Researchers at The University of Queensland (UQ) have found that a native New Zealand stinging tree produces toxins that could hold clues for future pain medication. The findings were announced in the journal Biological Chemistry on July 27. In a quest to find new molecules that affect pain pathways, Dr. Thomas Durek, Dr. Sam Robinson and a team from UQs Institute for Molecular Bioscience (IMB) studied toxins from the tree nettle known as ongaonga, one of New Zealands most poisonous plants that can cause painful stings that last for days, and in severe cases can even be fatal. Dr. Robinson and a team from UQ previously investigated toxins found in an Australian gympie-gympie stinging tree but found the New Zealand tree nettle toxins activated pain receptors in a new way. "We discovered that the New Zealand nettle tree toxins target the same receptor as their Australian counterparts, but they cause pain in a different way, " Robinson said in a report published on the university’s website. The Australian stinging tree and New Zealand tree nettle are both members of the nettle family but separated millions of years ago and have evolved differently. The New Zealand tree nettle can grow up to four meters tall and its leaves and stems are covered with stinging hairs that pierce the skin and deliver venom which causes long-lasting pain. Fossil remains show that the large flightless bird, the Moa, had a liking for eating the tree nettle and its likely the strong toxins evolved to fend off the now-extinct bird. The team faced challenges during the study due to international COVID travel restrictions. "COVID made it difficult to source nettles, but to keep our research going through the pandemic, we managed to source seeds from the New Zealand tree nettle and grow the plant under quarantine in the lab," Robinson said. Professor Irina Vetter, director of IMBs Centre for Pain Research and co-author on the study, said understanding pain pathways was key to finding new ways to treat chronic pain