Time-related effects of gonadotropin-releasing hormone analog treatment in experimentally induced endometriosis in the rat

The purpose of our study was to characterize the time-dependent effect of gonadotropin-releasing hormone analog (GnRH-a) therapy on endometriosis explant using the rat model. Endometriosis was induced in 60 mature female rats. One group of treated animals as well as controls were killed at 2, 4, 6, and 8weeks of treatment at which time the explant was evaluated. Explant volume was significantly reduced in all treatment groups, an effect that was more significant in animals treated for ≥4weeks compared with those treated for only 2weeks. We conclude that GnRH-a treatment caused gradual regression of endometrial explant that was effectively complete by 4weeks of treatment. We further conclude that this experimental model may be useful in the evaluation of other modes of endometriosis therapy.