Bone mass and bone quality are altered by hypoactivity in the chicken

Area of Science:

• Bone Biology and Disease
• Animal Models of Osteoporosis
• Skeletal Physiology

Background:

• Sedentary lifestyles and reduced physical activity are recognized risk factors for osteoporosis in adults.
• The effects of hypoactivity and confinement on bone mass are not well understood, with limited animal models available.

Purpose of the Study:

• To investigate the impact of confinement-induced hypoactivity on bone mass and microarchitecture in a chicken model.
• To evaluate the efficacy of a confined chicken model for studying hypodynamia-related bone loss.

Main Methods:

• Comparison of bone parameters between chickens bred in large enclosures (FREE group) and those confined to small cages (HYPO group).
• Assessment of femurs and tibias using texture analysis, dual-energy X-ray densitometry (DXA), microcomputed tomography (microCT), and histomorphometry.
• Evaluation at 53 days of age.

Main Results:

• Confinement (HYPO group) significantly reduced bone mineral density (BMD), microCT-derived bone volume, and trabecular microarchitecture compared to the FREE group.
• BMD reductions were observed in both femur and tibia diaphyses, with significant effects on the femur metaphysis but not the tibia.
• Increased osteoid volume and surfaces were noted in the HYPO group, but mineral phase alterations were absent, indicating no change in osteoid thickness.

Conclusions:

• Confinement-induced hypoactivity leads to significant bone loss and altered bone microarchitecture in chickens, particularly in the femur metaphysis.
• The confined chicken model effectively demonstrates hypodynamia-induced bone changes without requiring surgical procedures.
• This model offers a valuable tool for further research into the mechanisms of disuse osteoporosis.