Relationship between nitric oxide and tibia histomorphometry in ovariectomised rats

Objective To investigate the relationship between the changes in nitric oxide (NO) and the tibia in ovariectomized rats. Methods Sixty-six female Wistar rats were divided into six groups randomly. The first group was sham-ovariectomized for one month, and the second group for four months. The third group was ovariectomized for one month, and the fourth for four months, the fifth for seven months, and the sixth for one year. All rats were killed at the end of experiment. Their right proximal tibia were processed into undecalcified sections, and the bone narrow stromal cells of left tibia and femora were cultured in vitro. Then the concentration of NO in supernatant of culture and the changes in histomorphometry were examined. Results The NO concentration and trabecular bone volume in ovariectomized groups were significantly lower, and the osteoblast surface and the osteotoid surface were smaller than those in sham-operated groups, while the number of osteoclasts and erosion surface were significantly greater. Conclusions NO plays an important role in bone resorption, and may be related to that the increase in number and the enhancement in activity of osteoclasts during osteoporosis.