Izquierdo I, Dalmaz C, Dias R D, Godoy M G
Departamento de Bioquimica, Instituto de Biociencias, Porto Alegre, Brazil.
Behav Neurosci. 1988 Oct;102(5):803-6. doi: 10.1037//0735-7044.102.5.803.
Rats were trained in a step-down inhibitory avoidance task using a 0.3-mA, 2-s, 60 Hz footshock and tested 24 hr later. The animals received, 1 min after training and/or 5 min before testing, an ip injection of saline, ACTH (0.2 microgram/kg), lysine-vasopressin (10 micrograms/kg), epinephrine (5 micrograms/kg), naloxone (0.4 mg/kg), or a combination of naloxone with one of the hormones. Both the posttraining and the pretest injection of the hormones enhanced retention test performance; the enhancement was larger in animals that received the two treatments. Posttraining, but not pretest, naloxone administration also caused an enhancement. However, posttraining naloxone potentiated, and pretest naloxone antagonized, the effect of the concomitantly injected hormones. These data show that the posttraining and the pretest effect of the hormones are independent, are due to different mechanisms, and can be additive. In addition, it does not seem possible to explain posttraining memory facilitation by the hormones as owing to an addition to the reinforcement.
大鼠在使用0.3毫安、2秒、60赫兹足部电击的一步式抑制性回避任务中接受训练，并在24小时后进行测试。动物在训练后1分钟和/或测试前5分钟接受腹腔注射生理盐水、促肾上腺皮质激素（0.2微克/千克）、赖氨酸加压素（10微克/千克）、肾上腺素（5微克/千克）、纳洛酮（0.4毫克/千克），或纳洛酮与其中一种激素的组合。激素的训练后注射和测试前注射均增强了记忆保持测试的表现；在接受两种治疗的动物中增强作用更大。训练后而非测试前给予纳洛酮也会导致增强作用。然而，训练后给予纳洛酮会增强，而测试前给予纳洛酮会拮抗同时注射的激素的作用。这些数据表明，激素的训练后效应和测试前效应是独立的，是由不同机制引起的，并且可以相加。此外，似乎不可能将激素训练后记忆促进解释为是由于强化作用的增加。
