Decoded: How does estrogen protect bones?

Tokyo: The researchers discovered a new molecular link between estrogen and bone aging, which could eventually lead to new strategies for treating osteoporosis in postmenopausal women. Osteoporosis is a condition in which the bones become weak and prone to fractures.

Women over 50 are at high risk of osteoporosis, which may be due to the loss of estrogen after menopause. "In recent decades, we have learned that estrogen plays an important role in maintaining a functional bone matrix," said Tomoki Nakashima of the Tokyo Medical and Dental University (TMDU) in Japan. .

However, how estrogen does this has not been completely understood, the researchers said. In the study, the researchers discovered a protein called Sema3A, able to maintain bone matrix – proteins and minerals in bone – suggesting a relationship between estrogen and Sema3A.

In addition, the researchers found that serum blood levels of Sema3A protein decreased with age in pre-menopausal women and decreased even more once they reached menopause.

In the mouse study, mouse ovaries were removed, but it was found that estrogen loss did not prevent their bones from deteriorating. In addition, Sema3A has been shown to promote the survival of osteocytes – bone cells – in these mice.

"We believe that when women lose estrogen with age and that Sema3A levels fall, osteocytes begin to die and bones lose the ability to maintain their supporting structure," said Mikihito. Hayashi from the university.