Drugs we take can weaken our bones and so can aging, and scientists working to prevent both have some of the first evidence that the best target may not be the logical one.
They are finding that in aging bone, the mineralocorticoid receptor, better known for its role in blood pressure regulation, is a key factor in bone health, says Dr. Meghan E. McGee-Lawrence, biomedical engineer in the Department of Cellular Biology and Anatomy at the Medical College of Georgia. And drugs that block the receptor, like the hypertension medications spironolactone and eplerenone, may help protect bone cells.
Drugs like prednisone are glucocorticoids, which are better known for their roles in reducing inflammation and suppressing the immune response, which is why they work so well for problems like irritable bowel syndrome and arthritis. But, like aging, they can also disrupt the healthy, ongoing dynamic of bone being made and being destroyed.
Our natural glucocorticoid levels increase with age, and bone, at least when we are young, has more glucocorticoid receptors than mineralocorticoid receptors. Glucocorticoids can actually coax stem cells to make bone-forming osteoblasts, but it also causes those osteoblasts to store more fat, and too much fat in the bone, like anywhere on our body, is probably not good and typically correlates with bone loss.
So reducing the impact of glucocorticoid receptors seemed like a logical way to protect bone.