Washington: a new study provides convincing evidence to suggest that insects also experience chronic pain, which persists long after an initial wound has healed.
The study published in the journal Science Advances offers the first genetic evidence of the cause of chronic pain in Drosophila (fruit flies) with good evidence that similar changes also drive chronic pain in humans.
The continuous search for these mechanisms could lead to the development of treatments that, for the first time, aim at the cause and not only at the symptoms of chronic pain.
"If we can develop drugs or new stem cell therapies that can target and repair the underlying cause, instead of symptoms, this could help many people," said associate professor Neely, whose team of researchers studies pain with the goal of developing non-opioid solutions for pain management.
"People do not really think of insects as experiencing any kind of pain. But it has already been shown in many different invertebrate animals that they can perceive and avoid dangerous stimuli that we perceive as painful. In non-humans, we call this sense & # 39; "nocicezione", the sense that detects potentially harmful stimuli such as heat, cold or physical injuries, but for simplicity, we can refer to what insects experience as "pain", said the professor associated with Neely.
"So we knew that insects could perceive the" pain ", but what we didn't know is that a lesion could lead to a lasting hypersensitivity to normally painless stimuli in a way similar to the experiences of human patients".
The study of fruit flies examined neuropathic "pain", which occurs after damage to the nervous system and, in humans, is usually described as burning or stabbing pain.
Neuropathic pain can occur in human conditions such as sciatica, a pinched nerve, spinal cord injury, post-herpetic neuralgia (fire of Saint Anthony), diabetic neuropathy, tumor bone pain and accidental injury.
In the study, associate professor Neely and lead author Dr Thang Khuong damaged a nerve in one leg. The wound was therefore allowed to heal completely. After the wound was healed, they discovered that the fly's other legs had become hypersensitive.
"After the animal is hurt once badly, they are hypersensitive and try to protect themselves for the rest of their lives. It's a cute and intuitive thing," associate professor Neely said.
Subsequently, the team genetically analyzed exactly how it works.
"The fly receives from its body messages of pain that pass through the sensory neurons to the ventral nerve, the version of the fly in our spinal cord. In this nerve are the inhibitory neurons that act as a" gate "to allow or block the perception of pain based on the context After the injury, the injured nerve discharges all of its load into the nerve cord and kills all the brakes, forever.
So the rest of the animal has no restraints on its "pain". The threshold of "pain" changes and they are now hypervigilant, "said associate professor Neely.
"In humans, chronic pain is assumed to develop through peripheral sensitization or central disinhibition. From our precise genomic dissection of neuropathic" pain "on the fly, all of our data point to central disinhibition as a critical and underlying cause of pain chronic neuropathic, "the professor said.