Significant suppression of inflammatory bone destruction by NDGA in AA rats. NDGA (30 mg/kg) was injected i.p. into CFA-injected rats on day 11. Injections were given once every 2 days until the end of experiments (day 28). The clinical score (a) and swelling of hind paws (b) were monitored on the indicated days. (c) AA rats were treated with NDGA as described above. At 28 days after CFA injection, hind paws were collected and analyzed by μCT. Upper panels show the three-dimensional surface images of bones in the ankle joints. Distal parts of the tibia were analyzed histologically by H&E staining (middle panels) and TRAP staining (lower panels). (d) Data showing the quantitative analysis of the μCT scanning images at a distance of 2 mm from the distal growth plate of tibia. BV/TV, bone volume per tissue volume; BS/TS, bone surface per tissue surface; Tb.N, trabecular number; Tb.Sp, trabecular separation. **P<0.01, ***P<0.01 (n=7). (e) Quantitative demonstration of osteoclastogenesis in AA rats treated with or without NDGA. Number of TRAP-positive cells was counted per unit area (500 μm2) of the TRAP-stained sections of the distal tibia (6 unit-areas from three independent sections). ***P<0.01 (n=6). (f) Effect of NDGA on normal bone metabolism. NDGA was administered intraperitoneally to normal Lewis rats (30 mg/kg) every 2 days for 26 days followed by the μCT analysis. Radiographs of sagittal axis for control rats (‘none’), to which vehicle PBS was injected, and NDGA-treated rats (‘NDGA’) are demonstrated. Data show radiographs of tibia and femur involving knee joints from three different rats for each experimental group.