A subset of sensory neurons is thought to sense changes in thermal energy directly, through their endings in the skin, and very little was known about which molecules let them do it. One relative in the family was already known to answer noxious heat. The cold end was open.
Because menthol opens the cold channel. The authors cloned , a distant relative of the heat-activated vanilloid receptor, and found it specifically expressed in a subset of pain- and temperature-sensing neurons. Cells the channel respond both to cold temperatures and to menthol, a cooling agent.
A distinct subset of sensory neurons is thought to sense changes in thermal energy directly, through their termini in the skin. Very little was known about the molecules that mediate by those neurons, which is the gap this work addresses.
One anchor existed already. , a member of the TRP family of channels, is activated by noxious heat, and a family with one temperature sensor in it is a good place to look for another.
The paper describes the cloning and characterization of TRPM8, a distant relative of that receptor. It is specifically expressed in a subset of pain- and temperature-sensing neurons, which is where a cold sensor would have to be.
Cells overexpressing the channel can be activated by cold temperatures and by menthol, a cooling agent. That is the explanation for the sensation: the plant compound opens the same gate the cold does, and the nerve has no way to tell the difference.
wat. Menthol opens the channel that cold opens, so the nerve reports cold.
wat wat
A sensation everybody has had turns out to be a molecule being opened by the wrong key, and the same logic runs the other way for chili and heat.
How do we know?
Peier and colleagues cloned and characterized the channel, mapped where it is expressed among sensory neurons, and tested the response of overexpressing cells to cold and to menthol.
What is still unknown
This is cloning and cell-level characterization; what a whole animal or person feels involves more than one channel.
Learn something?
Where to next
Does an ice bath right after strength training help a muscle grow?cold
Does being cold burn more than being active?cold
What happens to helium below two degrees above absolute zero?cold