Male rats of a Wistar-derived strain (Harlan, Zeist, The Netherlands) weighing 175-225 g were used. ISOCLOZAPINE (0.3, 1, 3, 10, 30 mkM/kg) were administered Subcutaneously 30 min before the administration of 1 mg/kg apomorphine. After administration of apomorphine, rats were transferred to an automated activity monitoring system (Automex II, Columbus, OH) and activity was measured for 30 min. Experiments were done in parallel on four different animals and per session three experimental groups and one salinetreated group were studied.

Incubations were carried out in 50 mM Tris-HCl buffer, pH 7.35, containing 120 mM NaCl, 5 mM MgCl2, and 1 mM EDTA. The assay contained in a total volume of 1 mL: 0.15 nM [3H]spiperone, specific radioactivity 3.6 TBq/mmol, and membranes of A9L cells expressing the human D2 dopamine receptor (40-60 íg of protein/assay). Incubations were run for 15 min at 37 °C and terminated by rapid filtration on Whatman GF/B filters and 3 washes with ice-cold 50 mM Tris-HCl buffer, pH 7.35 (without salts and EDTA). Nonspecific binding was determined in the presence of 1 mM (+)-butaclamol.