SYDNEY – Few people would hesitate to take a newspaper and crush an annoying fly that had been buzzing in the kitchen for hours. But if you've ever wondered if insects felt pain when you were trying to kill them, a new study is the first to prove that not only do insects feel hurt, but they suffer from chronic pain after handed.
Researchers at the University of Sydney in Australia said the discovery builds on earlier research conducted in 2003 that insects had a pain-related sensation.
"People do not really think that insects feel any pain," says co-author Greg Neely, an associate professor at the university, in a statement. "But it has already been shown in many invertebrate animals that they can detect and avoid the dangerous stimuli we perceive as painful. In non-humans, we call this sense "nociception", the sense that detects potentially harmful stimuli such as heat, cold or physical injury, but for simplicity we can talk about what insects feel like "pain ".
"So we knew insects could feel the pain," he continues, "but we did not know, an injury could result in sustained hypersensitivity to normally pain-free stimuli, just as the experience of patient. "
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For the study, the authors damaged one leg of a fruit fly and then allowed them to heal completely. They discovered that even after fruit flies have recovered, their leg without injury has become more sensitive, a reaction comparable to chronic human pain.
"Once the animal has been injured once, it is hypersensitive and tries to protect itself for the rest of its life," says Neely. "It's pretty cool and intuitive."
Neely and his team then determined exactly how insects felt such a response.
"The fly receives messages of" pain "from its body that then pass through sensory neurons to the ventral nerve cord, the version of our spine by the fly.In this nerve cord, inhibitory neurons act as a" gate " to allow or block the perception of pain depending on the context, "says Neely." After the injury, the injured nerve throws all its cargo into the nerve cord and kills all the brakes, forever. "Then the rest of the animal has no restraint on its "pain." The threshold of "pain" is changing and they are now hypervigilant.Ankids must lose the "painful" brakes to survive in dangerous situations, but when humans lose these brakes, our lives are miserable, we need to recover the brakes to lead a comfortable and painless existence. "
This type of chronic pain that flies live is called neuropathic pain, which occurs in humans under conditions such as sciatica, shingles, pinched nerve, spinal cord injury or other types of nerve damage. Patients with neuropathic pain usually report shooting or burning sensations.
Studies like these that help scientists understand the cause of chronic pain could eventually lead to first-line treatments that focus on the cause rather than on pain relief.
"It's important to note that now we know that the stage that causes neuropathic" pain "in flies, mice and probably humans, is the loss of pain brakes in the central nervous system," explains Neely. "We are focused on making new stem cell therapies or new drugs that target the underlying cause and permanently stop the pain."
The study is published in the journal Progress of science.
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