The effects of indomethacin on distribution and expression of COX-2 and IGF-I in the mandibular condyle of growing dogs

Nam, Jong Hyun; Lee, Ki Soo; Kang, Yoon Goo

Abstract

This study aimed to investigate the effects of indomethacin on distribution and expression of COX-2 and IGF-I in the mandibular condyle of growing dogs and to examine the number of chondroclasts around the mineralization zone. Indomethacin inhibits prostaglandin E2 production in the tissue by inhibiting synthesis of cyclooxygenase 2. Prostaglandin E2 stimulates insulin-like growth factor synthesis. Insulin-like growth factor stimulates growth of mandibular condylar cartilage. Eight mongrel dogs, aged 13 - 14 weeks, were divided into 4 groups. Group 1 and group 2 were administered indomethacin 2 mg/Kg/day orally two times a day for 7 days and 14 days respectively. Group 3 were administered indomethacin 8 mg/Kg/day orally 2 times a day for 14 days, and the control group were administered a placebo. The mandibular condyle heads were sectioned in 5 micrometer thickness. The specimens were stained with H-E staining, COX-2 immunohistochemical staining and IGF-I immunohistochemical staining and examined under light microscope. After TRAP staining, the number of chondroclasts were calculated. The observed results were as follows: Indomethacin inhibited expression and distribution of COX-2 and IGF-I on the proliferative zone of condylar cartilage. Indomethacin decreased the number of chondroclastes on the mineralization zone by a time-dependent manner (p < 0.05). Indomethacin inhibited expression and distribution of IGF-I by a dose- and time-dependent manner. These results show that indomethacin inhibited expression and distribution of COX-2 and IGF-I on the proliferative zone of condylar cartilage and decreased the number of chondroclasts and suggests that when indomethacin is administered for a long time, condyle growth could be delayed.