Lactate utilization as an energy substrate in ischemic preconditioned rat brain slices

Area of Science:

• Neuroscience
• Metabolism
• Biochemistry

Background:

• Brain cells rely on glucose for energy.
• Lactate is increasingly recognized as a crucial energy substrate.
• Ischemic preconditioning is a phenomenon that protects the brain against subsequent ischemic insults.

Purpose of the Study:

• To investigate if ischemic preconditioning alters the brain's capacity to utilize lactate as an energy source.
• To determine the impact of preconditioning on neuronal energy metabolism under ischemic conditions.

Main Methods:

• Utilized rat brain slices subjected to middle cerebral artery occlusion for preconditioning.
• Measured high-energy phosphate levels using 31P Nuclear Magnetic Resonance (NMR).
• Assessed neuronal function via population excitatory postsynaptic potentials and spikes in hippocampal slices.

Main Results:

• Ischemic preconditioned brain slices showed significant recovery of phosphocreatine (PCr) levels when supplied with lactate, unlike intact slices.
• Neuronal activity (population spikes) in hippocampal slices from preconditioned rats was maintained in lactate-containing artificial cerebrospinal fluid (ACSF).
• Intact slices demonstrated a complete abolition of PCr recovery and neuronal activity in lactate-containing ACSF.

Conclusions:

• Neurons subjected to ischemic preconditioning gain the ability to utilize lactate as an energy substrate.
• Ischemic preconditioning may induce changes in neurons, potentially involving lactate transporters or lactate dehydrogenase activity.
• Lactate serves as a viable energy source for neurons adapted through ischemic preconditioning.