Voltammetric study of extracellular dopamine near microdialysis probes acutely implanted in the striatum of the anesthetized rat
Voltammetric study of extracellular dopamine near microdialysis probes acutely implanted in the striatum of the anesthetized rat
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DOI：
10.1016/j.jneumeth.2005.02.002
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发表时间：
2005-08-15
影响因子：
3
通讯作者：
Michael, AC
中科院分区：
文献类型：
--
作者：
Borland, LM;Shi, GY;Michael, AC
建立体内微透析方法来定量测定脑细胞外间隙中的多巴胺浓度是一个重要而又具有挑战性的目标。挑战的来源是在活体实验中直接测量多巴胺的微透析回收率的困难。无论采用传统的还是无净助渗剂的方法，定量微渗析都需要回收率。结合扩散和主动转运过程的微透析的数值模型表明，多巴胺的回收受到发生在离探针最近的组织中的过程的强烈影响。一些证据表明，在植入探针的过程中，邻近探针的组织会被破坏。因此，本研究的目的是进一步确定探针附近的组织是否受到破坏，如果是的话，这种破坏是否会影响多巴胺的恢复。实验用微透析探针急性植入水合氯醛麻醉大鼠的纹状体内。使用碳纤维伏安微电极在探针附近的三个位置监测细胞外多巴胺：紧邻探针，距探针220~250微米，距探针1 mm。在30分钟的时间内缓慢降低探针，使透析液中的多巴胺水平稳定在低纳摩尔范围内，并在实验开始时部分对TTX敏感。从电极植入后2小时开始，在电刺激内侧前脑束和注射多巴胺摄取抑制剂诺米芬新的过程中，用快速扫描循环伏安法监测多巴胺。本研究结果表明，急性植入麻醉大鼠纹状体内的微透析探针至少延伸了220微米的多巴胺释放和摄取活性梯度。(C)2005 Elsevier B.V.保留所有权利。
Establishing in vivo microdialysis methods for the quantitative determination of dopamine concentrations in the extracellular space of the brain is an important yet challenging objective. The source of the challenge is the difficulty in directly measuring the microdialysis recovery of dopamine during an in vivo experiment. The recovery value is needed for quantitative microdialysis, regardless of whether conventional or no-net-flux methods are used. Numerical models of microdialysis that incorporate both diffusion and active transport processes suggest that dopamine recovery is strongly affected by processes occurring in the tissue closest to the probe. Some evidence suggests that the tissue adjacent to the probe becomes disrupted during probe implantation. Hence, the objective of the present study was to further identify whether the tissue adjacent to the probe is disrupted and, if so, whether that disruption might affect dopamine recovery. The experiments were conducted with microdialysis probes implanted acutely in the striatum of rats anesthetized with chloral hydrate. Carbon fiber voltammetric microelectrodes were used to monitor extracellular dopamine at three sites near the probes; immediately adjacent to the probe, 220-250 mu m from the probe, and 1 mm from the probe. Probes were lowered slowly over a 30 min period, so that dialysate dopamine levels were stable, in the low nanomolar range, and partially TTX-sensitive by the time experiments began. Starting 2 h after probe implantation, dopamine was monitored by fast-scan cyclic voltammetry during electrical stimulation of the medial forebrain bundle and during administration of the dopamine uptake inhibitor, nomifensine. The findings of this study show that a gradient of dopamine release and uptake activity extends at least 220 mu m from microdialysis probes implanted acutely in the striatum of the anesthetized rat. (c) 2005 Elsevier B.V. All rights reserved.