Semaglutide treatment in obese mice reduces femur mass, stiffness, and strength more than caloric restriction

The global rise in obesity has spurred the development of effective weight management strategies, with GLP-1 receptor agonists (GLP-1RAs) like semaglutide emerging as prominent therapeutic options. While these drugs are highly effective at promoting weight loss, they are known to reduce both fat and lean mass. The long-term implications of this body composition shift, particularly concerning bone health and bone mineral density, have remained largely unexplored. Understanding semaglutide's impact on skeletal integrity is crucial, especially for patients at risk of osteoporosis or those on prolonged treatment regimens, as current standard-of-care for obesity does not routinely monitor bone parameters.

Researchers investigated the effects of semaglutide on bone health in obese male C57BL/6J mice. The study involved treating mice with semaglutide and comparing their bone parameters to those of mice subjected to caloric restriction designed to achieve equivalent weight loss, as well as a vehicle-treated control group. The primary endpoints included measurements of femur mass, stiffness, and strength. Additionally, circulating levels of markers indicative of osteoblast activity were assessed. A separate cohort was established to evaluate the reversibility of any observed bone changes, with femur weight, strength, and stiffness re-examined 6 weeks after semaglutide discontinuation compared to vehicle.

Semaglutide treatment in obese mice led to significant reductions in key bone parameters. Femur mass, stiffness, and strength were consistently lower in the semaglutide-treated group compared to controls. Importantly, these negative effects on bone were more pronounced than those observed in mice that achieved similar weight loss through caloric restriction alone, suggesting a mechanism beyond just weight reduction. The observed decrements in bone health were paralleled by lower circulating levels of markers associated with osteoblast activity, indicating a potential suppression of bone formation processes.

In a crucial finding regarding treatment cessation, femur weight, strength, and stiffness returned to levels comparable to the vehicle group 6 weeks following the discontinuation of semaglutide. This suggests that the adverse bone effects are dependent on continuous drug exposure and are potentially reversible.