Introduction: Homocysteine (HCY) is an amino acid that is formed as an intermediate during the metabolism of methionine. The role of hyperhomocysteinemia in the pathogenesis of osteoporosis has been considered a focal point.
Aim of the work: Is to investigate the structural changes that occur in the bone and epiphyseal plate of femur in young male albino rats after being treated with oral HCY and the possible protective role of folic acid.
Materials and methods: Thirty six young male albino rats were used in this experiment. They were equally divided into three group. The control group, HCY treated group (group II) received 0.6mg HCY/kg b.w/day for 6 weeks and protected group (group III) received both HCY and folic acid (2 mg/kg) by oral gavages for 6weeks. At the end of experiment, the femurs of the animals were prepared for both light (hematoxylin and eosin, mallory trichrome stains and osteoprotegerin immunoreaction) and transmission electron microscopic examinations. Cortical and trabecular bone thickness were assessed using the image analyzer, in addition to counting the number of osteoclasts.
Results: HCY treated group showed significant reduction of cortical bone thickness of femur diaphysis with multiple cavity formation as well as a significant reduction in the trabecular bone thickness of distal metaphysis as compared with the control group. Additionally; the cancellous bone trabeculae were also separated by wide bone marrow rich in fat cells associated with a reduction in osteoprotegerin immunoexpression. The distal epiphyseal plate showed a lack of the orderly chondrocytes columns arrangement. Regarding the protected group, bone architecture was maintained so that the cortical and trabecular bone had nearly normal appearance in comparison with the control group. Ultrastructurally, osteocytes showed marked degenerative changes and were surrounded by irregular collagenous fibrils while the osteoclasts were increased as proved statistically.
Conclusion: Hyperhomocysteinemia induced profound histological changes in the epiphyseal plate, trabecular and cortical bone of femur in young rats. Folic acid could have a protective role against these alterations.
Keywords: Homocysteine, femur, folic acid, growing rats