Rats was treated i.v. with [11C]4 (LP-20) (16–18 MBq/200 lL, 0.07–0.11 nmol) as a single dose.

Four rat brains were quickly removed and frozen on powdered dry ice. Sagittal sections (20 mkM) of the brain were cut using a cryostat microtome (HM560; Carl Zeiss, Germany) and thaw mounted on glass slides, which were then dried and stored at -80 C until use. Brain sections were preincubated (3 x 5 min) in Tris–HCl (50 mM, pH 7.4) at room temperature. After preincubation, these sections were incubated for 30 min at room temperature in fresh buffer with [11C]4 (LP-20) (1 nM, 37 MBq/200 mL). Unlabeled LP-20 (1 mkM) was used to elucidate the specific binding of [11C]4 (LP-20) for 5-HT7. After incubation, the sections were washed (3 x 5 min) with cold buffer, dipped in cold distilled water, and dried with cold air. These sections were placed in contact with imaging plates (BAS-MS2025; FUJIFILM, Tokyo, Japan). Autoradiograms were obtained and photo-stimulated luminescence values (PSL) in the regions of interest (ROIs) were measured using a Bio- Imaging Analyzer System (BAS5000, FUJIFILM)