How the skin distinguishes cool from warm
Researchers in the lab of James Poulet have uncovered how the nervous system senses cool and warm temperatures. The findings, published in “Neuron” challenge a long-standing view of temperature sensing and could guide future research into pain and sensory disorders.
Imaging neurons in live mice
The researchers developed a method to image hundreds of temperature-sensing nerve cells in the spinal sensory ganglia of awake mice over time. They gently warmed and cooled the animals’ paws while recording the activity of individual neurons using two-photon microscopy. They also performed this experiment in anesthetized mice and found the same result. This proved that that the anesthetic itself did not affect their results.
The team then selectively blocked or activated temperature-sensitive ion channels. Blocking the protein TRPM8 — long known as the body’s main sensor for detecting cool temperatures — eliminated both the response to cooling and the dampening effect that warming has on these nerve cells. This showed that a single molecular sensor can generate signals for both cool and warm, challenging the traditional view that separate receptors are needed for each sensation.
The team also developed a computer model to test their hypothesis. It showed that simply changing the activity of a TRPM8 was enough to reproduce the different response patterns seen in the experiments.
Understanding sensory disorders
Temperature sensation is essential for everyday life, but it is also disrupted in many medical conditions, including neuropathic pain, diabetic neuropathy, chemotherapy-induced nerve damage and disorders that cause abnormal sensitivity to cold. “Understanding how healthy temperature sensing works is a prerequisite for understanding what goes wrong in disease,” says Whitmire.
The researchers next plan to investigate how these signals are processed in the spinal cord, how painful temperatures are encoded, and whether the same principles apply in humans.
Further information
Contacts
Dr. James Poulet
Group Leader
Neural Circuits and Behavior lab Max Delbrück Center
+49 30 9406 – 2334
james.poulet@mdc-berlin.de
Gunjan Sinha
Editor, Communications
Max Delbrück Center
+49 30 9406 – 2118
presse@mdc-berlin.de
