DISSOCIATION IN THE CONTROL OF CERVICAL EOSINOPHILIC INFILTRATION ANDCOLLAGENOLYSIS AT THE END OF PREGNANCY OR AFTER PSEUDOPREGNANCY IN OVARIECTOMIZED STEROID-TREATED RATS
Eh. Luque et al., DISSOCIATION IN THE CONTROL OF CERVICAL EOSINOPHILIC INFILTRATION ANDCOLLAGENOLYSIS AT THE END OF PREGNANCY OR AFTER PSEUDOPREGNANCY IN OVARIECTOMIZED STEROID-TREATED RATS, Biology of reproduction, 55(6), 1996, pp. 1206-1212
Previous studies have demonstrated that during parturition the physiol
ogical ripening that permits dilation of the cervical canal is doe to
a widespread collagenolysis that follows a heavy polymorphonuclear leu
kocyte invasion of the uterine cervix, The aim of this study was to in
vestigate whether there is any association between the ovarian steroid
hormones involved in rat parturition and this phenomenon, Pregnant or
pseudopregnant rats were ovariectomized (OVX) at Day 9 and then given
a hormonal treatment (sufficient to maintain fetal viability) until D
ay 23. Cervical biopsies, taken from animals killed intrapartum or 1 h
before expected parturition, were studied for eosinophilic infiltrati
on and collagen birefringence. Intrapartum or sham-OVX pregnant rats s
howed a massive eosinophilic infiltration and a widespread collagenoly
sis as indicated by a loss of collagen birefringence, Ovariectomized p
regnant rats treated with estrogen plus progesterone or with progester
one alone showed neither infiltration nor collagenolysis. In rats OVX
during pseudopregnancy, estrogen given alone induced a significant inf
iltration of eosinophils in the cervical stroma; however, treatment wi
th the combination of estrogen and progesterone was not able to promot
e eosinophilic infiltration. Collagenolysis was absent in all pseudopr
egnant animals, These results show that estrogen induced a cervical eo
sinophilic infiltration in rats but that when progesterone was added t
o the estrogen treatment the infiltration was not present; in addition
, none of the steroid hormones assessed were responsible for the colla
genolysis found in the cervical tissue at term.