Résumé
OBJECTIVE@#To explore the effect of methylprednisolone on bone mass, microarchitecture and microdamage in cortical bone of ulna in rats.@*METHODS@#Twenty female Sprague-Dawley rats (3.5 months old) were randomly assigned to two groups: a treatment group and a control group (n=10 per group). The treatment group was subcutaneously injected with methylprednisolone 3.5 mg/(kg.d) while the control group was subcutaneously injected with same volume of vehicle (saline). Rats were sacrificed at 9 weeks after the treatments. Before the sacrifice, the body weight and total bone mineral density (BMD) were measured. The right forelimb was separated through humeral shoulder and then single axial fatigue loading was performed on the right ulna. After fatigue load, the middle ulna section was bulkstained in basic fuchsin. Bone histomorphometry and microdamage analysis were performed on the middle ulna section.@*RESULTS@#Compared with the control group, the body weight, total bone BMD and ulnas BMD in the treatment group were decreased by 15%, 6.4% and 4.3% respectively (all P0.05). There was no significant difference in the cortical and total area between the 2 groups (both P>0.05). The number of microcrack, microcrack density and microcrack surface density in the treatment group were increased by 43%, 48% and 50%, respectively, compared with those in the control group (all P0.05).@*CONCLUSION@#Methylprednisolone can significantly induce the bone loss and the deterioration of microarchitecture and microdamage in ulna of rats.