Evaluation of matrix metalloproteinases-1 and -3 concentrations in the tunica albuginea, the apical wall of atretic follicles and the corpus luteum of normal human ovaries

Matrix metalloproteinases-1 (MMP-1) and -3 (MMP-3) are proteolytic enzymes involved in remodelling the ovarian extracellular matrix throughout the menstrual cycle. The aim of the present study was to evaluate the tissue concentrations of MMP-1 and MMP-3 in the apical wall of atretic follicles (androstenedione/estradiol ratio > 4), tunica albuginea dissected from the ovarian surface overlying areas devoid of follicles, corpus luteum, and tunica albuginea covering the corpus luteum. After extraction of MMPs from the tissue samples, their concentrations in the extracts were measured by enzyme-linked immunosorbent assays (ELISA). Significantly less MMP-1 was detected in the apical wall of atretic follicles compared to tunica albuginea taken from sites devoid of follicles. These data indicate that atresia is associated with relatively low concentrations of MMP-1 in the apical wall of the follicle. Moreover, there was a negative correlation between the amount of MMP-3 and the diameter of follicle. These data suggest that both MMPs play an important role in the final step of atresia. The amount of MMP-1 in the corpus luteum was several times lower than in the other tissues. This is likely due to stabilization of the extracellular matrix during the period of the corpus luteum maintenance. The concentration of MMP-3 did not differ significantly among the examined tissues.