A novel heterocyclic compound targeting the dopamine transporter improves performance in the radial arm maze and modulates dopamine receptors D1-D3

A series of compounds targeting the dopamine transporter (DAT) haS been shown to improve memory performance most probably by re-uptake inhibition. Although specific DAT inhibitors are available, there is limited information about specificity, mechanism and in particular the effect on dopamine receptors. It was therefore the aim of the study to test the DAT inhibitor 4-(diphenyl-methanesulfinylmethyl)-2-methyl-thiazole (code: CE-111), synthetized in our laboratory for the specificity to target DAT, for the effects upon spatial memory and for induced dopamine receptor modulation. Re-uptake inhibition was tested for DAT (IC₅₀ = 3.2 μM), serotonin transporter, SERT (IC₅₀ = 272291 μM) and noradrenaline transporter, NET (IC₅₀ = 174 μM). Spatial memory was studied in the radial arm maze (RAM) in male Sprague-Dawley rats that were intraperitoneally injected with CE-111 (1 or 10 mg/kg body weight). Performance in the RAM was improved using 1 and 10 mg/kg body weight of CE-111. Training and treatment effects on presynaptic, postsynaptic and extrasynaptic D1 and D2- receptors and dopamine receptor containing complexes as well as on activated DAT were observed. CE-111 was crossing the blood-brain barrier comparable to modafinil and was identified as effective to improve memory performance in the RAM. Dopamine re-uptake inhibition along with modulations in dopamine receptors are proposed as potential underlying mechanisms.