Growth restriction and the cerebral metabolic response to acute hypoxia of chick embryos in-ovo: a proton magnetic resonance spectroscopy study.
BACKGROUND
Perinatal brain injury is more common in growth-restricted (GR) than normally grown (NG) fetuses. This study addresses the hypothesis that chronic oxygen and substrate deprivation during pregnancy will engender an abnormal fetal cerebral metabolic response to acute hypoxia.


METHODS
Cerebral metabolite resonance amplitudes relative to that of creatine were measured by proton magnetic resonance spectroscopy in chick embryos on day 19 of incubation. Measurements were obtained before, during and after acute hypoxia (8% ambient oxygen concentration for 44 min) in NG and GR embryos (10% albumen extracted day 0 and 14% oxygen exposure from day 10 of incubation).


RESULTS
In both NG and GR embryos, the cerebral lactate/creatine increased during acute hypoxia and slowly recovered after restoration of normoxia. However, the mean (+/-SD) increase in lactate/creatine was significantly less in GR compared to NG embryos (0.51 +/- 0.36 vs. 0.94 +/- 0.36; P = 0.02, t test). Alanine increased during acute hypoxia in NG but not GR embryos. Mean beta-hydroxybutyrate was increased only in GR embryos (0.63 +/- 0.01 vs. 0.22 +/- 0.01; P < 0.001, ANOVA).


CONCLUSIONS
Acute hypoxia increases cerebral lactate and alanine in NG chick embryos; these increases are reduced by pre-exposure to substrate deprivation and chronic hypoxia.
Dixon
James C
JC
Department of Obstetrics and Gynaecology, University College London, 86-96 Chenies Mews, London WC1E 6HX, UK.
Cady
Ernest B
EB
Priest
Andrew N
AN
Thornton
John S
JS
Peebles
Donald M
DM
D020155:3-Hydroxybutyric Acid / Q000378:metabolism; D000409:Alanine / Q000378:metabolism; D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D002531:Cerebellum / Q000196:embryology / Q000378:metabolism*; D002642:Chick Embryo; D005311:Fetal Hypoxia / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011522:Protons; D012149:Restraint, Physical / Q000379:methods; D013997:Time Factors
D011522:Protons; D001224:Aspartic Acid; D019344:Lactic Acid; C000179:N-acetylaspartate; D000409:Alanine; D020155:3-Hydroxybutyric Acid