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Authors & Affiliations
Liv Svenningsson Krogstad, Markus A. Teppen, Harald S. Mjønes, Samuel Geiseler, Cecilie Morland
Abstract
The African naked mole rat (NMR) is an extremely long-lived species compared to its body size and can reach above 30 years of age. The NMR show unique adaptations to resist damage to the brain. They can survive up to 20 minutes of complete anoxia [1] and express high levels of amyloid-β without developing amyloid plaques [2]. Our aim is to understand if altered lipid metabolism through regulation of lipid droplets (LDs) in brain cells is one of the NMRs intrinsic adaptations, giving them their long-lived phenotype and resistance to neurological damage. Immunohistochemistry was performed on brain slices from young and aged NMRs (4 years/13 years) and mice with respective ages (24 weeks/1 year). Neutral lipids were stained with BODIPY, LDs were analyzed inside microglia and neurons in the CA1 and CA3 areas of the hippocampus. To investigate other adaptations that might benefit neuronal health in the NMR brain, capillary density was measured in the subgranular zone of the hippocampus and neurogenesis was measured in the hilus of the hippocampus and somatosensory cortex. We observe a dramatic increase in LD content in microglia of the NMR compared to mice in both hippocampal areas, but no change in LD content with increased age. Microglia in CA3 of mouse but not NMR were more activated with increased age, suggesting less inflammation in the old NMR brain. LDs were larger in mice than NMR in neurons and strikingly, capillary density was higher in the mouse hilus than NMR.