It is vital for mammals to maintain their internal water equilibrium. The neurobiological mechanisms linking thirst response behaviour and fluid balance maintenance raise intriguing questions, given that these two components operate on different timescales. Two papers in this issue of Nature identify areas of the mouse brain that respond to and anticipate thirst. Zachary Knight and colleagues reveal a role for thirst-promoting neurons in the subfornical organ (SFO). During eating and drinking, feedback from the oral cavity to the SFO—one of the three sensory circumventricular organs of the brain—is integrated with information regarding blood composition, providing an indication of how oral consumption is likely to alter fluid balance, leading to behavioural adjustments. Charles Bourque and colleagues identify a projection from central clock neurons that drives anticipatory water intake just prior to sleep, regardless of physiological need. Without this specifically timed increase in water intake, animals suffered from dehydration near the end of a period of sleep.
- Forecast for water balance (News & Views p626, doi: 10.1038/537626a)
- Thirst neurons anticipate the homeostatic consequences of eating and drinking (Letter p680, doi: 10.1038/nature18950)
- Clock-driven vasopressin neurotransmission mediates anticipatory thirst prior to sleep (Letter p685, doi: 10.1038/nature19756)
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