Matrilysin activity in the rat uterus during the oestrous cycle and implantation

The objective of this study was to follow changes in the activity of the sm all matrix metalloproteinase matrilysin (MMP-7) in the rat uterus during th e oestrous cycle and embryo implantation. Matrilysin was extracted from rat uteri, partially purified and separated into active and latent forms. The two forms Of the enzyme were quantified at all stages of the oestrous cycle and after oestradiol and progesterone treatment. The activity was also mea sured during the first 7 days of pregnancy. Both latent and active forms of MMP-7 reached a peak during the pro-oestrous stage of the cycle; the conce ntrations were three times higher than at dioestrus and metoestrus. In rats treated with 0.1 mg oestradiol at metoestrus, both latent and active forms of the enzyme increased by more than two-fold after 24 h. In fats treated at pro-oestrus with 0.4 mg progesterone, there was a 70% increase in latent MMP-7, but no change in the active form. The highest concentrations of MMP -7 were observed on the first day of pregnancy. Between days 3 and 7 of pre gnancy, the concentrations were relatively constant and comparable to the l ow concentrations at dioestrus. Enzyme activities were not different at imp lantation sites compared with remote sites.