Walters J R, Bunney B S, Roth R H
Adv Neurol. 1975;9:273-84.
Piribedil and apomorphine can cause a complete but temporary inhibition in firing of the DA-containing neurons. The cells recover to approximately 30 to 40% of the original firing rate, and with subsequent administration of the drug become more and more resistant to further inhibition. At this point they are also resistant to inhibition by other direct- or indirect-acting DA agonists that are normally able to inhibit the firing of DA cells. This effect may be due to an interaction of the DA agonists with the postsynaptic DA receptors, but apomorphine at least is able to inhibit the firing of DA cells directly when iontophoresed onto the DA cell body (Aghajanian and Bunney, 1973). These drugs can block the increase in DA synthesis observed in the absence of impulse flow, indicating a presynaptic site of acttion. Taken together, these results suggest that in interpreting the effects of drugs interacting with the DA systems several points of interaction should be considered.
吡贝地尔和阿扑吗啡可导致含多巴胺（DA）神经元的放电完全但暂时受到抑制。这些细胞恢复到原始放电率的约30%至40%，并且随着后续给药，对进一步抑制变得越来越有抗性。此时，它们对其他通常能够抑制DA细胞放电的直接或间接作用的DA激动剂的抑制也具有抗性。这种效应可能是由于DA激动剂与突触后DA受体相互作用，但至少阿扑吗啡在离子导入到DA细胞体上时能够直接抑制DA细胞的放电（阿加贾尼安和邦尼，1973年）。这些药物可以阻断在无冲动流时观察到的DA合成增加，表明其作用位点在突触前。综上所述，这些结果表明，在解释与DA系统相互作用的药物的作用时，应考虑几个相互作用点。
