Emmett-Oglesby M W, Herz A
Psychopharmacology (Berl). 1987;92(3):313-9. doi: 10.1007/BF00210836.
Rats were trained to detect the stimulus properties of pentylenetetrazol (PTZ), 16 mg/kg, and prototypic drugs for mu, kappa and sigma opioid receptors were tested for their ability to block or substitute for PTZ. Only the sigma agonist, phencyclidine, showed any capacity for blocking the PTZ stimulus. Drugs with selective kappa or sigma actions did not substitute for PTZ. However, morphine, fentanyl and Mr 2034 did substitute for the PTZ stimulus. This substitution was found to be centrally mediated in that quaternary morphine did not produce a PTZ-like stimulus. In contrast to the substitution of these drugs for PTZ, in rats trained to detect the stimulus properties of fentanyl, no substitution of PTZ for the fentanyl stimulus occurred. In tests of the capacity of various drugs to block the PTZ-like stimulus of mu agonists, the stimulus produced by morphine or fentanyl was blocked by naloxone, diazepam and haloperidol, but not by scopolamine. These results demonstrate that drugs with mu agonist properties show a one-way substitution for the discriminative stimulus produced by PTZ. The observation that haloperidol blocked the PTZ-like stimulus of mu agonists suggests the possible involvement of dopaminergic mechanisms in the mediation of the effect.
训练大鼠检测16毫克/千克戊四氮（PTZ）的刺激特性，并测试μ、κ和σ阿片受体的原型药物阻断或替代PTZ的能力。只有σ激动剂苯环己哌啶显示出任何阻断PTZ刺激的能力。具有选择性κ或σ作用的药物不能替代PTZ。然而，吗啡、芬太尼和Mr 2034确实能替代PTZ刺激。发现这种替代是由中枢介导的，因为季铵化吗啡不会产生类似PTZ的刺激。与这些药物替代PTZ相反，在训练大鼠检测芬太尼刺激特性的实验中，未出现PTZ替代芬太尼刺激的情况。在测试各种药物阻断μ激动剂类似PTZ刺激的能力时，吗啡或芬太尼产生的刺激被纳洛酮、地西泮和氟哌啶醇阻断，但未被东莨菪碱阻断。这些结果表明，具有μ激动剂特性的药物对PTZ产生的辨别性刺激表现出单向替代。氟哌啶醇阻断μ激动剂类似PTZ刺激的观察结果表明，多巴胺能机制可能参与了该效应的介导。
