Objective:To investigate whether the extract from the nacreous layer of pearl oysters (nacre extract) improves impairments in memory caused by scopolamine administration in rodents.Methods:Nacre extract was prepared from the inner shell layer of pearl oyster.Effects of nacre extract on scopolamine-induced memory impairment were estimated using novelobject recognition test,Y-maze test,and Bes maze test.Effect of nacre extract on mRNA expressions which are genes associated with memory in the hippocampus was investigated using semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) analysis.Results:Administration of nacre extract led to the protection against scopolamine-induced impairments in object recognition,short-term memory,and spatial memory.Treatment with nacre extract reversed the mRNA expression of brain-derived neurotrophic factor (BDNF) and Homer protein homolog 1 (Homer-1a) in the hippocampus,which decreased with the treatment of scopolamine.Conclusions:These results suggest that nacre extract has attenuating effects on memory impairments induced by scopolamine through the increase in mRNA expression of BDNF and Homer-1a.