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Updated: Aug 17, 2026
Minimizing Hypoxia in Hippocampal Slices from Adult and Aging Mice
Published on: July 2, 2020
Hypothermia and amiloride preserve energetics in a neonatal brain slice model
Nicola J Robertson1, Kishore Bhakoo, Basant K Puri
1Department of Paediatrics, Division of Paediatrics, Obstetrics and Gynaecology, Division of Clinical Sciences, Hammersmith Hospital, Imperial College London, London W12 ONN, UK. n.robertson@ucl.ac.uk
Insights
Hypothermia and amiloride can delay secondary energy failure in neonatal rat brain slices, a condition marked by declining phosphocreatine/inorganic phosphate and rising lactate. These findings suggest potential neuroprotective strategies for neonatal encephalopathy.
Area of Science:
- Neuroscience
- Biochemistry
- Medical Imaging
Background:
- Neonatal encephalopathy is associated with secondary energy failure, characterized by reduced phosphocreatine/inorganic phosphate (PCr/Pi), increased brain lactate, and alkaline intracellular pH (pH(i)).
- Strategies mitigating this energy failure may offer neuroprotection.
Purpose of the Study:
- To investigate if hypothermia or amiloride can ameliorate the progressive decline in energetics in a neonatal rat brain slice model.
- To characterize the energetic changes and pH(i) shifts during secondary energy failure in this model.
Main Methods:
- Utilized interleaved phosphorus-31 ((31)P) and proton ((1)H) magnetic resonance (MR) spectroscopy.
- Acquired spectra from 350 µm neonatal rat brain slices over 8 hours at 37°C and 32°C (hypothermia).
- Investigated amiloride's effects in a bicarbonate-free buffer at 37°C in a 14-day-old model.
Main Results:
- Neonatal rat brain slices exhibited secondary energy failure, evidenced by decreased PCr/Pi and increased lactate/N-acetylaspartate (NAA) at 37°C.
- Hypothermia (32°C) significantly preserved PCr/Pi and lactate/NAA levels, maintaining nucleotide triphosphate (NTP)/phosphomonoester (PME) ratios compared to normothermia.
- Amiloride treatment prevented significant changes in pH(i) and maintained NTP/PME ratios, indicating a delay in energy failure.
Conclusions:
- The neonatal rat brain slice model successfully replicates secondary energy failure observed in neonatal encephalopathy.
- Hypothermia and amiloride demonstrate neuroprotective potential by delaying or ameliorating this energy failure.
- These findings support further investigation of hypothermia and amiloride as therapeutic strategies for neonatal brain injury.
Abstract:
A period of secondary energy failure consisting of a decline in phosphocreatine/inorganic phosphate (PCr/Pi), a rise in brain lactate, and alkaline intracellular pH (pH(i)) has been described in infants with neonatal encephalopathy. Strategies that ameliorate this energy failure may be neuroprotective. We hypothesized that a neonatal rat brain slice model undergoes a progressive decline in energetics, which can be ameliorated with hypothermia or amiloride. Interleaved phosphorus ((31)P) and proton ((1)H) magnetic resonance (MR) spectra were obtained from 350 microm neonatal rat brain slices over 8 h in a bicarbonate buffer at 37 degrees C and at 32 degrees C in 7- and 14-d models. (31)P MR spectra were obtained with amiloride in a bicarbonate-free buffer at 37 degrees C in the 14-d model. Findings were similar in 7- and 14-d models. In the 14-d model, there was a Pi doublet structure corresponding to alkaline pH(i) values of 7.50 +/- 0.02 and 7.21 +/- 0.04. Compared with the stabilized baseline of 100, at 5 h PCr/Pi was 65 +/- 6.3 and lactate/NAA was 187 +/- 3 at 37 degrees C, but PCr/Pi and lactate/NAA were not significantly different from baseline at 32 degrees C. Nucleotide triphosphate (NTP)/phosphomonoester (PME) was 0.93 +/- 0.23 at 37 degrees C and 1.81 +/- 0.21 at 32 degrees C at 5 h. With amiloride exposure in the 14-d model, baseline pH(i) values were 7.25 +/- 0.09 and 6.98 +/- 0.02 and NTP/PME was 1.81 +/- 0.05; these parameters were not significantly different at 5 h. Our interpretation of these findings is that the brain slice model underwent secondary energy failure, which was delayed with hypothermia or amiloride.
