Three types of cells in our brain work together to suppress thirst during a night’s sleep and at the same time to prevent dehydration, according to scientists from Canada in the journal Nature Neuroscience.
The amount of water retained in our body is under the strict control of vasopressin – a hormone released by the so-called neurosecretory cells in the brain’s hypothalamus. Vasopressin increases the resorption, i.e. the recovery of water from the urine. The neurosecretory cells that release it are activated by the so-called osmosensor cells capable of monitoring the water content of the blood.
In the hypothalamus of the brain there are also cells of the main biological clock of our body, the so-called suprachiasmatic nuclei. Daily, rhythmically repeated changes in the activity of these cells affect the natural rhythm of our body, the feeling of hunger and satiety, the need for sleep, etc.
Eric Trudel and Charles Bourque from the Research Institute of the McGill University Health Center in Quebec studied the connections and signaling mechanisms between these three groups of cells.
They observed that late at night, the connection between the osmosensor cells controlling the water level and the vasopressin-secreting neurosecretory cells becomes stronger – and even a slight decrease in the water level causes a significant increase in vasopressin release and an increase in water resorption from the urine.
In addition, scientists have shown that the activity of the brain’s suprachiasmatic nuclei decreases at night. When researchers artificially increased the excitation of the cells of the biological clock, they found that the connections between osmosensory and neurosecretory cells weakened.
According to the authors of the study, their results allow us to conclude that the activation of the suprachiasmatic nuclei weakens the connections between osmosensory and neurosecretory cells and acts as a brake.
During the day, your body’s water level can be replenished by simply drinking a little water. At night, the situation changes – the activity of the biological clock decreases, which releases the brake and allows more water to be reabsorbed from the urine. (PAP)