Zebrafish reveal how the sleep switch is activated

An international team of scientists has identified a new brain circuit in the zebra fish which acts as a sleep “biological switch”. The discovery, published in the magazine Current Biologyhas had the participation of the Higher Scientific Research Council (CSIC) through its Marine Research Institute (IIM-CSIC), and could have Future applications in the treatment of insomnia in people.

The study, led by the California Institute of Technology (CalTech) and with the participation of the California State University and the British University of Exeter, analyzed the activity of a group of hypothalamic neuronsor in zebrafish larvae, a species widely used in biomedical research for its similarities with the human brain.

The researchers identified some neurons that express the Qrfp and Pth4 genes as sleep promoters. According to Josep Rotllant, researcher at the IIM-CSIC, “during the process, genetic editing techniques were used to examine fish that lacked the neuropeptide Qrfp or Pth4, with the aim of determining the effects of each of them on sleep.”

The conclusion is that the neuropeptide Pth4 It activates the sleep mechanism through a double system: it inhibits the neurons that keep the animal awake and, at the same time, enhances those that promote rest.

These neurons, furthermore, do not work alone. According to Rotllant, “they communicate with other deep regions of the brain through neurotransmitters such as norepinephrine and serotoninwhich allows the brain to progressively transition from wakefulness to sleep, in a much more dynamic and coordinated process than previously thought.

A signal that measures accumulated fatigue

The CSIC has pointed out that these neurons are activated especially when the fish has been awake for a long time, forming part of the system that measures the accumulated need for rest. This mechanism guarantees the transition to sleep at critical moments, protecting vital functions such as memory, cellular repair and energy regulation.

Although humans do not have exactly the same molecule, researchers believe that the discovered circuit reflects “an ancient evolutionary system, shared between different species, that helps save energy and maintain the balance of the organism,” in the words of Rotllant, who concludes that its understanding “could open new avenues for treat insomnia and other sleep disorders“.