Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2554516 | Life Sciences | 2006 | 8 Pages |
Abstract
In vitro binding of the iodinated imidazopyridine, Nâ²,Nâ²-dimethyl-6-methyl-(4â²-[123I]iodophenyl)imidazo[1,2-a]pyridine-3-acetamide [123I]IZOL to benzodiazepine binding sites on brain cortex, adrenal and kidney membranes is reported. Saturation experiments showed that [123I]IZOL, bound to a single class of binding site (nH = 0.99) on adrenal and kidney mitochondrial membranes with a moderate affinity (Kd = 30 nM). The density of binding sites was 22 ± 6 and 1.2 ± 0.4 pmol/mg protein on adrenal and kidney membranes, respectively. No specific binding was observed in mitochondrial-synaptosomal membranes of brain cortex. In biodistribution studies in rats, the highest uptake of [123I]IZOL was found 30 min post injection in adrenals (7.5% ID/g), followed by heart, kidney, lung (1% ID/g) and brain (0.12% ID/g), consistent with the distribution of peripheral benzodiazepine binding sites. Pre-administration of unlabelled IZOL and the specific PBBS drugs, PK 11195 and Ro 5-4864 significantly reduced the uptake of [123I]IZOL by 30% (p < 0.05) in olfactory bulbs and by 51-86% (p < 0.01) in kidney, lungs, heart and adrenals, while it increased by 30% to 50% (p < 0.01) in the rest of the brain and the blood. Diazepam, a mixed CBR-PBBS drug, inhibited the uptake in kidney, lungs, heart, adrenals and olfactory bulbs by 32% to 44% (p < 0.01) but with no effect on brain uptake and in blood concentration. Flumazenil, a central benzodiazepine drug and haloperidol (dopamine antagonist/sigma receptor drug) displayed no effect in [123I]IZOL in peripheral organs and in the brain. [123I]IZOL may deserve further development for imaging selectively peripheral benzodiazepine binding sites.
Keywords
Related Topics
Health Sciences
Medicine and Dentistry
Cardiology and Cardiovascular Medicine
Authors
Filomena Mattner, Karine Mardon, Christian Loc'h, Andrew Katsifis,