The Effect of GnRH Agonist and Bilateral Oophorectomy on Experimental Endometriosis in the Rabbit

Cho, C H; Kim, S H; Seo, J H; Kim, M K; Park, H M; Hur, M

Abstract

Endometriosis is the presence of functioning endometrial glands and stroma outside the uterine cavity. However, the exact mechanism of endometriosis involved remains unclear. To prove Sampson`s hypothesis of retrograde menstruation as a cause of endometriosis, we evaluated endometriosis artificially induced in the rabbits. Sampson`s hypothesis of retrograde menstruation as a cause of endometriosis was proved by evaluating the result of intrapelvic implantation of endometrium. Endometrium obtained from one uterine horn after stimulation with estradiol injection was surgically implantated into the peritoneum, and the viabilities of the implants were studied histologically. Thirty rabbits were used for this study and were randomly assigned to three groups. Group 1 served as a control, group 2 was those with intramuscular injection with GnRH agonist and group 3 was those that were operated for bilateral ovariectomy. Laparotomies were performed after 25 days in all rabbits to assess the histologic evaluation and the volume of endometrial implants. And blood sampling was done from descending aorta, 17beta-estradiol were estimated. The results were summarized as followings: 1. The concentration of 17beta-estradiol was checked 91+/-19 pg/ml in control, 34+/-7 pg/ml after injection with GnRH agonist, 25+/-6 pg/ml in bilateral ovariectomy. Administration of GnRH agonists and bilateral ovariectomy significantly decreased the serum estradiol level. 2. The volume of endometrial implants after injection with GnRH agonists (5.9+/-1.4 mm3) and after ovariectomy (1.4+/-0.1 mm3) were significantly less than those of control group (30.0+/-6.2 mm3)(p<0.01). 3. In the histologic evaluation of endometrial implants, the number of endometrial gland and stroma was increased in control, but was significantly decreased in other groups (p<0.05). This study showed that intrapelvic implantation with endometrium can cause endometriosis, and Sampson hypothesis was experimentally proved thouse indirectly. And estradiol level was significantly suppressed in GnRH agonists and ovariectomized group. It can be stated that GnRH agonists may be one of the potential modalities of treatment in the patients with endometriosis.