Mandibular bone alterations of ovariectomized rats under vitamin D insufficiency

Experimental osteoporosis was studied in mandible bone by means of ovariectomy and vitamin D insufficiency.

42 female Wistar rats were divided into the following four groups: (1) ovariectomized rats maintained in 12h day-night light conditions (ov-l), (2) ovariectomized rats maintained in 24h dark light conditions (ov-ob), (3) sham-operated rats maintained in 12h day-night light conditions (ch-l) and (4) sham-operated rats maintained in 24 h dark conditions (ch-ob). 12 weeks later the animals were sacrificed, the mandibles were excised, cleaned and weighed, the right side of the mandibles were histologically examined and the left side of the mandibles were prepared for mineral phase analysis by X-ray diffraction. Immunohistochemical analysis was performed to detect apoptotic cells by anti-PARP p85 antibody.

In group 2, the weight of mandibles significantly decreased. Chondroid areas were observed in ovariectomized groups and polarized light observation validated the collagen distribution disturbance in these groups (groups 1 and 2). Apoptotic osteoblasts were localized in groups 1, 2 and 4. They were numerous in group 2. The mineral phase analysis did not find differences between the groups.

This study validates a new model of osteoporotic animal associating estrogens deficiency and vitamin D insufficiency where matrix synthesis and osteoblast biology are altered, but not biomineralization.