Kracke George R, Uthoff Katherine A, Tobias Joseph D
Department of Anesthesiology and Perioperative Medicine, University of Missouri School of Medicine, Columbia, MO 65212, USA.
Anesth Analg. 2005 Jul;101(1):64-8, table of contents. doi: 10.1213/01.ANE.0000152617.11003.42.
Glucose or sucrose solutions administered orally provide effective analgesia for procedural pain in neonates. Because analgesia with sugar solutions can be decreased by opioid receptor antagonists, we tested the hypothesis that glucose directly activates opioid receptors. Mu opioid receptors (MOR-1) were expressed in Xenopus oocytes, a well recognized expression system, and glucose was tested for possible agonist, antagonist, and modulatory effects on the receptor. In control experiments, 10 nM of Tyr-D-Ala-Gly-Me-Phe-Gly-ol (DAMGO), a synthetic enkephalin and specific mu agonist, activated the MOR-1, whereas 20 mM of glucose had no effect. In addition, glucose had no effect on the activation of the mu receptor by DAMGO. Finally, glucose did not modulate acute receptor desensitization induced by DAMGO. We conclude that glucose does not directly interact with MOR-1 in an in vitro expression system and that the purported interaction between glucose and the opioid system may be an indirect one, involving release of endogenous opioids.
口服葡萄糖或蔗糖溶液可为新生儿程序性疼痛提供有效的镇痛作用。由于阿片受体拮抗剂可降低糖溶液的镇痛效果，我们检验了葡萄糖直接激活阿片受体的假说。在非洲爪蟾卵母细胞（一种广为人知的表达系统）中表达了μ阿片受体（MOR-1），并测试了葡萄糖对该受体可能的激动、拮抗和调节作用。在对照实验中，10 nM的酪氨酸-D-丙氨酸-甘氨酸-甲硫氨酸-苯丙氨酸-甘醇（DAMGO，一种合成脑啡肽和特异性μ激动剂）激活了MOR-1，而20 mM的葡萄糖则无作用。此外，葡萄糖对DAMGO激活μ受体也无作用。最后，葡萄糖并未调节由DAMGO诱导的急性受体脱敏。我们得出结论，在体外表达系统中，葡萄糖不直接与MOR-1相互作用，葡萄糖与阿片系统之间所谓的相互作用可能是间接的，涉及内源性阿片类物质的释放。
