Ninety‐day ketogenic diet intervention has differential effects on neuronal and astrocytic transcriptional pathways in mouse brain

Abstract

AbstractBackgroundGlucose hypometabolism and mitochondrial dysfunction are early deficits in Alzheimer’s disease (AD) brains. The ketogenic diet (KD) has been suggested as a treatment for AD. The KD is theorized to support the brain through the generation of ketone bodies that serve as an alternative fuel to glucose and possibly through other unknown mechanisms. Historically many studies examine CNS function as though it is a homogenous bioenergetic compartment and under value how different CNS cell populations may respond to metabolic interventions or contribute to disease. Here, we characterized how a 3‐month KD intervention influences transcriptional pathways in enriched mouse neuron and astrocyte isolations through magnetic assisted cell separation and RNAseq analysis.MethodAll protocols were reviewed and approved by the KUMC Institutional Animal Care and Use Committee. 30 C57Bl6/N mice were maintained for 90‐days on either chow or ketogenic diet. Upon completion of the dietary intervention mice were euthanized, whole brains dissected, and single cell suspensions were generated. Neuronally and astrocytically enriched fractions were generated immunologically using cell‐type specific antibodies and magnetic selection. Isolated total single stranded RNA was processed and sequenced using Illumina Novaseq 6000 Genome Sequencer and analyzed statistically for differentially expressed genes.ResultKD increased the number of transcriptional pathways activated in mouse neurons whereas astrocytes were observed to have mainly suppressed transcriptional pathways. Molecular pathways with lowest q‐values activated by KD in neurons included endoplasmic reticulum protein processing, insulin signaling pathway, and oxidative phosphorylation. Top disease associated pathways activated by KD in neurons included Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. Top significant pathways suppressed in astrocytes by KD intervention included axon guidance, glutamatergic synapse, and circadian entrainment.ConclusionNeurons and astrocytes have substantially different responses to KD in terms of their transcriptional pathways. Treatment of neurologic disease with drugs that target molecules common to multiple CNS cell types may have diluted, antagonistic effects. Beneficial effects of KD or other therapies may be improved through the identification and targeting of not only disease relevant pathways, but disease relevant cellular compartmentalization of pathways and in doing so improve our ability to treat AD and other neurodegenerative diseases.