Distribution of dopamine D1 and D2 receptors in rabbit cortical areas, hippocampus, and neostriatum in relation to dopamine contents

✍ Scribed by Karen M. Dewar; Tomás A. Reader

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 922 KB
• Volume: 4
• Category: Article
• ISSN: 0887-4476
• DOI: 10.1002/syn.890040413

✦ Synopsis

The densities of dopamine D1 and D, receptors were measured by using L3H]SCH23390 and [3Hlraclopride, respectively, in the rabbit cingulate, visual, sensorimotor, and entorhinal-piriform cortical areas; the dorsal and ventral hippocampus; and the putamen as well as the medial and lateral caudate. Endogenous dopamine (DA) and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC), 4-hydroxy-3-methoxyphenylacetic acid (HVA), and 3-methoxytyramine (3-MT) were assayed by HPLC with electrochemical detection. The distributions of [3HlSCH23390 and [3Hlraclopride binding were heterogenous with the greatest densities in the neostriatum. The concentrations of DA and its metabolites were also highest in this structure. Regions with low DA content, i.e., cortex and hippocampus, had lower densities of [3HlSCH23390 and 13Hlraclopride binding. Furthermore, these sites were differentially localized within the various regions and there were substantially more D, than D, receptors. The functional significance and heterogeneities in the distribution of D, and D2 receptors are discussed in relation to the dopaminergc innervation and the turnover estimated by the ratios between endogenous DA and its metabolites. SCH23390, Caudate, Cerebral cortex, Raclopride, Putamen Ci/mmol) were purchased from Dupont (Boston, MA), the agonist (? Ism38393 HCl from Research Biochemicals Inc. (Natick, MA), sodium octyl sulfate from Eastman Kodak (Rochester, NY), and the scintillation fluid BetamaxR from ICN Biomedicals Inc. (Irvine, CAI. The following compounds were from Sigma Chemical Co. (St. Louis, MO): (2)sulpiride base, Tris[hydroxymethyll-aminomethane, ascorbate oxidase (E.C. 1.10.3.3.1, 4-hydroxy-3-methoxyphenylglycol (MHPG) piperazin-tionally identified areas oft R e rabbit CNS by using the