Imagine you live in Canada and it is December. The cold has started to creep in. It takes layers of warm clothes and central heating to keep you from shivering. You look outside the window, see birds fluttering around and think to yourself, “How do animals survive out there?”
Many mammals (like rodents and bears) and birds (like hummingbirds) have the amazing ability to undergo ‘torpor’, during which they slow down their bodily functions to conserve energy. Animals make use of this to survive harsh environmental conditions. However, the mechanism by which animals sense the surrounding temperature and exhibit such a response is not known.
Researchers from Yale University explored this in a recent study published in eLife. They describe how a group of cells called POA neurons in the hypothalamus region of the mouse brain sense cold and get activated to relay the signal forward.
To understand what sets POA neurons apart from other cells, the scientists looked at the different components they are composed of. All neurons receive information with the help of small pores on their surface, which open only when their partner molecule sticks to them. What makes POA neurons special is the abundance of one such pore, which becomes increasingly likely to open as temperatures drop and it becomes more attracted to its partner. Once open, it allows the neuron to become active and pass on the message. The property of the pore to unlock for low concentrations of the partner molecule at cold, but not warm temperatures, is what makes it a cold sensor.
Findings from this study shed light on one possible mechanism of cold temperature sensing. But in order to fully understand how animals survive frigid conditions, we still need to tease apart the steps from sensing temperature to regulating it.