β-Hydroxybutyrate preferentially enhances neuron over astrocyte respiration while signaling cellular quiescence

While ketone bodies support overall brain energy metabolism, it is increasingly clear specific brain cell types respond differently to ketone body availability. Here, we characterized how SH-SY5Y neuroblastoma cell, primary neuron, and primary astrocyte bioenergetics and nutrient sensing pathways respond to β-hydroxybutyrate (βOHB). SH-SY5Y cells and primary neurons, but not astrocytes, exposed to βOHB increased respiration and decreased PI3K-Akt-mTOR signaling. Despite increased carbon availability and respiration, SH-SY5Y cells treated with βOHB reduced their overall metabolic activity and cell cycling rate. Levels of the quiescence-regulating Yamanaka factors increased to a broader extent in SH-SY5Y cells and primary neurons. We propose a βOHB-induced increase in neuron respiration, accompanied by activation of quiescence associated pathways, could alleviate bioenergetic stress and limit cell senescence. This in turn could potentially benefit conditions, including brain aging and neurodegenerative diseases, that feature bioenergetic decline and cell senescence.