New Insights on the Effects of Krill Oil Supplementation, a High-Fat Diet, and Aging on Hippocampal-Dependent Memory, Neuroinflammation, Synaptic Density, and Neurogenesis

Krill oil (KO) has been described as having the potential to ameliorate the detrimental consequences of a high-fat diet (HFD) on the aging brain, though the magnitude and mechanism of this benefit is unclear. We thus hypothesized that dietary KO supplementation could counteract the effects of cognitive aging and an HFD on spatial learning, neuroinflammation, neurogenesis, and synaptic density in the cortex and hippocampus of aged rats. Sixteen-month-old Sprague Dawley rats were fed for 12 weeks while being divided into four groups: control (CON); control with KO supplementation (CONKO); high-fat diet (HF); and high-fat diet with KO supplementation (HFKO). We measured food consumption, body mass, spatial memory (Morris water maze), microglia, neurogenesis, cytokine concentrations, and synaptic markers (post-synaptic density-95 and synaptophysin). Predictably, an HFD did induce significant differences in body weights, with the high-fat groups gaining more weight than the low-fat controls. However, KO supplementation did not produce significant changes in the other quantified parameters. Our results demonstrate that the dietary KO dose provided in the current study does not benefit hippocampal or cortical functions in an aging model. Our results provide a benchmark for future dosing protocols that may eventually prove to be beneficial.