title: Mapping of human cerebral sigma1 receptors using positron emission tomography and [11C]SA4503.
abstract: The objective of this study was to establish the kinetic analysis for mapping sigma(1) receptors (sigma1Rs) in the human brain by positron emission tomography (PET) with [(11)C]SA4503. The sigma1Rs are considered to be involved in various neurological and psychiatric diseases. [(11)C]SA4503 is a recently developed radioligand with high and selective affinity for sigma1Rs, and we have first applied it to clinical studies. Nine healthy male subjects each underwent a dynamic 90-min PET scan after injection of [(11)C]SA4503. In addition to the baseline measurement, three of the nine subjects underwent a second [(11)C]SA4503-PET after partial blockade of sigma1Rs by oral administration of haloperidol, a sigma receptor antagonist. Full kinetic analysis using two times nonlinear estimations was applied for fitting a two-tissue three-compartment model to determine the binding potential (BP) and total distribution volume (tDV) of [(11)C]SA4503. Graphical analysis with a Logan plot was also applied for estimations of tDV. The regional distribution patterns of BP and tDV in 11 regions were compatible with those of previously reported sigma1Rs in vitro. The reduced binding sites of sigma1Rs by haloperidol were appropriately evaluated. The tDVs derived from the two methods matched each other well. The Logan plot offered images of the tDV, which reflected sigma1R densities, and the tDV in the images decreased after haloperidol loading. Moreover, comparison of BPs calculated with and without metabolite correction for plasma input function indicated that the metabolite correction could be omitted. We concluded that this method enables the quantitative analysis of sigma1Rs in the human brain.
authors.affiliation: Graduate School of Information Science, Nara Institute of Science and Technology, Japan.
authors.forename: Muneyuki
authors.initials: M
authors.lastname: Sakata
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kimura
authors.forename: Mika
authors.initials: M
authors.lastname: Naganawa
authors.forename: Keiichi
authors.initials: K
authors.lastname: Oda
authors.forename: Kenji
authors.initials: K
authors.lastname: Ishii
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Chihara
authors.forename: Kiichi
authors.initials: K
authors.lastname: Ishiwata
mesh_terms: D000328:Adult; D001711:Biotransformation; D001921:Brain / Q000000981:diagnostic imaging*; D001923:Brain Chemistry / Q000187:drug effects; D001931:Brain Mapping; D002851:Chromatography, High Pressure Liquid; D003627:Data Interpretation, Statistical; D018492:Dopamine Antagonists / Q000494:pharmacology; D006220:Haloperidol / Q000494:pharmacology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D017711:Nonlinear Dynamics; D010879:Piperazines / Q000493:pharmacokinetics; D049268:Positron-Emission Tomography; D011869:Radioligand Assay; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D017480:Receptors, sigma / Q000378:metabolism*; D000097605:Sigma-1 Receptor
chemical_list: D018492:Dopamine Antagonists; D006220:Haloperidol; D010879:Piperazines; D019275:Radiopharmaceuticals; D017480:Receptors, sigma; D000097605:Sigma-1 Receptor; C101789:SA 4503