Being a fruit fly is not unlike being really old.
While we might find the thought of insects to be incredibly annoying, scientists have recently discovered that insects, when injured, can experience chronic pain well after the initial injury took place.
The study was reported in Science Advances. It discussed genetic evidence on the causes of chronic pain in fruit flies and what researchers believe could be a connection to what drives chronic pain in humans. If this pans out, there could be treatments that target the cause of chronic pain and reduce it moving forward.
Insects have a sense called ‘nociception.’ This sense detects potentially harmful stimuli such as heat, cold, or physical injury. Insects have been seen to avoid dangerous situations, so it only makes sense that they can feel pain or know that it could potentially be coming. But, what wasn’t known was that the pain persisted longer than expected.
The study was carried out by damaging the nerve in one leg of a fly. They waited until the injury fully healed, but they noticed that the rest of the fly’s legs were hypersensitive. This lingering pain stays with the flies and forces them to protect themselves for the rest of their lives.
They determined this by noticing that the fly was receiving ‘pain’ messages from its body that went through the sensory neurons to the ventral nerve cord. This is similar to our spinal cord. Usually this cord serves as a gate and blocks the pain. But, once it is damaged, there is no longer a gate and their pain threshold changes.
The loss of these pain brakes in the central nervous system is how chronic pain lingers in insects, animals, and humans. With this knowledge, scientists are looking at ways to design a drug or a new stem cell therapy that can target the pain brakes and stop the pain for good.