Frontiers in Neurology (Sep 2020)

Proton Magnetic Resonance Spectroscopy Lactate/N-Acetylaspartate Within 48 h Predicts Cell Death Following Varied Neuroprotective Interventions in a Piglet Model of Hypoxia–Ischemia With and Without Inflammation-Sensitization

  • Raymand Pang,
  • Kathryn A. Martinello,
  • Christopher Meehan,
  • Adnan Avdic-Belltheus,
  • Ingran Lingam,
  • Magda Sokolska,
  • Tatenda Mutshiya,
  • Alan Bainbridge,
  • Xavier Golay,
  • Nicola J. Robertson

DOI
https://doi.org/10.3389/fneur.2020.00883
Journal volume & issue
Vol. 11

Abstract

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Despite therapeutic hypothermia, survivors of neonatal encephalopathy have high rates of adverse outcome. Early surrogate outcome measures are needed to speed up the translation of neuroprotection trials. Thalamic lactate (Lac)/N-acetylaspartate (NAA) peak area ratio acquired with proton (1H) magnetic resonance spectroscopy (MRS) accurately predicts 2-year neurodevelopmental outcome. We assessed the relationship between MR biomarkers acquired at 24–48 h following injury with cell death and neuroinflammation in a piglet model following various neuroprotective interventions. Sixty-seven piglets with hypoxia–ischemia, hypoxia alone, or lipopolysaccharide (LPS) sensitization were included, and neuroprotective interventions were therapeutic hypothermia, melatonin, and magnesium. MRS and diffusion-weighted imaging (DWI) were acquired at 24 and 48 h. At 48 h, experiments were terminated, and immunohistochemistry was assessed. There was a correlation between Lac/NAA and overall cell death [terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)] [mean Lac/NAA basal ganglia and thalamus (BGT) voxel r = 0.722, white matter (WM) voxel r = 0.784, p < 0.01] and microglial activation [ionized calcium-binding adapter molecule 1 (Iba1)] (BGT r = −0.786, WM r = −0.632, p < 0.01). Correlation with marker of caspase-dependent apoptosis [cleaved caspase 3 (CC3)] was lower (BGT r = −0.636, WM r = −0.495, p < 0.01). Relation between DWI and TUNEL was less robust (mean diffusivity BGT r = −0.615, fractional anisotropy BGT r = 0.523). Overall, Lac/NAA correlated best with cell death and microglial activation. These data align with clinical studies demonstrating Lac/NAA superiority as an outcome predictor in neonatal encephalopathy (NE) and support its use in preclinical and clinical neuroprotection studies.

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