Ultrastructural investigation of the trabecular bone from rat femur following spinal cord injury

Objective To investigate the histomorphological response of bone to spinal cord injury (SCI) and its significance in bones metabolism Methods Forty SD rats with 3 months old were equally divided into SCI group and control group.Rats in the experimental group underwent spinal cord transection at the tenth thoracic vertebrea.Control rats underwent laminectomy without any spinal cord lesion.Rats in both groups were sacrificed at 1 and 3 weeks postoperatively,with 10 animals at each interval.Biochemical testing of the serum concentrations of ionized calcium,ALP,urine concentrations of calcium and creatinine were performed at each interval.Ultrastructural observation of trabecular bone in distal femur was performed with the use of transmission electron microscopy.Results Condensation and margination of heterochromatins,which were the typical features of apoptosis,were obviously seen in osteoblasts at 1 week and osteocytes at 3 weeks in SCI group.Compared with control,rats with SCI had high level of serum ionized calcium,urinary calcium and urinary calcium/creatinine at each interval.At 1 week,the significant decrease of serum ALP was found in rats with SCI,however,it returns to the normal level at 3 weeks.Conclusion Suppression of osteogenesis in early stage may be related to apoptosis of osteoblasts and the apoptosis of osteocytes may play an important role in disorder of activation resorption formation cycle.