2.4. Radioligand Binding Assays

A screening at 29 receptor and transporter binding sites was performed by the NIMH Psychoactive Drug Screening Program (NIMH PDSP). Most of these screenings were performed with cloned human receptors; exceptions are listed in Table 2. Test compounds were dissolved in DMSO and were tested at 10 μM in competition assays against radioactive probe compounds. Sites exhibiting > 50% inhibition at 10 μM were tested in secondary assays at the identified receptor or transporter using 12 concentrations of the drug (0.1 nM – 10 μM), measured in triplicate, to generate competition binding isotherms. K_i values were obtained from nonlinear regression of these binding isotherms from best-fit IC₅₀ values using the Cheng-Prusoff equation (Cheng and Prusoff 1973). The radioligands used were as follows: [³H]8-OH-DPAT (5-HT_1A), [³H]{"type":"entrez-nucleotide","attrs":{"text":"GR125743","term_id":"238374404","term_text":"GR125743"}}GR125743 (5-HT_1B/1D), [³H]ketanserin (5-HT_2A), [³H]LSD (5-HT_2B/5A/6/7), [³H]mesulergine (5-HT_2C), [³H]citalopram (serotonin transporter), [³H]prazosin (α_1A/1B/1D), [³H]rauwolscine (α_2A/2B/2C), [¹²⁵I]pindolol (β₁), [³H]{"type":"entrez-protein","attrs":{"text":"CGP12177","term_id":"877152897","term_text":"CGP12177"}}CGP12177 (β₂, β₃), [³H]nisoxetine (norepinephrine transporter), [³H]SCH23390 (D₁, D₅), [³H]N-methylspiperone (D_2/3/4), [³H]WIN35428 (dopamine transporter), [³H](+)-pentazocine (σ₁), and [³H]DTG (σ₂). For more information, see: Besnard et al. (2012). The experimental protocols are available from the NIMH PDSP website (Roth 2013).

Summary of radioligand binding data for the 2-aminoindan analogues