Types I and IV collagenolytic and plasminogen activator activities in preovulatory ovarian follicles

Abstract

During ovulation, enzymatic degradation of the extracellular matrix occurs within and around the graafian follicles. In this study, the activities of several different proteolytic enzymes were measured in the culture media of follicles taken from pregnant mare serum gonadotropin (PMSG)-primed immature rats. At 52 h after PMSG, the follicles were cultured for 2 to 15 h in media with or without human chorionic gonadotropin (hCG). Type I collagenase activity in hCG-stimulated follicles gradually increased within 6 h to 3.3-fold above that of the controls. Relatively pure populations of granulosa cells produced type I collagenase to a similar extent. Likewise, type IV collagenase increased 3.8-fold by 6 h after exposure of the follicles to hCG. In contrast, plasminogen activator activity increased by 3.9-fold at 2 h after hCG, but was negligible at 4, 6, and 15 h after incubation. These results suggest that plasminogen activator may activate both type I and type IV collagenase in hCG-stimulated ovulatory follicles.

Ovarian Intrabursal Administration of Transforming Growth Factor β1 Inhibits Follicle Rupture in Gonadotropin-Primed Mice1

“…In addition, in vitro data have indicated that the expression of plasminogen, plasminogen activator, and plasminogen activator inhibitor-i are differentially regulated by TGF3, which in turn acts as a self-regulating system for TGF3 activation [46,47]. Ovarian tissue expresses all the components of this system, which may be utilized for TGF3 activation [1, [35][36][37][38][39][40][41]. Plasminogen and collagenase are constituents of follicular fluid, and FSH-dependent production of plasminogen activator is well documented [1, 31,41].…”

“…Matrix metalloproteinases (MMPs), which are essential in connective tissue remodeling, have been shown to play an important role in the mechanism of follicle rupture [31,[33][34][35][36][37][38][39][40][41][42]. The production and activity of ovarian collagenase have been shown to substantially increase during the preovulatory period, and administration of MMP inhibitors prevents ovulation [35][36][37][38][39][40][41]. In addition to promoting ECM expression and deposition, TGF3 inhibits the synthesis of MMPs and increases synthesis of tissue inhibitors of MMPs and cell surface membrane proteins that bind ECM proteins [43][44][45].…”

“…Changes in the composition and content of steroid hormones, proteolytic enzymes, and colloid osmotic pressure are among the contributing factors in facilitating ovulation [1, [31][32][33][34][35][36][37][38][39][40][41][42]. Among the proteolytic enzymes, plasminogen activator, which stimulates the proteolytic conversion of plasminogen to plasmin, has been suggested to play an important role in this process [1,37].…”

“…Among the proteolytic enzymes, plasminogen activator, which stimulates the proteolytic conversion of plasminogen to plasmin, has been suggested to play an important role in this process [1,37]. Plasminogen and collagenase are constituents of follicular fluid, and FSH-dependent production of plasminogen activator has been well documented [1].…”

Relaxin Modulates the Ovulatory Process and Increases Secretion of Different Gelatinases from Granulosa and Theca-Interstitial Cells in Rats1

“…Second, Too and coworkers demonstrated that porcine relaxin increases the secreted activities of plasminogen activator, collagenase (type I), and proteoglycanase from cultured granulosa cells of gonadotropin-primed immature rats [22,23]. These proteinases, involved in extracellular matrix remodeling, have been shown to play important roles in ovulation in rats [24][25][26][27][28][29]. Finally, in a recent study human relaxin induced a small number of ovulations in the in vitro-perfused rat ovary [30].…”