Gestational changes in calbindin-D9k in rat uterus, yolk sac, and placenta: implications for maternal-fetal calcium transport and uterine muscle function.
Calbindin-D9k was quantified and its cellular location was defined in uterus, yolk sac, and placenta. In late gestation (days 17 to term) coordinated induction of calbindin-D9k was seen in uterine epithelial lining cells and juxtaposed yolk sac visceral epithelium as well as the intraplacental yolk sac epithelium. The induction of calbindin-D9k in these cells coincided with the time of exponential fetal bone growth and maximal fetal accumulation of calcium, suggesting a role of the protein in these epithelial layers in maternal-fetal calcium transport. Dynamic changes also occurred in the calbindin-D9k contents of the two layers of uterine smooth muscle (outer longitudinal and inner circular) during mid- and late gestation. During early pregnancy (days 0-4), calbindin-D9k was present in the two smooth muscle layers. By midgestation (day 10), calbindin-D9k had decreased by a factor of 10 in these tissue layers. During late gestation calbindin-D9k rebounded in the inner circular smooth muscle layer. These uterine changes of early and midgestation were reproduced by the endocrine changes of pseudopregnancy. Progesterone appeared to be a good candidate for controlling the midgestational decrease of uterine muscle calbindin-D9k, as it blunted estrogen's induction of the protein in the muscle layers and stroma in a dose-dependent manner. Changes in myometrial calbindin-D9k may reflect variations in muscular calcium storage, thereby representing alterations in potential for contraction.
Mathieu
C L
CL
Department of Pathology, University of Virginia School of Medicine, Charlottesville 22908.
Burnett
S H
SH
Mills
S E
SE
Overpeck
J G
JG
Bruns
D E
DE
Bruns
M E
ME
D000818:Animals; D001692:Biological Transport; D064026:Calbindins; D002118:Calcium / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005333:Fetus / Q000378:metabolism; D007150:Immunohistochemistry; D008431:Maternal-Fetal Exchange; D009130:Muscle, Smooth / Q000032:analysis / Q000502:physiology; D010920:Placenta / Q000032:analysis*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D064030:S100 Calcium Binding Protein G / Q000032:analysis* / Q000502:physiology; D014590:Uterine Contraction; D014599:Uterus / Q000032:analysis* / Q000187:drug effects / Q000502:physiology; D015017:Yolk Sac / Q000032:analysis*
D064026:Calbindins; D064030:S100 Calcium Binding Protein G; C576508:S100g protein, rat; D011374:Progesterone; D004958:Estradiol; D002118:Calcium