Effects of Spaceflight on Cancellous and Cortical Bone in Proximal Femur in Growing Rats

This research looked at how space travel affects the bones of rats, which can help us understand what might happen to astronauts' bones during long flights. The study found that male and female rats experienced a significant loss in bone density (osteopenia) specifically in their femoral heads after being flown into space or simulated conditions for extended periods. This is similar to the kind of bone thinning astronauts experience on Earth during long-duration missions, like staying up all night and working continuously without regular breaks - a condition that can lead to weakened bones over time. The researchers discovered this by examining different strains (types) of rats before, during, and after their flights or simulations. They found out the most likely reason for these changes in bone density is not because new bone isn't being made but rather that old bone might be breaking down faster than it should - a process called increased resorption (Turner et al., 1995).

In this study, the effects of spaceflight and simulated microgravity on bone density were investigated using strains of growing male Sprague Dawley rats (SD) and female Fisher 344 ovx rats. The research aimed to understand whether long-duration exposure in a weightless environment could lead to osteopenia, similar to what is observed in astronauts during space missions. Methodology: Two groups of growing male Sprague Dawley and female Fisher 344 rats were flown on the Space Transportation System (STS)-41 mission for a duration that mimicked long-term exposure to microgravity conditions, while control groups remained grounded. The femoral heads from both strains of animals underwent thorough examinations postflight using various techniques including measurement error analysis and histomorphometric evaluation. Additionally, the study assessed longitudinal bone growth as well as mRNA levels for key bone matrix proteins to determine if there was a reduction in new bone formation or overall skeletal development during space travel.