Mechanism of action of Tripterygium Wilfordii polyglycoside on experimental endometriosis.

PURPOSE OF INVESTIGATION: This study was designed to examine the therapeutic effectiveness and mechanism of action of Tripterygium Wilfordii polyglycoside (TWP) in the treatment of endometriosis. METHODS: An experimental endometriosis model was developed using New Zealand White rabbits where endometrial tissue was autotransplanted into the peritoneum. Six weeks after transplantation, a total of 22 rabbits were randomly placed into two groups: Group I (n=17) was treated with TWP (10 mg/kg/day) and Group 2 (n=5) served as the water-fed control for three successive months. The volume of endometrial implants was measured before and after administration of TWP and water. Immune and endocrine systems were investigated in the normal phase, six weeks after induction of endometriosis, and three months after TWP treatment and water administration. RESULTS: After treatment with TWP, the average volume of endometrial implants significantly decreased (p < 0.0001), and the antiendometrial antibody (EmAb) level decreased (p < 0.05) to near normal levels, but it did not decrease in the untreated controls. Serum FSH and LH levels also decreased after TWP treatment. Furthermore, electron microscopic examination of the pituitary ultrastructure revealed morphological changes in gonadotropic cells (G-cell) after treatment with TWP, and changes gradually disappeared four weeks after withdrawal of TWP. CONCLUSION: This study indicates that TWP has both hormonal and immune system action that is effective as a medical treatment for experimental endometriosis by modulating both reproductive endocrine functions and immunosuppression that results in remission of the disease.