Elucidation of a Novel Metabolic Pathway of Morphine and Its Physiological Role

我们已经证明，吗啡6-脱氢酶产生的吗啡酮（MO），约9倍（s.c.）注射）和4次（i.c.注射）的吗啡（M）在小鼠中的毒性。经MO预处理后，M的镇痛活性在单次i.c.预处理1小时后下降至对照的20%。MO预处理后，这种作用至少持续168小时。吗啡酮进一步代谢为吗啡酮-谷胱甘肽加合物（MO-GSH），并经豚鼠胆汁排泄。经s.c. MO-GSH无毒性。腹腔注射（500 mg/kg），其致死量约为MO的2倍。本研究的总结如下。1.产生MO的酶活性位于细胞溶质中，在较小程度上位于动物（豚鼠、大鼠、兔、小鼠和仓鼠）各组织（肝、肾、肺、小肠和脑）的微粒体中。2.由M生成MO， ...更多信息 羟基自由基清除剂抑制了微粒体反应，因此，NADPH-细胞色素P-450产生的羟基自由基可能起形成MO的作用。结果表明，MO是由Fe（II）-EDTA-抗坏血酸盐形成的。3.通过与真实样品的比较，还检测并鉴定了痕量的M-GSH和MO-半胱氨酸加合物。4.建立了豚鼠尿和胆汁中MO和M及其非结合代谢物的高效液相色谱测定方法。5.用马来酸二乙酯（500 mg/kg）或与M同时皮下注射石胆酸-3-硫酸酯（25 mg/kg）可使胆汁中MO-GSH排泄量减少，MO排泄量增加。6.豚鼠皮下注射预处理。注射纳洛酮（25 mg/kg）可增加MO和MO-GSH的胆汁排泄。7.通过二维核磁共振光谱法确定MO-GSH的明确结构归属为8（S）-（谷胱甘肽-S-基）二氢吗啡酮。8.在阳性GAB-Mass上观察到典型的三个钠阳离子化离子峰，碘化钠在MO-GSH上。这些钠离子化的阳离子探针可用于代谢产物的检测和确证。少

We have demonstrated that morphinone (MO), which produced by morphine 6-dehydrogenase, gave about 9 times (s.c. injection) and 4 times (i.c. injection) of the toxicity of morphine (M) in mice. By the pretreatment of MO, the analgesic activity of M was decreased to 20 % that of control after 1 hr pre-treatment by a single i.c. injection, and this effect continued for at least 168 hr after MO pretreat-ment. MO was further metabolized to from morphinone-glutathione adduct (MO-GSH), and this metabolite was excreted in the bile of guinea pig. MO-GSH gave no toxicity by s.c. injection (500 mg/kg), however, it gave about 2 timea of the lethal dose of MO in mice by i.c. injection.Summary of the present investigations are as follows. 1. The enzyme activity to produce MO was localized in the cytosol and to a lesser extent in the micro-somes of each tissue (liver, kidney, lung, small intestine and brain) of animals (guinea pig, rats, rabbits, mice and hamsters). 2. The production of MO from M by … More microsomal reaction was suppressed by hydroxyl radical scavengers; consequently, it is possible that the hydroxyl radical generated from NADPH-cytochrome P-450 func-tions to form MO. It was shown that MO was formed by Fe(II)-EDTA-ascorbate. 3. Trace amounts of M-GSH and MO-cysteine adduct were also detected and identified by comparison with the authentic samples. 4. We establish the method for determination of not only MO but also M and its unconjugated metabolites in the urine and bile of guinea pig by high-performance liquid chromatography. 5. Pretreatment of guinea pig with diethyl maleate (500 mg/kg) or simutaneous injection of lithocholic acid-3-sulfate (25 mg/kg) with M decreased the biliary excretion of MO-GSH and increased that of MO in comparison with untreated animals. 6. Pretreatment of guined pig by s.c. injection with naloxone (25 mg/kg) increased biliary excretion of both MO and MO-GSH. 7. the unambiguous structure assignment of MO-GSH was identified as 8(S)-(glutathion-S-yl)dihydromor-phinone by two dimensional NMR spectroscopy. 8. The typical three sodium cationized ion peaks are observed on the positive GAB-Mass with sodium iodide on the MO-GSH. These sodium cationized ion praks were available for the detection and iden-tification of the metabolite. Less