0.3 mg as a single dose

The frontal cortex or hippocampal brain regions from 20-40 rats were pooled and homogenized in 4 or 8 volumes of 0.32 M sucrose for frontal cortex or hippocampus, respectively. The homogenates were centrifuged at 36000g for 10 min, and the resulting pellets were resuspended in the same volume of sucrose. All experiments were performed with triplicate determinations using the appropriate buffer to which 200-400 mkg of protein was added, giving a final volume of 1 mL. The tubes were allowed to equilibrate for 15 min at 37 C before filtering through Whatman GF/C filters using a cell harvester followed by two 5 mL washes using icecold Tris buffer. Specific binding was defined as that displaceable with 10 mkM cinanserin in both the [3H]ketanserin and [125I]DOI binding study and with 10 mkM 5-HT in the [3H]-8-OH-DPAT binding study. Filters were air-dried and placed into scintillation vials with 10 mL of Ecolite scintillation cocktail and allowed to sit overnight before counting at an efficiency of 37% for tritium and directly counted in a y counter for [125I]-labeled ligand at an efficiency of 79.4%.