Menstrual-like changes in mice are provoked through the pharmacologic withdrawal of progesterone using mifepristone following induction of decidualization.
BACKGROUND
Cyclic shedding of the endometrium is unique to menstruating species, and mouse menstruation models by physiologic progesterone withdrawal have been previously reported. Since progesterone action ablated pharmacologically may provide more insight into the mechanism of action, a mouse menstruation model using mifepristone was established.


METHODS
Mifepristone was administered following oil-induced decidualization in ovarectomized mice primed with hormones. Morphology, hormone levels, leukocytes and apoptosis were evaluated over a period of 48 h after treatment. Vaginal smears were used to monitor bleedings.


RESULTS
Mifepristone induced menstrual-like changes. Tissue breakdown was drastic by 16 h, and the decidual zone was shed by 24 h while the mice bled. The endometrium regenerated from 24 h onwards and became completely restored by 48 h. These results are consistent with previous reports. However, although progesterone levels remained constant, estradiol levels increased after the treatment. The CD45(+) cells showed two peaks of increase at 16 h (breakdown phase) and 32 h (regeneration phase) (Leukocyte levels also increased in the unstimulated horns, but no breakdown changes occurred there). Moreover, apoptosis drastically increased by 16 h concurrent with tissue destruction. These results differed from those of the physiologic withdrawal models.


CONCLUSIONS
The pharmacologic withdrawal of progesterone by mifepristone successfully provoked a menstrual-like process in mice after artificial decidualization.
Xu
X B
XB
Department of Cell Biology, National Research Institute for Family Planning, Beijing 100081, People's Republic of China.
He
B
B
Wang
J D
JD
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D003656:Decidua / Q000187:drug effects* / Q000502:physiology; D004958:Estradiol / Q000097:blood; D005260:Female; D007962:Leukocytes / Q000187:drug effects; D008598:Menstruation / Q000187:drug effects* / Q000502:physiology; D008600:Menstruation-Inducing Agents / Q000494:pharmacology*; D051379:Mice; D008815:Mice, Inbred Strains; D015735:Mifepristone / Q000494:pharmacology*; D011374:Progesterone / Q000097:blood*; D014626:Vaginal Smears
D008600:Menstruation-Inducing Agents; D015735:Mifepristone; D011374:Progesterone; D004958:Estradiol