Early compensatory adaptations in maternal undernourished pregnancies in rats: role of the aquaporins.
OBJECTIVE
To investigate the effect of maternal undernutrition (MUN) during pregnancy on fetal and placental weight, amniotic fluid (AF) volume, AF osmolality and ion concentrations at gestational ages E16 and E20. We also quantified protein expression of water channels (aquaporins; AQPs).


METHODS
Pregnant rat dams were fed an ad libitum diet (AdLib; n = 6) or were 50% MUN (n = 6) beginning at E10 of gestation. At E16 and E20, we assessed the effect of MUN on fetal and placental weights, AF volume and osmolality, and placental expression of AQP1, 8 and 9. We focused on two uterine positions (proximal and mid-horns) with the extremes of nutrient/oxygen supply. We also separately studied the basal zone (hormone production) and the labyrinth zone (feto-maternal exchange).


RESULTS
We showed that at E16, MUN fetal, and placental weights were unchanged and that, similarly, MUN AF volume, osmolality were comparable to AdLib. At E20, however, MUN fetal and placental zonal weights were significantly decreased. Inversely, due to MUN, maternal and fetal plasma osmolality and Na+ concentrations were significantly increased. Further, MUN AF volume was significantly reduced, while AF osmolality and Na+ concentration were increased at E20.


CONCLUSIONS
Placental basal zone showed variable changes in AQP expression unrelated to position in the uterus or the gestational age (and thus severity of the fetal/placental growth restriction). In the labyrinth zone, MUN placental AQP1 was significantly decreased, whereas AQP8 and 9 expressions were significantly increased at E16 and E20. Dysregulation of AQPs' expression prior to the occurrence of oligohydramnios may represent a compensatory mechanism under conditions of early MUN.
Department of Obstetrics and Gynecology, Harbor-UCLA Medical Center, Los Angeles Biomedical Research Institute at Harbor-UCLA and David-Geffen School of Medicine at UCLA, Torrance, CA 90502, USA. lbelkacemi@obgyn.humc.edu
Louiza
L
Belkacemi
Mina
M
Desai
Marie H
MH
Beall
Qinghai
Q
Liu
James T
JT
Lin
D Michael
DM
Nelson
Michael G
MG
Ross
D000653:Amniotic Fluid; D000818:Animals; D020346:Aquaporins / Q000378:metabolism*; D001835:Body Weight; D004326:Drinking; D004573:Electrolytes / Q000097:blood; D005260:Female; D020567:Fetal Weight; D044342:Malnutrition / Q000378:metabolism* / Q000473:pathology; D016104:Oligohydramnios / Q000378:metabolism*; D009929:Organ Size; D009994:Osmolar Concentration; D010920:Placenta / Q000378:metabolism* / Q000473:pathology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley
D020346:Aquaporins; D004573:Electrolytes