使用电生理评估功能，在啮齿动物的视网膜和远程肢体缺血预适应的保护作用
Summary
The electroretinogram (ERG) is an electrical potential generated by the retina in response to light. This paper describes how to use the ERG to assess retinal function, in dark-adapted rats, and how it can be can be used to assess a neuroprotective intervention, in the present case remote ischemic preconditioning.
Abstract
The ERG is the sum of all retinal activity. The ERG is usually recorded from the cornea, which acts as an antenna that collects and sums signals from the retina. The ERG is a sensitive measure of changes in retinal function that are pan-retinal, but is less effective for detecting damage confined to a small area of retina. In the present work we describe how to record the ‘flash’ ERG, which is the potential generated when the retina is exposed to a brief light flash. We describe methods of anaesthesia, mydriasis and corneal management during recording; how to keep the retina dark adapted; electrode materials and placement; the range and calibration of stimulus energy; recording parameters and the extraction of data. We also describe a method of inducing ischemia in one limb, and how to use the ERG to assess the effects of this remote-from-the-retina ischemia on retinal function after light damage. A two-flash protocol is described which allows isolation of the cone-driven component of the dark-adapted ERG, and thereby the separation of the rod and cone components. Because it can be recorded with techniques that are minimally invasive, the ERG has been widely used in studies of the physiology, pharmacology and toxicology of the retina. We describe one example of this usefulness, in which the ERG is used to assess the function of the light-damaged retina, with and without a neuroprotective intervention; preconditioning by remote ischemia.
Introduction
ERG的是由视网膜响应于光产生的，并且从眼睛的角膜表面记录的电势。当记录条件精心管理，ERG的可以以各种不同的方式来评估视网膜功能被使用。在这里，我们介绍了如何记录“闪光ERG”，时产生的视网膜暴露在一个简短的，明亮的闪光在Ganzfeld背景呈现的潜力。该Ganzfeld分散的均匀光与光的闪光灯到达视网膜整体大致均匀。如果视网膜记录前暗适应和暗适应被保持为动物准备用于记录，ERG的获得是通过两个杆和视锥感光细胞生成的。
暗适应闪光ERG的具有特征的波形，这已在两个方面进行了分析。首先，ERG的波形的早期和晚期成分被区分开来，并与神经元的序人活化在视网膜上。最早的组件是一个短潜伏期负向电位的一个波（ 图1）。这之后是一个正向电位，称为b波。 b波的上升阶段表示振荡，这被认为是一个单独的部件（振荡电位或有机磷）。在一个波被认为是由光感受器产生，b波由内核层细胞和有机磷由无长突细胞1。
根据刺激强度，反应非常昏暗闪烁称为暗门槛响应是可能的。暗视阈响应被理解为从视网膜神经节细胞2-4生成的。第二，闪光ERG可以通过光适应来分离，或通过两个闪光协议如下所述，成棒状和锥驱动的组件。明视下的条件下，一个波是在大鼠未检测到，因为锥体人口低，但有机磷和b波是明确5。在灵长类动物，其视网膜具有较高的人口锥，既杆状和锥途径产生可探测的一个波6。
常从闪速ERG提取两个有用措施是a-和b-波的振幅，测量为在图1中，与图2中所示的典型闪光的反应。当感光体人口被减少，例如通过暴露于破坏力亮光，ERG的所有成分减少。神经保护措施，如远程缺血预处理（RIP），可以由a-和b-波（ 图3）的振幅的保存进行验证。综上所述，ERG的分析使得健康，光损伤和neuroprotected视网膜之间的比较。
Protocol
Representative Results
Discussion
上述的暗适应闪光ERG方法是评估在大鼠视网膜功能的可靠方法。两者的a波和b波被光伤害减少。远程缺血预处理减轻光损伤诱导的减少在一个波和B波。这种防护视网膜功能的建议，远程缺血性预处理已引起神经保护作用，类似其他形式的防护预处理，如缺氧，缺血和运动8-10。记录设置中，光刺激的参数，和动物的状态 – 记录ERG的信号是由三组因素来决定。
录像设置
<…Disclosures
The authors have nothing to disclose.
Acknowledgements
作者感谢沙龙Spana夫人的鼠害监测，处理和试验的帮助。博士的资金支持已经由悉尼大学和澳大利亚研究中心卓越视觉提供的。
Materials
| PC computer | |||
| Powerlab, 4 channel acquistion hardware | AD Instruments | PL 35044 | Acquistion of ERG |
| Animal Bio Amp | AD Instruments | FE 136 | Amplifier for ERG |
| Lab chart | AD Instruments | Signal collection software | |
| Ganzfield | Photometric solutions | FS-250A | Light stimulus |
| Ganzfield operating system | Photometric solutions | ||
| Research Radiometer | International light technologies | ILT-1700 | calibrate light series |
| Lux meter | LX-1010B | check red light illumanation | |
| Excel | microsoft | ||
| Lead wires | AD Instruments | Connect postive, negative ground electrodes to amplifier | |
| Lead wires -aligator | AD Instruments | ground ganzfield and acquistion hardware to computer | |
| Platinum wire 95% | A&E metals | postive electrode | |
| Mouth electrode Ag/AgCl Pellet | SDR | E205 | negative electode |
| 26 gauge needle | BD | ground electode | |
| Water pump | |||
| Water bath | |||
| Tubing | |||
| Homeothermic blanket system with flexible probe | Harvard Appartus | 507222F | |
| Atropine 1% w/v | Bausch & Lomb | topical mydriasis | |
| Proxmethycaine 0.5% w/v | Bausch & Lomb | topical anaesthetic | |
| Visco tears eye drops | Novartis | carbomer polymer | |
| Thread | retract eye lid | ||
| Tweezers | |||
| Reusable adhesive | Blu tac | Dim red headlamp. Affix electrodes | |
| Absorbent bedding | |||
| Ketamil – ketamine 100 mg/ml – 50 ml | Troy Laboratories Pty Ltd | dissociative | |
| Xylium – Xylazine 100 mg/ml – 50 ml | Troy Laboratories Pty Ltd | muscle relaxant | |
| Scale |
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