Abstract
The objectives of this study were to clarify the inhibitory effect of relaxin (RLX) on the relapse after expansion of the midpalatal suture in rats, and to assess the expressions of type I collagen and matrix metalloproteinase-1 (MMP-1) using the immunohistochemical and image analysis techniques. Twenty four Wistar male rats (age : six weeks old, body weight : about 200 g) were used in this study. They were divided into the placebo injection group (control group) of 12 rats and the RLX injection group (experimental group) of 12 rats. The expansion period was set to 7 days and the amount of relapse was measured for 14 days. After expansion, immunohistochemical analyses of type I collagen and MMP-1 were performed on 1, 3, 7, 14 days. The amount of expansion was 0.37±0.05 mm in the experimental group and amount of expansion was 0.32±0.08 mm in the control group. The amount of relapse in the experimental group was inhibited about 40% than that of the control group on the 14 days. The type I collagen and MMP-1 showed positive immunoreactivity in the fibroblasts, connective tissues and osteoblasts of the midpalatal suture area. The injection of RLX increased the expression of MMP-1 and decreased that of type I collagen after the expansion of the midpalatal suture, comparing with the control group. The results suggest that RLX may reduce the relapse after expansion of the midpalatal suture through its antifibrotic properties.
