Effects of relaxin on matrix remodeling enzyme activity of cultured equineovarian stromal cells

Relaxin participates in extracellular matrix (ECM) remodeling in many repro ductive organs, including the ovary by regulating proteolytic enzyme activi ty. Accumulated evidence indicates this action of relaxin is involved in ov arian follicle development and ovulation, Equine follicles are embedded in cortex that is at the center of the ovary and they must expand/emigrate to the fossa, the only site in the ovary for ovulation Due to the tremendous e xpansion of the follicle in this species, we hypothesized that ovarian stro mal remodeling would be extensive. Therefore, cultured equine ovarian strom al cell (EOSC) lines were obtained from stroma at the apex of large follicl es and the effects of relaxin on gelatinases A and B, tissue inhibitors of matrix metalloproteinases (TIMPS), plasminogen activators (PAs) and PA inhi bitor-1 (PAI-1) activities were assessed. Our results showed that equine re laxin increased the activity of total gelatinase A (both pro forms and matu re forms) and latent progelatinase B present in conditioned medium. latent progelatinase A present in cell extracts, and TIMP-1 and TIMP-2 present in conditioned medium. This study also revealed that equine relaxin increased the urokinase-type PA activity in conditioned medium and cell extracts, tis sue-type PA activity in ECR I and PAI-1 activity in conditioned medium. The se results suggest that relaxin may contribute to equine follicle growth an d migration, and facilitate ovulation by modulating the degradation of ECM in ovarian stromal tissue. (C) 2001 Elsevier Science B.V. All rights reserv ed.