Short-term effect of ovariectomy on osteoprogenitors in the healing rat mandibular incisor extraction socket.
OVX increased the percentage of AP-positive CFU-F in healing rat mandible. The increase of the number of osteoprogenitors was not significant in rat mandible-derived cultures but was in femur-derived ones. This suggests that the effect of OVX on osteoprogenitors is either smaller or develops later in mandible relative to femur.


BACKGROUND
Osteoprogenitors play an essential role in the regeneration process that leads to the successful integration of dental implants. However, it is unclear how systemic osteoporosis affects osteoprogenitors in oral bone. The present study was designed to determine the short-term effects of ovariectomy (OVX) on osteoprogenitors from the healing extraction socket in rat mandible.


METHODS
Six-month-old rats were ovariectomized (n=8) and control rats were left intact (n=8). Two weeks post-OVX, the right mandibular incisor was extracted. Four weeks post-extraction, the basal mandibular bone between the 1st and 3rd molar in the healing extraction socket was used to determine the number of fibroblastic progenitors (CFU-F), alkaline phosphatase-positive fibroblastic progenitors (AP-positive CFU-F), Dex-dependent osteoprogenitors (CFU-O Dex) and Prog-dependent osteoprogenitors (CFU-O Prog) using colony assays (n=5). Osteocalcin mRNA expression was evaluated using in situ hybridization (n=3). Data were analyzed using two-way ANOVA or Student's t-test.


RESULTS
OVX increased the percentage of AP-positive CFU-F in both mandible and femur. The number of CFU-O was increased only in femur. Osteocalcin mRNA expression in regenerating mandible was not statistically different between control and OVX animals.


CONCLUSIONS
Our results suggest that the effect of OVX on osteoprogenitors is either smaller or develops later in mandible relative to femur.
Shoji
K
K
Division of Periodontology and Endodontology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan. kana@ddh.tohoku.ac.jp
Basso
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Elsubeihi
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Heersche
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JN
D000818:Animals; D001861:Bone Regeneration; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D004195:Disease Models, Animal; D005260:Female; D005269:Femur / Q000503:physiopathology; D005786:Gene Expression Regulation; D007180:Incisor; D008334:Mandible / Q000378:metabolism / Q000503:physiopathology; D015675:Osteocalcin / Q000096:biosynthesis / Q000235:genetics; D010024:Osteoporosis / Q000503:physiopathology*; D010052:Ovariectomy; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013234:Stem Cells / Q000502:physiology*; D014081:Tooth Extraction; D020390:Tooth Socket / Q000378:metabolism / Q000503:physiopathology; D014945:Wound Healing
D012333:RNA, Messenger; D015675:Osteocalcin