What makes us feel thirsty and not? Neuroscientists have identified neurons that trigger the sense of thirst and the ones that turn it off too i a new finding that could also lead to new therapies for dehydration and excessive thirst.
For years, researchers have suspected that thirst is regulated by neurons in the subfornical organ (SFO) in the hypothalamus but failed to pinpoint the exact neurons involved.
“When researchers used electrical current to stimulate different parts of the SFO of mice, they got confusing results,” said lead author Yuki Oka, postdoctoral research scientist in the laboratory of professor Charles S. Zuker at Columbia University’s Medical Centre in the US.
The Columbia varsity team has hypothesized that there are at least two types of neurons, ones that drive thirst and others that suppress it. “Those electrostimulation experiments were probably activating both types of neurons at once, so they were bound to get conflicting results,” Oka added.
The team used optogenetics, a more precise technique for controlling brain activity, to control specific sets of neurons in the brain after inserting light-activated molecules into them.
These “mind-control” experiments helped them to identify the two types of neurons in the SFO that control thirst: CAMKII neurons, which turn thirst on, and VGAT neurons, which turn it off.
The SFO is one of few neurological structures that is not blocked by the blood-brain barrier but completely exposed to the general circulation. “This raises the possibility that it may be possible to develop drugs for conditions related to thirst,” Oka said.
The paper has been published in the online edition of journal Nature.