Dopamine and mushroom bodies in Drosophila: Experience-dependent and -independent aspects of sexual behavior

Depletion of dopamine in Drosophila melanogaster adult males, accomplished through systemic introduction of the tyrosine hydroxylase inhibitor S-iodo- tyrosine, severely impaired the ability of these flies to modify their cour tship responses to immature males. Mature males, when first exposed to imma ture males, will perform courtship rituals; the intensity and duration of t his behavior rapidly diminshes with time. Dopamine is also required for nor mal female sexual receptivity; dopamine-depleted females show increased lat ency to copulation. One kilobase of 5' upstream information from the Drosop hila tyrosine hydroxylase (DTH) gene, when fused to the Escherichia coli be ta-galactosidase reporter and transduced into the genome of Drosophila mela nogaster, is capable of directing expression of the reporter gene in the mu shroom bodies, which are believed to mediate learning acquisition and memor y retention Ln flies. Ablation of mushroom bodies by treatment of newly hat ched larva with hydroxyurea resulted in the inability of treated mature adu lt males to cease courtship when placed with untreated immature males. Howe ver, functional mushroom bodies were not required for the dopaminergic modu lation of an innate behavior, female sexual receptivity, These data suggest that dopamine acts as a signaling molecule within the mushroom bodies to m ediate a simple form of learning.