Mayer D J, Hayes R L
Science. 1975 May 30;188(4191):941-3. doi: 10.1126/science.1094537.
Analgesia resulting from focal electrical stimulation of the brain of the rat shows tolerance with repeated exposures; this tolerance dissipates after a period of nonstimulation. Addiction to morphine reduces greatly the analgesia produced by electrical stimulation of the brain, which demonstrates cross-tolerance between morphine analgesia and stimulation-produced analgesia. Recovery of the stimulation-produced analgesia is seen after discontinuing administration of morphine. These results suggest that morphine and electrical stimulation produce analgesia by common mechanisms. The fact that tolerance occurs to the analgesic effect of electrical stimulation indicates that tolerance may be an alteration of an endogenous neuronal process.
对大鼠大脑进行局部电刺激所产生的镇痛作用会随着反复刺激而产生耐受性；在一段时间不刺激后，这种耐受性会消失。吗啡成瘾会大大降低电刺激大脑所产生的镇痛效果，这表明吗啡镇痛和刺激产生的镇痛之间存在交叉耐受性。停止给予吗啡后，电刺激产生的镇痛作用会恢复。这些结果表明，吗啡和电刺激通过共同机制产生镇痛作用。电刺激镇痛作用会产生耐受性这一事实表明，耐受性可能是内源性神经元过程的一种改变。
