Development of an animal model for quantitatively evaluating effects of drugs on endometriosis

The present study was conducted to induce endometriosis in an experimental animal model in which the condition and its response to pharmacologic agents could be quantified. Endometriosis was induced in New Zealand White rabbits by transplanting endometrial sections into various sites throughout the peritoneum. After 7 weeks, the mean implant weight increased in concomitant controls from 10.3 to 89.0 mg. In the next 8 weeks, endometrial implant weight increased to 163.6 mg. Daily subcutaneous administration of a luteinizing hormone-releasing hormone agonist, histrelin, or oral administration of danazol, reduced the ectopic implant weight within 8 weeks to 21.7 and 46.0 mg, respectively. In a group of animals that were bilaterally ovariectomized, implant weight decreased significantly in the same 8-week period to 22.4 mg. Furthermore, histologic analysis of the endometriomas showed that ovariectomy, histrelin, or danazol treatment reduced the number of endometrial glands and atrophied the stroma. We conclude that this animal model represents an excellent method for quantitative evaluation of potential therapeutic agents for endometriosis.