20 mg p.o

Synaptosomes were prepared from rat striatum for the DAT assays, whereas synaptosomes were prepared from whole brain minus striatum and cerebellum for the NET and SERT assays. For release assay procedures, 9 nM [3H]1-methyl-4-phenylpyridinium ([3H]MPP+) was used as the radiolabeled substrate for DAT and NET, while 5 nM [3H]serotonin was used as a substrate for SERT. All buffers used in the release assay methods contained 1 μM reserpine to block vesicular uptake of substrates. The selectivity of release assays was optimized for a single transporter by including unlabeled blockers to prevent the uptake of [3H]MPP+ or [3H]serotonin by competing transporters. Synaptosomes were preloaded with radiolabeled substrate in Krebs-phosphate buffer for 1 h (steady state). Release assays were initiated by adding 850 μl of preloaded synaptosomes to 150 μl of test drug (5-(2-Aminopropyl)indole); incubations were allowed to proceed for 30 min for DAT and NET assays, or 5 min for SERT assays. Release was terminated by vacuum filtration and retained radioactivity was quantified by liquid scintillation counting.