Enhanced learning and memory of normal young rats by repeated oral administration of Krill Phosphatidylserine.

Objective: Phosphatidylserine, a major acidic phospholipid in the brain, has been studied extensively in regard to its actions on brain functions. The present study examined the effects of Krill phosphatidylserine (Krill-PS) on the learning and memory function and the neural activity in the normal young rats.

Methods: The rats were administered saline or Krill-PS (Krill-PS 50, 100 mg/kg, per oral) daily for 30 days. The cognitive improvement effect of Krill-PS on the normal young rats was investigated by assessing the Morris water maze (MWM) test and by insulin-like growth factor (IGF) and brain-derived neurotrophic factor (BDNF) immunohistochemistry. A positron emission tomography (PET) scan was also performed.

Results: Treatment with Krill-PS (100 mg/kg) produced a significant improvement of the escape latency to find the platform in the MWM at the 3rd day compared to that of the normal group. In the retention test, the Krill-PS100 group showed markedly increased time spent, distance, and crossing number around the platform compared to that of the normal group. Consistent with the behavioral data, the Krill-PS 100 group was significantly enhanced the BDNF and IGF immuno-positive neurons in the hippocampal CA1. In the PET analysis, the glucose uptake of the Krill-PS-treated groups was increased in the frontal lobe and hippocampus. These results suggest that repeated Krill-PS treatment may be useful for improving the cognitive function via regulation of neuronal growth factor activity.