Garris P A, Wightman R M
Department of Chemistry, University of North Carolina at Chapel Hill 27599-3290.
J Neurosci. 1994 Jan;14(1):442-50. doi: 10.1523/JNEUROSCI.14-01-00442.1994.
The regulation of extracellular dopamine (DA) concentrations was examined and compared in vivo in four projection fields of mesotelencephalic dopaminergic neurons with fast-scan cyclic voltammetry at carbon-fiber microelectrodes. Transient electrical stimulation of ascending DA fibers in a near physiological range of frequencies (10-20 Hz) elicited similar levels of extracellular DA in the medial prefrontal cortex (MPFC), basal lateral amygdaloid nucleus (BAN), caudate-putamen (CP), and nucleus accumbens (NAc) despite the documented 90-fold disparity in DA tissue levels and terminal density. However, marked differences were observed in the dynamics and overall frequency dependence of the evoked synaptic overflow of DA. These differences are due to the significantly different rates of release and uptake found in each of the four regions. For example, rate constants for the release of the four regions. For example, rate constants for the release and uptake of DA were similar in the MPFC and BAN but approximately 8 and 50 times less, respectively, than that in the CP and NAc. When the parameters were normalized to endogenous DA tissue content, a unique picture emerged: compared to all other regions, relative release was 10-fold greater in the MPFC while relative uptake was at least 10 times less in the BAN. The results further differentiate the functional characteristics of mesotelencephalic dopaminergic systems and demonstrate the regiospecific nature of DA neural transmission in the brain. In addition, the regulation of extracellular DA levels in the MPFC and BAN is suitable for the "long-range" transfer of chemical information in the brain and is consistent with a hypothesis of extrasynaptic neurotransmission.
运用碳纤维微电极通过快速扫描循环伏安法，在中脑多巴胺能神经元的四个投射区域对细胞外多巴胺（DA）浓度的调节进行了体内研究和比较。在接近生理频率范围（10 - 20赫兹）对上行DA纤维进行短暂电刺激时，尽管已记录到DA组织水平和终末密度存在90倍的差异，但在内侧前额叶皮质（MPFC）、基底外侧杏仁核（BAN）、尾状核 - 壳核（CP）和伏隔核（NAc）中引发的细胞外DA水平相似。然而，在DA诱发的突触溢出的动力学和总体频率依赖性方面观察到显著差异。这些差异是由于在四个区域中发现的释放和摄取速率明显不同。例如，四个区域的释放速率常数。例如，DA在MPFC和BAN中的释放和摄取速率常数相似，但分别比CP和NAc中的约低8倍和50倍。当将这些参数归一化为内源性DA组织含量时，出现了一幅独特的图景：与所有其他区域相比，MPFC中的相对释放量高10倍，而BAN中的相对摄取量至少低10倍。这些结果进一步区分了中脑多巴胺能系统的功能特征，并证明了大脑中DA神经传递的区域特异性性质。此外，MPFC和BAN中细胞外DA水平的调节适合大脑中化学信息的“长距离”传递，并与突触外神经传递的假设一致。
