MESSENGER-RIBONUCLEIC-ACID LEVELS OF COLLAGENASE (MMP-13) AND MATRILYSIN (MMP-7) IN VIRGIN, PREGNANT, AND POSTPARTUM UTERUS AND CERVIX OF RAT

Evidence indicates that matrix metalloproteinases (MMPs) are essential ly involved in the postpartum involution of the uterus. As Little info rmation exists about the gene regulation of those MMPs in the uterus, this study aimed to characterize the time course of messenger RNA (mRN A) levels of rat collagenase (MMP-13) and matrilysin (MMP-7) in virgin , late pregnant (18th and 21st day), and postpartum rats (1, 2, 3, and 4 days postpartum). Rat collagenase (MMP-13) mRNA levels were very lo w in virgin and pregnant animals, but increased transiently 30-fold po stpartum, reaching a maximum on the second day postpartum. The tempora l course of mRNA levels of matrilysin (MMP-7) shows similarity with th at of collagenase mRNA levels, but at any stage the abundance of matri lysin mRNA was at least 100-fold higher than that of collagenase; In v irgin animals, matrilysin mRNA levels were dependent on the estrous cy cle, being 3- to 4-fold higher in the estrous and diestrous stages tha n during metestrus. MMP-7 shows an approximately 25-fold induction whe n comparing the mRNA levels in late pregnancy and 2 days postpartum. I n cervexes of virgin, pregnant, and postpartum groups, collagenase mRN A was not detectable. Matrilysin in cervix shows temporal mRNA express ion similar to that in uterus, with a maximum on day 1 postpartum. In cervix, we found a 14-fold induction when comparing levels in late pre gnancy and those 1 day postpartum. Taken together, our findings sugges t that the increased activity of MMPs in the postpartum uterus is due to a strong increase in the mRNA levels of MMP-13 and MMP-7.