Sarkar D K, Gottschall P E, Meites J, Horn A, Dow R C, Fink G, Cuello A C
Neuroscience. 1983 Nov;10(3):821-30. doi: 10.1016/0306-4522(83)90219-1.
The accumulation and release of [3H]dopamine by the median eminence in vitro was studied after treatments with different pharmacological agents, to determine whether such a procedure would be useful for measuring neuronal activity in the tuberoinfundibular dopaminergic system. The accumulation of [3H]dopamine was temperature, time, and sodium dependent, and reduced by unlabelled dopamine and by a potent dopamine uptake blocker, nomifensine. The outflow of tritium was studied after blocking the oxidative deamination of dopamine by nialamide. The outflow of tritium was elicited consistently by biphasic square wave electrical pulses and by high molarity potassium ions. The response to electrical stimulation was dependent largely on calcium and partially on sodium. The response to high molarity potassium ions was reduced in the absence of calcium ions. The response to electrical stimulation was increased by nomifensine and by a dopaminergic antagonist, haloperidol, and was reduced by dopamine and by a dopaminergic agonist, piribedil. The inhibitory action of dopamine was antagonized by haloperidol. These results indicate the existence of uptake and release mechanisms in the tuberoinfundibular dopamine neurons, and suggest that dopamine may inhibit its own release via dopaminergic receptors. This in vitro method may be useful for measuring dopamine uptake and release by tuberoinfundibular dopaminergic neurons.
在用不同药理剂处理后，对体外正中隆起中[3H]多巴胺的积累和释放进行了研究，以确定这样的程序是否可用于测量结节漏斗多巴胺能系统中的神经元活性。[3H]多巴胺的积累依赖于温度、时间和钠，并且会被未标记的多巴胺和一种有效的多巴胺摄取阻滞剂诺米芬辛所减少。在用尼亚酰胺阻断多巴胺的氧化脱氨基作用后，研究了氚的流出情况。双相方波电脉冲和高摩尔浓度钾离子能持续引发氚的流出。对电刺激的反应很大程度上依赖于钙，部分依赖于钠。在没有钙离子的情况下，对高摩尔浓度钾离子的反应会降低。诺米芬辛和一种多巴胺能拮抗剂氟哌啶醇会增强对电刺激的反应，而多巴胺和一种多巴胺能激动剂匹立哌唑会降低该反应。多巴胺的抑制作用会被氟哌啶醇拮抗。这些结果表明结节漏斗多巴胺神经元中存在摄取和释放机制，并提示多巴胺可能通过多巴胺能受体抑制其自身的释放。这种体外方法可能有助于测量结节漏斗多巴胺能神经元对多巴胺的摄取和释放。
