Cyclooxygenase-2 selective inhibitor prevents implantation of eutopic endometrium to ectopic sites in rats

OBJECTIVE: To evaluate Cox-2 inhibition on surgically induced endometriosis in rats. DESIGN: Prospective, randomized study SETTING: Academic facility. ANIMAL(S): Seventy adult female Sprague-Dawley rats. INTERVENTION(S): Uterine fragments were implanted into abdominal peritoneum with suture (site A), and/or into the pelvic cavity without suture (site B). Oral gavage of Cox-2 inhibitor (5 mg/kg/day, twice/day) was started 4 weeks postimplantation (protocol-1), after implantation (protocol-2), or beforehand (protocol-3). Controls received vehicle. Immunohistochemistry evaluated Cox-2 expression after treatment. MAIN OUTCOME MEASUREMENT(S): Presence and size of ectopic implants after treatment. RESULT(S): Protocol-1: After 4 weeks' treatment, size of ectopic implants (site A) was significantly reduced compared with pretreatment size. After 8 weeks' treatment, no ectopic implants were detected in 2 (40%, site A) and 3 (60%, site B) rats. Protocol-2: After 2 weeks' treatment, no ectopic implants were detected in 3 (50%, site A) and 2 (33%, site B) rats. After 4 weeks' treatment, no ectopic implants were detected in 3 (50%, site A) and 3 (50%, site B) rats. Protocol-3: After 2 or 4 weeks' vehicle-only treatment, ectopic implants were in all rats (site B). CONCLUSION(S): Cox-2 selective inhibition was effective in a rat model of endometriosis, particularly in prevention of ectopic implants.