Morphine is a potent painkiller harvested from opium poppies. We can make it synthetically in the lab, but it’s cheaper to let plants do the hard work. If you haven’t taken morphine, you may have taken its sibling codeine. Codeine in converted to morphine in your liver, so it’s much the same thing albeit in a smaller dose.
For the study they labeled tetrahydropapaveroline (THP) found normally in mice brains. Labeling is often used in molecular biology, you can label things by including rare radioactive atoms, or by sticking another molecule onto the original molecule. It works like a tracking device.
The labeled THP was injected into mice, and out of their urine appeared labeled salutaridine which is a precursor to morphine in the opium poppies.
Then they labeled some synthetic salutaridine and injected it into the mice, and in the urine came out labeled thebaine. Labeled thebaine was injected and finally, lo and behold, labeled morphine appeared.
It took several steps, but the mouse converted THP into morphine. Here’s the kicker, THP is found normally in mice brains AND human brains! So this process could be happening in people. Right now, you could be making your own morphine. Indeed traces of morphine are found in human urine, but until now they weren’t sure if it was something in the diet.
If morphine is made in humans, what is it doing there? It could help control pain, which would explain why our bodies respond so strongly to a dose of morphine.
Grobe, N., Lamshoft, M., Orth, R., Drager, B., Kutchan, T., Zenk, M., & Spiteller, M. (2010). Urinary excretion of morphine and biosynthetic precursors in mice Proceedings of the National Academy of Sciences, 107 (18), 8147-8152 DOI: 10.1073/pnas.1003423107