Neuroresearchers at the UT Southwestern Medical Center have cleared the key cells inside the brain that are essential for the determination of circadian rhythms, the 24-hour system that controls both sleep and wake cycles, as well as other relevant body functions like metabolism, hormone manufacturing and blood pressure.
The circadian rhythms are created thanks to the suprachiasmatic nucleus (SCN), which is located inside the hypothalamus of the brain. However, until now, scientists have been unable to understand which of the thousands and thousands of neurons residing in that region were actually involved in controlling this complex timekeeping system of the body.
“We have found that a group of SCN neurons that express a neuropeptide called neuromedin S (NMS) is both necessary and sufficient for the control of circadian rhythms,” explained Joseph Takahashi, respected researcher at UT Southwestern.
These results were published in the Neuron journal and are very promising since it might offer important targets to be investigated to create new treatments that can address diseases and heath conditions somehow related to circadian dysfunction, such as sleep disorders, jet lag, Alzheimer’s disease, metabolism problems, depression and other psychiatric disorders.
The SCN controls circadian rhythms since it coordinates cells throughout the body; however, the SCN includes too many neurons with completely different expression patterns of neurotransmitters and neuropeptides.
NMS is a neuropeptide that allows the brain to communicate. Scientists created special mouse models to determine that NMS-expressing neurons actually regulate circadian rhythms. Furthermore, the team found that modulating the internal clock in just the NMS neurons changed the circadian period throughout the entire test animal.
Dr. Takahashi was able to identify and then clone “Clock,” the first mammalian gene concerning circadian rhythms. The research team found that disruptions in the Clock and Bmal1 genes in mice can modify the release of insulin by the pancreas (causing diabetes) and they cleared the 3D structure of the protein complex formed by CLOCK-BMAL1. Several more research projects are being developed at Yanagisawa’s laboratory that also connects this theme with the cardiovascular system, the control of appetite, blood pressure and emotions.