据国外媒体报道，一项新研究显示，我们的身体能产生少量而数量稳定的天然吗啡，但用途尚不清楚。
据悉，吗啡是鸦片中最主要的生物碱（含量约10-15%），吗啡有强大的镇痛作用，对一切疼痛均有效，吗啡的麻醉、镇痛作用是自然存在的任何一种化合物无法比拟的，它的镇痛范围广泛，几乎适用于各种严重疼痛包括晚期癌变的剧痛。吗啡这种化学物质，往往也能在小鼠身上和人尿里发现，这使科学家发出疑问：吗啡是人体自然产生的还是由饮食而来？
根据一项对小鼠的研究，哺乳动物可能通过类似于植物生物合成吗啡的生物化学路径而在体内天然制造吗啡。这项新的研究表明，小鼠产生了“令人难以置信的止痛药”，而人类和其他哺乳动物具有相同的生物化学路径。在这项研究中，研究人员向小鼠注射了一定剂量的潜在吗啡前体，即人类和小鼠的大脑可自然产生的四氢巴马汀（THP）。使用质谱仪分析老鼠的尿液，研究人员发现，THP在体内发生了化学变化，产生了吗啡。更重要的是，研究发现，小鼠产生吗啡的方式与罂粟的几乎一样。该研究报告发表在本周的美国《国家科学院院刊》（PNAS）上。
用于做实验的吗啡，研究发现人体能自动产生吗啡，但用途尚不清楚。
吗啡能在罂粟和哺乳动物内产生，这意味着它有某种存在价值。通过对罂粟植物的充分研究，科学家认为吗啡可防御天敌。例如，一只兔子想吃罂粟，罂粟可释放吗啡麻醉兔子，使兔子变得行动迟缓，希望被飞过的鹰看到，将兔子吓走。同样，如果一个动物袭击人，人体释放出的吗啡可减轻疼痛，这样人就可赶快逃跑。
研究人员称，这项研究可能有助于确定吗啡和类似化合物在人体中的作用，这可能帮助疼痛和药物依赖性研究。当科学家找到减轻人的疼痛感的办法，就不用注射吗啡了，吗啡注射会产生很多副作用，尤其是便秘。
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PNAS发表论文摘要（英文）
Urinary excretion of morphine and biosynthetic precursors in mice
Nadja Grobea,1, Marc Lamshöftb,1, Robert G. Orthc, Birgit Drägerd, Toni M. Kutchana, Meinhart H. Zenka,2,3, and Michael Spitellerb,2
Published online before print April 26, 2010, doi: 10.1073/pnas.1003423107
Abstract
It has been firmly established that humans excrete a small but steady amount of the isoquinoline alkaloid morphine in their urine. It is unclear whether it is of dietary or endogenous origin. There is no doubt that a simple isoquinoline alkaloid, tetrahydropapaveroline (THP), is found in human and rodent brain as well as in human urine. This suggests a potential biogenetic relationship between both alkaloids. Unlabeled THP or [1,3,4-D3]-THP was injected intraperitoneally into mice and the urine was analyzed. This potential precursor was extensively metabolized (96%). Among the metabolites found was the phenol-coupled product salutaridine, the known morphine precursor in the opium poppy plant. Synthetic [7D]-salutaridinol, the biosynthetic reduction product of salutaridine, injected intraperitoneally into live animals led to the formation of [7D]-thebaine, which was excreted in urine. [N-CD3]-thebaine was also administered and yielded [N-CD3]-morphine and the congeners [N-CD3]-codeine and [N-CD3]-oripavine in urine. These results show for the first time that live animals have the biosynthetic capability to convert a normal constituent of rodents, THP, to morphine. Morphine and its precursors are normally not found in tissues or organs, presumably due to metabolic breakdown. Hence, only that portion of the isoquinoline alkaloids excreted in urine unmetabolized can be detected. Analysis of urine by high resolution-mass spectrometry proved to be a powerful method for tracking endogenous morphine and its biosynthetic precursors.
