NEW RESEARCH
Brain Plays Key Role in Regulating Bone Density September 07 2005
http://www.hunews.huji.ac.il/articles.asp?cat=6&artID=518
Interior views of bone tissue in genetically engineered mice in which
interleukin 1 was released in the brain (right) and in which it was not (left).
As can be seen, the bone density is severely depleted in the left sample.
The brain plays an important role in the maintenance of proper bone density,
researchers at the Hebrew University of Jerusalem have revealed.
The results of this research, involving a study of the activity of the protein
interleukin 1 in the brain, comprise not only a breakthrough in understanding
the regulation of bone density by the brain but also hold promise for the
development of future treatment for osteoporosis, say the researchers. An
article about their work appears in the current edition of the prestigious
American journal, Proceedings of the National Academy of Sciences.
The Hebrew University research project is headed by Prof. Itai Bab of the Bone
Laboratory, working in cooperation with Prof. Raz Yirmiya of the Department of
Psychology, Prof. Esther Shahami of the of the Laboratory for the Study of Brain
Trauma, Ph.D. students Alon Bagin and Inbal Goshen and master's degree student
Sharon Feldman.
Osteoporosis is the most widespread, degenerative disease in the Western world.
It is characterized by loss of bone density and consequent structural weakening
of the skeleton. Osteoporosis sufferers are highly susceptible to fractures, in
some cases leading to severe physical disability and complications that can even
end in death.
In humans and other vertebrates, one-tenth of the bone tissue is involved in an
"exchange" process of continuous bone loss and generation. In adult humans and
other mammals, this process is balanced; that is, the amount of bone tissue that
is generated is equal to that which is lost, thus preserving bone density. With
age, this balance is disrupted, and the amount of bone tissue that is lost is
greater than that which is created, with the result that bone density declines
and bone structure is impaired.
The interleukin 1 protein has been known for many years as a stimulator of the
immune system. In the skeleton the protein causes an increase in the number and
activity of osteoclastic cells - the cells which break down bone tissue and
which develop from the same cells as those of the immune system.
By experimenting with genetically engineered laboratory mice whose ability to
react to interleukin 1 was controlled, the Hebrew University researchers were
able to demonstrate that the proper loss/generation balance in bone tissue is
regulated by the level of activity of interleukin 1 in the brain. A normal,
optimal level of interleukin 1 activity in the brain is required to protect bone
density by impeding bone tissue breakdown, say the scientists.
"The connection between the brain and the bone structure is a new area of
research about which very little is known," said Prof Bab. "These new findings
from our laboratories at the Hebrew University regarding the action of
interleukin 1 on the breakdown of bone tissue indicate a complex neural system
controlling bone structure and point the way towards new revelations in the near
future in this area."
The research was conducted within the framework of a project directed at
clarifying the connection between the brain, behavior and changes in skeletal
structure. The research was funded by the Bikura [First] Program of the Israel
Science Foundation, which supports pioneering, innovative, interdisciplinary
initiatives.
Interior views of bone tissue in genetically engineered mice in which
interleukin 1 was released in the brain (right) and in which it was not (left).
As can be seen, the bone density is severely depleted in the left sample.
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