Rationale for frequency and dose of administration in gestrinone therapy for pelvic endometriosis in the experimental model of rabbit uterus

Does gestrinone antagonize the effects of estrogen on endometrial implants upon the peritoneum of rats?

OBJECTIVE

To evaluate the effects of estrogen treatment in combination with gestrinone on an experimental rat model of endometriosis.

METHODS

Uterine transplants were attached to the peritoneum of female Wistar rats via a surgical autotransplantation technique. The implanted area was measured during the proestrus phase and after hormonal treatment. We performed morphometric analysis and examined the macroscopic and morphometric alterations of endometrial implants after hormonal treatment in ovariectomized rats.

RESULTS

The high dose of estrogen caused macroscopic increases in the endometrial implant group compared with other groups, which were similar to increases in the proestrus phase. The low dose showed morphometric development of implants, such as an increase in number of endometrial glands, leukocyte infiltration and mitosis. Gestrinone antagonized both doses of estrogen.

CONCLUSION

Our findings suggest that gestrinone antagonizes estrogen's effects on rat peritoneal endometrial implants.

Individual and combined effects of triptoreline and gestrinone on experimental endometriosis in rats

OBJECTIVES

To evaluate the effects of triptoreline, gestrinone, and both, on experimental endometriosis in rats.

STUDY DESIGN

Experimental endometriosis was surgically induced in 225 Wistar rats. Of these, 202 rats showed at least one grown implant, 22 of which composed the control group, while 180 were treated with triptoreline, gestrinone, or both, for 28 days. The implants were evaluated again after 25 days.

RESULTS

There were no changes in size in the control group. About 73% of the implants treated with triptoreline showed a high reduction (> 50%), vs. 51% with gestrinone (P < 0.0005) and 65% with both (P < 0.005). Triptoreline caused macroscopic resolution in 40% of the implants vs. 31% for gestrinone (not significant) and 26% for both substances (P < 0.05). In the triptoreline group, the mean size of the implants decreased by 65% between the 25th and 28th days, 58% between the 29th and the 35th, and 39% after the 36th day. This reduction was 51%, 36%, and 33%, respectively, in gestrinone group.

CONCLUSIONS

Triptoreline was more effective than gestrinone, but perhaps not in the long run. Their association did not improve the results.