Clozapine

The following drugs were used: L-DOPA (50 mg/kg; Sigma-Aldrich, St Louis, MO, USA), methamphetamine (METH; 1 mg/kg; Dainippon Sumitomo Pharma, Osaka, Japan), haloperidol (1 mg/kg; Sigma-Aldrich), clozapine (5 and 10 mg/kg; Toronto Research Chemicals, Toronto, ON, Canada), 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT; 1 mg/kg; Sigma-Aldrich), ritanserin (3 mg/kg; Sigma-Aldrich), prazosin hydrochloride (1 mg/kg; Sigma-Aldrich), pyrilamine maleate salt (20 mg/kg; Sigma-Aldrich), clonidine (0.1 mg/kg; Sigma-Aldrich), oxotremorine-M (0.1 mg/kg; Sigma-Aldrich), donepezil hydrochloride (3 mg/kg, Tokyo Chemical Industry, Tokyo, Japan), and ziprasidone hydrochloride monohydrate (3 mg/kg; Toronto Research Chemicals). L-DOPA was prepared as 1.4 mg/ml in a 2.5 mg/ml ascorbic acid solution dissolved in saline. Methamphetamine, 8-OH-DPAT, pyrilamine, clonidine, and oxotremorine-M were dissolved in saline. haloperidol and ritanserin were dissolved in 0.8% lactic acid. clozapine was dissolved in a minimum amount of 0.1 N HCl and diluted to the required doses with saline. Prazosin and donepezil were dissolved in water. Ziprasidone was prepared as a suspension in aqueous Tween-80 (1% v/v in distilled water). L-DOPA was administered i.p. in a volume of 35 ml/kg, and the other drugs were administered s.c. in a volume of 10 ml/kg.