Porcine global flash multifocal electroretinogram: Possible mechanisms for the glaucomatous changes in contrast response function
Porcine global flash multifocal electroretinogram: Possible mechanisms for the glaucomatous changes in contrast response function
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DOI：
10.1016/j.visres.2008.05.006
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发表时间：
2008-07-01
期刊：
影响因子：
1.8
通讯作者：
Wong, Fulton
中科院分区：
文献类型：
--
作者：
Chu, Patrick H. W.;Chan, Henry H. L.;Wong, Fulton
目的：本研究的目的是通过药理学解剖方法，结合刺激对比变化的方法，更好地了解细胞对猪全球闪变mfERG的贡献，该方法已被用于证明人类青光眼mfERG的变化。方法：对10头6周龄约克郡猪的14只眼进行不同刺激对比设置（99%、65%、49%、29%）的全局闪烁mferg，分别在对照条件下和吸入异氟醚（ISO）、注射河河毒素（TTX）和n -甲基- d -天冬氨酸（NMDA）抑制视网膜内反应后进行记录。通过注射2-氨基-4-磷酸丁酸（APB）和顺式-2,3-哌啶二羧酸（PDA）分离ON和off通路反应。结果猪全脑闪变mfERG由早期直接成分（DC）和晚期诱导成分（IC）组成。ISO和TTX去除视网膜内部对IC的贡献；NMDA的应用进一步消除了直流中的振荡小波，并去除了残留的IC波形。内层视网膜向直流电输出规则的振荡样小波（W1、W2和W3），并形成IC。去除内层视网膜后，猪的全局闪烁mfERG波形与传统mfERG刺激获得的波形相当。其余波形（平滑DC）主要由APB或PDA注射后显示的ON和off双极细胞贡献。光感受器对N1的前缘贡献较小的信号。结果表明，直流电的对比度响应函数特性是由视网膜内振荡样小波贡献的。结论我们认为，猪整体闪光mfERG的DC主要由光感受器和ON- and - off双极细胞组成，其中视网膜内活动通过叠加的规则小波部分塑造了DC。然而，IC主要是由视网膜内部活动。DC的对比响应函数由视网膜外响应和视网膜内响应的振荡样小波组成。两者在刺激的对比度调制过程中具有不同的特征，其中视网膜内反应的W2的变化似乎独立于对比度调制。直流电对比响应特征主要取决于视网膜内活动的相对贡献；视网膜内细胞的丢失可能改变直流对比度响应函数，使其趋于线性。(c) 2008 Elsevier Ltd.版权所有。
Purpose: The aim of this study was to obtain a better understanding of the cellular contributions to the porcine global flash mfERG by using a pharmacologic dissection method, together with the method using variation of stimulus contrast which has been used to demonstrate mfERG changes in human glaucoma.Methods: Global flash mfERGs with different stimulus-contrast settings (99%, 65%, 49% or 29%) were recorded from 14 eyes of ten 6-week-old Yorkshire pigs in control conditions and after suppression of inner retinal responses with inhalation of isoflurance (ISO), and injections of tetrodotoxin (TTX) and N-methyl-D-aspartic acid (NMDA). ON- and OFF-pathway responses were isolated by injection of 2-amino-4-phosphonobutyric acid (APB) and cis-2,3-piperidinedicarboylic acid (PDA). ResultsThe porcine global flash mfERG consisted of an early direct component (DC) and a late induced component (IC). ISO and TTX removed inner retinal contributions to the IC; NMDA application further abolished the oscillatory wavelets in the DC and removed the residual IC waveform. The inner retina contributed regular oscillation-like wavelets (W1, W2 and W3) to the DC and shaped the IC. After removing the inner retinal contributions, the porcine global flash mfERG waveform becomes comparable to that obtained with conventional mfERG stimulation. The remaining waveform (smoothed DC) was mainly contributed by the ON- and OFF-bipolar cells as revealed after APB or PDA injection. Photoreceptors contributed a small signal to the leading edge of N1. The characteristic of contrast response function of DC was demonstrated to be contributed by the inner retinal oscillation-like wavelets.ConclusionWe believe that the DC of the porcine global flash mfERG is mainly composed of contributions from photoreceptors, and ON- and OFF-bipolar cells, where inner retinal activity partially shaped the DC with superimposed regular wavelets. However, the IC is dominated by inner retinal activity. The contrast response functions of DC consisted of both outer retinal response and oscillation-like wavelets of the inner retinal response. Both contain different characteristics during contrast modulation of the stimulus, where the changes of W2 of the inner retinal response seem independent of contrast modulation. The DC contrast response feature depends mainly on the relative contribution of inner retinal activities; the loss of inner retinal cells may alter the DC contrast response function, making it tend toward linearity. (c) 2008 Elsevier Ltd. All rights reserved.