1H/13C NMR metabolomics in a neonatal rat brain slice model of early and late mild hypothermia treatments of asphyxia

Abstract

Clinical trials with neurological outcomes have led to using mild therapeutic hypothermia (≈4°C decrease) in early treatments of newborns with hypoxic‐ischemic encephalopathy from birth asphyxia, which we simulated by oxygen‐glucose deprivation (OGD) in superfused brain slices. Temperature differently modulates metabolic fluxes and concentrations. Although 4°C changes are small, three hypothermia treatment groups (nothing, immediate, and delayed) were distinctly separated by PLS‐DA multivariate analyses in 14.1 T (Tesla) and 21.15 T NMR metabolic profiling of perchloric acid brain slice extracts. Changes in tricarboxylic acid cycle (TCA) fluxes and neuron‐glial metabolic differences were measured after simultaneous administration of [1‐13C]glucose and [1,2‐13C]acetate. High energy phosphates, quantified by 31P NMR at 14.1 T, were quantified by 1H NMR at 21.15 T (900 MHz). Mild hypothermia's influence on neuron/glial metabolic differences was measured via two ratios: acetate/glucose utilization, which had significant changes; and (pyruvate carboxylase)/(pyruvate dehydrogenase) activity, which had minimal changes. Combining 13C data with 1H data further sharpened metabolomic distinctions. Support: NIH GM34767