Abbott F V, Etienne P, Franklin K B, Morgan M J, Sewitch M J, Young S N
Department of Psychiatry, McGill University, Montreal, Quebec, Canada.
Psychopharmacology (Berl). 1992;108(1-2):60-6. doi: 10.1007/BF02245286.
The effects of depletion of the serotonin precursor, L-tryptophan, on the threshold and tolerance to cold pressor pain, and the analgesic effect of morphine (10 mg intramuscularly), were tested in a double blind trial on human volunteers. Effects on mood were also assessed using the Profile of Mood States and the Addiction Research Center Inventory (ARCI) Scales. To deplete tryptophan, subjects were fed a tryptophan-deficient amino acid mixture 4.5 h before morphine was administered. Controls received the mixture with tryptophan, which is equivalent to a nutritionally balanced protein. The tryptophan-deficient meal reduced plasma tryptophan more than 70% but had no effect on threshold or tolerance to cold pressor pain. After morphine, tolerance to cold pressor pain increased in controls. Tryptophan depletion abolished this analgesic effect. Pain threshold was not altered by morphine. In subjects with normal tryptophan, the analgesic effect of morphine was predicted by the level of plasma morphine-6-glucuronide, but not by the level of morphine. Morphine increased scores on the LSD scale of the ARCI, but had no effect on other measures of mood. Tryptophan depletion also failed to alter mood in these subjects, who had unusually low depression scores before tryptophan depletion.
在一项针对人类志愿者的双盲试验中，测试了血清素前体L-色氨酸耗竭对冷加压疼痛阈值和耐受性以及吗啡（10毫克肌肉注射）镇痛效果的影响。还使用情绪状态剖面图和成瘾研究中心量表（ARCI）评估了对情绪的影响。为了耗尽色氨酸，在给予吗啡前4.5小时给受试者喂食缺乏色氨酸的氨基酸混合物。对照组接受含色氨酸的混合物，其相当于营养均衡的蛋白质。缺乏色氨酸的餐食使血浆色氨酸减少超过70%，但对冷加压疼痛的阈值或耐受性没有影响。给予吗啡后，对照组对冷加压疼痛的耐受性增加。色氨酸耗竭消除了这种镇痛效果。吗啡未改变疼痛阈值。在色氨酸正常的受试者中，吗啡的镇痛效果由血浆吗啡-6-葡萄糖醛酸水平预测，而非吗啡水平。吗啡使ARCI的LSD量表得分增加，但对其他情绪指标没有影响。色氨酸耗竭也未能改变这些受试者的情绪，这些受试者在色氨酸耗竭前抑郁得分异常低。
