Publication Date

2019-01-23

Availability

Open access

Embargo Period

2019-01-23

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Neuroscience (Medicine)

Date of Defense

2018-12-06

First Committee Member

Juan I. Young

Second Committee Member

Carlos T. Moraes

Third Committee Member

Antonio Barrientos

Abstract

Neuroprotective agents administered post cerebral ischemia have failed so far in the clinic to promote significant recovery. Thus, numerous efforts were redirected towards prophylactic approaches such as preconditioning as an alternative therapeutic strategy. Our lab has revealed a novel long-term window of cerebral ischemic tolerance mediated by resveratrol preconditioning (RPC) that lasts for two weeks in mice. To identify its mediators, we conducted an RNA-seq experiment on the cortex of mice two weeks post RPC, which revealed 136 differentially expressed genes. The majority of genes (116/136) were downregulated upon RPC and clustered into biological processes involved in transcription, synaptic signaling, and neurotransmission. The downregulation in these processes was reminiscent of metabolic depression, an adaptation used by hibernating animals to survive severe ischemic states by downregulating energy-consuming pathways. Thus to assess metabolism, we used a neuronal-astrocytic co-culture model and measured the cellular respiration rate at the long-term window post RPC. Remarkably, we observed an increase in glycolysis and mitochondrial respiration efficiency upon RPC. We also observed an increase in the expression of genes involved in pyruvate uptake, TCA (tricarboxylic acid cycle) cycle, and oxidative phosphorylation, all of which indicated an increased reliance on energy-producing pathways. We then revealed that these nuclear and mitochondrial adaptations, which reduce the reliance on energy-consuming pathways and increase the reliance on energy-producing pathways, are epigenetically coupled through acetyl-CoA (acetylcoenzyme A) metabolism and ultimately increase baseline ATP (adenosine triphosphate) levels. This increase in ATP would then allow the brain, a highly metabolic organ, to endure prolonged durations of energy deprivation caused by cerebral ischemia.

Keywords

Resveratrol; cerebral ischemia; cerebral ischemic tolerance; preconditioning; brain metabolism; brain transcriptomic

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