Sch 23390 hydrochloride

(−)-Nicotine hydrogen tartrate (Sigma-Aldrich), SCH 23390 hydrochloride (Tocris bioscience), and A77636 hydrochloride (Tocris bioscience) were dissolved in sterile saline (0.9% sodium chloride). SCH 23390 and A77636 were administered subcutaneously (SC) in a volume of 1 ml/kg body weight. Nicotine was dissolved in sterile saline, and the rats self-administered 0.03 or 0.06 mg/kg/inf of nicotine in a volume of 0.1 ml/inf. Nicotine doses are expressed as base, and SCH 23390 and A77636 doses are expressed as salt. The treatment schedule was the same in experiments 1–3. Both SCH 23390 and A77636 were administered (SC) 15 min before nicotine self-administration, food responding, or the small open field test. It was also determined if SCH 23390 affected nicotine and food intake and locomotor activity 24 h after treatment and if A77636 affected these parameters 24 and 48 h after treatment. The doses of SCH 23390 and A77636 were based on previous studies in rats^{18 (link),61 (link)}. SCH 23390 (0, 0.003, 0.01, and 0.03 mg/kg), and A77636 (0, 0.1, and 0.3 mg/kg) were administered according to a Latin square design. The highest dose of A77636, 1 mg/kg, was not included in the Latin square design and was administered last. There was at least 48 h between injections with SCH 23390 and 72 h between injections with A77636^{61 (link)}.

8-(4-chlorophenylthio) adenosine-3’,5’-cyclic monophosphate (8-CPT-cAMP) was purchased from BIOLOG Life Science Institute. The inhibitors 9-(tetrahydro-2-furanyl)-9H-purin-6-amine (SQ22536), 1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butadiene (U0126), N-[2-[[3-(4-bromophenyl)-2-propenyl-]amino]ethyl]-5-isoquinolinesulfonamide dihydrochloride (H-89), and α-[amino[(4-aminophenyl)thio]methylene]-2-(trifluoromethyl)benzeneacetonitrile (SL327), and D1 receptor ligands SKF81297 hydrobromide and SCH-23390 hydrochloride were purchased from Tocris. Reserpine and phorbol 12-myristate 13-acetate (PMA) were obtained from Sigma. Drug stocks were prepared at 50 or 100 mM in DMSO, followed by dilution in culture media to final concentrations of 100 μM 8-CPT-cAMP, 10 μM Reserpine, 10 μM U0126, 30 µM H89, 1 mM SQ22536, 10 µM SCH-23390, 10 µM SKF 81297, and 100 nM PMA.