McCown T J, Napier T C, Breese G R
Pharmacol Biochem Behav. 1986 Jul;25(1):63-9. doi: 10.1016/0091-3057(86)90231-5.
The present study evaluated the effects of chronic electrode implantation on stimulus-dependent increases of the dopamine (DA) metabolite dihydroxyphenylacetic acid (DOPAC) in relationship to a well characterized in vivo model which used electrical stimulation from acute electrode placements in the nigro-striatal pathway. Five days after bipolar electrodes were implanted into the nigro-striatal pathway, non-contingent electrical stimulation (100 microA, 25 Hz, 1.5 msec duration, 20 min session) did not change DA or DOPAC concentrations in the caudate nucleus, nucleus accumbens, or olfactory tubercles, whereas the same stimulation from acute electrode placements causes significant ipsilateral increases in caudate DOPAC. Although DOPAC concentrations did not change when these chronically implanted electrodes were stimulated, similar chronic electrode placement supported intracranial self-stimulation (ICSS). In order to examine the effects of self-stimulation on DOPAC concentrations, five ICSS test groups were established for comparison: implanted only, trained only, minimum response rate, 50% maximum response rate and maximum response rate. Following a 50 min test session, a comparison of either DA, or DOPAC concentrations across the different ICSS conditions revealed no change for the caudate nucleus, nucleus accumbens or olfactory tubercles. Likewise, there was no change between the stimulated and unstimulated sides within each ICSS group. When a comparison was made between implanted only and maximal ICSS response rate groups for changes in DA or DOPAC concentrations in the frontal cortex, no differences were found. Apparently, chronic electrode implantation abolished the ability to electrically stimulate nigro-striatal dopaminergic neurons under non-contingent conditions, and the relationship between dopaminergic neurons and ICSS appears to be indirect in nature.
本研究评估了慢性电极植入对多巴胺（DA）代谢物二羟基苯乙酸（DOPAC）刺激依赖性增加的影响，该研究与一个特征明确的体内模型相关，该模型使用来自黑质纹状体通路急性电极植入的电刺激。在将双极电极植入黑质纹状体通路五天后，非条件性电刺激（100微安、25赫兹、1.5毫秒持续时间、20分钟疗程）并未改变尾状核、伏隔核或嗅结节中的DA或DOPAC浓度，而来自急性电极植入的相同刺激会导致尾状核DOPAC同侧显著增加。尽管在刺激这些慢性植入电极时DOPAC浓度没有变化，但类似的慢性电极植入支持颅内自我刺激（ICSS）。为了研究自我刺激对DOPAC浓度的影响，建立了五个ICSS测试组进行比较：仅植入、仅训练、最低反应率、50%最大反应率和最大反应率。在进行50分钟的测试疗程后，对不同ICSS条件下的DA或DOPAC浓度进行比较，结果显示尾状核、伏隔核或嗅结节没有变化。同样，每个ICSS组中刺激侧和未刺激侧之间也没有变化。当比较仅植入组和最大ICSS反应率组额叶皮质中DA或DOPAC浓度的变化时，未发现差异。显然，慢性电极植入消除了在非条件性条件下电刺激黑质纹状体多巴胺能神经元的能力，多巴胺能神经元与ICSS之间的关系似乎本质上是间接的。
