1. Chronic hypoxia in pregnant mice impairs the placental and fetal vascular response to acute hypercapnia in BOLD-MRI hemodynamic response imaging.
- Author
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Ginosar Y, Bromberg Z, Nachmanson N, Ariel I, Skarzinski G, Hagai L, Elchalal U, Shapiro J, and Abramovitch R
- Subjects
- Acute Disease, Animals, Chronic Disease, Disease Models, Animal, Embryo, Mammalian, Female, Fetal Growth Retardation diagnostic imaging, Fetal Growth Retardation pathology, Fetal Growth Retardation physiopathology, Fetal Hypoxia diagnostic imaging, Fetal Hypoxia etiology, Fetal Hypoxia pathology, Fetal Hypoxia physiopathology, Fetus diagnostic imaging, Hemodynamics, Hypercapnia diagnostic imaging, Hypercapnia pathology, Hypercapnia physiopathology, Hypoxia diagnostic imaging, Hypoxia pathology, Hypoxia physiopathology, Magnetic Resonance Imaging methods, Mice, Mice, Inbred ICR, Placenta diagnostic imaging, Placental Insufficiency diagnostic imaging, Placental Insufficiency pathology, Placental Insufficiency physiopathology, Pregnancy, Pregnancy Complications diagnostic imaging, Pregnancy Complications pathology, Pregnancy Complications physiopathology, Prenatal Diagnosis methods, Fetus blood supply, Hypercapnia etiology, Hypoxia complications, Placenta blood supply
- Abstract
Introduction: Brief hypercapnic challenge causes acute placental hypoperfusion with fetal brain sparing on BOLD-MRI. We hypothesize that this non-invasive imaging strategy can distinguish between normal pregnancy and chronic placental hypoperfusion (using the maternal hypoxia model)., Methods: Eighteen pregnant female ICR mice were randomized to three groups: normoxia, late-onset hypoxia (12%O
2 ;E13.5-17.5) and early-onset hypoxia (12%O2 ;E10.5-17.5). On E17.5, animals were imaged in a 4.7-T Bruker-Biospec MRI scanner. Fast coronal True-FISP was performed to identify organs of interest (placenta and fetal heart, liver and brain). BOLD-MRI was performed at baseline and during a 4-min hypercapnic challenge (5%CO2 ). %-change in placental and fetal signal was analyzed from T2*-weighted gradient echo MR images. Following MRI, fetuses and placentas were harvested, weighed and immuno-stained., Results: In normoxic mice, hypercapnia caused reduction in BOLD-MRI signal in placenta (-44% ± 7%; p < 0.0001), fetal liver (-32% ± 7%; p < 0.0001) and fetal heart (-54% ± 12%; p < 0.002), with relative fetal brain sparing (-12% ± 5%; p < 0.0001). These changes were markedly attenuated in both hypoxia groups. Baseline fetal brain/placenta SI ratio was highest in normoxic mice (1.14 ± 0.017) and reduced with increasing duration of hypoxia (late-onset hypoxia: 1.00 ± 0.026; early-onset hypoxia: 0.91 ± 0.016; p = 0.02). Both hypoxic groups exhibited fetal growth restriction with prominent placental glycogen-containing cells, particularly in early-onset hypoxia. There was increased fetal neuro- and intestinal-apoptosis in early-onset hypoxia only., Conclusions: BOLD-MRI with brief hypercapnic challenge distinguished between normoxia and both hypoxia groups, while fetal neuroapoptosis was only observed after early-onset hypoxia. This suggests that BOLD-MRI with hypercapnic challenge can identify chronic fetal asphyxia before the onset of irreversible brain injury., (Copyright © 2021 Elsevier Ltd. All rights reserved.)- Published
- 2021
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