirty rats were divided into 3 groups. Their 0.5 Hz and 20 Hz cone response was recorded respectively in adapted dark and 10 s, 5, 10, 15, 20, 25 and 30 min after background light was turned on. T

3、he stimulus intensities for the three group were 1.1, 3.5 and 11.0 cdsm-2, respectively. RESULTS:  There were some small oscillatory waves overlapped on the 0.5 Hz response bwave. For the 0.5 Hz response, with light adaptation, all three intensities' implicit time were shortened after the l

4、ighton, shortest at about 10 min, and prolonged again after then. The amplitudes also decreased after the lighton. However, with high intensity, the amplitude began to increased at about 5 min, reached an asymptotic state at 10-15 min but didn't reach the dark adapted level. For the 20 Hz respon

5、se, the low intensity's implicit time delayed during light adaptation while that of the high intensity's shortened in the whole course. The low intensity's amplitude decreased after the lighton while that of high intensity' increased and reached an asymptotic state at 10-15 min, whic

6、h was larger than that in dark adapted level. CONCLUSION:  The stimulus frequency of 20 Hz, with the intensity of at least 3.5 cdsm-2 and the duration for light adaptation more than 10 minutes, is proved better in recording the rat cone response. The changes of rat cone response during the ligh

7、t adaptation may reflect the summary effects of rods, cones and more neuromodulatary cells.【Keywords】 cone; light adaptation; ratssm-2的刺激光强，记录0.5 Hz及20 Hz反应. 结果：高光强时，0.5 Hz反应b波上叠加有子波. 明适应开始后，0.5 Hz反应b波的潜伏期开始缩短，在10 min左右达到最低，之后又开始延长；幅值也出现下降，低光强（1.1 cdsm-2）时，其幅值基本一直下降，高光强（110.0 cdsm-2）时，幅值很快又增加，并在1015

8、 min时达到最高，但一直未达到暗适应水平. 20 Hz反应，1.1 cdsm-2光强P1波潜伏期持续延长，3.5 cdsm-2光强在经历一个短暂的延长后缩短，在10 min时达到最低，随后又开始延长，110.0 cdsm-2光强在背景光打开后，潜伏期持续缩短，在1015 min后达到平台期；1.1 cdsm-2光强P1波的幅值持续下降，3.5，110.0 cdsm-2光强在经历短时间下降即开始增加，特别是在110.0 cdsm-2光强，其幅值几乎没有下降阶段，在1015 min达到最高，之后也进入平台期. 结论：在记录SD大鼠视锥细胞反应时，使用刺激频率为20 Hz较好，刺激光强应至少为3.

9、5 cdsm-2，明适应1015 min进行记录以保证结果的稳定性. 明适应过程中，视锥反应的发展变化反映了视锥、视杆细胞及更高水平神经调制细胞的综合作用.【关键词】 视锥细胞； 明适应； 大鼠0引言动物的生存环境决定了其视网膜光感受器的光谱及分布特性1. 大鼠作为夜行性动物，视网膜中主要为视杆细胞，视锥细胞只占约1%-32. 相对于暗适应视网膜电图（scotopic electroretinogram, ScotERG），大鼠明适应视网膜电图（photopic electroretinogram, PhotERG）的幅值要低得多，且较难记录，目前多通过在刺激野中施加一定的背景光，或是闪烁反应

10、来析出. 人明适应过程中ERG的幅值会逐渐升高，潜伏期也逐步缩短3；小鼠也有相似的情况4. 我们通过给SD大鼠施加不同刺激光强，记录明适应过程中0.5 Hz及20 Hz闪烁反应随时间及光强的变化规律，为客观评价大鼠视锥细胞反应提供依据.1材料和方法1.1动物二级成年雄性SD大鼠30只（第四军医大学实验动物中心），约10 wk龄，体质量250300 g，外眼及检眼镜检查无异常，随机分为3组，每组10只. 予以12 h明暗交替光照，不限食水，室温保持在2225.1.2视网膜电图记录按我实验室建立的方法对大鼠进行记录5. 3组大鼠分别使用1.1，3.5，11.0 cdsm-2的刺激光强，记录闪光频率为0.5 Hz及20 Hz的反应，各叠加3及10次. 首先在暗适应状态记录，然后在打开背景光后10 s和5，10，15，20，25及30 min时连续记录.2结果低光强时，0.5 Hz反应b波为单峰，当光强达到3.5 cdsm-2时变为双峰，光强为11.0 cdsm-2时成为三峰，未出现明显a波. 20 Hz反应类似正弦波，不同光强间波形无显著差别（Fig 1）.图1不同刺激光强下背景光打开后10 min所记录出的0.5 Hz及20 Hz反应的波形(略)明适应开始后：0.5 Hz反应b波的潜伏期开始缩短，10 min左右达到最低，之后开始延长（Fig 2A）；幅值