Dopamine is necessary for the aversive olfactory associative memory formation in Drosophila, but its effect on other stages of memory is not known. Herein, we studied the effect of enhanced dopaminergic signaling on aversive olfactory memory retention in flies. We used L-3,4-dihydroxyphenylalanine (L-DOPA) to elevate dopamine levels: L-DOPA-treated flies exhibited a normal learning performance, but a decrease in I-h memory. Dopamine transporter (DAT) mutant flies or flies treated with the DAT inhibitor desipramine exhibited poor memory retention, Flies subjected to heat stress after training exhibited a decrease in memory. Memory was restored by blocking dopaminergic neuronal output during heat stress, suggesting that dopamine is involved in heat stress-induced memory impairment in flies. Taken together, our findings suggest that increased dopaminergic signaling impairs aversive olfactory memory retention in flies. (c) 2008 Elsevier Inc. All rights reserved.