Researchers find insects feel chronic pain

The next time you go to whack a fly with a fly swatter or book, keep in mind new research published by The University of Sydney. Researchers there say that they have known for over a decade that insects experience something like pain. New research published by University of Sydney researcher Greg Neely and colleagues at the university have found that insects also experience chronic pain that lasts long after an injury has healed.

The study provides the first genetic evidence of what causes chronic pain in fruit flies. They say that studying these mechanisms could lead to the ability to target the cause of chronic pain and not just the symptoms in humans for the first time. The study is part of an attempt to develop non-opioid solutions for pain management.

The team says that most don't think of insects as feeling pain. However, it has been shown that lots of different invertebrate animals can sense and avoid dangerous stimuli that we perceive as painful. Researchers call the sense "nociception," and it detects potentially harmful stimuli like heat, cold, or physical injury. For simplicity, the team refers to this as pain.

The researchers say that chronic pain comes in two types – inflammatory pain and neuropathic pain. The fruit fly study looked at neuropathic pain that occurs after damage to the nervous system. This sort of pain is described as shooting or burning pain in humans. In the study, the team damaged a nerve in one leg of the fly and then allowed the injury to heal.

After the injury healed, the team found that the other legs had become hypersensitive and the flies try and protect themselves for the rest of their lives. The team then discussed how the pain works, noting that the fly is receiving pain messages from its body that go through sensory neurons to its ventral nerve cord. The team says after the injury the nerve causes all the "brakes" from the pain response to be removed, forever making the entire insect have a changed pain threshold.