Flies were constructed to knockdown the expression of DmSLC22A using 238Y-gal4
(A–C) or overexpress the transporter (D–F). These flies and their control groups were fed the precursors to the neurotransmitters acetylcholine (choline) (A, D), dopamine (L-dopa) (B, E), and histamine (histidine) (C, F). Memory was tested at either 3 or 6h after conditioning. (A) Choline supplementation significantly improved memory in both control flies and knockdown flies, but did not take the performance of the knockdown flies to a level that exceeded the non-supplemented control group. In contrast, both L-dopa and histidine supplementation impaired the performance of both control and knockdown flies (B, C). (D) Overexpression of DmSLC22A impaired memory, and choline supplementation partially rescued this impaired performance. (E, F) L-dopa and histidine supplementation further impaired the performance of DmSLC22A overexpressing flies. Statistics: Results are plotted as means ± SEM with * P<0.05, ** P<0.01, *** P<0.001. One-way ANOVA analysis with Tukey’s post hoc comparison. N=12 for all groups.