Red ginseng ameliorated place navigation deficits in young rats with hippocampal lesions and aged rats

Abstract

Effects of hippocampal lesions and aging on spatial learning and memory and ameliorating effects of red ginseng on learning deficits were investigated in the following two experiments: performance of young rats with selective hippocampal lesions with red ginseng by mouth (p.o.; Experiment 1) and aged rats with red ginseng (p.o.; Experiment 2) in the spatial tasks was compared with that of sham-operated or intact young rats. Each rat in these two behavioral experiments was tested with the three types of spatial-learning tasks (distance movement task, DMT; random-reward place search task, RRPST; and place-learning task, PLT) in a circular open field using intracranial self-stimulation as reward. The results in the DMT and RRPST tasks indicated that motivational and motor activity of young rats with hippocampal lesions with and without ginseng were not significantly different from that of sham-operated young rats in Experiment 1. However, young rats with hippocampal lesions displayed significant deficits in the PLT task. Treatment with red ginseng significantly ameliorated place-navigation deficits in young rats with hippocampal lesions on the PLT task. Similarly, red ginseng improved performance of aged rats on the PLT task in Experiment 2. The results, along with previous studies showing significant effects of red ginseng on the central nervous system, suggest that red ginseng ameliorates learning and memory deficits through effects on the central nervous system, partly through effects on the hippocampal formation.