Identification of a novel spinal nociceptive-motor gate control for Aδ pain stimuli in rats

What is it about?

A bee sting or a pinprick are examples of painful experiences that trigger an immediate response in humans and other animals. Scientists have begun mapping how different parts of the nervous system control how the body reacts to pain. But there are still many questions about what happens in the very first moments after pain. For example, does the response depend on what the body is doing when the painful event occurs? Examining how animals move in response to pain may help answer these questions and possibly point to new strategies for treating pain. Now, Blivis et al. show that the nervous system orchestrates a sequence of movements in the whole body in the first 500 milliseconds after a painful event. In the experiments, a high-speed video camera recorded what happened when rats experience a pinprick or brief burst from a hot laser on one paw. When a rat is on all four paws, it first moves it head and then picks up its foot after one of these painful experiences. In fact, the position of the rat’s entire body moves to enable the head to turn towards the source of the pain. This may help the rat assess the threat and decide what to do about it. When a rat is standing on two hind legs, however, the animal’s pain reaction is delayed until the animal attains a more stable footing. The rat puts its front paws down, before moving its foot from the source of the pain. Future studies are needed to identify which parts of the brain and spinal cord are active during these early, rapid movements and if something similar happens in humans. If a similar process occurs in humans, scientists might be able to develop new pain medications that take advantage of the system that temporarily suppresses the body’s immediate reaction to pain. These medications could, in future, be used to treat the heightened sensitivity to pain that can occur after an injury, or the intense “breakthrough” pain experienced by cancer patients that cannot be controlled by their usual pain medication. https://doi.org/10.7554/eLife.23584.002

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