Ngo Khanh T, Varner Erika L, Michael Adrian C, Weber Stephen G
Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States.
ACS Chem Neurosci. 2017 Feb 15;8(2):329-338. doi: 10.1021/acschemneuro.6b00383. Epub 2017 Feb 1.
Recently, our laboratory has demonstrated the technical feasibility of monitoring dopamine at 1 min temporal resolution with microdialysis and online liquid chromatography. Here, we monitor dopamine in the rat striatum during local delivery of high potassium/low sodium or nomifensine in awake-behaving rats. Microdialysis probes were implanted and perfused continuously with or without dexamethasone in the perfusion fluid for 4 days. Dexamethasone is an anti-inflammatory agent that exhibits several positive effects on the apparent health of the brain tissue surrounding microdialysis probes. Dopamine was monitored 1 or 4 days after implantation under basal conditions, during 10 min applications of 60 mM or 100 mM K, and during 15 min applications of 10 μM nomifensine. High K and nomifensine were delivered locally by adding them to the microdialysis perfusion fluid using a computer-controlled, low-dead-volume six-port valve. Each day/K/dexamethasone combination elicited specific dopamine responses. Dexamethasone treatment increased dopamine levels in basal dialysates (i.e., in the absence of K or nomifensine). Applications of 60 mM K evoked distinct responses on days one and four after probe implantation, depending upon the presence or absence of dexamethasone, consistent with dexamethasone's ability to mitigate the traumatic effect of probe implantation. Applications of 100 mM K evoked dramatic oscillations in dopamine levels that correlated with changes in the field potential at a metal electrode implanted adjacent to the microdialysis probe. This combination of results indicates the role of spreading depolarization in response to 100 mM K. With 1 min temporal resolution, we find that it is possible to characterize the pharmacokinetics of the response to the local delivery of nomifensine. Overall, the findings reported here confirm the benefits arising from the ability to monitor dopamine via microdialysis at high sensitivity and at high temporal resolution.
最近，我们实验室已证明通过微透析和在线液相色谱法以1分钟的时间分辨率监测多巴胺的技术可行性。在此，我们在清醒行为的大鼠局部给予高钾/低钠或诺米芬辛期间监测其纹状体中的多巴胺。将微透析探针植入大鼠体内，并在灌注液中添加或不添加地塞米松的情况下连续灌注4天。地塞米松是一种抗炎剂，对微透析探针周围脑组织的表观健康具有多种积极作用。在植入后1天或4天的基础条件下、60 mM或100 mM K的10分钟给药期间以及10 μM诺米芬辛的15分钟给药期间监测多巴胺。通过使用计算机控制的低死体积六通阀将高钾和诺米芬辛添加到微透析灌注液中进行局部给药。每种每日/钾/地塞米松组合都会引发特定的多巴胺反应。地塞米松治疗可提高基础透析液中的多巴胺水平（即在不存在钾或诺米芬辛的情况下）。根据是否存在地塞米松，在探针植入后第1天和第4天，60 mM钾的给药引发了不同的反应，这与地塞米松减轻探针植入创伤作用的能力一致。100 mM钾的给药引发了多巴胺水平的剧烈振荡，这与植入微透析探针附近的金属电极处的场电位变化相关。这些结果共同表明了扩散性去极化在对100 mM钾的反应中的作用。以1分钟的时间分辨率，我们发现可以表征对诺米芬辛局部给药反应的药代动力学。总体而言，此处报道的研究结果证实了通过微透析以高灵敏度和高时间分辨率监测多巴胺的能力所带来的益处。
