Peroxisome proliferator-activated receptor-gamma induces regression of endometrial explants in a rat model of endometriosis

OBJECTIVE: To determine the effects of a thiazolidinedione, ciglitazone, in a rat model of endometriosis. DESIGN: Prospective, randomized, placebo-controlled study. SETTING: Experimental surgery laboratory in a university department. ANIMAL(S): Twenty female Sprague-Dawley rats given endometriotic lesions by transplanting autologous uterine tissue to ectopic sites on the peritoneum. INTERVENTION(S): Four weeks after surgery, 20 rats were randomly divided into two groups and treated with IP injections of vehicle every other day (control; n = 10) or ciglitazone (1 mg per rat; n = 10) and euthanized 4 weeks from the start of treatment. MAIN OUTCOME MEASURE(S): At the end of treatment, laparotomy was performed to photograph each explant and then they were measured and weighed. Histologic analysis was performed on the uterine allograft, ovary, and eutopic uterine tissue. RESULT(S): By histologic assessment, both groups maintained folliculogenesis and normal eutopic endometrial architecture. Treatment with ciglitazone significantly decreased the size of ectopic uterine tissues and the mean explant wet weight. The ciglitazone-treated group showed marked epithelial regression compared with the control group. CONCLUSION(S): We conclude that a PPAR-gamma ligand, ciglitazone, reduced the size of experimental endometriosis in the rat model of endometriosis. This animal model suggests that a thiazolidinedione drug may be helpful in women with endometriosis.