DALLAS June 12, 2014 Orexin proteins, which are blamed for spontaneous daytime sleepiness, also play a crucial role in bone formation, according to findings by UT Southwestern Medical Center researchers. The findings could potentially give rise to new treatments for osteoporosis, the researchers say.
Orexins are a type of protein used by nerve cells to communicate with each other. Since their discovery at UT Southwestern more than 15 years ago, they have been found to regulate a number of behaviors, including arousal, appetite, reward, energy expenditure, and wakefulness. Orexin deficiency, for example, causes narcolepsy spontaneous daytime sleepiness. Thus, orexin antagonists are promising treatments for insomnia, some of which have been tested in Phase III clinical trials.
UT Southwestern researchers, working with colleagues in Japan, now have found that mice lacking orexins also have very thin and fragile bones that break easily because they have fewer cells called osteoblasts, which are responsible for building bones.
"Osteoporosis is highly prevalent, especially among post-menopausal women. We are hoping that we might be able to take advantage of the already available orexin-targeting small molecules to potentially treat osteoporosis," said Dr. Yihong Wan, Assistant Professor of Pharmacology, the Virginia Murchison Linthicum Scholar in Medical Research, and senior author for the study, published in the journal Cell Metabolism.
Osteoporosis, the most common type of bone disease in which bones become fragile and susceptible to fracture, affects more than 10 million Americans. The disease, which disproportionately affects seniors and women, leads to more than 1.5 million fractures and some
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UT Southwestern Medical Center