Gonadotropin-releasing hormone agonist (GnRH-a) therapy alters activity of plasminogen activators, matrix metalloproteinases, and their inhibitors in rat models for adhesion formation and endometriosis: Potential GnRH-a- regulated mechanisms reducing adhesion formation

Objective: To evaluate the effects of a gonadotropin-releasing hormone agonist (GnRH-a) on plasminogen activator (PA), matrix metalloproteinase (MMP), plasminogen activator inhibitor (PAI) and matrix metalloproteinase inhibitor (MMPI) activities in peritoneal fluid relative to GnRH-a-induced reduction of adhesion formation. Design: Continuation of prospective randomized study using surgical models for adhesion formation. Setting: Department of Obstetrics and Gynecology research laboratory at the University of Missouri School of Medicine. Patient(s): Forty reproductively cycling female Sprague-Dawley rats. Intervention(s): Female rats were injected with depot GnRH-a or diluent and randomly assigned to adhesion and endometriosis surgeries. Peritoneal fluid was collected prior to (time 1) and 7 weeks from (time 2) initial surgery. Main Outcome Measure(s): Peritoneal fluid was analyzed for PA, PAI, MMP, and MMPI activities. Result(s): At time 1, MMP and MMPI activities were similar in all rats; however, PA and PAI activities were less in rats pretreated with GnRH-a than with diluent. Between time 1 and time 2, GnRH-a-treated rats showed an increase in PAI and MMPI activities without significant changes in PA or MMP activities, whereas rats receiving diluent showed a significant increase in PAl and MMP activities but no significant changes in PA or MMPI activities. At time 2, rats receiving GnRH- a had less PA and MMP activities than those receiving diluent. Adhesion scores showed a positive correlation with MMP activity. Conclusion(s): In the absence of GnRH-a therapy, surgical tissue manipulation increased peritoneal fluid MMP and PAI activity. Gonadotropin-releasing hormone agonist therapy decreased PA and MMP activities and also increased PAI and MMPI activities. This GnRH-a-induced shift to a less invasive phenotype may alter fibrinolysis and extracellular matrix remodeling and thereby play a role in the mechanism of GnRH-a-induced reduction in adhesion formation.