人和小鼠视网膜双极细胞的形态及功能比较

目的比较人和小鼠视网膜视杆双极细胞形态和药物模拟对光反应的电流特性。方法实验研究。对视网膜冰冻切片行免疫荧光染色，用PKC-α抗体标记视网膜视杆双极细胞，以观察其形态分布特点。在灌流充氧的情况下制备视网膜薄片切片，行视网膜ON型以及OFF型双极细胞的全细胞膜片钳记录。分别在ON型双极细胞和OFF型双极细胞上给予快速加药40 µmol/L LY3414925或100 µmol/L AMPA，诱导出谷氨酸电流，以记录双极细胞模拟对光反应，并比较人和小鼠的谷氨酸电流动力学的差异，人和小鼠各项数据比较采用非参数检验（Mann-Whitney检验）进行处理。结果人和小鼠的视网膜视杆双极细胞形态分布相似，但PKC-α表达略有不同。膜片钳结果显示人视网膜ON型双极细胞的模拟对光反应的上升相的达峰时间为（1.91±0.11）ms，与小鼠视网膜ON型双极细胞（0.83±0.08）ms]相比明显较长（U=0.00，P＜0.01），而人视网膜ON型双极细胞的模拟对光反应恢复时间为（1.34±0.40）ms，明显短于小鼠（20.06±3.07）ms]（U=0.00，P＜0.01）。但人和小鼠视网膜OFF型双极细胞电流动力学即电流幅度人：（143.0±2.1）pA；小鼠：（136.3±2.2）pA]、反应上升时间人：（1.91±0.35）ms；小鼠：（1.28±0.52）ms]和恢复时间人：（220.5±10.8）ms；小鼠：（168.1±29.3）ms]差异均无统计学意义。结论 视杆双极细胞在人和小鼠视网膜中分布位置和形态大致相似。人和小鼠视网膜ON型双极细胞电流特性有差异。

Function and morphological characteristics of bipolar cells in human and mouse retinas

Objective To compare the morphological and electrophysiological properties of human and mouse retinal bipolar cells.Methods This was an experimental study.Immunofluorescence staining on cryosections of the retina was used to study the expression patterns of protein kinase C alpha (PKC-α) in human and mouse retinas.Retinal rod bipolar cells were labeled with PKC-α antibody.Using voltage clamp recording, glutamate currents from retinal ON bipolar cells and OFF bipolar cells were induced by applying 40 μmol/L LY341495 and 100 μmol/L AMPA, respectively.Data were analyzed using nonparametric tests (Mann-Whitney test).Results Retinal rod bipolar cells were similar in mice and humans, with slight differences in the PKC-α expression pattern.Rod bipolar cell bodies were located in the human and mouse INL (inner nuclear layer) with PKC-α staining.Using whole-cell recording, we found that there was a significant difference in LY341495-current kinetics in the human and mouse retinal ON bipolar cells (U=0.00, P＜0.01) but not in the kinetics of the AMPA-induced current, including amplitude (humans: 143.0±2.1 pA;mice: 136.3±2.2 pA), time to peak (humans: 1.91±0.35 ms;mice: 1.28±0.52 ms) and time to recovery (humans: 220.5±10.8 ms;mice: 168.1±29.3 ms) in the OFF bipolar cells.Conclusion Rod bipolar cells are expressed in both mouse and human retinas in a similar pattern with only a slight difference.Our results show the different simulated light response properties between human and mouse retinal ON bipolar cells.