Stroke Prevents Exercise-Induced Gains in Bone Microstructure But Not Composition in Mice

Area of Science:

• Neuroscience
• Orthopedics
• Bone Biology

Background:

• Ischemic stroke causes rapid bone mineral density loss, increasing fracture risk.
• Skeletal changes post-stroke, beyond density loss, remain poorly understood.
• Existing research often overlooks effects in ambulatory patients without bedrest.

Purpose of the Study:

• To investigate the impact of ischemic stroke on bone microstructure, dynamic bone formation, and tissue composition.
• To assess the effects of exercise on bone health in ambulatory stroke survivors.
• To differentiate stroke's direct skeletal effects from those related to immobility.

Main Methods:

• Utilized a middle cerebral artery occlusion model in C57Bl/6J mice.
• Assessed effects of stroke and treadmill exercise over 4 weeks in ambulatory mice.
• Analyzed bone microstructure, cortical area, endosteal bone formation rate, and mineral-to-matrix content.

Main Results:

• Stroke did not directly impair bone microstructure but prevented exercise-induced improvements in femoral bone volume fraction and trabecular thickness.
• Stroke led to decreased cortical area in the affected limb's distal femur and reduced bone formation rate in the affected tibia.
• Exercise increased mineral-to-matrix content in stroke-affected bone but not in sham controls.

Conclusions:

• Ischemic stroke negatively impacts bone health, affecting microstructure and bone formation even in ambulatory individuals.
• Stroke inhibits exercise-induced skeletal adaptations, particularly in femoral microstructure.
• These findings underscore the need for targeted interventions to address bone health deterioration following stroke, independent of immobility.