OBJECTIVETo clarify the effects of nylestriol on microarchitecture and interleukin-6 (IL-6) mRNA expression in tibial bone in ovariectomized rats.

METHODS30 female rats were randomly allocated into 3 groups: sham, OVX and nylestriol-treated group. Nylestriol-treated group were ovariectomized, then fed with nylestriol for 3 months and the bone mineral density (BMD) was measured in lumbar vertebra by dual energy x-ray absorptiometry. After sacrifice of the animal, bone histomorphometric parameters were measured to study the changes in bone microarchitecture, and RT-PCR was performed to detect the expression of IL-6 mRNA in bone tissue.

RESULTSBMD was significantly reduced, while IL-6 mRNA level elevated in the OVX group compared with the sham group. Static histomorphometric data showed that the trabecular bone volume, mean trabecular plate thickness and density were reduced while the mean trabecular plate space elevated remarkably in the OVX group in comparison with that in the sham group. As for dynamic parameters, trabecular osteoid surface, tetracyclin labeled surface and bone turnover rate were increased while osteoid maturation rate decreased significantly in the OVX group compared with the sham group. BMD, IL-6 mRNA expression and bone histomorphometric parameters were improved in nylestriol-treated rats.

CONCLUSIONNylestriol plays an important role in maintaining bone volume and improving bone microarchitecture by markedly inhibiting bone turnover and bone resorption, which might be to some degree attributed to reduced IL-6 expression.