Comparing The Effects of Glycyrrhiza glabra Root Extract, A Cyclooxygenase-2 Inhibitor (Celecoxib) and A Gonadotropin-Releasing Hormone Analog (Diphereline) In A Rat Model of Endometriosis

Background: The purpose of this study was to compare the effects of Glycyrrhiza glabra (Licorice), a cyclooxygenase- 2 inhibitor (Celecoxib) and a gonadotropin-releasing hormone analog (Diphereline®), with a control group on endometrial implants in rats. Materials and Methods: In this experimental study, endometriosis was induced in rats by auto transplantation and after confirmation, the rats were divided into 4 groups that were treated for 6 weeks with normal saline (0.5 ml/day, orally), licorice extract (3000 mg/kg/day, orally), celecoxib (50 mg/kg, twice a day, orally) or diphereline (3 mg/kg, intramuscularly). At the end of treatments, the mean area, volume, histopathology and hemosiderin-laden macrophage (HLM) counts of the endometrial implants were evaluated and compared among the four groups. Results: The mean area, volume and HLM counts of the implants in the licorice group were significantly lower than those of the control group (P<0.001). The histopathologic grades of endometrial implants were significantly decreased by licorice compared to the control group (P<0.001). There was no significant change in the mentioned parameters in rats treated with celecoxib compared to the control group. Diphereline was the most potent agent for suppressing the growth of endometrial implants in terms of all of the above-mentioned parameters. Conclusion: Licorice decreased the growth and histopathologic grades of auto-transplanted endometrial implants. However, while celcoxib had no significant effect, diphereline showed the highest potency for decreasing the endometrial growth. Licorice may have the potential to be used as an alternative medication for the treatment of endometriosis.