[Expression of beta-catenin during premaxillary suture distraction osteogenesis in rat].
OBJECTIVE
beta-catenin, as a glycoprotein in cytoplasm, was involved in osteoblast development and bone formation. This study was designed to observe the spacial and temporal expression of beta-catenin during premaxillary suture distraction osteogenesis in rat.


METHODS
Thirty two female SD rats were randomly allotted into experimental group (n=20) and control group (n=12). The experimental animals were subjected to premaxillary suture distraction by helix springs. They were sacrificed on the day 1, 3, 5 and 7. Toluidine blue staining was used to observe the morphology and distribution of the osteoblasts. The expression of beta-catenin and osteopontin (OPN) was identified by immunohistochemical staining.


RESULTS
During nature growth, osteoblasts were sparsely lining along the premaxillary suture. beta-catenin immunostaining was mainly localized in the membrane of these cells. The width of the suture was enlarged 1 day after distraction and osteoblasts were accumulated along the suture. Most of these osteoblasts showed positive OPN and beta-catenin immunostaining. beta-catenin signals were expressed additionally in the cytoplasm of the osteoblast and were more intensive in experimental sutures than those in control animals. New bone deposition was identified on the day 3 after suture distraction. Clusters of osteoblasts with weak OPN staining and strong beta-catenin signals in cytoplasm were projected into the suture. On the day 5, the level of beta-catenin expression began to decrease while intensive OPN staining was observed in the finger-shaped trabecular bone and those osteoblasts embedded in it. New bone formation was widespread in the expanded suture on the day 7.


CONCLUSIONS
The expression level of beta-catenin and the transition of the signals from membrane to cytoplasm along with the osteoblast maturation suggest that beta-catenin might be involved in the regulation of osteoblast differentiation during premaxillary suture distraction osteogenesis in rat.
Liu
Hai-xia
HX
Department of Orthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai 200011, China. liuhaixia_luck@163.com
Xu
Ji
J
Tang
Guo-hua
GH
D000818:Animals; D002454:Cell Differentiation; D010006:Osteoblasts; D010012:Osteogenesis; D019857:Osteogenesis, Distraction; D053495:Osteopontin; D051381:Rats; D017207:Rats, Sprague-Dawley; D013537:Sutures; D051176:beta Catenin
C495268:Ctnnb1 protein, rat; D051176:beta Catenin; D053495:Osteopontin