In addition to providing structural support to our bodies, our bones also speak. They produce hormones that talk to other organs and tissues, including the brain, kidneys and pancreas, an experiment in mice has shown.
At least three bone hormones act as messengers , according to recent studies, and there could be more. Scientists have only just begun to figure out what this type of health messaging means, but cataloging and researching these hormones will help us better understand how the body regulates sugar, energy, and fat, among other things.
From the list of bone messenger hormones, osteocalcin, sclerostin, and lipocalin 2 , the latter is particularly striking. This hormone secreted by bone cells can suppress appetite, according to a study by Columbia University Medical Center (USA) and published in the journal Nature.
Scientists believed that fat cells were responsible for the production of lipocalin 2, or LCN2. But in the mice they saw that the bones produced up to 10 times more of this hormone than the fat cells , especially after a meal. “It is a new role for bone as an endocrine organ,” says Stavroula Kousteni, leader of that study.
Bones are constantly reinventing themselves through intensive energy remodeling. Cells known as osteoblasts (bone cells responsible for synthesizing bone matrix) produce new bone; other cells, osteoclasts , destroy old bone. With this change, “the skeleton must have a very delicate adjustment mechanism that allows the whole body to be in sync with what is happening at the skeletal level,” says Clifford Rosen of the Center for Molecular Medicine in Scarborough, UK. . And it is that osteoblasts and osteoclasts send hormones to carry out their orders.
The most recent data on rodents indicate that osteocalcin may play a key role in energy metabolism. After an injection of the hormone, the older mice could run just as far as the younger ones. Old mice that didn’t get an osteocalcin boost ran about half the distance, according to another work by the same researchers published in Cell Metabolism. As the hormone increases endurance, it helps the muscles absorb more nutrients. In return, the muscles communicate with the bones, telling them to make more osteocalcin.
Much research remains to be done, but it is clear that in recent years, studies have shown that bone is an endocrine organ and produces hormones that affect brain development, glucose balance, kidney function, and male fertility. . What new approaches will our skeleton surprise us with?
“The era of the bone as a silent spectator is over,” Rosen says.
Reference: MC4R-dependent suppression of appetite by bone-derived lipocalin 2. Nature 2017. doi: 10.1038 / nature21697
