Preferential enhancement of working memory in mice lacking adenosine A(2A) receptors

There is evidence that adenosine acting at A(2A) receptors (A(2A)R) can influence striatal plasticity and cognitive functions. We examined spatial working memory in wild-type (WT) and A(2A) receptor knock-out (KO) mice using two assessments: the eight arm radial maze and a repeated trial Morris water maze (MWM) paradigm. Compared to WT littermates, A(2A)R KO mice displayed enhanced working memory as evidenced by a decrease in escape latency in trial 2 compared to trial 1 in the repeated trial MWM, and by a reduction in working memory errors in the radial arm maze. Both MWM and radial maze results indicated that this enhancement of working memory in A(2A)R KO mice was selective for this specific short-term memory. The decrease in escape latency in MWM was detected with an inter-trial interval of 15 s but not with intervals of 10 or 60 min. In the radial maze, spatial reference memory and memory retention after prolonged training (15 days but not 6 days) were not affected by the A(2A)R KO. These results demonstrate preferential improvement in spatial working memory by genetic inactivation of the A(2A)R and support a modulatory role of the A(2A)R in spatial working memory in mice.