Anti-amnestic properties of Ginkgo biloba extract on impaired memory function induced by aluminum in rats

Abstract

Aluminum is the most widely used non-ferrous metal. However, recently it is reported to be a neurotoxic agent that could induce biochemical defects in brain by affecting levels of neurotransmitters and generating reactive oxygen species resulting in oxidative stress. This study aimed at evaluating neuroprotective effect of Ginkgo biloba extract(2) (GBE) (200 mg/kg for 28 days) in antagonizing aluminum-induced neurotoxicity through investigating certain parameters such as serum aluminum level, brain aluminum content, brain regional distribution of aluminum, brain oxidative stress biomarkers' content, and brain acetylcholinesterase(3) (AChE) activity. Passive avoidance paradigm was used to assess memory retrieval of rats. Rats' activities were studied using open field test. Results showed that administration of aluminum (10 mg/kg for 28 days) impaired rats' memory retrieval associated with marked elevation of aluminum brain content, serum aluminum level and AChE activity. In addition, aluminum treatment induced significant elevation in its brain content in all tested regions. GBE treatment attenuated neurotoxic effects of aluminum as evidenced by improving rats' performance in passive avoidance and lowering brain AChE activity. Moreover, marked elevation in brain content of oxidized glutathione(4) (GSSG) and malonedialdehyde(5) (MDA) as well as depletion of reduced glutathione(6) (GSH) demonstrated following aluminum administration were reversed reaching normal levels after GBE treatment. Open field test, demonstrated no changes in latency period, number of ambulation, rearing, and grooming following aluminum or other treatments. Therefore, GBE may be a promising therapy ameliorating neurotoxicity of aluminum as an environmental toxic agent.

Keywords: Acetylcholinesterase; Aluminum; Ginkgo biloba; Glutathione; Neurotoxicity; Passive avoidance.