CD68-positive cells in the periodontium of Goto-Kakizaki rats

Objectives: Diabetes is a risk factor of periodontitis, whereas being also a risk factor of osteoporosis. However, it is unknown whether osteoporosis appears in the alveolar bone in periodontitis. In the present study, CD68-positiv cells involving osteoclasts in Goto-Kakizaki (GK) rats, a diabetes model, were examined immunohistochemically as an indication of resorption of the alveolar bone. Methods: Five 2-month-old GK rats (GK-2M) and five 5-month-old GK rats (GK-5M) were used. Five 2-month-old Wistar rats (W-2M) and five 5-month-old Wistar rats (W-5M) were used as controls. After euthanization, upper right maxillary molar regions were resected. Following fixation by a routine procedure, the specimens were decalcified with 10% EDTA and embedded in paraffin. Paraffin sections were cut and stained with hematoxylin-eosin. The sections were also stained immunohistochemically by using anti-CD68 monoclonal antibody and histofine simple stain MAX-PO. Results: In GK-2M, neutrophils were observed just beneath the gingival epithelium. In addition, a few multinucleated giant cells, odontoclasts/osteoclasts, were discernible along the root surface in the periodontium from the apical edge of the junctional epithelium. On the other hand, in comparison with W-2M, many more CD68-positive multinucleated giant cells were observed on the surface from the alveolar bone around the root apex to the palatal side of the alveolar crests. In GK-5M, cementum hyperplasia was hardly seen, but alveolar bone sometimes showed slight proliferation. However, many more CD68-positive multinucleated giant cells were observed as compared with W-5M. Conclusion: These results suggest that alveolar bone resorption has already progressed in GK rats by two months age.