Researchers have discovered a hormone in mice that prevents bone loss during lactation and could one day be used to treat osteoporosis
By Grace Wade
10 July 2024
We may be closer to understanding one of the mysteries of breastfeeding
Svetlana Repnitskaya/Getty Images
A newly discovered hormone in mice may solve the long-standing mystery of how adult bones stay strong during the stress of breastfeeding. The finding could lead to new treatments for osteoporosis, a condition in which bones become weak and brittle.
For decades, it was unclear how bones maintain strength during breastfeeding, when the body strips calcium from bones to produce nutrient-rich milk. Breastfeeding also lowers levels of oestrogen, a hormone essential for skeletal health. Despite this, lactation only causes temporary dips in bone mass that are resolved between 6 and 12 months after breastfeeding ends.
While conducting research unrelated to this conundrum, Holly Ingraham at the University of California, San Francisco, and her colleagues found that inhibiting oestrogen production by targeting receptors in an area of the brain’s hypothalamus actually strengthened bones in female mice.
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“It was a bit paradoxical because here we’re getting rid of oestrogen signalling, which you think of as being beneficial for bone, and creating females with these extremely dense bones,” says Ingraham.
To figure out why that was, she and her colleagues bred female mice that lacked these oestrogen receptors, which caused them to have unusually strong bones. They then surgically attached the animals to other female mice that had the receptors, connecting their circulatory systems.