TUESDAY, Sept. 21, 2004 (HealthDayNews) -- Morphine, a potent painkiller typically derived from the opium poppy plant, appears to be made by the human body as well.
Small amounts of morphine have been found in animal tissue before, but researchers had assumed these traces came from environmental contamination, such as a diet. But a new German study claims that human cells produce the substance "without doubt."
"Morphine is an alkaloid that has been known for 200 years, and people just thought that it occurs only in plants," said lead researcher Meinhart H. Zenk, a professor of plant biology at Halle University.
In experiments, Zenk's team has proven that morphine occurs naturally in human cells, according to the report in this week's online issue of the Proceedings of the National Academy of Sciences.
"We were able to absolutely, for sure, establish that the tiny bit of morphine in animal cells is really from a biosynthetic origin," Zenk said. "Human cells are able to synthesize this highly active molecule."
Having established that morphine occurs naturally in human cells, the next step is to find out if it will interact with human morphine receptors, Zenk said. "This receptor is present in every cell. But one has to see if this human-produced morphine has access to these receptors," he said. "If we can prove that, then there will be a change in the conception of pain in humans." Proving this would help explain pain reactions and immune responses, he added.
Until now, it had been assumed that morphine was a foreign compound, but now people may develop a new perception of morphine as a naturally occurring compound. In addition, it may be possible to enhance its effect so that it can be used directly by the body to treat pain, Zenk said.
Why the body produces morphine and how the body uses it is unclear, Zenk said. "If it is accessible to these receptors, then the body uses it," he added.
Much more work needs to be done with this discovery, according to Carl Y. Saab, a postdoctorate fellow at the Center for Neuroscience and Regeneration Research at Yale University School of Medicine.
"The authors claim morphine was detected in cells outside the body," he noted. Even if cells inside the body were to similarly synthesize and secrete morphine, it remains to be shown that these few morphine molecules will withstand metabolic degradation and still be able to impact neurons effectively, he added.
"Whether morphine could also impact immune cells of the central nervous system to reduce pain indirectly is still unknown," Saab said. "However, this study is a significant step towards understanding the biochemistry of morphine synthesis, which could potentially offer alternatives for clinical intervention to increase its 'internal' production and, perhaps, to prevent tolerance associated with long-term 'external' morphine administration."
More information
The National Institute of Neurological Disorders and Stroke has a page on coping with chronic pain.
