Waldbaum Simon, Dudek F Edward
Department of Biomedical Sciences, Anatomy and Neurobiology Section, Colorado State University, Fort Collins, Colorado, USA.
Epilepsia. 2009 Apr;50(4):904-16. doi: 10.1111/j.1528-1167.2008.01939.x. Epub 2008 Dec 15.
The paired-pulse technique has been widely used as a convenient but indirect measure of "inhibition" in hippocampal circuits of normal and epileptic animals. Most investigators have used a single paired-pulse protocol, whereas others have utilized repetitive paired pulses. This study investigated which parameters influence results from paired-pulse tests, focusing on the repetitive paired-pulse technique; it aims to assess how this technique may be used in an unbiased and quantitative manner across animal preparations for comparisons of control and experimental epileptic animals.
The perforant path was stimulated while field potentials were recorded from the granule cell layer under isoflurane anesthesia. Paired-pulse suppression was analyzed as a function of stimulation intensity and interpulse interval and frequency.
Paired-pulse suppression was greater with increased stimulus intensity and decreased interpulse interval (20-100 ms). During repetitive protocols, stimulation frequencies <or=1.0 Hz produced paired-pulse suppression similar to single paired-pulse responses, but caused more paired-pulse suppression between 1.0 and 4.0 Hz at all but the lowest intensities. The amplitude of the population spike produced by the conditioning pulse increased progressively during stimulation at higher frequencies (1.0-4.0 Hz).
The single paired-pulse technique is highly dependent on stimulation parameters, as is the repetitive paired-pulse protocol, which is more variable. To generate reliable, consistent, and unbiased data in comparisons of control and experimental epileptic groups, all parameters should be specified and controlled across experiments. Paired-pulse suppression is susceptible to alterations in many mechanisms, and, therefore, represents a circuit response rather than an assay of gamma-aminobutyric acid (GABA)ergic inhibition in epilepsy research.
配对脉冲技术已被广泛用作一种便捷但间接的方法，用于测量正常和癫痫动物海马回路中的“抑制”。大多数研究人员使用单一的配对脉冲方案，而其他研究人员则采用重复配对脉冲。本研究调查了哪些参数会影响配对脉冲测试的结果，重点关注重复配对脉冲技术；旨在评估如何以无偏且定量的方式在不同动物制剂中使用该技术，以比较对照和实验性癫痫动物。
在异氟烷麻醉下，刺激穿通通路，同时从颗粒细胞层记录场电位。分析配对脉冲抑制作为刺激强度、脉冲间隔和频率的函数。
随着刺激强度增加和脉冲间隔减小（20 - 100毫秒），配对脉冲抑制增强。在重复方案中，刺激频率≤1.0赫兹时产生的配对脉冲抑制与单个配对脉冲反应相似，但在除最低强度外的所有强度下，1.0至4.0赫兹之间会导致更多的配对脉冲抑制。在较高频率（1.0 - 4.0赫兹）刺激期间，条件脉冲产生的群体峰电位幅度逐渐增加。
单一配对脉冲技术高度依赖于刺激参数，重复配对脉冲方案也是如此，且其变化更大。为了在对照和实验性癫痫组的比较中生成可靠、一致且无偏的数据，所有参数在实验中都应明确规定并加以控制。配对脉冲抑制易受多种机制改变的影响，因此，在癫痫研究中它代表的是一种回路反应，而非γ-氨基丁酸（GABA）能抑制的测定。
