Rho is involved in periodontal tissue remodelling with experimental tooth movement in rats

Objective: To characterise in vivo the close relationship between the Rho signalling pathway and periodontal tissue remodelling in experimental tooth movement in rats. Materials and methods: In total, 24 male Sprague Dawley rats were divided randomly into four groups. Closed-coil springs were used to create a 40-g mesial force to move the right upper first molars in anaesthetised rats. The untreated contralateral side served as a control. On days 3, 7, 10, and 14 after force application, paraffin wax-embedded sections of the dissected maxilla were prepared for immunohistochemistry to localise Rho kinase (ROCK), LIM kinase (LIMK), and its downstream effector (cofilin). The immunoreactivity of the molecules investigated in the periodontal ligament area was converted into grey-scale values. Results: The expression of Rho and its signalling were detected mainly in the disto-coronal areas of the root in the periodontal ligament area of the control and loaded teeth. In contrast, ROCK-, LIMK-, and cofilin-positive cells were rare in the mesio-coronal areas. In the experimental group, the expression of ROCK, LIMK, and cofilin on the tension side (disto-coronal areas) increased significantly on days 7, 10, and 14, compared with those of untreated control teeth. Conclusions: These data suggest that Rho is involved in periodontal tissue remodelling during orthodontic tooth movement, modulating ROCK, LIMK, and cofilin activity. (C) 2015 Elsevier Ltd. All rights reserved.