A pill that blocks production of a natural chemical in the gut could potentially cure the common bone thinning disease osteoporosis, say scientists.
The drug prevents the synthesis of serotonin, best known for its functions in the brain.
It halted osteoporosis in mice and rats, and may be similarly effective in humans, researchers believe.
In the brain, serotonin assists the transmission of messages between nerve cells and has a big impact on mood.
But 95% of the body’s serotonin is found in the gut, where its major function is to inhibit bone formation, said the researchers.
By shutting off intestinal serotonin production, the scientists prevented osteoporosis in post-menopausal female mice.
In humans, the menopause is known to increase the risk of the disease dramatically.
The researchers found that an experimental drug called LP533401, which blocks serotonin production in the gut, had a major impact on osteoporosis.
They included the drug in the animals’ diets at small doses once a day for up to six weeks.
The results, published today in the journal Nature Medicine, showed that LP533401 prevented osteoporosis developing.
When the disease was already present, it could be fully cured.
Crucially, serotonin remained at normal levels in the brain despite the treatment.
Study leader Dr Gerard Karsenty, from Columbia University Medical Centre in New York, said: “New therapies that inhibit the production of serotonin in the gut have the potential to become a novel class of drugs to be added to the therapeutic arsenal against osteoporosis.
“With tens of millions of people worldwide affected by this devastating and debilitating bone loss, there is an urgent need for new treatments that not only stop bone loss, but also build new bone.
“Using these findings, we are working hard to develop this type of treatment for human patients.”
Most osteoporosis drugs do not generate new bone but prevent the breakdown of old bone.
The only drug currently on the market that can generate new bone must be taken by injection once a day.
Since research suggests that it carries a risk of bone cancer, it is only administered for short periods to patients with severe osteoporosis.
“There is an urgent need to identify new, safe therapies that can increase bone formation on a long-term basis, and to such an extent that they compensate for the increase in bone resorption caused by menopause,” said Dr Karsenty.
He stressed that the research findings would have to be confirmed in human patients before any new treatment can be developed.
In humans after the age of 20, the balance between bone formation and breakdown tips towards breakdown.
After the menopause, the rate of decline increases sharply in women as oestrogen levels drop and cells that tear down old bone become over-active.
Osteoporosis causes bones to become porous and fragile, increasing the risk of breaks.