Brain’s On-Off Switch for Thirst Identified

In a recent study published in the journal Nature, researchers from Columbia University Medical Center (CUMC) identified neurons in the brain responsible for triggering our sense of thirst. Researchers have long suspected that thirst is regulated by neurons in the subfornical organ (SFO), located in the hypothalamus. However, it’s been difficult to pinpoint exactly which neurons are involved. The research team at CUMC hypothesized that there are at least two types of neurons in the SFO — including ones that drive thirst and others that suppress it. To test their hypothesis, researchers utilized optogenetics, a more precise technique for controlling brain activity. With optogenetics, researchers can control specific sets of neurons in the brain after inserting light-activated molecules into them. Shining light onto these molecules turns on the neurons without affecting other types of neurons nearby. These “mind control” experiments revealed two types of neurons in the SFO that control thirst; CAMKII neurons, which turn thirst on, and VGAT neurons, which turn it off. When the researchers turned on CAMKII neurons, mice immediately began to seek water and drank intensively. Once the neurons were shut off — by turning off the light — the mice immediately stopped drinking. The researchers also found that light-stimulation of the CAMKII neurons did not induce feeding behavior. To read more about this study, click here.