Inosine,a natural derivative of adenosine,has been known to provide powerful protection for many kinds of cells and tissues against various insults both in vitro and in vivo.Recently,it was shown that exogenous inosine could stimulate collateral sprouting of intact neurons in the contralateral cerebral cortex of rats with corticospinal tract hemisection or cerebral hemisphere stroke and then improve their behavioral performance,which suggests that inosine treatment may represent a novel approach to improving function after stroke or CNS trauma.To determine whether inosine would influence the cognition of subjects as adenosine does,we investigated the potential effect of inosine on the spatial learning and memory of intact mice using the Morris water maze.Sixteen adult male C57 mice weighing (25+2) g were used in the present study.