1H nuclear magnetic resonance brain metabolomics in neonatal mice after hypoxia–ischemia distinguished normothermic recovery from mild hypothermia recoveries

Abstract

Background:Mild brain hypothermia (31–34 °C) after neonatal hypoxia–ischemia (HI) improves neurodevelopmental outcomes in human and animal neonates. Using an asphyxia model with neonatal mice treated with mild hypothermia after HI, we investigated whether 1H nuclear magnetic resonance (NMR) metabolomics of brain extracts could suggest biomarkers and distinguish different treatments and outcome groups.Methods:At postnatal day 7 (P7), CD1 mice underwent right carotid artery occlusion, 30 min of HI (8% oxygen), and 3.5 h of either hypothermia (31 °C) or normothermia (37 °C). Whole brains were frozen immediately after HI, immediately after 3.5 h of hypothermia or normothermia treatments, and 24 h later. Perchloric acid extractions of 36 metabolites were quantified by 900 MHz 1H NMR spectroscopy. Multivariate analyses included principal component analyses (PCA) and a novel regression algorithm. Histological injury was quantified after HI at 5 d.Results:PCA scores plots separated normothermia/HI animals from hypothermia/HI and control animals, but more data are required for multivariate models to be predictive. Loadings plots identified 11 significant metabolites, whereas the regression algorithm identified 6. Histological injury scores were significantly reduced by hypothermia.Conclusion:Different treatment and outcome groups are identifiable by 1H NMR metabolomics in a neonatal mouse model of mild hypothermia treatment of HI.

The challenge of understanding cerebral white matter injury in the premature infant

“…This model is classically performed in the P7 rat and is produced by unilateral common carotid ligation followed by a variable period of systemic hypoxia leading to a unilateral injury to white matter, cerebral cortex and deep nuclei (Vannucci and Vannucci, 2005). It has been adapted to younger ages (P3) (Segovia et al, 2008), to mice (Graham et al, 2004, Sheldon et al, 2007) and has been used to investigate molecular mechanisms of emerging neuroprotective therapies such as hypothermia (Liu et al, 2013) and erythropoietin (Fang et al, 2013) which are primarily targeted at term infants. Others have modified the P7 model to produce relative selectivity for white matter [but see (Selip et al, 2012)] and demonstrated a potential role for excitotoxicity in white matter injury (Follett et al, 2000, Follett et al, 2004, Manning et al, 2008).…”

Brain Region Mapping Using Global Metabolomics

“…For example, 1 H-NMR has been used to uncover specific highly abundant metabolites (N-acetyl-aspartate, myo-inositol, glutamate, glutamine, creatine, choline and GABA). Such studies have proven to be a key for the characterization of neurochemical and metabolic profiles relevant to brain health (Davidovic, et al, 2011; Liu, et al, 2013; Pears, et al, 2005; Prabakaran, et al, 2004; Tkac, et al, 2004). Granting high reproducibility, the MR technologies are restricted by their low sensitivity, which hinders comprehensive pathologic assessments.…”

Early Cord Metabolite Index and Outcome in Perinatal Asphyxia and Hypoxic-Ischaemic Encephalopathy

“…Hypoxia-ischaemia leads to alterations in cellular energy pathway molecules, such as glycerol and succinate, via mitochondrial dysfunction and subsequent disruption of the tricarboxylic acid cycle [22]. Altered O-phosphocholine has been described in animal models of hypoxia-ischaemia [23]. It is both an anabolic and catabolic metabolite of cell membrane metabolism and may indicate, along with glycerol, cellular membrane breakdown [24].…”