Takada Shunsuke, Kinoshita Junzo, Iwata Noriaki, Imaoka Masako, Tani Yoshiro
a Medicinal Safety Research Laboratories , Daiichi Sankyo Co., Ltd., Edogawa-ku , Tokyo , Japan.
Curr Eye Res. 2017 Sep;42(9):1302-1307. doi: 10.1080/02713683.2017.1304561. Epub 2017 May 30.
To investigate the response characteristics and retinal origin of the photopic negative response (PhNR) of the electroretinograms (ERGs) in dogs.
Photopic ERGs were elicited by white flash stimuli of different intensities under a steady white background illumination in four anesthetized dogs. These ERGs were also recorded in the same manner after intravitreal injection of tetrodotoxin (TTX). Additionally, retinal localization of voltage-gated sodium channel Nav 1.6 was assessed by immunohistochemistry.
The amplitude of the a-wave and the PhNR was increased as the stimulus intensity was raised, while the amplitude of the b-wave was peaked at the moderate stimulus intensity of 3.09 cd·s/m. TTX greatly attenuated the PhNR, while the reduction in the b-waves and a-wave was mild or insignificant. Nav 1.6-expression was specifically detected on the retinal ganglion cells (RGCs).
Our results are consistent with the PhNR primarily derived from the inner retina including RGCs in dogs, suggesting that the PhNR can be used to monitor function of these retinal components in dogs.
研究犬视网膜电图（ERG）明视负反应（PhNR）的反应特性及视网膜起源。
在四只麻醉犬的稳定白色背景照明下，用不同强度的白色闪光刺激诱发明视ERG。在玻璃体内注射河豚毒素（TTX）后，也以同样的方式记录这些ERG。此外，通过免疫组织化学评估电压门控钠通道Nav 1.6的视网膜定位。
随着刺激强度增加，a波和PhNR的振幅增大，而b波振幅在3.09 cd·s/m的中等刺激强度时达到峰值。TTX极大地减弱了PhNR，而b波和a波的减小则轻微或不明显。在视网膜神经节细胞（RGCs）上特异性检测到Nav 1.6表达。
我们的结果与PhNR主要源自犬包括RGCs在内的内视网膜一致，表明PhNR可用于监测犬这些视网膜成分的功能。
