Scientists Identify Brain Cells That Controls Circadian Rhythm

In early 1970s, researchers discovered the portion of the brain that manages circadian rhythms – the 24-hour processes that control our sleep and wake cycles and key body functions like hormone development, metabolism and blood pressure. But it has taken till now to determine accurately which cells in the master clock drive the underlying timekeeping.

In a new research presented in the journal Neuron, scientists from the University of Texas (UT) Southwestern Medical Center in Dallas explain how they discovered key cells within the suprachiasmatic nucleus (SCN) that are important for identifying circadian rhythms.

The scientists think their results could result in new medicines to treat a variety of disorders, such as sleep issues like jet lag, neurological disorders like Alzheimer’s, psychiatric problems like as depression, plus metabolism issues.

Circadian rhythms are the design of physical, mental and behavioral modifications that follow approximately24-hour cycle. They are identified in most living things – from small microbes to large mammals – and react mainly to modifications in light and dark in the organism’s surroundings.

Our circadian rhythms are managed by biological clocks – groups of communicating molecules identified in cells all over the body. The SCN or “master clock” – which sits in the hypothalamus, a part of the brain just over where the optic nerves from the eyes cross – maintains the molecular clocks in synch.

Study determines cells that show neuropeptide neuromedin S control circadian rhythms

Even though the SCN – which consists of about 20,000 neurons – was discovered 4 decades ago, this new study is the initial to pinpoint which group of SCN cells manages its underlying timekeeping mechanisms.

Joseph Takahashi, one of the authors of the research states that:

“We have identified that a group of SCN neurons that show a neuropeptide known as neuromedin S (NMS) is both essential and adequate for the control of circadian rhythms.”

NMS is a neuropeptide – a protein that brain cells use to deliver signals. Performing with specifically-bred mice, the team identified that brain cells that show NMS act as cellular pacemakers.

When they obstructed signal transmission in the NMS cells in the mice, the team identified it interrupted the timing mechanism of the SCN and impacted the biological clocks in the rest of the body.

The scientists also identified new hints about how light synchronizes the body clock.

Research is part of a long journey to deal with important questions about the body clock. The research shows one more step in what has been a long journey by Prof. Takahashi and his lab.

In the 1990s, they discovered the initial gene associated to circadian rhythms in mammals – a gene known as Clock. Since that time, they have shown that disruptions to Clock, and one more gene known as Bmal1, impact insulin secretion in the pancreas and can result in diabetes in mice.

Recently, they confirmed that the 3D structure of the protein complex established by these two genes is the battery of the biological clock. In a research presented in 2012, they discovered the initial atomic-level images of the CLOCK:BMAL1 complex.

The new research was financed by the National Institutes of Health (NIH) and the Howard Hughes Medical Institute (HHMI).

Senior author Masashi Yanagisawa, states that which of the neurons in the SCN are liable for producing circadian rhythms has been an essential question in neurobiology, and:

“This research marks a major progression in our understanding of the body clock.”

Prof. Yanagisawa, identified that one more neuropeptide known as orexin controls sleep/wakefulness.

He and his co-workers have since determined several pathways engaged in the management of appetite and blood pressure, plus other neuropeptides that help manage functions like metabolism, stress and feelings.