Ginkgo Biloba Extract (EGb 761) Independently Improves Changes in Passive Avoidance Learning and Brain Membrane Fluidity in the Aging Mouse

Abstract

Decreases in cell membrane fluidity may be a major mechanism of age-related functional decline. A prime cause for the decline of membrane fluidity may be the presence of free radicals. Gingko biloba extract EGb 761 protects neuronal cell membranes from free radical damage in vitro. Further, EGb 761 has repeatedly been shown to improve cognitive functions in man and in laboratory animals. To test if there is a link between these two actions we assessed the effects of EGb 761 on passive avoidance learning and on neuronal membrane fluidity in vivo in young (three-month-old), middle-aged (12-month-old) and aged (22 to 24-month-old) female NMRI mice. The animals were treated daily with 100 mg/kg EGb 761 for three weeks. There was a significant improvement in short-term memory, measured by the avoidance latency 60 seconds after the aversive stimulus (p < 0.0311), and of membrane fluidity (p < 0.01) in the aged animals, but no improvement in long-term memory as measured by the avoidance latency 24 hours after shock. However, no significant correlation between membrane fluidity and short-term memory performance was found. Taken together, these results indicate that EGb 761 independently improves changes in passive avoidance learning and brain membrane fluidity.

The Effects of BR003 on Memory and Cell Proliferation in the Dentate Gyrus of Rat Hippocampus

“…24) Ginkgo Folium has reproducible effects on cognitive functions in patients with Alzheimer's disease and independently improves changes in passive avoidance learning and brain membrane fluidity. 25,26) Ginseng Radix restores learning and memory deficits. 27) Poria promotes long-term potentiation in the hippocampus.…”

The neuroprotective potential of flavonoids: a multiplicity of effects

“…Ginkgo Biloba has a prominent effect on brain activity and short-term memory in animals and humans suffering from cognitive impairment [43, 93,131] and promotes spatial learning in aged rodents [40,114,126,131]. Furthermore, Ginkgo Biloba promotes inhibitory avoidance conditioning in rats with high-dose intake leading to short-term, but not long-term, passive avoidance learning in senescent mice [114,118].…”

“…Ginkgo Biloba has a prominent effect on brain activity and short-term memory in animals and humans suffering from cognitive impairment [43, 93,131] and promotes spatial learning in aged rodents [40,114,126,131]. Furthermore, Ginkgo Biloba promotes inhibitory avoidance conditioning in rats with high-dose intake leading to short-term, but not long-term, passive avoidance learning in senescent mice [114,118]. However, the pharmacological mechanisms by which Ginkgo Biloba promotes cognitive effects are unclear, with its ability to elicit a reduction in levels of ROS [72,73], to increase cerebral blood flow [33], to modulate brain fluidity [114], to interact with the muscarinic cholinergic system [18] and to protect the striatal dopaminergic system [81] all being suggested as possible mechanisms of brain action.…”

The impact of flavonoids on spatial memory in rodents: from behaviour to underlying hippocampal mechanisms

“…Here, it is likely that the improved information recall in aged animals after 24 h is related to CA1 region synaptic plasticity as CA1 spatial representations are known to be less stable in aged animals compared to young ones [18,31,52,208]. In terms of the underlying pharmacological mechanisms, GBE has been reported to reduce levels of reactive oxygen species (ROS) [155,156], to increase cerebral blood flow [63], to modulate brain fluidity [204], to interact with the muscarinin cholinergic system [36] and to protect the striatal dopaminergic system [161]. Whatever the mechanism, it is likely that GBE bioactives are acting at various levels to enhance the memory system in order that it may transmit information more efficiently through hippocampal circuits.…”