Bodnar R J, Lattner M, Wallace M M
Pharmacol Biochem Behav. 1980 Dec;13(6):829-33. doi: 10.1016/0091-3057(80)90215-4.
Methionine- and leucine-enkephalin produce mild and transient analgesic effects, presumably because of enzymatic degradation. Administration of high (250 mg/kg) doses of D-phenylalanine retards the degradation process and elicits analgesia which is reversed by naloxone and which summates with electroacupuncture analgesia. The present study evaluated D-phenylalanine's dose-dependent effects upon a non-opioid analgesic treatment, cold-water swims (CWS), and compared this with morphine. following determination of flinch-jump baselines, three groups of rats received respectively either 25, 50 or 100 mg/kg of D-phenylalanine intraperitoneally in three conditions: alone, with CWS (2 degrees C for 3.5 min), and with morphine (5 mg/kg, SC). Parallel controls with saline were also tested. Simultaneous exposure with each minimally analgesic dose of D-phenylalanine reduced significantly the analgesic, but not hypothermic effects of CWS. By contrast, morphine analgesia was unaffected by D-phenylalanine. These data provide further support that different pain-inhibitory systems mediate CWS and morphine analgesia and suggest that activation of one system is capable of exerting collateral inhibition upon the other.
甲硫氨酸脑啡肽和亮氨酸脑啡肽产生轻微且短暂的镇痛作用，推测是由于酶促降解。给予高剂量（250毫克/千克）的D-苯丙氨酸会延缓降解过程并引发镇痛作用，这种镇痛作用可被纳洛酮逆转，并且与电针镇痛作用相加。本研究评估了D-苯丙氨酸对一种非阿片类镇痛治疗——冷水游泳（CWS）的剂量依赖性作用，并将其与吗啡进行比较。在确定退缩-跳跃基线后，三组大鼠在三种情况下分别腹腔注射25、50或100毫克/千克的D-苯丙氨酸：单独注射、与CWS（2摄氏度，持续3.5分钟）同时进行、与吗啡（5毫克/千克，皮下注射）同时进行。还测试了用生理盐水作为平行对照。与每个最低镇痛剂量的D-苯丙氨酸同时接触可显著降低CWS的镇痛作用，但不影响其降温作用。相比之下，吗啡镇痛作用不受D-苯丙氨酸影响。这些数据进一步支持了不同的疼痛抑制系统介导CWS和吗啡镇痛作用，并表明一个系统的激活能够对另一个系统产生旁侧抑制作用。
