Does your brain have an on-off switch for thirst?

Neuroscientists at Columbia University Medical Centre have identified neurons in the brain of mice that trigger and inhibit thirst.

The two neurons, CAMK11 that triggers thirst and VGAT that inhibits thirst, are found in the subfornical organ, which is located in the hypothalamus. Until now, researchers were only aware that this region controlled thirst, however they found it difficult to pinpoint exactly which neurons in the region trigger it on and off.

According to Yuki Oka, the lead researcher in this experiment, previous research had gotten “confusing results” because they were “probably activating both types of neurons at once” and therefore could not pinpoint which neuron was the on switch, and which was the off switch.

Yuki Oka’s team used a more precise technique for controlling brain activity, called optogenetics, in order to control specific sets of neurons in a certain part of the brain. This involves shining light onto light-activating molecules that are inserted into these sets of neurons, which turns on only those specific neurons.

When the researchers turned on CAMK11 neurons, mice immediately began to seek water and to drink intensively. This behaviour was not affected by dehydration or hydration, as both groups of mice responded in a similar fashion. And when they turned on VGAT neurons, mice immediately stopped drinking, even if they were dehydrated.

Dr. Oka suggests that the findings of this experiment might make it “possible to develop drugs for conditions related to thirst”, such as excessive thirst, diabetes or dehydration.

Read the full journal article in Nature