Ginsenoside Rb1 and Rg1 improve spatial learning and increase hippocampal synaptophysin level in mice

Abstract

We investigated the cognition enhancing effects of ginsenoside Rb1 and Rg1. Mice were trained in a Morris water maze following injection (i.p.) of Rb1 (1 mg/kg) or Rg1 (1 mg/kg) for 4 days. Both Rb1‐ and Rg1‐injected mice showed enhanced spatial learning compared to control animals. The hippocampus, but not the frontal cortex, of treated mice contained higher density of a synaptic marker protein, synaptophysin, compared to control mice. Electrophysiological recordings in hippocampal slices revealed that Rb1 or Rg1 injection did not change the magnitude of paired‐pulse facilitation or long‐term potentiation. Our results suggest that Rb1 and Rg1 enhance spatial learning ability by increasing hippocampal synaptic density without changing plasticity of individual synapses. J. Neurosci. Res. 63:509–515, 2001.