Feeling drowsy during the day? Check your bones
If you often feel sleepy during the day, chances are that your bones may also be fragile. Researchers have found that orexin proteins – blamed for spontaneous daytime sleepiness – also play a crucial role in bone formation.
In lab experiments, mice lacking orexins were found to have very thin and fragile bones that break easily because they have fewer cells called osteoblasts – responsible for building bones.
The findings could potentially give rise to new treatments for osteoporosis.
Orexins seem to play a dual role in the process: they both promote and block bone formation.
On the bones themselves, orexins interact with another protein, orexin receptor 1 (OX1R) that decreases the levels of hunger hormone ghrelin.
This slows down the production of new osteoblasts and, therefore, blocks bone formation locally.
At the same time, orexins interact with orexin receptor 2 (OX2R) in the brain.
In this case, the interaction reduces the circulating levels of leptin, a hormone known to decrease bone mass, and, thereby, promotes bone formation.
The study appeared in the journal Cell Metabolism.
Source: Khaleej Times
Published: 14 June 2014
