Hebert G W, Baumeister A A, Nagy M
Department of Psychology, Louisiana State University, Baton Rouge 70803.
Neuropharmacology. 1990 Aug;29(8):771-7. doi: 10.1016/0028-3908(90)90131-a.
Previous studies have shown that morphine, injected into the substantia nigra of rats, had an antinociceptive effect on the tail-flick test. However, due to a transient behavioral stimulant effect of morphine, given intranigrally, valid tail-flick latencies cannot be obtained prior to 30 min after the injection into the nigra. In order to examine the effect of morphine (5-20 micrograms), injected into the nigra, on the nociceptive tail-flick reflex at earlier times, animals were anesthetized with either halothane or ketamine (100 or 150 mg/kg, i.m.). Halothane blocked the analgesic effect of intranigrally administered morphine. However, a dose-related antinociceptive effect of morphine was observed in ketamine-anesthetized rats. This effect was demonstrable at 5 min after the injection into the nigra animals that received the small dose of ketamine. This finding provides further evidence that the substantia nigra plays an important role in opiate-induced antinociception.
先前的研究表明，向大鼠黑质注射吗啡，在甩尾试验中具有抗伤害感受作用。然而，由于经黑质内注射的吗啡具有短暂的行为兴奋作用，在注射到黑质后30分钟之前无法获得有效的甩尾潜伏期。为了研究注射到黑质中的吗啡（5-20微克）在更早时间对伤害性甩尾反射的影响，动物用氟烷或氯胺酮（100或150毫克/千克，肌肉注射）麻醉。氟烷阻断了经黑质内注射吗啡的镇痛作用。然而，在氯胺酮麻醉的大鼠中观察到了吗啡剂量相关的抗伤害感受作用。在注射到接受小剂量氯胺酮的黑质动物后5分钟即可证明这种作用。这一发现进一步证明黑质在阿片类药物诱导的抗伤害感受中起重要作用。
