title: Three-dimensional comparison of peripheral benzodiazepine binding and histological findings in rat brain tumor.
abstract: Experiments were undertaken to determine the in vivo utility of the mixed benzodiazepine ligand [3H]flunitrazepam and the selective peripheral benzodiazepine ligand [3H]PK 11195 [1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinoline carboxamide] to outline the borders of rat C6 glial tumors in three dimensions. Intravenous injection of [3H]flunitrazepam resulted in a tumor/cortex ratio of radioactive densities between 2.7 and 1.5 within the first 60 minutes after injection. [3H]PK 11195 demonstrated a higher tumor/cortex ratio (5.3) than [3H]flunitrazepam. For three-dimensional studies, images were generated from thionin-stained histological sections and autoradiograms. The mixed type benzodiazepine ligand [3H]flunitrazepam was superior in showing some of the normal anatomical structures surrounding the tumor, whereas [3H]PK 11195, a specific peripheral ligand, demonstrated higher tumor/brain contrast and superior topographical correlation between histological and autoradiographic images. Implications of peripheral benzodiazepine receptor ligands for positron emission tomography are discussed.
authors.affiliation: Division of Neurosurgery, Jonsson Cancer Center, Los Angeles, California.
authors.forename: K
authors.initials: K
authors.lastname: Ikezaki
authors.forename: K L
authors.initials: KL
authors.lastname: Black
authors.forename: E M
authors.initials: EM
authors.lastname: Santori
authors.forename: M L
authors.initials: ML
authors.lastname: Smith
authors.forename: D P
authors.initials: DP
authors.lastname: Becker
authors.forename: B A
authors.initials: BA
authors.lastname: Payne
authors.forename: A W
authors.initials: AW
authors.lastname: Toga
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism; D005260:Female; D005445:Flunitrazepam / Q000378:metabolism*; D005910:Glioma / Q000000981:diagnostic imaging* / Q000378:metabolism; D007546:Isoquinolines / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011963:Receptors, GABA-A / Q000378:metabolism*; D014055:Tomography, Emission-Computed / Q000379:methods*
chemical_list: D007546:Isoquinolines; D011963:Receptors, GABA-A; D005445:Flunitrazepam; C037850:PK 11195