Hormonal modulation of prolyl endopeptidase and dipeptidyl peptidase IV activities in the mouse uterus and ovary

Prolyl endopeptidase and dipeptidyl peptidase IV are proline-specific peptidases, and are ubiquitously distributed in various tissues in mammals. The specific activities of these peptidases in both uterus and ovary were examined in the SHN strain of mice at estrus or diestrus. A marked change in prolyl endopeptidase activity was found in the uterus and ovary in intact mice during the estrous cycle, the activity being high at estrus and low at diestrus. In ovariectomized mice, prolyl endopeptidase activity was significantly higher in the uterus treated with progesterone or estradiol than in the uterus treated with vehicle oil only or a dopamine antagonist (perphenazine) which stimulates prolactin secretion. On the other hand, notable change in dipeptidyl peptidase IV activity during the estrous cycle was found only in the uterus of intact mice. The activity was low at estrus and high at diestrus. In ovariectomized mice, the uterus exposed to estradiol showed a lower dipeptidyl peptidase IV activity than the uteri treated with progesterone, the dopamine antagonist or vehicle oil. These findings reveal that there is a close correlation between the circulating level of ovarian steroids and the activities of these prolinespecific enzymes.