Astronauts who spend months in space experience significant bone density loss, which can be irreversible. A recent study on mice on the International Space Station found that microgravity affects bones in a unique way. The mice’s hindlimb femurs showed extensive damage, particularly at the ends where they join the hip and knee joint, while their lumbar spines remained intact.
The researchers suggest that weight-bearing bones are more susceptible to damage from microgravity. In two-legged humans, the lumbar spine carries most of the upper body’s weight, but in four-legged rodents, this isn’t the case. The study found that mice on Earth who were kept in cages with limited movement showed similar bone density losses as those in space.
The researchers argue that space radiation and systemic factors are unlikely to be the primary causes of bone loss during spaceflight. Instead, they propose that the lack of gravitational forces may lead to a form of disuse-related osteoporosis, where bones don’t get “worked out” like usual. The study’s findings have implications for astronaut health and suggest that conventional tactics like diet may not improve bone health in space.
The researchers plan to conduct further experiments to explore ways to protect astronauts’ health during space travel.
Source: https://www.sciencealert.com/nasa-took-mice-into-space-and-it-did-something-scary-to-their-bones