【摘要】 采用直流串单方波电刺激鼠尾部引起鼠嘶叫的电流值为动物痛阈指标，观察褪黑素（ Ｍ Ｔ） 对大鼠和小鼠的镇痛作用；进而观察纳络酮的拮抗作用，以探讨 Ｍ Ｔ 的镇痛作用与内源性阿片肽系统的关系。结果表明，ｉｐ Ｍ Ｔ 显著提高大鼠痛阈，具有明显的量效和时效关系；ｉｐ Ｍ Ｔ 也显著提高小鼠痛阈。表明 Ｍ Ｔ 对大鼠和小鼠均可产生显著的镇痛作用。纳洛酮显著拮抗 Ｍ Ｔ 对大鼠、小鼠的镇痛作用，提示 Ｍ Ｔ 的镇痛作用与内源性阿片肽系统有关。更多还原

【Abstract】 Using the vocalization test, we determind the antinociceptive activities of melatonin (MT) in rats and mice. To determine the vocalization threshold,two needle electrodes were inserted into the tail.Electrial stimulation was delivered to the tail from a high frequency, square wave, constant current stimulator,using a frequency of 50 Hz, with pulse width 1 msec and 500 msec trains. The intensity of the current(measured in mA) necessary for induction of vocalization was taken as a measure of nociception. It was showed that ip MT (45～105 mg/kg) raised the nociceptive threshold significantly in rats, with the obvious dose related and time related response. Additionly,ip MT (75～150 mg/kg) increased the nociceptive threshold significantly in mice. It was also showed that naloxone antagonized the antinociceptive activities of ip MT in rats and mice. These findings indicate that melatonin has analgesic effect in rats and mice. Furthermore, the endogenous opioid system may be involved in the analgesic effect of melatonin.更多还原