Differential Expression of Relaxin in Ovary during Orthodontic Tooth Movement

Objectives: Relaxin (Rln) is an ovary hormone that stimulates osteoclastic activity and connective tissue turnover. Effects of orthodontic tooth movement on the Rln expression in ovary were determined. Methods: Rats were placed with orthodontic appliances which connect from upper incisors to upper 1st molar with 70cN force and the contralateral side without appliances was used as the control. Six rats in each group were sacrificed at 6h, 2d and 6d after the appliance activation and the expression of Rln1 and Rln3 in the ovary was determined by real-time PCR, Western blot and immunofluorescence. Results: Rln1 mRNA expression increased 8, 10 and 40 fold higher than the control at 6h, 2d and 6d of tooth movement, respectively (P<0.01). Increase of Rln1 protein in the ovary was also confirmed by Western blot analysis. Immuoreactivity against Rln1 was localized in granulosa-lutein cells of the corpus luteum of the ovary and became stronger by the orthodontic force. In contrast, Rln3 expression was not changed by the force. Conclusions: This study suggests that Rln1 from the ovary may play a role in orthodontic tooth movement. “This work was supported by National Research Foundation of Korea Grant funded by the Korean Government (2009-0069147)”.