title: Chronic administration of a Ginkgo biloba leaf extract facilitates acquisition but not performance of a working memory task.
abstract: BACKGROUND
  Ginkgo biloba leaf extracts have been shown to improve learning and memory when administered chronically prior to the learning phase. However, the influence of Ginkgo on learning without prior chronic treatment and on memory per se (i.e., post-training administration) is less clear. Thus, experiment 1 investigated the influence of Ginkgo on acquisition, and experiment 2 examined the acute and chronic effects of Ginkgo on memory in rats using a food-reinforced two-component double Y-maze task.
  
  
  METHODS
  In experiment 1, 17 rats were treated daily with a standardized G. biloba extract (13.75 mg/kg, i.p.) or vehicle 30 min prior to daily maze training for 14 days. In experiment 2, 12 rats received 24 training trials daily, then received Ginkgo (0, 0.25, 2.5, 13.75, or 25 mg/kg, i.p.) 30 min prior to each test session. Subsequently, the same rats received daily injections of either Ginkgo (13.75 mg/kg, i.p.) or its vehicle. Memory was tested after 10 and 20 days of drug treatment, once under the influence of the drug and once in a drug-free state.
  
  
  RESULTS
  In experiment 1, Ginkgo-treated rats reached the training criteria significantly faster and made fewer errors. In experiment 2, post-training Ginkgo administration did not enhance memory.
  
  
  CONCLUSIONS
  Taken together, results demonstrate that repeated daily pre-session Ginkgo injection subtly facilitates acquisition of a spatial working memory task, but neither acute nor chronic post-training exposure enhances spatial working memory. We conclude that ongoing Ginkgo administration does not offer any continued beneficial effects in an already-learned working memory task.
authors.affiliation: Department of Psychology, Wilfrid Laurier University, 75 University Ave West, Waterloo, ON N2L3C5, Canada.
authors.forename: Elham
authors.initials: E
authors.lastname: Satvat
authors.forename: Paul E
authors.initials: PE
authors.lastname: Mallet
mesh_terms: D000818:Animals; D003627:Data Interpretation, Statistical; D004193:Discrimination Learning / Q000187:drug effects; D004192:Discrimination, Psychological / Q000187:drug effects; D020441:Ginkgo biloba / Q000737:chemistry*; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D008570:Memory, Short-Term / Q000187:drug effects*; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D011597:Psychomotor Performance / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D000096983:Ginkgo Extract
chemical_list: D010936:Plant Extracts; C063170:Ginkgo biloba extract; D000096983:Ginkgo Extract