Researchers have found a new molecular link between oestrogen and bone ageing, which may eventually lead to new strategies to treat osteoporosis among post-menopausal women.
Osteoporosis is a condition in which bones become weak and prone to fractures. Women over 50 are at a high risk of developing osteoporosis, which may be due to the loss of oestrogen that occurs after menopause. “Over the last few decades, we’ve learned that oestrogen plays an important role in maintaining a functional bone matrix,” said Tomoki Nakashima from the Tokyo Medical and Dental University (TMDU) in Japan. However, how oestrogen does this, was not fully understood, the researchers said.In the study, the researchers discovered a protein called Sema3A, which was found to maintain bone matrix—proteins and minerals in bone—suggesting a relationship between oestrogen and Sema3A.
Halfway through an eight-day teacher training, I began to feel it: a dull throbbing in my right hip. For hours, I’d been sitting cross-legged on the floor in front of 40 students, discussing how to make yoga safe and effective for older adults. In such a supportive environment, you’d think I’d have switched to a different position—or maybe even sat in a chair. Yet I stubbornly continued to return to Easy Pose, which I began to think of as Painful Pose, until getting up became so agonizing that I had to walk in circles to straighten out my hip. Welcome to my late 50s.Aging comes subtly. The risks and changes sometimes have a harbinger, like the pain in my hip, and sometimes they don’t. Signs such as graying hair, the softening underbelly of a chin, and joint stiffness are easy to see and feel. Yet other changes are completely hidden. Just after my 50th birthday, my physician suggested a bone-density scan since I had many risk factors for osteoporosis—including being a thin, postmenopausal woman with a family history of the disease. Osteoporosis is a disorder that thins and weakens bones, making them more porous. The resulting danger is a possible break, which is when many people discover they have this “silent” disease.In my case, the bone-density scan revealed that I have osteopenia, or low bone density, a precursor to osteoporosis that puts me at an increased risk of fracture. And I’m far from alone. It’s expected that by 2020, half of all American men and women over age 50 will have, or will be at risk of developing, osteoporosis of the hip; even more will be at risk of developing it elsewhere. Further, the researchers found that blood serum levels of the protein Sema3A decreased in pre-menopausal women as they get older and dropped even more once they reach menopause. In the study done on mice, the ovaries of mice were removed but it was found that the loss of oestrogen did not prevent their bones from deteriorating. In addition, Sema3A was found to promote the survival of osteocytes—bone cells—in these mice. “We believe that as women lose oestrogen with age and Sema3A levels drop, osteocytes begin to die and bone loses the ability to maintain its supportive structure,” Mikihito Hayashi from the varsity said.
